Question

Q. a) Explain in detail various financial aspect of procuring construction equipment.

     b) Discuss Rimpull and Drawbar pull in detail.

Answer 1

a) The various financial aspect of procuring construction equipment are-

1. Availability of fund

2. Capacity of equipment

3. Function of equipment’s

4. Availability of projects works

5. Cost of an equipment’s

6. Offer of loans by banks

7. Availability of expert operator

8. Running cost of equipment

9. Maintenance cost of equipment

10. Type of fuel and lubricants

Factors affecting selection of construction equipment are-

1.Economic factor

Economic factors such as the cost of owning the equipment and operation and fuel costs are some of the most important factors that play a deciding role in selecting the equipment. Besides, consideration over resale value is also very important.

2.Factors specific to companies

The selection of construction equipment also depends on the need of the company.

If the company has a lot of projects available in hand for the coming few months or even years then it definitely makes sense for it to invest in the heavy construction equipment’s.

3.Factors specific to the jobsite

Both ground as well as climatic conditions at the site also affect the selection of equipment used.

For example, if the soil and overall terrain at the jobsite and nearby surroundings define selection of construction equipments.

4.Factors specific to the equipment

Construction equipment’s are always very costly.

So,the standard equipment which are manufactured in large numbers by various manufacturers and whose spare parts are easily available are preferred by the companies.

The hape and size of the equipment is also an important factor.

The bigger the equipment then more the investment and other considerations.

5.Project timeline considerations

Project deadlines also affect the selection of the equipment.

If there is limited time available to complete a project, then companies may prefer to use highly advanced construction equipments that can reduce a project’s completion time significantly.

6.Labour considerations

It also affects the selection decision.

If there is a shortage of manpower at the jobsite then the companies always opt for highly automated machines.

(b) Rim pull and Drawbar pull

  

Rim pull is the usable power at the point of contact between tire and the ground for a wheel machine.

Drawbar pull is the available usable power which a crawler tractor can exert on a load that is being towed.

The difference between rim pull and drawbar is a matter of convention. Both drawbar pull and rimpull are measured in the same units like Pounds or Newtons .

In both the cases pull are subject to adequate traction being developed .

In mechanical process of developing rimpull or drawbar pull there are some power losses.

For both of these, tests are done on a level surface with your given operating terrain.

The results which we get in sand would be very different than on cement and very different from what you will get in snow.

To measure drawbar pull you can tie a rope to the center rear of the vehicle near where a hitch would go and attach the other end of the rope to an adjustable load.

This adjustable load can either be a programmable load like particle brake or actual physical weights that are added.

At basic level this will tell you how much the machine can pull.

In practice we look for the the amount of slip exhibited by the wheels for different loads.

In order to do this we need to have an independent way of determining machine position.

This is done with a long string potentiometer or a total station.

Rim pull is harder to measure in most of the cases.

The easiest way measure if a force sensor is integrated into the machine to measure force on the wheel.

Other way to do this is to drag a wheel through your desired surface and measuring those forces on the wheel as opposed to on the machine itself.