laporan kelompok

Pemindahan Tanah Mekanis dan Alat alat Berat

BAB I PENDAHULUAN

1.1 Latar Belakang Seiring dengan perkembangan ilmu pengetahuan dan teknologi atau lebih dikenal dengan IPTEK, terjadi banyak perubahan terhadap perilaku manusia dan mekanisasi dalam pekerjaan. Hal tersebut dimaksudkan untuk mempermudah dan mempercepat pekerjaan manusia. Pekerjaan pekerjaan yang biasanya dilakukan oleh manusia saja kini melibatkan mesin mesin canggih buatan manusia. Perkembangan dan mekanisasi juga terjadi pada pekerjaan teknik sipil. Penggunaan alat alat berat kini mulai banyak ditemukan di tempat tempat pembangunan dan proyek proyek garapan teknik sipil, baik pembangunan jalan dan jembatan, bangunan gedung maupun bangunan air. 1.2 Maksud dan Tujuan Adapun maksud dan tujuan dari pembuatan laporan ini adalah sebagai sala satu tugas mata kuliah PTM/alat alat berat yang merupakan syarat kelulusan dan juga untuk membantu para mahasiswa teknik sipil dalam mengetahui mengenai jenis dan fungsi beberapa alat alat berat yang banyak digunakan dalam pekerjaan teknik sipil. 1.3 Metode Penulisan Metode penulisan yang digunakan adalah studi pustaka yaitu mencari materi pembahasan dari berbagai sumber pustaka yang memuat mengenai materi yang diangkat. 1.4 Sistematika Penulisan Bab I pendahuluan memuat latar belakang pembuatan makalah, maksud dan tujuan yang diharapkan dari pembuatan makalah ini, metode penulisan makalah dan sistematika dalam makalah yang dibuat. Bab II alat alat berat memuat mengenai pengertian dan jenis jenis alat berat yang akan dibahas lebih lanjut. Bab III galian dan timbunan memuat materi yang berkaitan dengan penggunaan alat alat berat dalam pekerjaan teknik sipil. Bab IV perhitungan biaya pekerjaan memuat mengenai perhitungan biaya dalam setiap pekerjaan teknik sipil. Bab V kesimpulan memuat simpulan akhir dari laporan ini.Page 1 of 111 Laporan Kelompok


BAB II ALAT ALAT BERAT 2.1 Alat Alat Berat Alat berat adalah alat alat kerja yang digunakan manusia untuk pekerjaan pekerjaan yang tidak dapat dikerjaan manusia karena kemampuan manusia yang terbatas. Penggunaan alat berat biasanya untuk pekerjaan berat dan dalam cakupan daerah yang luas dan besar.

A. Faktor yang Mempengaruhi Produktivitas Alat Untuk memperkirakan produksi alat beras secara teliti perlu dipelajari faktorfaktor yang secara langsungdapat mempengaruhi hasil kerja alat tersebut. Faktorfaktor tersebut meliputi: 1) Tahanan gali (Digging Resistance) 2) Tahanan guling atau tahanan gelinding (Rolling Resistance) 3) Tahanan kemiringan (Grade Resistance), 4) Koefisien Traksi 5) Rimpull 6) Percepatan 7) Elevasi letak proyek 8) Evisiensi Operator 9) Faktor pengembangan atau pemuaian (Swell Factor), dan 10) Berat material.

1) Tahanan Gali (Digging Resistance) Tahanan gali (Digginr Resistance, sering disingkat DR) marupakan tahanan yang dialami oleh alat gali pada waktu melakukan penggalian material, penyebab timbulnya atahanan ini adalah: a. Gesekan antara alat gali dan tanah; umumnya semakin besar kelembaban dan kekerasan butiran tanah, maka semakin besar pula gesekan alat dan tanah yang terjadi. b. Kekerasan dari material yang digali. c. Kekasaran dan ukuran butiran tanah atau material yang digali.Page 2 of 111 Laporan Kelompok


d. Adanya adhesi antara tanah dengan alat gali, dan kohesi antara butiran tanah itu sendiri. e. Berat Jenis tanah (terutama berpengaruh pada alat gali yang berfungsi sebagai alat muat, misalnya Power Shovel, Clamshell, Dragline dan sejenisnya). f. Besarnya tahanan gali (DR) tak dapat dicari angka reratanya, oleh karena itu biasanya langsung ditentukan di tempat.

2) Tahanan Guling/ Tahanan Gelinding (Rolling Resistance) Tahanan guling/ tahanan gelincir (Rolling Resistance, biasa disingkat RR) merupakan segala gaya-gaya lyar yang berlawanan arah dengan arah gerak kendaraan yang sedang berjalan di atas suatu jalur. (Lihat Gambar: 4.1) Bagian yang mengalami Rolling Resistance (RR) secara langsung adalah ban bagian luar kendaraan, tahanan guling (RR) tergantung pada banyak faktor, diantaranya yang terpenting adalah: a. Keadaan jalan (kekerasan dan kemulusan permukaan jalan); semakin keras dan mulus atau rata jalan tersebut, maka tahanan gulingnya (RR) semakin kecil. b. Keadaan ban yang bersangkutan dan permukaan jalur jalan. Jika memakai ban karet, maka yang berpengaruh adalah ukuran, tekanan, dan permukaan dari ban alat berat yang digunakan; apakah ban luar masih baru, atau sudah gundul, dan bagaimana model kembangan ban itu. Jika menggunakan Crawler yang berpenaruh adalah kondisi jalan Besarnya RR dinyatakan dalam pounds (lbs) dan Rimpull yang diperlukan untuk menggerakkan tiap gross ton berat kendaraan beserta isinya pada jalur mendatar, dan dengan kondisi jalan tertentu.

Gambar: 4.1. Arah Tahanan Gulir (RR)Page 3 of 111 Laporan Kelompok


Contoh: Jalur jalan yang dibuat dari perkerasan tanah dilewati leh truck dengan tekanan ban 35 50 lbs. Diperkirakan roda tersebut memiliki tahanan gulir (RR) sebesar 100 lbs/ ton. Jika berat kendaraan dan isinya 20 ton, hitung besarnya kekuatan tarik yang diperlukan oleh mesin itu pada roda kendaraan (Rimpul) agar kendaraan tersebut dapat bergerak. Jawab: Rimpull (RP) = Berat kendaraan x RR = 20 ton x 100 lbs/ ton = 200 lbs. Pada prakteknya menentukan RR sangat sukar dilakukan, sebab dipengaruhi oleh ukuran dan tekanan ban, serta kecepatan kendaraan. Untuk perhitungan praktis RR dapat dihitung menggunakan rumus: RR = CRR x Berat Kenderaan beroda Keterangan: RR = Tahanan Guling (lbs/ gross ton) CRR = Koefisien Tahanan Guling (lihat Tabel: 4.1) Tabel: 4.1. Angka Tahanan Gulir dinyatakan dalam persen(*) Jenis Permukaan Jalan Beton yang kasar dan kering Perkerasan tanah dn batu yang terpelihara baik Anah urug kering dengan pemadatan sederhana Tanah urug lunak dengan penetrasi sekitar 4 Tanah/ pasir lepas dan batu pecah Jalan makadam Perkerasan kayu Jalan datar tanpa perkerasan, kering Kerikil tidak dipadatkan Pasir tidak dipadatkan Tanah lumpur (*) Sumber: Prodjosumarto Rochmanhadi (1992)Page 4 of 111 Laporan Kelompok

RR (% berat kendaraan dalam Lbs) Roda karet 2% 2% 3% 8% 10% 3% 3% 5% 15% 15% Crawler 4% 5% 3% 4% 12% 12% 16%


3) Tahanan Kemiringan (Grade Resistance) Grade Resistance (GR) adalah besarnya gaya berat yang melawan atau membantu gerak kendaraan karena kemiringan jalur jalan yang dilalui. Jika jalur jalan itu naik disebut kemiringan positif, Tahanan Kemiringan atau Grade Resistance (GR) akan menalwan gerak kendaraan; tetapi sebaliknya, jika jalan itu turun disebut kemiringan negatif, tahanan kemiringan akan membantu gerak kendaraan (Gambar: 4.2).

GR Positif

GR Negatif

Gambar: 4.2. Tahanan Kemiringan (GR) Tahanan kemiringan tergantung pada dua faktor yaitu: a) Besarnya kemiringan (dinyatakan dalam %) b) Berat kendaraan itu sendiri (dinyatakan dalam Gross-ton) Biasanya tahanan kemiringan dihitung sebagai berikut: Tiap kemiringan 1% besarnya tahanan kemiringan rata-rata = 20 lbs dari besarnya kekuatan tarik mesin yang digunakan untuk menggerakkan ban yang menyentuh permukaan jalur jalan. Besarnya dihitung untuk tiap gross-ton berat kendaraan beserta isinya.

Contoh Soal: Sebuah truck beserta muatan beratnya 20 ton, truck itu bergerak pada jalur jalan dengan tahanan gulir (GR) = 100 lbs/ ton. Hitung kekuatan tarik yang diperlukan oleh mesin truck untuk menggerakkan bannya. Jawab: Kekuatan tarik (Rimpull yang menahan kemiringan)

Page 5 of 111 Laporan Kelompok


= Berat kendaraan x GR x Kemiringan. = 20 ton x 100 lbs/ton/1% x 5% = 200 lbs Untuk menahan supaya truck tidak meluncur turun akibat kemiringan, maka diperlukan kekuatan tarik yang besarnya minimum 200 lbs juga. Kekuatan tarik yang diperlukan = Rimpull yang menahan kemiringan + gaya tarik yang menahan kemiringan Kekuatan tarik yang diperlukan = 200 lbs + 200 lbs = 400 lbs.

4) Koefisien Traksi (CT) Koefisien Traksi (CT) adalah faktor yang menunjukkan berapa bagian dari seluruh kendaraan itu pada ban atau truck yang dapat dipakai untuk menarik atau mendorong. Jadi CT adalah suatu faktor dimana jumlah berat kendaraan pada ban penggerak itu harus dikalikan untuk menunjukkan Rimpull maksimum antara ban dengan jaur jalan , tepat sebelum roda itu selip. Jika terdapat geseran yang cukup antara permukaan roda dengan permukaan jalan, maka tenaga mesin tersebut data dijadikan tenaga traksi yang maksimal. (Gambar: 4.3) Rumus: Traksi Kritis = CT x Berat total kendaraan

Gambar: 4.3. Koefisien TraksiPage 6 of 111 Laporan Kelompok


Contoh : Jumlah berat kendaraan yang diterima oleh roda kendaraan = 8000 lbs. Berdasarkan percobaan percobaan diketahui bila hanya tersedia Rimpull seberat 4800 lbs saja, maka roda akan selip. Hitunglah Koefisien Traksi (CT) Jawab: Jika Rimpull yang tersedia besarnya 4800 lbs, berarti traksi kritis dari kendaraan tersebut = Rimpull.

Traksi Kritis = Rimpull = CT x Berat Total Alat (W) Traksi Kritis = CT x W 4800 lbs CT = CT x 8000 lbs = 0,60

Besarnya CT tergantung pada: 1) Kondisi ban yang meliputi: macam dan bentuk kembangannya; untuk crawlwer truck tergantung pada keadaan dan bentuk trucknya. 2) Kondisi permukaan jalan (basah, kering, keras, lunak, rata,bergelombang, dan sebagainya) 3) Bert kendaran yang diterima oleh roda. Menurut pengalaman, besarnya CT pada macam-macam keadaan jalan seperti terdapat pada Tabel 4.2. Tabel 4.2. Besar CT untuk Macam-macam Keadaan Jalur Jalan*) Macam Jalan Jalan Beton yang kasar dan kering Lempung kering Lempung basah Pasir basah yang bercampur kerikil Pasir lepas dan kering *) Sumber: Prodjosumarto Ban Karet 0,80 1,00 0,50 0,70 0,40 0,50 0,30 0,40 0,20 0,30 Crawler 0,45 0,90 0,70 0,35 0,30

Contoh 1.



Jumlah berat suatu kendaran (W) = 20 ton (40.000 lbs), seluruhnya diterima oleh roda penggerak. Kendaraan tersebut akan bergerak pada jalur jalan tanah liat yang kering. Tahanan guling (RR) 100 lbs/ ton, kemiringan jalan = 5%. Coba analisa, apakah rodak kendaraan itu tidak selip?

Jawab: Menurut Tabel: 4.2, CT untuk tanah liat kering = 0,50 Traksi Kritis (TK) = CT x W = 0,50 x 40.000 lbs = 20.000 lbs Kekuatan tarik = W x GR x kemiringan = 20 ton x 20 lbs/ ton berat kendaraan /1% kemiringan x 5% = 2000 lbs Jadi untuk menahan agar supaya truck tidak melorot turun, diperlukan gaya tarik yang besarnya minimum 2000 lbs juga. Rimpull = Kekuatan tarik + Gaya tarik truck agar tidak melorot. = 2.000 lbs + 2.000 lbs = 4.000 lbs. 20.000 lbs > 4.000 Lbs TK > Rimpull Rimpull adalah besarnya kekuatan tarik yang dapat diberikan oleh mesin atau ban penggerak yang menyentuh tanah. Traksi Kritis (TK) adalah jumlah tenaga yang diperlukan untuk menarik kendaraan itu. Jika jumlah tenaga yang diperlukan untuk menarik kendaraan itu (traksi kritis) besarnya = 20.000 lbs, sedangkan kekuatan tarik yang dapat diberikan oleh mesin/ ban penggerak yang menyentuh tanah (Rimpull) besarnya = 4.000 lbs, maka disimpulkan bahwa roda kendaraan itu selip.

Contoh 2. Kendaraan yang sama, tetapi roda penggerak dianggap hanya menerima 50% dari berat total kendaraan seluruhnya (W). Coba analisa apakan kendaraan itu masih tetap saja selip?



Jawab: TK = CT x W x 50% = 0,50 x 40.000 lbs x 50% = 10.000 lbs Menurut contoh 1 besarnya Rimpull = 4.000 lbs Jadi TK = 10.000 lbs > Rimpull (=4.000 lbs) ------- Kendaraan masih tetap selip. Contoh 3. Kendaraan yang sama berjalan pada tanah pasir lepas dengan RR = 250 lbs/ ton berat kendaraan. Jika berat kendaraan yang diterima oleh roda besarnya 50%, coba analisa apakah kendaraan tersebut selip? Jawab: Menurut Tabel 4.2, CT untuk pasir kering yang lepas = 0,20 TK = CT x W x 50% = 0,20 x 4.000 lbs x 50% TK = 4.000 lbs

Rimpull untuk mengatasi RR = W x RR = 20 ton x 250 lbs/ ton = 5.000 lbs Rimpull untuk mengatasi GR = W x GR x Kemiringan = 20 ton x 20 lbs/ ton/ 1% x 5% = 2.000 lbs Rimpull total = 5.000 lbs + 2.000 lbs = 7.000 lbs TK = 4.000 lbs TK < Rimpull Jadi Kendaraan tidak selip

Rimpull total = 7.000 lbs

5) Rimpull Rimpull adalah besarnya kekuatan tarik yang dapat diberikan oleh mesin atau ban penggerak yang menyentuh permukaan jalur jalan dari suatu kendaraan. Rimpull biasanya dinyatakan dalam satuan kg atau lbs. Jika Koefisien Traksi (CT) cukup tinggi sehingga roda tidak selip, atau CT mampu menghindari selip, maka besarnya Rimpull maksimum yang dapat diberikan oleh mesin/ ban kendaraan adalah fungsi dari tekaga mesin (dsalam Horse Power) dan verseneling antara mesin dan rodanya.Page 9 of 111 Laporan Kelompok


Jadi: RP = (HP x 375 x Efisiensi mesin)/ (Kecepatan mesin dalam mph) Keterangan rumus: RP = Rimpull (Kekuatan t arik kendaraan) lbs HP = Horse Power (Tenaga mesin) HP 375 = Angka konversi Efisiensi mesin = 80 85%

Tetapi jika ban kendaraan telah selip, maka besarnya Rimpull dihitung sama dengan tenaga pada roda penggeraknya dikalikan CT . Jadi saat selip RP = Tenaga Roda Penggerak x CT

Contoh 1. Traktor dengan kekuatan 160 HP, menggunakan roda karet, berjalan pada gigi 1 dengan kecepatan 3,6 mph (mile per hour= mil/ jam). Hitung Rimpull maksimum yang dapat diberikan oleh roda itu. Jawab: Traktor roda karet, kondisi yang tidak selip. Menurut rumus Rimpull (RP) = RP RP = = 13.500 lbs

Contoh 2 Buldoser 140 HP, roda karet bergerak pada versenelling 1 dengan kecepatan 3,25 mph. Hitung Rimpull maksimum yang dapat diberikan oleh roda buldoser itu. Jawab: Kondisi kendaraan tidak selip. RP = = = 13.730 lbs Rimpull tidak dapat dihitung pada roda rantai (Crawler); istilah yang dipakai penggantinya adalah Draw Pull Bar (DPB). Dalam DPB pada traktor, mesin traktur harus mampu untuk menahan:

Tahanan guling (RR) dan tahanan kemiringan (GR)Page 10 of 111 Laporan Kelompok


Tahanan gulir dan tahanan kemiringan dari alat yang ditariknya.

Contoh 3. Sebuah traktor/ buldoser yang beratnya (W) 15 ton, bergerak di atas jalur jalan yang mempunyai tahanan gulir (RR) 100 lbs/ ton, dengan kemiringan jalan sebesar 5%. Buldoser itu berjalan pada versenellling 1 dan memiliki DPB maksimum sebesar 28.019 lbs. Hitung DPB yang dapat digunakan untuk menarik muatan lain. Jawab: DPB Maksimum = 28.019 lbs. DPB untuk mengatasi RR = W x RR = 15 ton x 100 lbs/ ton = 1.500 lbs DPB untuk mengatasi GR = W x GR x kemiringan jalan = 15 ton x 20 lbs/ton/ 1% x 5% = 1.500 lbs DPB Total = DPB untuk mengatasi RR + DPB untuk mengatasi GR = 1.500 lbs + 1.500 lbs = 3.000 lbs DPB untuk menarik muatan = DPB Maksimum - DPB Total = 28.019 lbs - 3.000 lbs = 25.019 lbs Rimpull tergantung pada HP dan kecepatan gerak dari alat berat tersebut. Biasanya pabrik telah memberikan pedoman tentang berapa besar kecepatan maksimum dan Rimpull yang dapat dihasilkan oleh masing-masing gigi verseneling seperti terdapat pada Tabel 4.3. Tabel 4.3. Contoh Kecepatan Maksimum pada masing-masing versenelling (*) Versenelling ke 1 Ban karet (140 hp) Kec (mph) 3,25 RP (lbs) 1.73 Crawler (15 ton) Kec (mph) 1,72 DPB (lbs) 28.019Page 11 of 111 Laporan Kelompok


2 3 4 5 6

7,10 12,48 21,54 33,86 ---

6.285 3.576 2.072 1.319 ---

2,18 2,76 3,50 4,36 7,00

22.699 17.265 13.769 10.074 5.579

(*) Sumber: Prodjosumartono. 6) Percepatan (Acceleration) Percepatan (Acceleration) adalah waktu yang di[perlukan untuk mempercepat kendaraan dengan memakai kelebihan Rimpull yang tidak digunakan untuk menggerakkan kendaran pada jalur tertentu. Lama waktu yang dibutuhkan untuk mempercepat kendaraan tergantung pada beberapa faktor yaitu: 1. Berat kendaraan; semakin berat kendaraan beserta isinya, semakin lama waktu yang dibutuhkan oleh kendaraan tersebut untuk menambah kecepatannya. 2. Kelebihan Rimpull yang ada.; semakin besar kelebihan Rimpull pada suatu kendaraan, maka semakin cepat kendaraan itu dapat dipercepat. Percepatan tak mungkin dihitung secara tepat, tetapi dapat diperkirakan memakai rumus Hukum Mewton. F= a= Keterangan Rumus: F G W a = Kelebihan Rimpul (lbs) = Percepatan karena gaya gravitasi = 32,2 ft/ det2 = Berat kendaraan beserta isinya (lbs) = Percepatan (ft/ det2)

Contoh 1 Suatu alat berat dengan bobot 1 ton ( 2000 lbs) mempunyai kelebihan Rimpull sebesar 10 lbs. Jika kelebihan Rimpull tersebut digunakan untuk menambah kecepatan, berapakah percepatan maksimum yang dapat dihasilkan? Jawab: a = (F x f)/ W =( )



= 0,161 ft/ det2 = 0,11 mph/ det Catatan: 1 mil = 1,61 km = 1.610 m 1 ft = 0,30 m Jadi dalam satu menit kecepatannya bertambah sebesar 0,11 x 60 = 6,6 mph. Biasanya untuk perhitungan percepatan digunakan dengan cara tidak langsung, yaitu dengan menghitung kecepatan rata-ratanya. Kecepatan rata-rata = Kecepatan maksimum x Faktor Kecepatan Faktor kecepatan dipengaruhi oleh jarak yang ditempuh, semakin jauh jarak yang ditempuh; tanpa memperhatikan bagaimana kondisi jalur jalan yang ditempuh semakin jauh jalan yang ditempuh, berarti semakin besar pula faktor ketepatan itu. Tabel 4.4 di bawah ini menunjukkan beberapa faktor kecepatan dan jarak yang ditempuh. Tabel 4.4. Hubungan Faktor Kecepatan dan Jarak yang Ditempuh.*] Jarak yang Ditempuh (ft) 500 1.000 1.000 1.500 1.500 2.000 2.000 2.500 2.500 3.000 3.000 3.500 3.500 4.000 *]Prodjosumarto. Faktor Kecepatan 0,46 0,78 0,59 0,82 0,65 0,82 0,69 0,83 0,73 0,83 0,75 0,84 0,77 0,85

Contoh 2. Sebuah Dump truck bergerak pada versenelling 3 di atas jalur jalan dengan kecepatan maksimum 12,48 mph. Truck itu menempuh perjalanan sepanjang jarak 1250 ft. Hitung keceptan rata-rata dari Dump truck tersebut. Jawab: Faktor kecepatan pada jarak 1250 ft didapat dari cara interpolasi Tabel 4.4. = = 0,705 Kecepatan rata-rata x (0,82 0,59) + 0,59 0,70 = Kecepatan maksimum x Faktor kecepatanPage 13 of 111 Laporan Kelompok


= 12,48 x 0,70 = 8,74 mph.

7) Elevasi Letak Proyek. Elevasi berpengaruh terhadap hasil kerja mesin, karena kerja mesin dipengaruhi oleh tekanan dan t emperatur udara luar. Berdasarkan pengalaman, kenaikan 1000 ft (300 m) pertama dari permukaan laut, tidak akan berpengaruh pada mesin-mesin empat tak, tetapi untuk selanjutnya setiap kenaikan 1000 ft ke dua (dihitung dari permukaan laut) HP rata-rata berkurang sebesar + 3% sedangkan pada mesin-mesin 2 tak, kemerosotannya berkisar 1%.

Contoh Pada permukaan laut sebuah mesin empat tak dengan tenaga 100 HP; Jika mesin itu dibawa pada proyek yang berada pada elevasi 10.000 ft (3.000 m) di atas permukaan laut, berapa besar HP yang dimiliki alat itu? Jawab: Hp pada permukaan laut = 100 HP Penurunan karena ketinggian = = 27 HP HP efektif alat = 100 HP - 27 HP = 73 HP

8) Efisiensi Operator Faktor manusia sebagai operator alat sangat sukar ditentukan dengan tepat, sebab selalu berubah-ubah dari waktu ke waktu, bahkan dari jam ke jam, tergantung pada keadaan cuaca, kondisi alat yang dikemudikan, suasana kerja dan lain-lain. Biasanya memberikan perangsang dalam bentuk bonus dapat mempertinggi efisiensi operator alat. Dalam bekerja seorang operator tak akan dapat bekerja selama 60 menit secara penuh, sebab selalu ada hambatan-hambatan yang tak dapat dihindari seperti



pengantian komponen yang rusak, memindahkan alat ke tempat lain, dan sebagainya.Pada Tabel 4.5 diberikan beberapa nilai efisiensi operator.

Tabel 4.5. Nilai Evisiensi Operator.(*) Jenis Alat Kriteria Evisiensi per-jam Baik Sekali 55 menit 92% 50 menit 83% Sedang 50 menit 83% 45 menit 75% Kurang (malam hari) 45 menit 75% 40 menit 67%

Crawler Ban Karet

(*) Sumber: Prodjosumarto Beberapa pengunaannya. a. Avability Index (AI) Avability Index (AI) adalah suatu cara untuk mengetahui kondisi dari alat tersebut sesungguhnya. AI = Keterangan Rumus: AI W R = Ability Index (%) = Jumlah Jam Kerja (jam) = Jumlah jam untuk perbaikan alat (jam) pengertian untuk menentukan kondisi alat dan efisiensi

b. Physical Avaibility (PA) Adalah satatan tentang kondisi fisik dari alat yang digunakan PA = Keterangan Rumus: PA S = Psycal Ability (%) = Jumlah jam suatu alat yang tidak rusak tapi tidak digunakan



W + R + S = Jumlah seluruh jam jalan dimana alat dijadwalkan untuk beroperasi.

c. Use of Ability (UA) Menunjukkan berapa persen waktu yang digunakan oleh suatu alat untuk beroperasi pada saat alat itu digunakan. UA = UA menjadi ukuran seberapa baik pengelolaan peralatan yang digunakan itu. d. Effective Utilization (EU) Pengertian EU sebenarnya sama saja dengan pengertian efisiensi kerja, yaitu menunjukkan berapa persen dari seluruh waktu kerja yang tersedia itu dapat dimantaatkan untuk bekerja secara produktif. EU =

Contoh 1. Dari hasil rekaman operator Shovell, dalam setiap bulan dicatat data sebagai berikut: Jumlah jam kerja (W) = 300 jam Jumlah jam untuk perbaikan alat (R) = 100 jam Jumlah jam alat suap tunggu (S) = 200 jam Hitung: AI, PA, AU, EU

Jawab: AI = = 300 jam/ (300 + 100 jam) x 100% AI PA = 75% = = PA AU = 82% = = AU = 60%Page 16 of 111 Laporan Kelompok

(300+ 200) x 100%


EU

= =

EU

= 50%

Contoh 2. Dari rekaman Shovell yang lain dan dengan operator yang lain pula tercatat data sebagai berikut: W = 450 jam R = 150 jam S = 0 jam (berarti tak ada alat yang sampai menunggu) Hitung: AI, PA, AU, EU, lalu analiasa operator mana yang bekerja lebih efisien Jawab: AI = = 450 jam/ (450 + 150 jam) x 100% AI PA = 75% = = PA AU = 75% = = AU EU = 100% = = EU = 75% W+R+S W+R+S

Analisa efisiensi kerja operator Kondisi dan efisiensi Penggunaan Alat (%) AI 75 75Page 17 of 111 Laporan Kelompok

Operator 1

Operator 2


PA AU EU

82 60 50

75 100 75

Dari tabel tersebut terlihat bahwa cakra kerja operator 2 lebih baik dari operator 1.

9) Faktor Pengembangan dan Pemuaian (Swell Factor) Tanah maupun massa batuan yang ada di alam ini telah dalam kondisi terkonsolidasi dengan baik, artinya bagian-bagian yang kosong atau ruangan yang terisi udara diantara butirannya sangat sedikit; namun demikian jika material tersebut digali dari tempat aslinya, maka terjadilah pengembangan atau pemuaian volume. Tanah asli yang di alam volumenya 1 m3, jika digali volumenya bisa menjadi 1,25%, ini terjadi karena tanah yang digali mengalami pengembangan dan pemuaian dari volume semula akibat ruang antar butiranya yang membesar. Faktor pengembangan dan pemuaian volume material perlu diketahui, sebab pada waktu penggalian material volume yang diperhitungkan adalah volume dalam kondisi Bank Yard, yaitu volume aslinya seperti di alam. Akan tetapi pada waktu perhitungan penangkutan material, volume yang dipakai adalah volume material setelah digali, jadi material telah mengembang sehingga volumenya bertambah besar. Kemampuan alat angkut maksimal biasanya dihitung dari kemampuan alat itu mengangkut material pada kapasitas munjung, jadi bila kapasitas munjung dikalikan dengan faktor pengembangan material yang diangkut, akan diperoleh Bank Yard Capacity-nya. Tetapi sebaliknya, bila Bank Yard itu dipindahkan lalu dipadatkan di tempat lain dengan alat pemadat mekanis, maka volume material tersebut menjadi berkurang. Hal ini disebabkan karena material menjadi benar-benar padat, jika 1 m3 tanah dalam kondisi Bank Yard dipadatkan, maka volumenya menjadi sekitar 0,9 m3,tanah mengalami penyusutan sekitar 10%.Beberapa angka pemuaian dan penyusutan jenis material galian disajikan pada Tabel. 4.6. Tabel 4.6. Angka Penyusutan/ Pemuaian Tanah (SF)*) Kondisi Tanah Jenis Tanah Semula (A) Kondisi tanah yang akan dikerjakan Tanah Asli 1,00 Tanah Lepas 1,11 Tanah Padat 0,95

Pasir



(B) (C) Tanah liat berpasir/ Tanah biasa (A) (B) (C) (A) Tanah liat (B) (C) Tanah liat bercampur kerikil (A) (B) (C) (A) Kerikil (B) (C) (A) Kerikil kasar (B) (C) Pecahan cadas atau batuan lunak Pecahan granit atau batuan keras (A) (B) (C) (A) (B) (C) (A) Pecahan Batu (B) (C) Batuan hasil peledakan (A) (B) (C)

0,90 1,05 1,00 0,80 1,11 1,00 0,70 1,11 1,18 1,00 1,09 1,00 0,88 1,97 1,00 0,70 1,77 1,00 0,61 1,82 1,00 0,59 1,76 1,00 0,57 1,71 1,00 0,56 0,77

1,00 1,17 1,25 1,00 1,39 1,25 1,00 1,59 1,13 1,00 1,10 1,13 1,00 1,10 1,42 1,00 1,10 1,65 1,00 1,35 1,70 1,00 1,30 1,75 1,00 1,24 1,80 1,00 1,38

0,86 1,00 0,90 0,72 1,00 0,90 0,63 1,00 1,03 0,91 1,00 1,03 0,91 1,.00 1,29 0,91 1,00 1,22 0,74 1,00 1,31 0,77 1,00 1,40 0,80 1,00 1,30 0,72 1,00

Keterangan: (A) = tanah Asli (B) Tanah Lepas (C) Tanah Padat *) Sumber: Perhitungan Biaya Pelaksanaan Pekerjaan dengan Manggunakan Alat-alat Berat. [Rochmanhadi, 1985].



Contoh 1. Sebuah Power Scrapper memiliki kapasitas munjung 15 yd3, akan digunakan untuk mengangkut tanah liat. Berapakah kapasitas alat sebenarnya mampu mengangkut tanah liat asli?

Jawab: Menurut Tabel 4.6, tiap 1 bagian tanah liat asli bila digali akan mengembang menjadi 1,25 bagian. Kapasitas munjung 15 yd3 Kapasitas tanah liat asli = 1,25 x kapasitas tanah liat asli = 1,25 x kapasitas tanah liat asli = (15/ 1,25) cu yd = 120 cu yd.

Contoh 2. Bila atanah liat tersebut untuk urugan yang dipadatkan, berapa volume padatnya? Jawab: Volume padat = volume asli x 0,90 (Lihat Tabel 4.6) = 120 cu yd x 0,90 = 108 cu yd.

10) Berat Material Berat material yang diangkut oleh alat-alat angkut dapat berpengaruh pada: a. Kecepatan kendaraan dengan HP yang dimiliinya, b. Membatasi kemampuan kendaraan untuk mengatasi tahanan kemiringan dan tahanan gulir dari jalur jalan yang dilalui, c. Membatasi volume material yang diangkut. Oleh sebab itu, berat jenis material harus diperhitungkan pengaruhnya terhadap kapasitas alat muat maupun alat angkat. Bobot isi dan faktor pengembang dari berbagai material terdapat pada Tabel 4.7. Tabel 4.7. Berat Jenis Tanah Asli, Berat Jenis Tanah Lepas % Kembang Berat Jenis Tanah Material kg/m3 Asli % Berat Jenis Tanah Lepas kg/m3 Lh/cu Yd

Lh/cu Yd Kembang



(Asli) Bauksit Caliche Cinders Karnotit, Bijih Uranium Lempung : Tanah Lliat asli Kering untuk digali Basah untuk digali Lempung dan Kerikil : Kering Basah Batu bara : Antrasit muda Tercuci Bitumen Muda Tercuci Batu lapukan : 75% batu 25% tanah biasa 50% batu 50% tanah biasa 25% batu 75% tanah biasa Tanah Kering : Padat Basah Lanau (Loam) Batu granit pecah Kerikil siap pakai Kerikil kering Kering 1/4' sd 2" (6 sd 51 mm) Basah 1/4' sd 2" (6 sd 51 mm) Pasir dan tanah liat lepas Pasir dan tanah liat padat 1920 2040 1560 2760 2190 1710 1920 2280 2040 2820 2310 1980 1620 1500 1290 1140 1680 1860 2040 1860 2100 1920 2280 870 2220

(Bank) 3200 3800 1450 3700 33 82 52 35

(Lepas) 1440 1260 570 1650

(Loose) 2400 2100 950 2750

3400 3100 3500

22 23 25

1680 1500 1680

2800 2500 2800

2800 3100

41 11

1200 1680

2000 2800

2700 2500 2150 2150

35 35 35 35

1200 1110 960 890

2000 1850 1600 1400

4700 3850 3300

43 33 25

1980 1740 1590

3300 2900 2650

3200 3400 2600 4600 3650 2850 3200 3800 3400 -

25 27 23 64 12 12 12 12 27 -

1530 1620 1260 1680 1650 1530 2040 1620 1620 2430

2550 2700 2100 2800 3250 2550 3400 2700 2700 4050



Gips dengan pecahan agak besar Gips dengan pecahan lebih kecil Hematit, bijih besi Batu kapur pecah Magnetit, bijih besi Pyrit, bijih besi Pasir batu Pasir kering lepas Sedikit basah Basah Pasir dan kerikil kering Pasir dan kerikil basah Slag - pecah Batu - pecah Takonit Tanah permukaan (top soil) Traprock - pecah catatan :

3210

5350

75

1830

3050

2820 2940 2640 3300 3060 2550 1620 1920 2100 1950 2250 2970 2970 4260 sd 5670 1380 2640

4700 4900 4400 5500 5100 4250 2700 3200 3500 3250 3750 4950 4950 7100 sd 9450 2300 4400

75 18 69 18 18 67 12 12 12 12 10 67 67 75 - 72 43 49

1620 2490 1560 2820 2610 1530 1440 1710 1740 1740 2040 1770 1620 2460 sd 3240 960 1770

2700 4150 2600 4700 4350 2550 2400 2850 2900 2900 3400 2950 2700 4100 sd 5400 1600 2950

1 lb = 0.4536 kg ; 1 cu yd = 0.76455 m3 ; 1 lb/cu yd = 0.5933 kg/m3 0.6 kg/m3

B. Manajemen Alat Berat Manajemen pemilihan dan pengendalian alat berat adalah proses

merencanakan, mengorganisir, memimpin dan mengendalikan alat berat untuk mencapai tujuan pekerjaan yang ditentukan. Beberapa faktor yang harus diperhatikan dalam pemilihan alat berat, sehingga kesalahan dalam pemilihan alat dapat dihindari, antara lain adalah: a. Fungsi yang harus dilaksanakan. Alat berat dikelompokkan berdasarkan fungsinya, seperti untuk menggali, mengangkut, meratakan permukaan



b. Kapasitas peralatan. Pemilihan alat berat didasarkan pada volume total atau berat material yang harus diangkut atau dikerjakan. Kapasitas alat yang dipilih harus sesuai sehingga pekerjaan dapat diselesaikan pada waktu yang telah ditentukan c. Cara operasi. Alat berat dipilih berdasarkan arah (horisontal maupun vertikal) dan jarak gerakan, kecepatan, frekuensi gerakan d. Pembatasan dari metode yang dipakai. Pembatasan yang mempengaruhi pemilihan alat berat antara lain peraturan lalu lintas, biaya, dan pembongkaran. Selain itu metode konstruksi yang dipakai dapat membuat pemilihan alat dapat berubah e. Ekonomi. Selain biaya investasi atau biaya sewa peralatan, biaya operasi dan pemeliharaan merupakan faktor penting didalam pemilihan alat berat f. Jenis proyek. Ada beberapa jenis proyek yang umumnya menggunakan alat berat. Proyek-proyek tersebut antar lain proyek gedung, pelabuhan, jalan, jembatan, irigasi, pembukaan hutan, dam. g. Lokasi proyek. Lokasi proyek juga merupakan hal lain yang perlu diperhatikan dalam pemilihan alat berat. Sebagai contoh lokasi proyek di dataran tinggi memerlukan alat berat yang berbeda dengan lokasi proyek didataran rendah h. Jenis dan daya dukung tanah. Jenis tanah di lokasi proyek dan jenis material yang akan dikerjakan dapat mempengaruhi alat berat yang akan dipakai. Tanah dapat dalam kondisi padat, lepas, keras, atau lembek i. Kondisi lapangan. Kondisi dengan medan yang sulit dan medan yang baik merupakan faktor lain yang mempengaruhi pemilihan alat berat. Selain itu hal-hal yang perlu diperhatikan dalam menyusun rencana kerja alat berat antara lain: a. Volume pekerjaan yang harus diselesaikan dalam batas waktu tertentu b. Dengan volume pekerjaan yang ada tersebut dan waktu yang telah ditentukan harus ditetapkan jenis dan jumlah alat berat yang diperlukan untuk menyelesaikan pekerjaan tersebut. c. Dengan jenis dan jumlah alat berat yang tersedia, dapat ditentukan berapa volume yang dapat diselesaikan, serta waktu yang diperlukan 2.1 .Jenis Jenis Alat BeratPage 23 of 111 Laporan Kelompok


Pemilihan suatu alat sebenarnya bukan di dasarkan pada besarnya produksi atau kapasitas alat tersebut, tetapi di dasarkan pada biaya termurah untuk setiap cu yd atau cu mtr produksinya. Untuk itu penting untuk mengetahui bagaimana cara memperkirakan biaya produksi suatu alat berat. Komponen-komponen biaya produksi yang mempengaruhi harga satuan pekerjaan tersebut adalah:

a) Biaya pemilikan (owner ship cost), Yang termasuk biaya pemilikan tanah ialah: Harga pokok pembelian ditambah biaya assembling dan biaya angkut hingga ke job-site. Penyusutan, dihitung dengan menjumlahkan harga alat, ongkos angkut, ongkos muat, ongkos bongkar dan ongkos pasang bagi umur alat yang bersangkutan. Bunga, pajak dan sewa gudang biasanya diambil 10 % (bunga 6 %, pajak 2 % dan asuransi serta ongkos gudang 2 %).

b) Biaya operasi (operating cost) Yang termasuk biaya operasional adalah: - Biaya penggantian dan reparasi ban. - Biaya reparasi umum, termasuk biaya suku cadang dan ongkos pasang serta pemeliharaan. - Biaya alat pergantian alat gali. - Biaya pemakaian bahan baker. - Untuk mesin yang menggunakan bensin 0,31/ pk/jam. - Untuk mesin yang menggunakan solar 0.21/ pk/jam - Biaya perbaikan (repairing cost) - Biaya tidak langsung (indirect cost). Pemilihan Alat 1. Karakterisitik material (sifat fisik, kekerasan, abrasive, Liat dll.) 2. Bentuk endapan commodity/bijih 3. Struktur batuan 4. Tingkat produksi yang diharapkan 5. Ukuran produk 6. Metoda/Cara penambangan dll.Page 24 of 111 Laporan Kelompok


Alat Pemberaian Batuan Metoda yang umum digunakan untuk pemberaian material overburden,bijih (ore) dan batubara adalah ripping dan drilling blasting

A. RIPPING Ripping digunakan untuk pemberaian material sebelum dimuat oleh Shovel/Back Hoe/Loader/Dragline ke dalam Truck atau ke tempat lain.Faktor yang paling berpengaruh dalam produksi Ripping adalah : Dozer Power and Weight Type batuan (karakteristik batuan) Jumlah Ripper Panjang Ripping Kedalaman Penetrasi Struktur geologi (Spasi joint, sesar dan orientasinya)

B. PEMBORAN Produksi & Peledakan Prinsip dari Metoda Pemboran adalah : ROTARY-PERCUSSION and ROTARY

1) ROTARY PERCUSSION DRILLING o Top Hammer Drilling Hammer Piston yang ditempatkan di posisi paling atas (Top) diteruskan ke Drill Bit melalui batang Bor jenis ini digunakan untuk lubang diameter kecil dan dangkal o Down The Hole Drilling Piston diposisikan di bawah batang bor dan langsung memukul Bit digunakan untuk diameter lubang sekitar 85 s/d 200 mm dan kedalaman sampai dengan 20 meter.

2) ROTARY DRILLING Umumnya digunakan untuk lubang yang lebih besar sampai dengan 400 mm, dan kemampuan penetrasi maximum sampai dengan 100 meterPage 25 of 111 Laporan Kelompok


Pemilihan Mesin Bor 1. Ukuran material (fragmentasi) yang diharapkan dan dapat ditangani oleh alat Loading , Hauling & Crushing 2. Tingkat Produksi 3. Kondisi/Lingkungan kerja 4. Kedalaman lubang 5. Kekerasan Batuan

A. Crane 1. Pengertian dan Fungsi Crane dalam bahasa Indonesia berarti mesin Derek. Crane adalah mesin pengangkat, umumnya dilengkapi dengan winder ( atau juga disebut drum tambang kawat), wire ropes (tambang kawat) atau rantai dan sheaves, yang dapat digunakan untuk mengangkat dan menurunkan material dan memindahkannya secara horizontal. Crane menggunakan satu atau lebih mesin sederhana untuk menghasilkan keuntungan otomatis dan memindahkan muatan yang jauh dari kapasitas normal manusia. Crane biasanya digunakan pada industry angkut untuk memuat atau menurunkan muatan, pada industry konstruksi untuk memindahkan material dan segala macam industry untuk mengumpulkan barang barang berat.

2. Sejarah CranePage 26 of 111 Laporan Kelompok


Crane digunakan secara domestik sejak jaman kuno. Cerobong asap atau crane perapian digunakan untuk mengayunkan kendi atau ceret diatas api dan ketinggiannya diatur oleh trammel. Prinsip yang digunakan pada perangkat tungku ditemukan di pelabuhan dan menara crane. Konstruksi crane yang pertamakali

kemungkinan diciptakan oleh Ancient Greeks dan diperkuat oleh laki laki atau binatang binatang pengangkut beban, seperti keledai. Crane jenis ini digunakan pada konstruksi bangunan tinggi. Crane yang lebih besar baru baru ditemukan, mengunakan manfaat dari treadwheels manusia, perizinan memindahkan beban berat. Pada zaman pertengahan

terpenting, crane pelabuhan diperkenalkan untuk memuat dan menurunkan kapal kapal dan membantu dengan kontstruksinya beberapa darinya dibangun dengan menara batu untuk kekuatan ekstra dan kestabilan. Crane yang baru baru lagi disusun dari kayu, tetapi besi pembalut dan baja ditambahkan seiring dengan munculnya Revolusi Industri.

Dalam beberapa abad, kekuatannya berasal dari penggunaan kekuatan fisik laki laki atau pun hewan hewan, meskipun dorongan ke atas dengan watermills dan windmills dapat dijalankan dengan memanfaatkan kekuatan alam. Kekuatan otomatis yang pertama dilengkapi dengan mesin uap, crane uap yang baru baru mulai diperkenalkan pada abad ke-18 atau ke-19, dan dapat digunakan dengan baik pada akhir abad ke-20. Crane yang modern biasanya menggunakan mesin pembakaran internal, atau motor listrik dan sistem hidrolik untuk melengkapi kemampuan memindahkan yang lebih besar daripada kemungkinan sebelumnya,

meskipun crane manual masih digunakan dimana



perlengkapan kekuatannya mungkin tidak ekonomis. Crane ada dalam perubahan jenis bentuk yang sangat besar dan masing masing disesuaikan pada kegunaan yang khusus. Perbedaan ukuran dari penggerak layar pada crane yang terkecil digunakan didalam ruang kerja, menara crane tertinggi digunakan untuk konstruksi bangunan tinggi, dan crane apung yang terbesar digunakan untuk membangun rigs oli dan penyelamatan harta kapal sunken.

Harbor cranes loading cargo on a ship at the Mundra Port in India

Berikut ini akan dipaparkan mengenai perkembangan crane dalam beberapa masa. In Ancient Greece

Greco-Roman Trispastos ("Three-pulley-crane"), the simplest crane type (150 kg load)

Greco-Roman Pentaspastos ("Five-pulley-crane"), a mediumsized variant (ca. 450 kg load)

Crane pengangkut muatan muatan berat diciptakan oleh Ancient Greeks pada akhir abad ke-6 sebelum masehi. Catatan ilmu purbakala memperlihatkan tidak kurang dari c.515 sebelum masehi khusus potongan baik tongs pemindah maupun besi lewis mulai muncul pada batu penghalang pada kuil - kuil Greek. Sejak titik keadaan sulit pada penggunaan alat pemindah, dan sejak mereka menemukan salah satu sebelumnya mengenai pusat grafitasi pada balok, atau pasangan berjarak sama dari ujung atas pusat



grafitasi, mereka dihormati ahli purbakala sebagai bukti wajib pasti bagi adanya crane. Pengenalan derekan dan katrol angkat segera menyebar luas menggantikan ramps sebagai alat utama dari gerakan vertikal. Selama 200 tahun kedepan, bangunan Greek terbukti nyata memperkecil bobot pegangan, sebagai teknik pengangkatan terbaru membuat penggunaan dari beberapa batu yang lebih kecil lebih praktis daripada yang lebih besar. Berbeda dari periode kuno dengan kecenderungannya selalu menambah ukuran balok, kuil masa klasik Greek seperti the Parthenon tidak berubah ubah istimewa balok balok batu dengan bobot kurang dari 15 20 ton. Juga kepraktisan pemasangan kolom monolit berukuran besar adalah hal yang praktis yang ditinggalkan dalam membantu penggunaan beberapa drum(drums) kolom. Meskipun teliti dasar dari perubahan dari ramp ke crane teknologi tertinggal tidak jelas, telah debat bahwa meledak berubah social dan politik kondisi dari Greece lebih sesuai untuk pekerjaan kecil, tim konstruksi professional daripada tubuh besar buruh tak terlatih, membuat crane lebih disukai oleh Greek polis daripada banyak buruh ramp kuat yang telah berkaidah dalam masyarakat otokrasi dari bangsa mesir atau Assyria. Literature tidak samar samar yang pertama membuktikan keberadaan penyelesaian system katrol dimunculkan pada the Mechanical Problems (Mech. 18, 853a32-853b13) menganggap berasal dari Aristoteles, tapi

mungkin dirubah menjadi lebih ramping pada tanggal sebelumnya. Sekitar waktu yang sama, ukuran balok pada kuil Greek mulai menyesuaikan kekunoan nenek moyang lagi, menunjukkan bahwa kecanggihan penyelesaian katrol mungkin telah ditemukan caranya untuk konstruksi kuil Greek selanjutnya.

In Ancient Rome


Pemindahan Tanah Mekanis dan Alat alat BeratReconstruction of a 10.4m high Roman Polyspastos at Bonn, Germany (I)

The heyday of the crane in ancient times came during the Roman Empire, when construction activity soared and buildings reached enormous dimensions. The Romans adopted the Greek crane and developed it further. We are relatively well informed about their lifting techniques, thanks to rather lengthy accounts by the engineers Vitruvius (De Architectura 10.2, 1-10) and Heron of Alexandria (Mechanica 3.2-5). There are also two surviving reliefs of Roman treadwheel cranes, with the Haterii tombstone from the late first century AD being particularly detailed. The simplest Roman crane, the Trispastos, consisted of a single-beam jib, a winch, a rope, and a block containing three pulleys. Having thus a mechanical advantage of 3:1, it has been calculated that a single man working the winch could raise 150 kg (3 pulleys x 50 kg = 150), assuming that 50 kg represent the maximum effort a man can exert over a longer time period. Heavier crane types featured five pulleys (Pentaspastos) or, in case of the largest one, a set of three by five pulleys (Polyspastos) and came with two, three or four masts, depending on the maximum load. The Polyspastos, when worked by four men at both sides of the winch, could already lift 3000 kg (3 ropes x 5 pulleys x 4 men x 50 kg = 3000 kg). In case the winch was replaced by a treadwheel, the maximum load even doubled to 6000 kg at only half the crew, since the treadwheel possesses a much bigger mechanical advantage due to its larger diameter. This meant that, in comparison to the construction of the Egyptian Pyramids, where about 50 men were needed to move a 2.5 ton stone block up the ramp (50 kg per person), the lifting capability of the Roman Polyspastos proved to be 60 times higher (3000 kg per person). However, numerous extant Roman buildings which feature much heavier stone blocks than those handled by the Polyspastos indicate that the overall lifting capability of the Romans went far beyond that of any single crane. At the temple of Jupiter at Baalbek, for instance, the architrave blocks weigh up to 60 tons each, and the corner cornices blocks even over 100 tons, all of them raised to a height of about 19 m. In Rome, the capital block of Trajan's Column weighs 53.3 tons, which had to be lifted to a height of about 34 m.



It is assumed that Roman engineers lifted these extraordinary weights by two measures: First, as suggested by Heron, a lifting tower was set up, whose four masts were arranged in the shape of a quadrangle with parallel sides, not unlike a siege tower, but with the column in the middle of the structure (Mechanica 3.5). Second, a multitude of capstans were placed on the ground around the tower, for, although having a lower leverage ratio than treadwheels, capstans could be set up in higher numbers and run by more men (and, moreover, by draught animals). This use of multiple capstans is also described by Ammianus Marcellinus (17.4.15) in connection with the lifting of the Lateranense obelisk in the Circus Maximus (ca. 357 AD). The maximum lifting capability of a single capstan can be established by the number of lewis iron holes bored into the monolith. In case of the Baalbek architrave blocks, which weigh between 55 and 60 tons, eight extant holes suggest an allowance of 7.5 ton per lewis iron, that is per capstan. Lifting such heavy weights in a concerted action required a great amount of coordination between the work groups applying the force to the capstans.

In the Middle Ages

Small-scale reconstruction of the medieval gantry crane at Brugge harbor



Medieval port crane with building overhanging in the former Hanse town of Danzig.

During the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire. The earliest reference to a treadwheel (magna rota) reappears in archival literature in France about 1225, followed by an illuminated depiction in a manuscript of probably also French origin dating to 1240. In navigation, the earliest uses of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Brugge in 1288 and Hamburg in 1291, while in England the treadwheel is not recorded before 1331. Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. Typical areas of application were harbors, mines, and, in particular, building sites where the treadwheel crane played a pivotal role in the construction of the lofty Gothic cathedrals. Nevertheless, both archival and pictorial sources of the time suggest that newly introduced machines like treadwheels or wheelbarrows did not completely replace more labor-intensive methods like ladders, hods and handbarrows. Rather, old and new machinery continued to coexist on medieval construction sitesand harbors. Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes, cranks and by the 15th century also by windlasses shaped like a ship's wheel. To smooth out irregularities of impulse and get over 'dead-spots' in the lifting process flywheels are known to be in use as early as 1123. The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance



of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Alternatively, the medieval treadwheel may represent a deliberate reinvention of its Roman counterpart drawn from Vitruvius' De architectura which was available in many monastic libraries. Its reintroduction may have been inspired, as well, by the observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities.Structure and placement

The medieval treadwheel was a large wooden wheel turning around a central shaft with a treadway wide enough for two workers walking side by side. While the earlier 'compass-arm' wheel had spokes directly driven into the central shaft, the more advanced 'clasp-arm' type featured arms arranged as chords to the wheel rim, giving the possibility of using a thinner shaft and providing thus a greater mechanical advantage. Contrary to a popularly held belief, cranes on medieval building sites were neither placed on the extremely lightweight scaffolding used at the time nor on the thin walls of the Gothic churches which were incapable of supporting the weight of both hoisting machine and load. Rather, cranes were placed in the initial stages of construction on the ground, often within the building. When a new floor was completed, and massive tie beams of the roof connected the walls, the crane was dismantled and reassembled on the roof beams from where it was moved from bay to bay during construction of the vaults. Thus, the crane grew and wandered with the building with the result that today all extant construction cranes in England are found in church towers above the vaulting and below the roof, where they remained after building construction for bringing material for repairs aloft. Less frequently, medieval illuminations also show cranes mounted on the outside of walls with the stand of the machine secured to putlogs.Mechanics and operation



Tower crane at the inland harbour of Trier from 1413.

In contrast to modern cranes, medieval cranes and hoists - much like their counterparts in Greece and Rome - were primarily capable of a vertical lift, and not used to move loads for a considerable distance horizontally as well. Accordingly, lifting work was organized at the workplace in a different way than today. In building construction, for example, it is assumed that the crane lifted the stone blocks either from the bottom directly into place, or from a place opposite the centre of the wall from where it could deliver the blocks for two teams working at each end of the wall. Additionally, the crane master who usually gave orders at the treadwheel workers from outside the crane was able to manipulate the movement laterally by a small rope attached to the load. Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340. While ashlar blocks were directly lifted by sling, lewis or devil's clamp (German Teufelskralle), other objects were placed before in containers like pallets, baskets, wooden boxes or barrels. It is noteworthy that medieval cranes rarely featured ratchets or brakes to forestall the load from running backward. This curious absence is explained by the high friction force exercised by medieval treadwheels which normally prevented the wheel from accelerating beyond control.Harbor usage

Beyond the modern warship stands a crane constructed in 1742, used for mounting masts to large sailing vessels. Copenhagen, Denmark



According to the present state of knowledge unknown in antiquity, stationary harbor cranes are considered a new development of the Middle Ages. The typical harbor crane was a pivoting structure equipped with double treadwheels. These cranes were placed docksides for the loading and unloading of cargo where they replaced or complemented older lifting methods like see-saws, winches and yards. Two different types of harbor cranes can be identified with a varying geographical distribution: While gantry cranes which pivoted on a central vertical axle were commonly found at the Flemish and Dutch coastside, German sea and inland harbors typically featured tower cranes where the windlass and treadwheels were situated in a solid tower with only jib arm and roof rotating. Interestingly, dockside cranes were not adopted in the Mediterranean region and the highly developed Italian ports where authorities continued to rely on the more laborintensive method of unloading goods by ramps beyond the Middle Ages. Unlike construction cranes where the work speed was determined by the relatively slow progress of the masons, harbor cranes usually featured double treadwheels to speed up loading. The two treadwheels whose diameter is estimated to be 4 m or larger were attached to each side of the axle and rotated together.[12] Today, according to one survey, fifteen treadwheel harbor cranes from pre-industrial times are still extant throughout Europe.[28] Beside these stationary cranes, floating cranes which could be flexibly deployed in the whole port basin came into use by the 14th century.[26]

Mechanical principles

Cranes can mount many different utensils depending on load (left). Cranes can be remote-controlled from the ground, allowing much more precise control, but without the view that a position atop the crane provides (right).



The stability of a mobile construction crane can be jeopardized when outriggers sink into soft soil, which can result in the crane tipping over.

There are two major considerations in the design of cranes. The first is that the crane must be able to lift a load of a specified weight and the second is that the crane must remain stable and not topple over when the load is lifted and moved to another location.

Lifting capacityCranes illustrate the use of one or more simple machines to create mechanical advantage.

The lever. A balance crane contains a horizontal beam (the lever) pivoted about a point called the fulcrum. The principle of the lever allows a heavy load attached to the shorter end of the beam to be lifted by a smaller force applied in the opposite direction to the longer end of the beam. The ratio of the load's weight to the applied force is equal to the ratio of the lengths of the longer arm and the shorter arm, and is called the mechanical advantage.

The pulley. A jib crane contains a tilted strut (the jib) that supports a fixed pulley block. Cables are wrapped multiple times round the fixed block and round another block attached to the load. When the free end of the cable is pulled by hand or by a winding machine, the pulley system delivers a force to the load that is equal to the applied force multiplied by the number of lengths of cable passing between the two blocks. This number is the mechanical advantage.

The hydraulic cylinder. This can be used directly to lift the load or indirectly to move the jib or beam that carries another lifting device. Cranes, like all machines, obey the principle of conservation of energy. This

means that the energy delivered to the load cannot exceed the energy put into thePage 36 of 111 Laporan Kelompok


machine. For example, if a pulley system multiplies the applied force by ten, then the load moves only one tenth as far as the applied force. Since energy is proportional to force multiplied by distance, the output energy is kept roughly equal to the input energy (in practice slightly less, because some energy is lost to friction and other inefficiencies).

StabilityFor stability, the sum of all moments about any point such as the base of the crane must equate to zero. In practice, the magnitude of load that is permitted to be lifted (called the "rated load" in the US) is some value less than the load that will cause the crane to tip (providing a safety margin). Under US standards for mobile cranes, the stability-limited rated load for a crawler crane is 75% of the tipping load. The stability-limited rated load for a mobile crane supported on outriggers is 85% of the tipping load. Standards for cranes mounted on ships or offshore platforms are somewhat stricter because of the dynamic load on the crane due to vessel motion. Additionally, the stability of the vessel or platform must be considered. For stationary pedestal or kingpost mounted cranes, the moment created by the boom, jib, and load is resisted by the pedestal base or kingpost. Stress within the base must be less than the yield stress of the material or the crane will fail.

Types MobileThe most basic type of mobile crane consists of a truss or telescopic boom mounted on a mobile platform - be it on road, rail or water.

Type of crane

Description

Image



A crane mounted on a truck carrier provides the mobility for this type of crane. Generally, these cranes are able to travel on highways, eliminating the need for special equipment to transport the crane. When working on the jobsite, outriggers are extended horizontally from the chassis then vertically to level and stabilize the crane while stationary and hoisting. Many truck cranes have slow-travelling capability (a few miles per hour) while suspending a Truckmounted crane load. Great care must be taken not to swing the load sideways from the direction of travel, as most antitipping stability then lies in the stiffness of the chassis suspension. Most cranes of this type also have moving counterweights for stabilization beyond that provided by the outriggers. Loads suspended directly aft are the most stable, since most of the weight of the crane acts as a counterweight. Factory-calculated charts (or electronic safeguards) are used by crane operators to determine the maximum safe loads for stationary (outriggered) work as well as (on-rubber) loads and travelling speeds. Truck cranes range in lifting capacity from about 14.5 US tons to about 1300 US tons. A sidelifter crane is a road-going truck or semi-trailer, Sidelift crane able to hoist and transport ISO standard containers. Container lift is done with parallel crane-like hoists, which can lift a container from the ground or from a railway vehicle. A crane mounted on an undercarriage with four rubber tires that is designed for pick-and-carry operations and for off-road and "rough terrain" applications.

Rough terrain



crane

Outriggers are used to level and stabilize the crane for hoisting. These telescopic cranes are single-engine machines, with the same engine powering the undercarriage and the crane, similar to a crawler crane. In a rough terrain crane, the engine is usually mounted in the

undercarriage rather than in the upper, as with crawler crane. A mobile crane with the necessary equipment to travel at speed on public roads, and on rough terrain at the job site using all-wheel and crab steering. ATs combine the All terrain crane roadability of Truck-mounted Cranes and the

manoeuvrability of Rough Terrain Cranes. ATs have 2-9 axles and are designed for lifting loads up to 1200 metric tons.[29] A crawler is a crane mounted on an undercarriage with a set of tracks (also called crawlers) that provide stability and mobility. Crawler cranes range in lifting capacity from about 40 US tons to 3500 US tons. Crawler cranes have both advantages and disadvantages

Crawler crane

depending on their use. Their main advantage is that they can move around on site and perform each lift with little set-up, since the crane is stable on its tracks with no outriggers. In addition, a crawler crane is capable of traveling with a load. The main disadvantage is that they are very heavy, and cannot easily be moved from one job site to another without significant expense. Typically a large crawler must be disassembled and moved by trucks, rail cars or ships to its next location.



A railroad crane has flanged wheels for use on railroads. The simplest form is a crane mounted on a Railroad crane Different types of crane are used for maintenance work, recovery operations and freight loading in goods yards. Floating cranes are used mainly in bridge building and port construction, but they are also used for occasional loading and unloading of especially heavy or awkward loads on and off ships. Some floating cranes are mounted on a pontoon, others are specialized crane barges with a lifting capacity exceeding 10,000 tons and Floating crane have been used to transport entire bridge sections. Floating cranes have also been used to salvage sunken ships. Crane vessels are often used in offshore construction. The largest revolving cranes can be found on SSCV Thialf, which has two cranes with a capacity of 7,100 metric tons each. Aerial crane or 'Sky cranes' usually are helicopters designed to lift large loads. Helicopters are able to travel to and lift in areas that are difficult to reach by conventional cranes. Helicopter cranes are most commonly used to lift units/loads onto shopping centers Aerial crane and highrises. They can lift anything within their lifting capacity, (cars, boats, swimming pools, etc.). They also perform disaster relief after natural disasters for cleanup, and during wild-fires they are able to carry huge buckets of water to extinguish fires. Some aerial cranes, mostly concepts, have also used lighter-than air aircraft, such as airships. railroad car. More capable devices are purpose-built.



FixedExchanging mobility for the ability to carry greater loads and reach greater heights due to increased stability, these types of cranes are characterised that they (or at least their main structure) does not move during the period of use. However, many can still be assembled and disassembled.

Type crane

of

Description

Image

The tower crane is a modern form of balance crane. Fixed to the ground (and sometimes attached to the sides of structures as well), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. The jib (colloquially, the 'boom') and counter-jib are mounted to the turntable, where the slewing bearing and slewing machinery are located. The counter-jib carries a counterweight, usually of concrete blocks, Tower crane while the jib suspends the load from the trolley. The Hoist motor and transmissions are located on the mechanical deck on the counter-jib, while the trolley motor is located on the jib. The crane operator either sits in a cabin at the top of the tower or controls the crane by radio remote control from the ground. In the first case the operator's cabin is most usually located at the top of the tower attached to the turntable, but can be mounted on the jib, or partway down the tower. The lifting hook is operated by using electric motors to manipulate wire rope cables through a



system of sheaves. In order to hook and unhook the loads, the operator usually works in conjunction with a signaller (known as a 'rigger' or 'swamper'). They are most often in radio contact, and always use hand signals. The rigger directs the schedule of lifts for the crane, and is responsible for the safety of the rigging and loads. A tower crane is usually assembled by a telescopic jib (mobile) crane of greater reach (also see "selferecting crane" below) and in the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will often be lifted to the roof of the completed tower to dismantle the tower crane afterwards. It is often claimed that a large fraction of the tower cranes in the world are in use in Dubai. The exact percentage remains an open question.[30][31] Generally a type of tower crane, these cranes, also called self-assembling or "Kangaroo" cranes, lift themselves off the ground using jacks, allowing the Self-erecting next section of the tower to be inserted at ground level crane or lifted into place by the partially erected crane itself. They can thus be assembled without outside help, or can grow together with the building or structure they are erecting. A telescopic crane has a boom that consists of a Telescopic crane number of tubes fitted one inside the other. A hydraulic or other powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are often



used for short term construction projects, rescue jobs, lifting boats in and out of the water, etc. The relative compactness of telescopic booms make them

adaptable for many mobile applications. Note that while telescopic cranes are not

automatically mobile cranes, many of them are. These are often truck-mounted. The "hammerhead", or giant cantilever, crane is a fixed-jib crane consisting of a steel-braced tower on which revolves a large, horizontal, double cantilever; the forward part of this cantilever or jib carries the lifting trolley, the jib is extended backwards in order to form a support for the machinery and counterbalancing weight. In addition to the motions of lifting and revolving, there is provided a so-called "racking" motion, by which the lifting trolley, with the load suspended, can be moved in and out along the jib without altering the level of the load. Such horizontal Hammerhead movement of the load is a marked feature of later crane crane design. These cranes are generally constructed in large sizes, up to 350 tons. The design of hammerkran evolved first in Germany around the turn of the 19th century and was adopted and devloped for use in British shipyards to support the battleship construction program from 1904-1914. The ability of the hammerhead crane to lift heavy weights was useful for installing large pieces of battleships such as armour plate and gun barrels. Giant cantilever cranes were also installed in naval shipyards in Japan and in the USA. The British Government also installed a giant cantilever crane at



the Singapore Naval Base (1938) and later a copy of the crane was installed at Garden Island Naval Dockyard in Sydney (1951). These cranes provided repair support for the battle fleet operating far from Great Britain. The principal engineering firm for giant cantilever cranes in the British Empire was Sir William Arrol & Co Ltd building 14. Of around 60 built across the world few remain; 7 in England and Scotland of about 15 worldwide.[32] The Titan Clydebank is one of the 4 Scottish cranes on the Clydebank and preserved as a tourist attraction.

Normally a crane with a hinged jib will tend to have Level luffing crane its hook also move up and down as the jib moves (or luffs). A level luffing crane is a crane of this common design, but with an extra mechanism to keep the hook level when luffing.

A gantry crane has a hoist in a fixed machinery house or on a trolley that runs horizontally along rails, usually fitted on a single beam (mono-girder) or two beams (twin-girder). The crane frame is supported on a gantry system with equalized beams and wheels that Gantry crane run on the gantry rail, usually perpendicular to the trolley travel direction. These cranes come in all sizes, and some can move very heavy loads, particularly the extremely large examples used in shipyards or industrial installations. A special version is the container crane (or "Portainer" crane, named



by the first manufacturer), designed for loading and unloading ship-borne containers at a port. Also known as a 'suspended crane', this type of crane work very similar to a gantry crane but instead of the Overhead crane whole crane moving, only the hoist / trolley assembly moves in one direction along one or two fixed beams, often mounted along the side walls or on elevated columns in the assembly area of factory. Some of these cranes can lift very heavy loads. Located on the ships and boats, these are used for Deck crane cargo operations or boat unloading and retrieval where no shore unloading facilities are available. Most are diesel-hydraulic or electric-hydraulic. A jib crane is a type of crane where a horizontal member (jib or boom), supporting a moveable hoist, is fixed to a wall or to a floor-mounted pillar. Jib cranes are used in industrial premises and on military Jib crane vehicles. The jib may swing through an arc, to give additional lateral movement, or be fixed. Similar cranes, often known simply as hoists, were fitted on the top floor of warehouse buildings to enable goods to be lifted to all floors. Bulk-handling cranes are designed from the outset to carry a shell grab or bucket, rather than using a hook and a sling. They are used for bulk cargoes, such as coal, minerals, scrap metal etc.

Bulkhandling crane



A loader crane (also called a knuckle-boom crane or articulating crane ) is a hydraulically-powered articulated arm fitted to a truck or trailer, and is used for loading/unloading the vehicle. The numerous jointed sections can be folded into a small space when the crane is not in use. One or more of the sections may be telescopic. Often the crane will have a degree of automation and be able to unload or stow itself without an operator's instruction. Unlike most cranes, the operator must move around the vehicle to be able to view his load; hence modern cranes may be fitted with a portable cabled or radioLoader crane linked control system to supplement the cranemounted hydraulic control levers. In the UK and Canada, this type of crane is almost invariably known colloquially as a "Hiab", partly because this manufacturer invented the loader crane and was first into the UK market, and partly because the distinctive name was displayed prominently on the boom arm. A rolloader' crane is a loader crane mounted on a chassis with wheels. This chassis can ride on the trailer. Because the crane can move on the trailer, it can be a light crane, so the trailer is allowed to transport more goods. A crane with a forklift type mechanism used in automated (computer controlled) warehouses (known Stacker crane as an automated storage and retrieval system (AS/RS)). The crane moves on a track in an aisle of the warehouse. The fork can be raised or lowered to any of the levels of a storage rack and can bePage 46 of 111 Laporan Kelompok


extended into the rack to store and retrieve product. The product can in some cases be as large as an automobile. Stacker cranes are often used in the large freezer warehouses of frozen food manufacturers. This automation avoids requiring forklift drivers to work in below freezing temperatures every day.

Similar machinesThe generally-accepted definition of a crane is a machine for lifting and moving heavy objects by means of ropes or cables suspended from a movable arm. As such, a lifting machine that does not use cables, or else provides only vertical and not horizontal movement, cannot strictly be called a 'crane'. Types of crane-like lifting machine include:

Block and tackle Capstan (nautical) Hoist (device) Winch Windlass

More technically-advanced types of such lifting machines are often known as 'cranes', regardless of the official definition of the term.

Special examples

Finnieston Crane (aka the Stobcross Crane) Category A -listed example of a 'hammerhead' (cantilever) crane in Glasgow's former docks 50 m tall, 175 tons capacity, built 1926

Taisun double bridge crane at Yantai, China.



20,000 tonne capacity, World Record Holder 133 m tall, 120 m span, lift-height 80 m

Kockums Crane shipyard crane formerly at Kockums, Sweden. 138 m tall, 1500 tonne capacity, since moved to Ulsan, South Korea

Samson and Goliath (cranes) two gantry cranes at the Harland & Wolff shipyard in Belfast Goliath is 96 m tall, Samson is 106 m span 140 m, lift-height 70 m, capacity 840 tonnes each (1600 tonnes combined)

Breakwater Crane Railway self-propelled steam crane that formerly ran the length of the breakwater at Douglas ran on 10 feet (3.05 m) gauge track, the broadest in the British Isles

B. Backhoe Kelebihan : o Mampu menggali material pada berbagai kondisi (Loading di floor, Channel, dan Roof) o Manuver lebih baik o Dapat beroperasi dengan areal kerja lebih sempit o Pada Kelas yang sama, Backhoe mempunyai ketinggian gali ke atas dan ke bawah lebih besar dari pada Shovel.Page 48 of 111 Laporan Kelompok


Kekurangan : Ukuran Bucket lebih kecil dibanding Shovel untuk ukuran mesin yang sekelas

Uses of back hoes These machines are suitable for excavating trenches, pits for basement and smaller machines can handle general grading work. It is a versatile machine in that it can perform both excavation and lifting works. Example in drainage works or utility works , the back hoe can perform the trench excavation and handle the pipes or culverts. Thus this makes the need for a second lifting machine unnecessary. During excavation the penetration force in to the material being excavated is achieved by the stick cylinder and the bucket cylinder. The buckets can be selected depending on the type of material excavated. For easily excavated material wide buckets are used. When excavating rocky material or blasted rocks, a narrow bucket is used. In utility works, the width of the required trench is the deciding factor in selecting the bucket. A backhoe, also called a rear actor or back actor, is a piece of excavating equipment or digger consisting of a digging bucket on the end of a two-part articulated arm. mounted on the front loader. They are typically

back of a tractor or The section of the armPage 49 of 111

Laporan Kelompok


closest to the vehicle is known as the boom, and the section which carries the bucket is known as the dipper or dipperstick. The boom is attached to the vehicle through a pivot known as the kingpost, which allows the arm to slew left and right, usually through a total of around 200 degrees. Modern backhoes are powered by hydraulics.

Characteristics Most backhoes are at their strongest curling the bucket, with the dipperstick next most powerful, and boom movements the least powerful. Similar attachments for skid loaders are still called backhoes even though they are mounted on the front. This is because the name refers to the action of the shovel, not its location on the vehicle: a backhoe digs by drawing earth backwards, rather than lifting it with a forward motion like a bulldozer. A backhoe loader is a tractor-like vehicle with an arm and bucket mounted on the back and a front loader mounted on the front. This type of vehicle is often known colloquially as a JCB in Europe and simply a Backhoe or a Tractor Loader Backhoe, or TLB, in North America. In North American terms, a Backhoe includes both a front bucket and a rear hoe, on a chassis originally derived from farm tractors. A dedicated hoe on its own chassis is more properly referred to as an excavator. Backhoes can be designed and manufactured from the start as such, or can be the result of a farm tractor equipped with a Front End Loader (FEL) and rear hoe. Though similar looking, the designed backhoes are much stronger, with the farm variation more suitable for light work.



With the advent of hydraulic powered attachments such as a tiltrotator, breaker, a grapple or an auger, the backhoe is frequently used in many applications other than excavation and with the tiltrotator attachment, serves as an effective tool carrier. Many backhoes feature quick-attach mounting systems for simplified attachment mounting, dramatically increasing the machine's utilization on the jobsite. Backhoes are usually employed together with loaders and bulldozers. Excavators that use a backhoe are sometimes called "trackhoes" by people who do not realize the name is due to the action of the bucket, not its location on a backhoe loader. Backhoes are general purpose tools, and are being displaced to some extent by multiple specialist tools like the excavator and the specialty Front End Loader, especially with the rise of the mini-excavator. On many jobsites which would have previously seen a backhoe used, a skidsteer (colloquially often called a Bobcat after the most well known manufacturer and inventor of the category) and a mini excavator will be used in conjunction to fill the backhoes role. However, backhoes still are in general use. Sometimes a backhoe's scoop can be mounted the "wrong" way round, to work in "face shovel" mode. Origins The British company JCB developed the early hoes. Their first tractor equipped with both a hoe and a front-mounted loading bucket was completed in 1953 and set the standard pattern for future designs of backhoe loader. Because of the long-time predominance of this marque in the United Kingdom and Ireland, it has become a genericized trademark there, and all backhoe-equipped diggers are commonly called JCBs, while the term "hoe" is almost unknown to the general public in this context. The founder of the JCB company, Joseph Cyril Bamford, holds the honour of being the only non-American in the US construction industry's Hall of fame. The American tractor company Case Corporation made the first Americanbuilt backhoe in 1967. The design of the Case backhoes, from the straight arm boom assembly, to the "Extendahoe" design, which can extend the dipper from four to eightPage 51 of 111 Laporan Kelompok


feet longer, are all registered with the U.S. Patent Office, along with the chassis design. Originally, the Case backhoes were not meant to be called such, instead, they had the words "Construction King" painted somewhere noticeable, either on the rear fenders, or on the boom arm, but the name backhoe stuck. Backhoe fade Backhoe fade or JCB fade is a humorous term coined by the telecommunications industry, referring to the accidental severing of a cable by a backhoe or similar construction activity.[1] The term comes from the sudden and initially inexplicable loss of signal ("fading") experienced when a cable is accidentally dug up and damaged. Depending on the particular cable destroyed, service may be interrupted to just a few customers or, for a large fiber optic cable, millions of customers across an entire continent.

C. Roller / Stoom Wales Roller atau yang lebih dikenal masyarakat dengan sebutan Stoom adalah alat yang digunakan untuk meratakan tanah sambil memadatkannya. Penamaan Stoom sebenarnya berasal dari steam atau yang berarti uap air. Hal tersebut dikarenakan pada awal penggunaannya dahulu sistem kerjanya dengan memanfaatkan energy uap untuk dapat menjalankannya. Terdapat jenis jenis roller diantaranya yaitu : 1.Smooth steel roller Berikut adalah gambar smooth steel roller

Pada jenis ini, terdapat lubang pada rollernya. Fungsi lubang tersebut untuk tempat masuknya air sehingga menambah bobot roller tersebut yang ditujukan untuk mempercepat proses perataan dan pemadatan tanah.



2.Smooth well roller 3.Sheep foot roller Penamaan Sheep Foot Roller dikarenakan bentuk dari gerigi rollernya menyerupai kaki domba, namun juga ada bentuk geriginya yang sedikit lebih banyak. Fungsi utama dari roller jenis ini adalah untuk memadatkan tanah. Berikut ini adalah gambar gambar dari Sheep Foot Roller :

Hasil pekerjaan dengan menggunakan roller jenis ini adalah sebagai berikut :

4.Vibratory roller



Pada roller jenis Vibratory Roller, roda penggiling disertai alat yang dapat menggetarkan roda, sehingga pada saat alat digunakan akan terjadi getaran pada roda penggilingnya.

5.Mesh grid roller Roller jenis ini memiliki roda penggiling dengan bentuk anyaman.

6.Segmen roller Roller jenis ini memiliki roda penggiling dengan gerigi gerigi yang bersegmen, sehingga letak geriginya seperti warna hitam putih pada papan catur.

D. Bull Dozer Buldoser merupakan sebuah kendaraan berantai (traktor dengan rantai caterpillar) dilengkapi dengan "blade". Istilah buldoser sering kali digunakan untuk menggambarkan suatu kendaraan teknik berat meskipun istilah ini resminya hanya menunjuk ke traktor (seringkali dengan rantai) yang dilengkapi dengan "blade", yang artikel ini liput.



Caterpillar

Inc.

buldoser

tipe-rantai

D9R.

Di kanan adalah "blade", di kiri adalah ripper-belakang.

A bulldozer is a crawler (caterpillar tracked tractor), equipped with a substantial metal plate (known as a blade), used to push large quantities of soil, sand, rubble, etc., during construction work. The term "bulldozer" is often used to mean any heavy engineering vehicle (sometimes a loader and sometimes an excavator), but precisely, the term refers only to a tractor (usually tracked) fitted with a dozer blade. That is the meaning used here.



The first bulldozers were adapted from Holt farm tractors that were used to plough fields. Their versatility in soft ground for logging and road building led directly to their becoming the armoured tank in World War I. In 1923, a young farmer named James Cummings and a draftsman named J. Earl McLeod made the first designs for a bulldozer. A replica is on display at the city park in Morrowville, Kansas where the two built the first bulldozer.[1] By the 1920s, tracked vehicles became common, particularly the Caterpillar 60. To dig canals, raise earth dams, and do other earthmoving jobs, these tractors were equipped with a large thick metal plate in front. This metal plate (it got its curved shape later) is called a "blade". The blade peels layers of soil and pushes it forward as the tractor advances. In some early models the driver sat on top in the open without a cabin. There are three main types of bulldozer blades: a U-blade for pushing and carrying dirt relatively long distances, a straight blade for "knocking down" and spreading piles of dirt, and a brush rake for removing brush and roots. These attachments (home-built or built by small equipment manufacturers of attachments for wheeled and crawler tractors and trucks) appeared by 1929. Widespread acceptance of the bull-grader does not seem to appear before the mid1930s. The addition of power down-force provided by hydraulic cylinders instead of just the weight of the blade made them the preferred excavation machine for large and small contractors alike by the 1940s, by which time the term "bulldozer" referred to the entire machine and not just the attachment. Over the years, bulldozers got bigger and more powerful in response to the demand for equipment suited for ever larger earthworks. Firms like Caterpillar, Komatsu, Fiat-Allis, John Deere, International Harvester, Case, Liebherr, Terex, and JCB manufactured large tracked-type earthmoving machines. Bulldozers grew more sophisticated as time passed. Important improvements include more powerful engines, more reliable drive trains, better tracks, raised cabins, and blades controlled by hydraulic cylinders instead of early models' cable winch. Hydraulic cylinders enabled more precise manipulation of the blade and automated controls. As an option, bulldozers can be equipped with rear ripper claw(s) to loosen rocky soils or to break up pavement (roads). A more recentPage 56 of 111 Laporan Kelompok


innovation is the outfitting of bulldozers with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Inc, Leica Geosystems or Mikrofyn for precise grade control and (potentially) "stakeless" construction. The best known maker of bulldozers is probably Caterpillar, which earned its reputation by making tough, durable, reliable machines. Komatsu and John Deere are present-day competitors. Although these machines began as modified farm tractors, they became the mainstay for big civil construction projects, and found their way into use by military construction units world-wide. The best known model, the Caterpillar D9, was also used to clear mines and demolish enemy structures. History of the word

1800s: term used in engineering for a horizontal forging press. 1886: "bulldozer" meant a large-caliber pistol and the person who wielded it. Around 1880: In the USA, a "bull-dose" was a large and efficient dose of any sort of medicine or punishment. 'Bull-dosing' meant a severe whipping or coercion, or other intimidation such as at gunpoint.

Late 1800s: "bulldozing" meant using big force to push over or through any obstacle.

1930s: applied to the vehicle. These appeared as early as 1929, but were known as "bull grader" blades,

and the term "bulldozer blade" did not appear to come into widespread use until the mid 1930s, and now refers to the whole machine not just the attachment. In contemporary usage, "bulldozer" is often shortened to "dozer". Description Most often, bulldozers are large and powerful tracked engineering vehicles. The tracks give them excellent ground hold and mobility through very rough terrain. Wide tracks help distribute the bulldozer's weight over large area (decreasing pressure), thus preventing it from sinking in sandy or muddy ground. Extra wide tracks are known as 'swamp tracks'. Bulldozers have excellent ground hold and a torque divider designed to convert the engine's power into improved dragging ability.



The Caterpillar D9, for example, can easily tow tanks that weigh more than 70 tons. Because of these attributes, bulldozers are used to clear areas of obstacles, shrubbery, burnt vehicles, and remains of structures. Sometimes a bulldozer is used to push another piece of earthmoving equipment known as a "scraper". The towed Fresno Scraper, invented in 1883 by James Porteous, was the first design to enable this to be done economically, removing the soil from the cut and depositing it elsewhere on shallow ground (fill). Many dozer blades have a reinforced center section with this purpose in mind, and are called "bull blades."The bulldozer's primary tools are the blade and the ripper.

The ripper is the long claw-like device on the back of the bulldozer. Rippers can come singly (single shank/giant ripper) or in groups of two or more (multi shank rippers). Usually, a single shank is preferred for heavy ripping. The ripper shank is fitted with a replaceable tungsten steel alloy tip. Ripping rock lets the ground surface rock be broken into small rubble easy to handle and transport, which can then be removed so grading can take place. Agricultural ripping lets rocky or very hard earth (such as podzol hardpan) be broken up so otherwise unploughable land can be farmed. For example, much of the best land in the California wine country consists of old lava flows. With heavy bulldozers the lava is shattered, allowing agriculture. Also, hard earth can be ripped and decompacted to allow planting of orchards where trees could not otherwise grow. The bulldozer blade is a heavy metal plate on the front of the tractor, used to push objects suck it, and shoving sand, soil and debris. Dozer blades usually come in three varieties: 1. A Straight Blade ("S-Blade") which is short and has no lateral curve, no side wings, and can be used for fine grading. 2. A Universal Blade ("U-Blade") which is tall and very curved, and has large side wings to carry more material. 3. A "S-U" combination blade which is shorter, has less curvature, and smaller side wings. This blade is typically used for pushing piles of large rocks, such as at a quarry.



In military use, dozer blades are fixed on combat engineering vehicles and can optionally be fitted on other vehicles, such as artillery tractors like the Type 73 or M8 Tractor. Dozer blades can also be mounted on Main battle tanks, where it can be used to clear antitank obstacles, mines, and dig improvised shelters. Combat applications for dozer blades include clearing battlefield obstacles and preparing fire positions.[5] Modifications Bulldozers have been further modified over time to evolve into new machines which can work in ways that the original bulldozer cannot. One example is that loader tractors were created by removing the blade and substituting a large volume bucket and hydraulic arms which can raise and lower the bucket, thus making it useful for scooping up earth and loading it into trucks. Other modifications to the original bulldozer include making it smaller to let it operate in small work areas where movement is limited, such as in mining. A very small bulldozer is sometimes called a calfdozer.[6] Some lightweight form of bulldozer are commonly used in snow removal and as a tool for preparing winter sports areas for ski and snowboard sports. Nevertheless, the original earthmoving bulldozers are still irreplaceable as their tasks are concentrated in deforestation, earthmoving, ground levelling, and road carving. Heavy bulldozers are mainly employed to level the terrain to prepare it for construction. The construction, however, is mainly done by small bulldozers and loader tractors. An armored Caterpillar D9 Bulldozer used by Israel Defense forces Some bulldozers, especially bulldozers in military usage, have been fitted with armor to protect the driver from enemy fire, enabling the bulldozer

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