1. Undercarriage
• Undercarriage is the system of self
propulsion of construction
equipment to travel from one
place to another place.
• It converts the rotating motion of
wheels or crawler tracks into linear
motion of construction equipment.
2. Undercarriage
• It should be wear resistance to overcome
high impact load and severe wear condition
during travelling over metal to metal ,working
over mud, hard gravel, hard stone etc.
• The large surface area of the tracks distributes
the weight of the vehicle better than steel or
rubber tyres on an equivalent vehicle due to
which it can easily travel in soft or muddy
ground .
3. Undercarriage construction
• The aggressive treads of the tracks provide
good traction in soft surfaces but can damage
paved surfaces.
• Special tracks that incorporate rubber pads
can be installed for use on paved surfaces to
prevent the damage that can be caused by all-
metal tracks.
16. Undercarriage construction
1. Rear wheel (sprocket) drive 2. Track 3.Return
or carrier rollers 4. Front drive wheel
(sprocket) 5.Road wheels 6. idler
17. Main components of Undercarriage
1. Track frame 2. Equalizer bar 3. Drive sprocket
4. Front idler 5. Track rollers 6. Carrier rollers
7. Track chain assembly 8. Track Roller Guards
1. Track frame : It is steel structure box shape
and withstands severe shocks, bending ,
deformation and breakage. It houses various
other components of undercarriage.
18. Main components of Undercarriage
2. Equalizer bar : It is a beam of steel plates used
to distribute the weight of front portion of the
machine equally to the two track frames.
3. Sprocket or sprocket wheel : it is driven by
engine power or hydraulic motor in
hydrostatic drive . It drives endless track chain
to run construction equipment.
19. Main components of Undercarriage
4. Front idler: It supports the front end part of the
track chain to allow the track to roll straight over
rough ground. It maintains track tension tight
enough to keep sufficient engagement of the
sprocket wheel with track.
5. Track rollers : They are attached to the track
frame and guide and support the lower half of
the track chain for proper rolling and distributing
equal load of construction equipment.
20. Main components of Undercarriage
6. Carrier rollers: They are attached to the upper
part of the track frame and guide and support
the upper half of the track chain for proper
rolling and it prevents dangling (slack) due to
its weight.
7. Track chain assembly : They consist of joining
links, pins, bushings, mounting track shoes
etc. They are driven by sprocket to travel
construction equipment on various roads.
21. Main components of Undercarriage
Track chain assembly : They support the weight
of equipment. They also provide well grip to
ground and penetrate soil to its full depth for
a good traction and protect against side
slippage under most conditions.
8. Track Roller Guards: They protect track rollers
damaged by rocks and debris and prevent
track from slipping.
