What to consider when buying an undercarriage?

Construction worker working outdoors with the project

Before you buy a car, there are probably lots of checks you will make before you decide it is the one for you. Unfortunately, fewer people pay as much attention when considering a tracked machine’s undercarriage, but they really should. The main benefits of tracked machines over wheels are their ability to operate in a wide range of conditions, so it is important to know that they are built to increase productivity. 

The undercarriage of a tracked vehicle is similar regardless of whether it is a bulldozer, excavator or loader, as the undercarriage is inside the track mechanism. The most common moving components include the links, pins, bushings, sprockets, rollers, idlers, shoes and the overall frame.

Here are four things you need to consider when considering the undercarriage on a tracked machine.

  1. Types of suspension systems

There are three types of suspension system, rigid, roller and torsion.

  • A rigid system, of course, is attached to the loader frame,
  • A roller system has suspended rollers to reduce vibration and sudden shifts
  • A torsion axle system allows the main frame move a little independently from an undercarriage.

Rigid systems have very low suspension, so that the effects of every single bump are transmitted straight to the operator. This has the potential to accelerate wear of the track, front wheel and undercarriage frame. On the plus side, this kind of machine tends to cost less up front than suspended systems due to its simple design and the limited amount of moving parts.

Full suspension systems like roller systems and torsion axle systems absorb a great deal of vibration before it reaches the operator or the attachment.

Operator Comfort: A more comfortable ride for the operator will be the major advantage of using a suspended system. There is less vibration and impact on the person in the seat. A loaded bucket also escapes some of the ups and downs experienced with a rigid system.

Long-term savings on maintenance: The rubber in the torsion bars reduces vibration which enhances the preservation of material and improves track life. It is expensive to replace tracks on any track loader so the savings on a torsion suspension machine over the lifetime of the machine can go up to thousands of dollars.

The disadvantage of the full-suspension systems is that they of course require a higher upfront cost than rigid systems.

  1. Open or closed design

Another factor to consider in an undercarriage is whether it has an open or closed design. 

Closed undercarriages need sealed designs because of their specific requirements for track tensioners, wheels and sprockets. This metal box protects components of the underside well. But it does allow the possibility that dirt, rocks or sticks which enter the box could speed up wear within the undercarriage. 

With more open undercarriage designs, debris falls away naturally during operation. Open designs are also lower maintenance to clean than closed designs because of how open they are. Open designs have been shown to be able to extend some parts ‘ service life by up to 50% in field tests. In addition, open undercarriages allow quick access to parts that can be replaced rapidly, like sprockets and bogie wheels.

  1. The track’s material composition

Tracked machines usually come with tracks in one of three materials:

  • steel-embedded
  • all-steel
  • all-rubber

Each one offer benefits and drawbacks according to the conditions in which it is used.

First of all, steel embedded carriages are made mainly of steel components: rollers made with steel fittings to move rubber tracks. Because of fewer moving parts, this type of track material boasts low maintenance and high durability. Several suppliers also offer all-steel paths to extend wear life in specialist applications. These heavier and more expensive stainless steel tracks are more suited to challenging work like demolitions and other work where other materials can damage the tracks. Our steel-embedded and all-steel tracks come with a 3 year/4000 hour warranty, which should give you an idea of the kind of durability steel can provide.

Some manufacturers produce tracks with fiber-reinforced rubber and industrial strength rubber and polyurethane. These are all-rounder tracks, ideal for a wide variety of conditions. There is no steel, too, which means no rust. When the time comes to replace the track, it is also easier to handle rubber, which is more flexible and is half the weight of stainless steel tracks. The downside is that rubber tracks inevitably wear out much quicker than steel or steel-embedded tracks. These tracks carry a 15 month/1500 hour warranty when bought from us.

  1. The drive system

Maintenance, operational costs and performance can also be affected by the type of drive system used on an undercarriage. Based on the type of tracks, manufacturers provide either external drive or internal drive sprockets.

External drive sprockets shift steel tracks using steel teeth, protruding through track holes. These systems could lead to drive torque passing through one or two rocket teeth simultaneously, accelerating tooth wear and generating stainless steel hooks which can lower track life. The operator must also replace the entire sprocket when the teeth have been worn down.

Internal drive sprockets, on the other hand, have replaceable steel rollers, which fit with molded rubber lugs in order to move rubber track designs. There’s no wear between rolls and track locks, and their replaceable sleeves mean that when specific rollers are worn down, operators don’t have to change the entire sprocket.

Remember, when buying a tracked machine, you should consider more than its horsepower or cab features. Just as important factor is the design of the undercarriage. Keep the above features in mind the next time you’re shopping for a tracked machine. Depending on your choices, this can have a massive impact on comfort, performance and your return on your investment.


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