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The undercarriage of heavy earthmoving machinery, such as excavators, bulldozers, and loaders, includes several critical components that contribute to the machine's stability, mobility, and overall performance. 

Undercarriage Parts:

Track Frame

Provides structural support for the entire undercarriage and helps distribute the machine's weight evenly.


These provide traction and allow the machine to move over various terrains. Tracks help distribute the machine's weight over a larger surface area, reducing ground pressure and improving stability.

Track Chains

These are a series of interconnected links that hold the track shoes in place and help move the machine.

Track Shoes (Grousers)

Attached to the track chains, they make direct contact with the ground. Track shoes increase the surface area to provide traction and propel the machine forward or backward.


Idlers are stationary wheels at the front and rear of the tracks that guide and maintain tension on the track chain, preventing it from sagging and ensuring smooth movement.


Top Rollers (Carrier Rollers) Support the track's weight and help maintain its shape as it moves.

Bottom Rollers (Track Rollers) Support the machine's weight and allow the tracks to roll smoothly over the ground.


Sprockets, located at the rear of the track frame, engage with the track links and drive the chain by converting the machine's engine power into movement.

Track Tensioners / Adjusters

These hydraulic or mechanical devices maintain proper tension in the track chain, preventing it from becoming too loose or too tight, which can cause excessive wear or derailment.

Track Guards

Protect the track chain and rollers from debris and damage, helping to extend the life of the undercarriage components. Track guards are designed and proven to reduce wear on your tracks before you start having problems. Lucas Parts’ track guide will keep your tracks in place and prevent them from snaking and coming off.

Swing Bearing (Turntable)

In machines like excavators, the swing bearing allows the upper structure to rotate independently of the undercarriage, enabling 360-degree movement.

Final Drive

Transmit power from the engine to the sprockets by use of gear reductions providing the necessary torque to move the machine.

Hydraulic Motors and Pumps

Power the movement of the tracks. Hydraulic motors drive the final drives, which in turn move the sprockets and the tracks.

Bushings and Pins

Connect the individual track links and provide pivot points that allow the tracks to flex and conform to the terrain.

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