This document discusses dragline excavators, which are large excavation machines used in surface mining and civil works. It describes the key parts of a dragline including the boom, bucket, and hoist and drag mechanisms. The bucket can hold 30 cubic meters of material and the boom length varies from 9-96 meters. Draglines have a long reach, require no auxiliary haulage equipment, and can excavate in soft rock, mud, and unstable conditions. They are well-suited for handling unconsolidated materials and excavating deep pits and box cuts. Walking draglines have a larger base area and require less power than stationary draglines, but they are slower.

1. “ACTIVE LEARNING ASSIGNMENT”
Advanced construction equipments
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Engineering
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Draglines

2.  Introduction
 Dragline is basically an intermittant excavator
 In our country there are only about 50 dragline
 It has longer reach and it requires no auxilary haulage equipment
 For softer rock dragline of capacity 6 -10 cubic meter is used
 Digging depth around 56m while the dumping radius 92m
 Improvement over shovel:
a) stripping into the under water
b) Works in muddy and unstable condition
c) Stripping soft ore
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3. Line diagram showing parts of Dragline
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4.  Parts of a Dragline:-
Bucket : Its capacity is 30 cubic meter
 Boom made of made of low alloy steel tubes or steel angles, length varies from
9m to 96 m
 Operator’s cab
 Fairlead
 Bucket hoist mechanism: concerned with raising and lowering of bucket
 Boom hoist mechanism :
a. Boom is lowered or raised by 4 part rope suspension system
b. The rope is coiled or uncoiled to the boom hoist rope which is operated by a
seperate motor
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5.  Parts of Dragline
c) In case of smaller dragline model the ropes are revved between sheaves at
the apex of the A frame and at the boom point
d) In case of a larger one the rope is revved between A frame apex and
sheaves at top of the mast
 Drag mechanism:-
a) One end of drag rope is connected to drag drum unit and the other end
connected to drag chain of the bucket by dragline yoke
b) Its purpose is to handle the bucket under control of the drag controlled
lever
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6.  Parts of Dragline
c) The drum is a split lagging type with grooves for the drag rope
d)An electrically controlled brake mounted over the pinion shaft
Bucket hoist mechanism
 Meant for raising and lowering the bucket:-
a) Motor provides power to the hoist drum via the gear box
b) Shaft of the gearbox are connected to the hoist drum
c) The hoist rope pasees round the A frame apex ,then over the sheave
mounted at top of the mast over the sheave at the boom point to the
dump sheave
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Engineering
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7.  Parts of Dragline:-
 The brake of boom hoist drum is electrically operated and is
air released type:
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8.  Parts of Dragline:-
 Boom unit:-
 It is of lattice and cross braced construction . Lower
end of the boom unit is connected to the revolving
unit
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Engineering
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9.  Merits of Dragline:-
 Used for handling softer unconsolidated material
 Can dig well above and below grade and can excavate deep box cut
 Greater digging depth and dumping radius
 It has more flexibility in operation
 Dragline boom length can be varied according to desire so it may or may
not require a disposal equipment
 Can negotiate gradient up to 12(degree) and ground pressure of 1-2kg/sqcm
 Presence of a hopper reloader helps in loading material onto belt conveyor
,rail wagon etc.
 Maintainance is cheap
 Superior in wet pits
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10.  Limitation of Dragline:-
 If the blasted rocks are of large lump causes insufficient
filling and bucket and drag rope wear rapidly
 Production cost more compared to shovel
 Lesser spottying ability
 Lesser output than powered shovel
 Bucket fill factor is less as compared to powered shovel
 Lesser efficiency than shovel
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11.  Walking Dragline:-
 MERITS:-
a) It produces low pressure because of its larger base area
b) Turning off the machine is easy and possible in less space
c) Requirement of power is less
d) It does not damage the ground
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12.  Demerits of Waking Dragline:-
 Time consuming
 Could cause damage to vital features such as power line etc.
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13. Gandhinagar Institute of Technology : Department of Civil
Engineering
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