When to replace the undercarriage

What the undercarriage consists of

• The track chain, to which the shoes are fixed with bolts and nuts.
• Track shoes, which provide traction and carry the machine.
• Bottom rollers (track rollers), which carry the weight of the machine on the chain.
• Top rollers (carrier rollers), which support the upper run of the chain so that it does not sag.
• The drive sprocket, which transmits drive to the chain.
• The track adjuster (recoil spring) with the idler, which keeps the correct track tension.

Signs of wear, part by part

The exact wear limits (permitted chain pitch, grouser height, roller diameter) are given by the machine manufacturer in the service documentation. Measure against it.

Why they are replaced as a set

The chain and the drive sprocket work as a pair. As the chain stretches, the sprocket teeth wear to match its pitch. A new chain on an old sprocket does not seat properly on the teeth, so both wear quickly and the chain may jump.

• Replace the chain and the drive sprocket together.
• Check the rollers when replacing the chain. A worn roller wears out the new chain.
• Wear on one part damages the others, so putting off one part usually makes the whole undercarriage more expensive.

If you are replacing only one part, tell us the condition of the others and we will assess together whether it pays off.

Track tension: regular checks

Incorrect tension is the most common cause of premature undercarriage wear.

• An over-tight track loads the pins, bushings, rollers and drive sprocket, so everything wears faster.
• A track that is too slack slaps, skips teeth and can come off.

1. Stop the machine on level ground.
2. Clean the mud and stones out of the undercarriage.
3. Measure the track sag at the point and in the way specified by the machine manufacturer.
4. Adjust the tension at the track adjuster, following the instructions.

On muddy or stony ground, check more often. Mud between the parts changes the tension and speeds up wear.

How to extend its life

• Clean the undercarriage after working in mud, especially in winter.
• Avoid unnecessary spot turns and long runs in reverse.
• On a slope, work so that the load is spread evenly over both tracks.
• Do not drive faster than needed on hard ground.
• Regularly check the shoe bolts and the rollers for leaks.

What to send in your enquiry

1. The make, model and serial number of the machine.
2. The number of chain links and the shoe width.
3. Photos of the drive sprocket, rollers and track adjuster.
4. A list of the parts you are replacing.

We supply undercarriage parts for machines of makes such as Caterpillar, Komatsu, New Holland and Fiat Hitachi. For an overview, see the Undercarriage page, and for mini excavators with rubber tracks see how to measure a rubber track.

Warranty

Undercarriage parts carry a 6-month warranty from the invoice date, provided they are fitted at an authorised service centre and no used parts or parts from other manufacturers are used alongside ours. Details are on the Warranty page.