The undercarriage is the tracked base of a crawler excavator, the part that carries the whole machine and lets it move and turn on its two steel or rubber tracks. It is made up of the track chains and shoes, the rollers, the front idler, the drive sprocket and the track tensioner, all working together to spread the machine’s weight and drive it forward. On a tracked excavator the undercarriage takes the hardest punishment of any system, and it can eat up close to half of the machine’s lifetime repair bill. Knowing its parts and how to look after them is one of the simplest ways to protect your investment.

Last updated: July 2026

What is the undercarriage of an excavator?

The undercarriage of an excavator is the lower running gear on which the machine sits and travels. On a crawler (tracked) excavator this is the pair of tracks and everything inside them; on a wheeled excavator the job is done by tyres and axles instead. This guide is about the crawler undercarriage, which is what most Indian excavators, from a 2-tonne mini to a 20-tonne machine, run on.

Its two jobs are simple. First, it spreads the heavy weight of the machine over a large area so the excavator does not sink into soft ground. Second, it turns the engine’s power into movement, driving the tracks so the machine can crawl, climb and turn. Everything above it, the cab, engine and digging arm, is called the upper structure, and it swings on top of the undercarriage. To see where it sits among all the other parts, read our guide to excavator components and how they work.

What are the main parts of an excavator undercarriage?

An excavator undercarriage is built from a set of wearing parts that work as one system. When people say a machine “needs undercarriage work”, they usually mean one or more of these have worn out. Here is what each does.

Part What it does
Track chain The loop of steel links, pins and bushings that forms the track and carries the machine forward
Track shoes (grouser plates) The wide plates bolted onto the chain that touch the ground and give grip; the raised ridge is the grouser
Track (bottom) rollers The small wheels under the frame that carry the machine’s weight and keep the track in line
Carrier (top) rollers The wheels on top that support the upper run of the track and stop it sagging
Front idler The large wheel at the front that guides the track and, with the tensioner, keeps it tight
Drive sprocket The toothed wheel at the rear, driven by the travel motor, that pulls the track and moves the machine
Track adjuster (recoil spring) A grease-filled cylinder and spring that sets track tension and absorbs shocks
Final drive / travel motor The hydraulic motor and gears that turn the sprocket on each side

Steel tracks are used for hard, rocky and heavy digging work. Rubber tracks are used on mini excavators and on surfaces that must not be damaged, like finished roads and paved yards. The shoe width also matters: narrow shoes bite hard ground for traction, while wide shoes float better on soft, marshy or sandy sites. You will find more on tracked machines in our guide to crawler excavator types, specs and applications, and the full family in our types of excavators guide.

Why does the undercarriage wear out so fast?

The undercarriage wears fast because it is in constant contact with the ground, grinding against soil, sand, stone and grit all day. Every one of its parts is a metal surface rubbing against another metal surface, with abrasive material forced in between. That is why it is a set of wear parts, made to be replaced over the machine’s life, not to last forever.

The cost is real. Manufacturers and fleet owners often say the undercarriage accounts for up to half of an excavator’s total repair spend over its life, and a big share of daily running cost. The good news is that a large part of this wear comes from how the machine is used and maintained, rather than its age alone, so an owner has real control over the bill. Two excavators of the same make and hours can show very different undercarriage wear, and the difference is almost always the ground they worked and the hands that ran them.

How do you maintain an excavator undercarriage?

You maintain an excavator undercarriage mainly by keeping the track tension correct, cleaning off packed mud daily, and checking the parts for wear before they fail. None of this needs special tools, and it saves large sums over the years.

  • Clean the tracks every day. Packed mud, clay and stones force the parts apart and grind them down. Clear the undercarriage at the end of each shift, especially in the monsoon and in sticky black-cotton soil.
  • Keep the track tension right. A track that is too tight wears the pins, bushings and sprocket quickly and steals engine power. Too loose, and the track can slap, jump off or damage the rollers. Set it to the machine’s specified sag and check it often.
  • Check for wear regularly. Look for worn grousers, cracked shoes, oil leaking from a roller or final drive, and shiny worn spots. Catching a small problem early stops it from wrecking a bigger part.
  • Drive gently. Avoid spinning the tracks, turning constantly on one spot, and travelling fast over rock. Climb slopes straight up, not across. Rough operating habits are the single biggest cause of early undercarriage wear.

Fresh operators cause most of the damage, so a little training pays back fast. Our overview of excavators and how to run and own them covers the wider maintenance picture.

How do you know when the undercarriage needs replacing?

You know the undercarriage needs work when the wear parts reach the end of their measured life or start to fail on the job. Signs include tracks that keep coming loose however much you tension them, loud clicking or grinding while travelling, teeth worn thin on the sprocket, oil weeping from a roller or final drive, and the machine pulling to one side.

Dealers measure the exact remaining life with wear gauges on the chain, shoes, rollers, idler and sprocket, and give a percentage worn for each. This lets you plan and budget the replacement instead of being caught out by a breakdown mid-project. Parts can often be changed one at a time as they wear, which spreads the cost. Because pricing depends on the machine, the make and the parts, undercarriage components are quoted on request by the dealer rather than carried as a fixed catalogue price; always take a written quote before approving the work.

Does the undercarriage differ between mini and large excavators?

Yes. The undercarriage scales with the machine, and the parts and their cost grow quickly with size. A mini excavator around 2 to 5 tonnes usually runs on rubber tracks with a light undercarriage, kind to finished surfaces and cheaper to replace. A 20 to 21-tonne excavator, the workhorse size on Indian sites, runs on heavy steel tracks built for rock and hard digging, and its undercarriage parts cost far more.

The machine prices below show how the size classes sit, and the undercarriage cost roughly follows the same order.

Class Undercarriage Example model & indicative price (as of July 2026)
Mini (about 2 tonne) Rubber tracks, light XCMG XE20U, Rs 20–22 Lakh
Mid (about 21 tonne) Steel tracks, heavy SANY SY210C-9, Rs 51–57 Lakh
Mid (about 20–21 tonne) Steel tracks, heavy Tata Hitachi EX 210, Rs 60–65 Lakh

For the trade-offs between tracked and wheeled machines, see our comparison of wheeled vs crawler excavators, and for the smaller class our mini excavator guide.

Ready to see machines for your work? Browse the full range of excavators and prices and connect with a dealer.

Undercarriage care is the cheapest way to protect an excavator

The undercarriage is the one system where a small daily effort makes the biggest difference to lifetime cost. Clean tracks, correct tension, a trained operator and early checks can add years to the parts and cut the machine’s biggest repair bill. When it does come time to replace parts, take a proper wear reading and a written quote, and change parts as they wear rather than all at once where you can.

If a new machine is on your mind, spreading the cost is common; you can weigh the options through construction equipment finance. Compare live excavator models and prices and talk to a dealer about the right size for your ground conditions.

Disclaimer: Prices, specifications and features are indicative, vary by variant, location and date, and should always be confirmed with the official OEM or authorised dealer before any purchase decision. DesiMachines is not liable for decisions taken on the basis of information that may have changed after publication. Price figures are taken from our listings at the time of writing (July 2026).