TRACTORS AND RELATED EQUIPMENTS

The earth moving equipment can be broadly divided into two groups

Excavating equipmentExcavating and earth moving equipment

CONSTRUCTION MANAGEMENT AND PLANNING

ASSIGNMENT

Tractor:

Tractor is an engineering vehicle specially designed to deliver a high tractive effort or torque at slow speeds for the purpose of hauling a trailer or machinery used in construction.

These are multi purpose machines used mainly for pulling and pushing the other equipments or heavy loads.

They are also used for agricultural purposes.

Tractor Uses:

Primary purpose is to pull or push loads,Also used as mounts for many types of

accessories There are types and sizes to fit almost any

job for which they are usable.

FACTORS FOR SELECTION 1. The size required for a given job 2. The kind of job for which it will be used3. The type of footing over which it will

operate 4. The firmness of the haul road 5. The smoothness of the haul road 6. The slope of the haul road7. The length of the haul road 8. Finally, the type of work it will do after

this job is completed.

TYPES OF TRACTORSCrawler Tractors: Usually rated by size or

weight and power. The weight is important on

many projects because the maximum tractive effort that a unit can provide is limited to the product of weight times the coefficient of traction for the unit and the particular road surface, regardless of the power supplied by the engine.

Most manufacturers make crawler tractors with some or all models.

Wheel Tractors: Either two-wheel or four-wheel. One of the primary advantages of a

wheel tractor compared with a crawler tractor is the higher speed that may exceed (50 km/hr).

In order to attain a higher speed a wheel tractor must sacrifice pulling effort.

Because of lower coefficient of traction between rubber tires and soil surfaces, the wheel tractor may slip its wheels before developing its rated pulling effort.

COMPARISON BETWEEN CRAWLER TRACTOR AND WHEELED TRACTOR

Crawler typeSlow speedMore compact and powerful

and can handle heavier jobsCostlyCost of operation and

maintenance is highStick control for steeringMoves on rough roads onlyUsed for short distancesRequires skillful operation,

maintenance and repairs

Wheeled typeGreater speedCan handle only lighter jobsCheaperOperation and maintenance

cost is lessWheel steering controlledMoves on rough as well as good

roadsUsed for longer distanceLesser skills required for

operation, maintenance and repairs

RELATED EQUIPMENTS

The other related equipments are

ScrapersBull Dozers

Scrapers

scrapers have an important position in the earth moving field.

It is a unique machine for digging and long distance hauling.

It is a self-operating machine.The wheels of the machine cause some compaction. The

ability of these machines to deposit the loads in uniformly thick layers facilitates the succeeding spreading operations.

They are classified as Crawler -tractor- pulled and wheel- tractor- pulled, depending on the type of tractor used to pull them.

The basic parts of scrapers are bowl, apron and tail gate and ejector.

Bull DozerCommonly used in construction projects. It is a heavy steel blade mounded on the front

of the tractor. The tractor can be of Crawler or Wheeled

type. The heavy blade attached to the tractor

pushes the materials from one place to another.

CLASSIFICATIONS BASED ON POSITION OF BLADES

Bull dozers with blades perpendicular to the direction of movement

Angle dozers in which the blade is set an angle with the direction of movement.

BASED ON MOUNTINGSWheel mountedCrawler mounted

BASED ON THE CONTROLCable controlledHydraulically controlled

ApplicationsFor spreading the earth fillFor opening up pilot road through

mountainous and rocky terrainsClearing construction sitesMaintaining hawl roadsClearing land from trees and stemsBackfilling trenches at constructions sites by

earth from one place to another.