Excavator Final Drive: Signs of Failure and Replacement Options

An excavator final drive is the hydraulic travel motor and reduction gearbox that turns the drive sprocket on each track. The main signs of a failing excavator final drive are a machine that pulls to one side, loss of travel power, grinding or whining from the hub, oil leaking around the sprocket and metal particles in the gearbox oil. If you see these, stop and check before it gets worse. When replacement is needed, quote your machine model, serial number and part number so the new drive fits first time.

What an excavator final drive does

Every tracked excavator has two final drives, one for each track. Hydraulic oil from the main pump drives a travel motor, and a planetary gearbox reduces that speed into the slow, high torque turn that moves the tracks. The sprocket bolts to the hub and drives the track. Sitting low down in mud, stones and water, it works in some of the harshest conditions on the machine.

Signs your excavator final drive is failing

Look and listen for these warning signs:

• The machine pulls to one side. If one track is slower or weaker when travelling straight, one drive may be losing power.
• Loss of travel power or speed. Struggling on slopes, or a two-speed machine that will not shift into high speed, can point to the motor.
• Noise from the hub. Grinding, knocking or whining from one side usually means worn bearings or damaged gears inside the gearbox.
• Oil leaks around the sprocket. Oil on the hub or sprocket often means the main seal (often called a floating or duo-cone seal) is failing and dirt can get in.
• Metal in the gearbox oil. Fine glitter or chunks on the drain plug or in the drained oil is a warning that something inside is wearing.
• Excess heat. A hub that runs much hotter than the other side after work deserves a closer look.

Quick checks before you replace an excavator final drive

Not every travel problem means a new final drive. Rule out the simple causes first:

• Check the gearbox oil. Check the level and condition at the hub plugs, following the operator’s manual. Deal with low oil or water in the oil straight away.
• Check track tension. A track that is far too tight puts extra load on the drive. Your manual gives the correct sag.
• Clear packed debris. Mud, stones or wire wrapped around the sprocket and rollers can slow a track and mimic a drive fault.
• Get the hydraulics tested. A hydraulic engineer can test pressures and case drain flow to show whether the fault is the motor, the gearbox or elsewhere.

Repair, new or used: your replacement options

Once a final drive is confirmed as faulty, owners usually choose between three routes:

• Repair or rebuild. Seals, bearings or gears are replaced in your existing unit.
• New replacement final drive. A complete new unit, either from the machine maker or an aftermarket supplier, bolts on in place of the old one.
• Used or reconditioned final drive. A tested drive from a specialist can get an older machine back to work. Ask about its history and warranty.

The right choice depends on the age and value of the machine, how quickly you need it working and the warranty on offer.

How to make sure the replacement fits

Drives that look alike can differ in small but important ways. Have these details ready:

• Machine make, model and serial number.
• The part number from the old drive or the parts book, plus any cross references.
• Whether the machine is single speed or two speed.
• The mounting bolt pattern on the frame and the sprocket bolt pattern.

This is the same information parts sellers on Plant And Tractor Trader ask for. On the final drive listings from Excavator Parts, prices are on application and buyers are asked to quote the machine model, serial number and part number when they enquire.

Excavator final drives and parts on Plant And Tractor Trader

You can browse final drives, idlers, track chains, tensioners and other parts in our excavator parts listings and the wider parts section. Examples include:

• Kubota KX022 final drive
• Kobelco SK30 final drive, part no. PM15V00012F1
• CASE CX50 final drive
• JCB 8030 final drive
• CAT 320D final drive

Replacing a drive is a good time to check the rest of the undercarriage, as a worn sprocket wears a new track faster. See the Hitachi ZX130 track tensioner, Hitachi ZX250-5 idler wheel and Hitachi EX165 track chain. If your mini digger runs on rubber, see our rubber track listings, our mini digger rubber tracks guide, or get a quote from Cheapest Rubber Tracks, who supply rubber tracks across mainland UK.

Looking for a whole machine instead? Browse used excavators and mini excavators, or read our guide to buying a used excavator. Sign up for stock alerts to hear when new parts are listed.

Selling excavator parts?

If you supply final drives, undercarriage or other parts, you can advertise on Plant And Tractor Trader in front of UK and Irish buyers. A single 8-week listing is £150 + VAT, or parts suppliers and dealers can list their full range on our unlimited listings plan for £100 + VAT a month.

Frequently asked questions

How do I know if my excavator final drive is bad?

The usual signs are the machine pulling to one side, weak or slow travel, grinding or whining from one hub, oil leaking around the sprocket and metal in the gearbox oil. Check the oil level and track tension first, then have the hydraulics tested to confirm whether the drive is at fault.

Can an excavator final drive be repaired instead of replaced?

Often, yes. If the fault is a leaking seal or worn bearings and the housing and motor are sound, a rebuild can be an option. If the motor or gears are badly damaged, a new or reconditioned replacement is usually the better route.

What information do I need to order a replacement final drive?

Have the machine make, model and serial number, plus the part number from the old drive or the parts book. Photos of the ports, bolt patterns and data plate also help.

Need help finding the right final drive?

Not sure which part you need, or want to list your parts? Send us a message on WhatsApp on 07470 093663 with your machine make, model and serial number, and we will point you in the right direction.