tractor and related equipments like bulldozer

2. The earth moving equipment can
be broadly divided into two groups
 Excavating equipment
 Excavating and earth moving equipment

4. 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.

5. 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.

6. FACTORS FOR SELECTION
 1. The size required for a given job
 2. The kind of job for which it will be used
 3. 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 road
 7. The length of the haul road
 8. Finally, the type of work it will do after this job is
completed.

7. TYPES OF TRACTORS
Crawler 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.

8. COMPARISON BETWEEN CRAWLER
TRACTOR AND WHEELED TRACTOR
Crawler type
 Slow speed
 More compact and powerful and
can handle heavier jobs
 Costly
 Cost of operation and
maintenance is high
 Stick control for steering
 Moves on rough roads only
 Used for short distances
 Requires skillful operation,
maintenance and repairs
Wheeled type
 Greater speed
 Can handle only lighter jobs
 Cheaper
 Operation and maintenance cost
is less
 Wheel steering controlled
 Moves on rough as well as good
roads
 Used for longer distance
 Lesser skills required for
operation, maintenance and
repairs

10. RELATED EQUIPMENTS
The other related equipments are
 Scrapers
 Bull Dozers

11. 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.

12. Bull Dozer
 Commonly 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.

13. 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 MOUNTINGS
 Wheel mounted
 Crawler mounted
BASED ON THE CONTROL
 Cable controlled
 Hydraulically controlled

14. Applications
 For spreading the earth fill
 For opening up pilot road through mountainous and
rocky terrains
 Clearing construction sites
 Maintaining hawl roads
 Clearing land from trees and stems
 Backfilling trenches at constructions sites by earth
from one place to another.