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How Undercarriage Rollers Dictate the Performance of Your Equipment

How Undercarriage Rollers Dictate the Performance of Your Equipment

The right side of a compact track loader, focused on the track components

How Undercarriage Rollers Dictate the Performance of Your Equipment

Reading time: 6 min

While construction equipment comes in a wide variety of makes and models, there’s one thing all machines have in common—they’re heavy. With popular machines like excavators weighing up to 90,000 lbs., properly distributing a machine’s weight is a critical aspect of heavy equipment design.

In tracked heavy equipment like skid steers and excavators, rollers play a key role in facilitating the efficient distribution of a machine’s weight across its components. Tracked machines typically feature between eight and 10 rollers on each side of the undercarriage.

Rollers are attached at the top and bottom of a machine’s undercarriage. Each roller is affixed to an axel, allowing it to spin freely. A machine’s track chain is supported by its rollers, which help facilitate the smooth and even movement of the tracks.

In this guide, we’ll take a closer look at rollers and their importance in optimal machine performance. By understanding how these critical components impact performance, you can better care for your fleet and get the most out of your tracked heavy equipment.

Types of Rollers in Tracked Machinery

Tracked heavy equipment relies on two types of rollers—top rollers and bottom rollers—to support the machine’s weight and facilitate the movement of the tracks.

Top Rollers

Top rollers, sometimes called carrier or upper rollers, are located at the top of a machine’s undercarriage. These rollers are typically made from steel and have a cylindrical design with a bearing in the middle. Each top roller is mounted to an axle, which allows it to rotate freely about its center.

Most commonly, tracked heavy equipment features two top rollers on each side of the undercarriage. As a machine’s track chain rotates about the undercarriage, the top rollers support the track’s weight and help maintain proper tension. Top rollers do not support the weight of the entire machine, they only support the weight of the track chain as it rotates.

Bottom Rollers

Also called track rollers or lower rollers, bottom rollers have a similar design to top rollers. They are cylindrical-shaped, steel components that feature bearings. Unlike top rollers, which are mounted to the top of the undercarriage, bottom rollers are mounted to the bottom of the undercarriage.

Most machines feature six to eight bottom rollers on each side of the undercarriage. Bottom rollers support the entire weight of the machine, so having more of them helps distribute the machine’s weight evenly across a greater number of rollers.

As a machine moves, the bottom rollers help the undercarriage glide smoothly over the tracks. Bottom rollers help reduce the load placed on the sprockets and idlers, improving efficiency.

Roller Flanges

When shopping around for rollers, you may come across terms like “single flange,” “inner flange,” “double flange,” or even “triple flange.” While all rollers perform a similar function, they differ in the configuration of their flanges.

A roller’s flanges are round, ring-like ridges that protrude out from the roller’s cylindrical body. In some rollers, the flanges are situated to the inside, or center, of the cylinder body; these are called inner flange cylinders. In other rollers, called outer flange rollers, the flanges are situated at both ends or to the outside of the cylinder.

The type of rollers you need for your machine depends on its make and model. Your equipment’s service manual should indicate which type(s) of rollers to use and their optimal configuration. 

Keep in mind, it’s not unusual to use different types of rollers throughout the undercarriage. For example, it’s common to use both inner and outer rollers within a single undercarriage.

Functions of Rollers in Heavy Machinery

While the main job of rollers in heavy equipment is simply to roll, they have an outsized impact on a machine’s performance and efficiency. 

One primary function of rollers is to support and distribute the weight of the machine evenly, reducing ground pressure and lessening friction with the terrain. This weight distribution is vital for preventing excessive wear on the undercarriage components and ensuring efficient operation. 

Another critical function of rollers is maintaining even track tension. The top rollers, in particular, play a key role in keeping the track chain from sagging as it rotates around the undercarriage. 

Proper track tension ensures that the tracks remain securely engaged with the sprockets and idlers. The coordinated movement of rollers, sprockets and idlers prevents slippage, reduces wear and enhances the overall balance and stability of the machine. 

While rollers help reduce wear on undercarriage components, worn rollers can negatively impact the longevity of a machine’s tracks.  Misshapen or damaged rollers can result in excessive friction with the track chain, accelerating the rate of wear of both components. Therefore, frequently inspecting rollers and servicing them when necessary is a critical part of maintaining tracked machines such as excavators, bulldozers and track loaders.

Maintenance and Best Practices: Extending the Lifespan of Undercarriage Rollers

As an important part of undercarriage performance, it’s essential to keep your machine’s rollers in optimal condition. Like other components of the undercarriage, rollers require regular inspections, cleaning and lubrication, as well as adherence to certain operational best practices.

Regular Inspections of Rollers

Rollers should be inspected regularly, up to once per day during periods of heavy use. During inspections, pay careful attention to any signs of roller wear like loss of diameter, cracks, dents, or other deformities.

When rollers become worn down, resulting in a loss of diameter, it’s time for them to be replaced. For the best results, replace your machine’s rollers according to the intervals set out in its service manual.

Cleaning and Lubrication

When rollers become dirty or go for long periods without lubrication, excessive friction may result. This, in turn, can degrade the rollers over time, resulting in poor performance and possible side effects in other components of the undercarriage.

To prevent excessive friction in your machine’s rollers, clean them frequently and lubricate them according to the guidelines set in your equipment’s service manual.

Operational Best Practices

When operators are too hard on their machines, certain components take the brunt of the resulting damage. Since rollers are in direct contact with the tracks, they are particularly susceptible to aggressive operation.

To improve the longevity of your machine’s rollers, it’s important to avoid excessive speed, sudden direction changes and operating in abrasive terrain whenever possible.

Cost Analysis

While roller maintenance, including regular inspections, lubrication and timely replacement incurs some upfront costs, it is more cost-effective than the potential consequences of neglecting maintenance. 

These maintenance costs are predictable and can be budgeted for. Meanwhile, neglecting roller maintenance may lead to unforeseen costs related to machine failure, downtime, repairs and potential damage to other components.

Final thoughts

Rollers are an indispensable aspect of heavy equipment performance, specifically as they relate to the smooth operation of a machine’s undercarriage. Regular maintenance of these vital components will help your machine run smoothly and keep you from paying for the costly pitfalls of neglecting the undercarriage.

The EquipmentShare Shop is ready to help you get the most out of your heavy equipment. At the EquipmentShare Shop, you can find OEM and aftermarket undercarriage parts, including rollers, and get them shipped directly to your door. Don’t see what you’re looking for? Reach out to our parts experts and get personalized assistance.

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