Question

Q. a) Enlist excavating equipment. Draw a neat sketch and explain working of any two excavating equipment.
   b) Write short note on
i) Crawler Tractor.
ii) Wheel Tractor.

Answer 1

a)

Excavation equipment:

These are widely used in construction projects. They are basically self driven and are opted for varoius earth moving operations. Some excavating equipments are listed below.

• Black hoe
• Drag line
• Trenching machines
• Power shovel
• Clam shell
• Tower cranes
• Graders
• Bulldozer

Power shovel

It is used for excavating the earth upto a specified depth and loading it into the truck. It is also known as stripping shovel or electric mining shovel. Bucket capacity of power shovel ranges from 8 m^3 to 80m^3. All type of earth can be excavated other than hard rock using this equipment.

Basic parts are cabin, cables, boom, boom foot pin, saddle blocks, bucket, boom point shades etc.

Several main motions of different basic parts helps in the working of the powet shovel.

• Hoist cable : it helps in pulling the bucket through the material which was dug.
• Crowd : this is important during positioning of the dump by moving the dipper handle out into the control of the depth.
• Propel: this motion is used while moving the shovel into different depths and raising the bucket to a desired height.
• Swing: while rotating the shovel between digging and dumping, swinging motion is employed.

The output of power shovel is expressed as :

Measuring capacity of the dipper×3600/ cycle time(secs)

Dragline

It is used in exacavation and dumping operations. It is mainly deployed on de-coaled area for side casting. There are various methods of working such as simple casting, extended bench method, continous bench and horse.

Extended bench method

The overburdened bench is dumped by the dragline into the decoaled area to extend the dragline bench. Now the previous space is levelled by dozing it and now the dragline moves into the second position on the dumped overburdened bench. The distance between the 1st and 2nd position is increased considerably by the extended cut method. With the increase in this distance, the capability of the dragline increases in dumping the overburdened bench to a greater distance into a decoaled area. As a result of which sliding is minimized.

b)

Short note.

Crawler tractor:

As the name suggests this engineering vehicle runs on tracks and are also known as track laying vehicle. It is extremely useful for working on soft, low pressure , friction less surface such as mud and snow. The primary advantage of this tractor is that it covers large surface area and exerts less pressure on the ground. It is extremely beneficial in farming operations where the soil suffer from compactions. Sometimes they are equipped with blades and are then called bulldozers, used for irrigation and construction operations.

Wheel tractor

This is a heavy engineering equipment which is mainly used for earth moving. The hopper in the rear part is vertically placed with a front edge. It is mainly used for cutting the soil. The hopper can be raised when it is full with soil and then it is transported to a lower fill area. It is very efficient in areas where the cutting and filling areas are closely located. Wheel tractors generally have two engines for driving the front and rear wheels. Various types of wheel tractors are there such as open bowl tractor, auger, pull type pusher, elevating scrapper etc.