LD COLLEGE OF ENGINEERING

Sub :- Advanced Construction & Equipments

Topic :- Excavating Equipments

Prepared By :- Makwana Tulsi 130280106052

Excavating Equipments :

excavation + equipments The act of digging An instrumentality

needed for an undertaking or to perform a service

Types of excavating equipments:-

Power shovels

Draglines

Hoes

Clam shells

Trenching machines

POWER SHOVELS:- Primarily used to excavate and load into hauling vehicles. Size,indicated by size of dipper(in ). sizes Bank measure volume. 4 less than loose vol. of soil. 5 The reason is swelling.(25%) Applications : For excavating above its own track. Heavy cutting and loading in all types of soil.

Basic parts:

Hoist lineBoom

axis of rotation Bucket Cab Crawler mounting

Types of power shovel:

Crawler mounted. Low travel speed.On soft grounds. Wheel mounted. High speed.On hard ground.

Conditions for operation: Large open pit , floor must be well drained , haul road must be well. Angle of swing 90°. Optimum depth.

Output / production(: Output = Production cycle: Factors affecting output :

Class of material Job conditions Height of cut. Size of hauling unitsAngle of swing Haul unit exchangeManagement conditions Operator’s skill

Load bucket Swing with load Dump load Return7 - 9 secs 4 – 6 secs 2 – 4 secs 4 – 5 secs

DRAGLINES : Named : Its prominent operation of dragging the bucket against the material to be dug. Capacity – Size of the bucket (). Applications :

Digging softer material & below its tracks.

It has long reaches. Mostly used in excavation of

canals and depositing on embankment without hauling equipments.

Basic parts :

Hoist cable Hoisting cable

Crane boom Gantry Hoist Chain Drag Cable Cab Drag Chain Crawler Bucket Mounting

Factors affecting the output: Size and type of bucket (0.38 to 3.06 )

Light bucket – loose,dry.Medium – clays,compacted gravel.Heavy – hard materials

Length of crane boom (50,60 and 70 ft) Type of material Angle of swing Depth of cut Working conditions,maintainance Size of hauling unit Operator skill

Types of draglines : Crawler mounted - Low travel speed,soft ground, large projects Wheel mounted - high travel speed,firm ground & scattered job Truck mounted - high travel speed,firm ground & scattered jobs Walking draglines

Output : Output = dragline capacity × C × F where C = cycles/hr

F = correcting factor

Advantages Disadvantages Can work from the ground surface

while shovel has to be taken into the pit.

Hauling equipments need not to go in the pit.

Excavated material disposed in one operation.

High range than shovel.

Less digging force. As the boom length increases the

bucket size must be decreased. Output is less than shovel.

HOES : Machine of power shovel group. Used generally to excavate below the natural surface resting on.

Parts :

Bucket cylinder stick cylinder cab boom dipper cylinder stick Bucket boom(dipper)

Applications : Though not efficient as shovel. Most suitable for digging below the machine level. Levelling and loading. Used to trim the surface.

Points for Selection of hoe : Maximum Excavation depth. Maximum Working radius. Maximum dumping height. Hoisting capability.

Factors affecting output : Excavation depth. Most affective digging when boom stick is at 90 to boom. Max. output when excavation near machine. Optimum depth.(50 to 60% of max digging depth)

Advantages Disadvantages Hoe exert greater tooth pressure than

shovel due to direct pull. Due to rigidity superior than draglines. Superior to trenching machines when

the side banks are allowed to have natural slope.

Not efficient as shovels. Slow in working when dumping in

hauling machines. Liable to fall.

CLAM SHELLS :

The name the machine is derived from the shape of its bucket.

The shape of bucket is that of the shell hinged at the top which can be closed and opened in two parts.

Selection depends largely on the requirement of the job.

Crane

Clam shellBucket cabin

Bucket : Consists of two shells with hinged at the

top and provided with sharp edges at the bottom.

Heavy types of buckets with sharp cutting edges are used for hard soils and light buckets with plane edges for loose soil.

Used mostly in lifting the heavy rock pieces.

Sometimes more than two jaws are used for lifting large sized particles.

Shell Shell

Hinge

Hoist line

Sheaves

brackets

Effective use : Unit must be on level ground. Bucket teeth should be sharp. Dumping distance = digging distance. In soft soils teeth should be removed.

Output/production of clam shell : Production = capacity() × C × F C = cycles/hr

F = correction factor

Factors affecting the output : Height of lift. Angle of swing. Method of disposing. Operator’s skill.

Applications : Used for loose materials such as crushed stones. Main function is to vertical lifting of material from one place to another. Digging and dumping in vertical plane. Accurate dumping. Charging and removing the materials from a stock pile,cofferdams,etc.

TRENCHING MACHINES : Excavate all type of soils except rocks. Mostly crawler mounted.

Applications : Excavating trenches for water,oil,gas pipes,sewers & telephone cable . Deepening of existing drainages. Used where control on depth and width is required. Fast digging. Reduces the cost of hand finishing.

Types of trenching machines :Wheel type : Consists of power driven wheel

mounted with number of removable buckets with teeth.

They can cut trench of width upto 30 to 150 cm.

Maximum cutting depth 2.5 – 3 m. Have greater digging speeds. For narrow trench in firm soil this

type is suitable.

Ladder type :

Consists of two endless chains which travel along the boom and the buckets equipped with teeth are attached.

Sometimes side cutters are attach to increase the width of the trench.

The conveyer belt disposes the excavated soil on the either side.

Maximum cutting width upto 360 cm. Maximum cutting depth 9.0 to 10.0 m. Digging speed is 30 m or more.

Vertical boom type : Modified of ladder type. Trench width ranges from 40 to 70 cm.

Points taken care while selecting the type :Type of soil. ObstructionsDepth and width of the trench. Right of way for disposal of earth.Amount of work. Topography of the area.Water table. Climatic conditions

Comparison between different types of excavating equipments :

Items Power shovel Hoe dragline Clam shellExcavation in hard soil or rock

Good Good Not good Poor

Excavation in wet soil or mud.

Poor Poor Moderate Moderate

Distance between footing and digging.

Small Small Long Long

Loading efficiency. Very good Good Moderate Precise but slow

Footing required. Close to work Close to pit Fairly away from pit

Fairly away from pit

Digging level Digs at or above footing

Digs below footing

Below footing Digs at or above footing

Cycle time Short Slightly more than shovel

More than power shovel

More than others

Example : (GTU May/June 2012) Determine the cost of production in terms of rupees/. Excavating equipment : Hoe with 1.51 having cycle time of 16 sec and operating factor 55 minute/hr.Cost 3500/hour. Material : good common earth with swell of 20% and fill factor of 0.85. Hauling units : trucks 8.5 capacity operating factor 50 minutes/hour and having

round trip time 22 mins.Cost 400/hour. Solution : Equipment type : hoe Bucket capacity : 1.51 Cycle time : 16 sec Fill factor : 0.85 Swelling : 20 % operation factor : 55 min / hour

Ideal hour output:no of cycle = = = 225 cycles

Ideal hourly output () : 225 × 1.51 = 340 Probable hourly output = 340 × operation factor × fill factor × swell

= 340 × (50/60) × 0.85 × (1/1.20) = 220.76 Cost 3500/hr Cost of excavation / = 3500/220.76 = 15.85 / Hauling cost/ : output /hour = 8.5 × 50/22 = 19.32 cost Rs. 400/hr Hauling cost/ = 400/19.32 = Rs. 20.70/ Total cost of excavation and hauling = 15.85 + 20.70 = Rs. 36.55/

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