Undercarriage: Types, Components, Functions You Must Know!

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Undercarriage is an element that maintains the continuity of heavy equipment operations. This part also plays an important role in the repair process, often accounting for half or more of the total repair costs over the life of your machine.

In this TransTRACK article, we will present a detailed overview of undercarriage parts and terms.

What exactly is undercarriage?

Heavy equipment undercarriage components refer to a group of parts that support and move the machine, including tracks or wheels, and their associated elements. Its function has a crucial role in the performance, stability and service life of the tool.

An undercarriage is a supporting structure located beneath various types of vehicles, including excavator undercarriages, dozer undercarriages, cars, or tractor-trailers. Wheels or tracks are installed on or connected to these undercarriage parts to support the movement of your machine.

Undercarriage function

As the main part of heavy equipment, the undercarriage plays a very important role with a big impact on machine performance and efficiency. Let’s explore some of these crucial functions in more depth:

Power Delivery

The undercarriage functions as an intermediary between the engine and the ground, transmitting engine power to the ground through its components. This allows the machine to move and carry out its tasks. Undercarriage components work together to maintain efficient power flow, reduce friction and overcome resistance, ensuring the engine operates optimally.


The main function of the undercarriage is to provide mobility to heavy equipment such as Asphalt Paver or Vibro Roller. The undercarriage allows the tool to move on a variety of terrain, from flat surfaces to rough and rocky terrain. This enables operators to reach hard-to-reach work areas and perform a variety of tasks.

Productivity and Efficiency

The undercarriage affects the productivity and efficiency of the machine. A properly designed and maintained undercarriage can increase productivity by maximizing power flow and mobility, and reducing downtime due to repairs. An efficient undercarriage also reduces fuel consumption, operational costs and the environmental impact of machine operation.

Types of Undercarriage

Based on their design and role, undercarriages can be divided into two main types: Oval Tracks and Raised Sprocket Tracks. Let’s examine these two types in more detail:

Oval Track

Oval track is a type of undercarriage with an oval shape. As the name suggests, this track has a shape similar to a circle that is slightly extended into an oval. Generally, heavy equipment such as excavators and backhoes are equipped with this type of undercarriage.

Elevated Sprocket Track

Elevated Sprocket Track is a type of undercarriage which has the characteristic that the drive gear (sprocket) is placed in a higher position than other components. In this arrangement, the sprockets are not directly in contact with the ground surface, providing several important advantages.

The first advantage is that by maintaining a distance between the sprocket and the ground, it helps protect the sprocket from damage and wear that may arise from friction with rocks, mud, or dust. This means the sprockets have a longer service life and require less maintenance.

Components in Undercarriage

While there are slight variations in part design and arrangement depending on the manufacturer, here are some of the most common components found on your bulldozer’s undercarriage.

Track Links

It is formed of various elements such as links, pins, seals and sleeves which are connected together in different mechanisms with the help of flexible connectors. In fact, track links are the undercarriage component that has the most vital role because they represent 50% of the total undercarriage replacement costs.

Track Shoes

Track shoes are designed to provide traction and support the weight of heavy equipment on the ground. Diverse working conditions emphasize the importance of selecting appropriate footwear. A wise rule of thumb is to choose a slimmer shoe to ensure adequate flotation.

Shoes that are too wide are more susceptible to sagging, bending and cracking. They require more force to turn, which can affect maneuverability. Choosing the right shoe width will provide optimal performance and reduce overall system costs as much as possible.

Have you ever wondered why track shoes have holes?

This helps reduce “build-up” under the undercarriage and clears debris.


Transferring the drive load from the final drive through the sleeve, the track sleeve is then picked up by the drive gear and drives the track group through which the machine travels. Please remember that installing a chain link on a worn drive gear will only increase wear and shorten the life of the link sleeve.

Track Rollers and Carrier Rollers

Track rollers are responsible for supporting the weight of heavy equipment and regulating load distribution along the track. There are two wheel variants, namely those with two flanges and one flange, both of which function to support the weight of the bulldozer and maintain its height from the ground.

Meanwhile, the carrier rollers at the top aim to prevent looseness of the track. So that the life of the track wheels can be extended, it is best to avoid rotations that do not make a productive contribution.

Idler Wheels

Idler wheels are used to direct the track when entering and exiting the track wheels and provide a way to regulate slack and tension in the track.


Ultimately, the undercarriage components on heavy equipment have a very important role in maintaining the performance, stability and service life of the heavy equipment. Carrying out regular inspections, appropriate use, and maintenance efforts have a high level of importance in order to detect and resolve problems as early as possible. This aims to prevent large repair costs and ensure optimal performance. By allocating the right time and resources for undercarriage maintenance, heavy equipment owners are able to maximize machine productivity and efficiency which will ultimately lead to a more profitable return on investment.

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