Rubber Tracks, Idlers, Rollers & Sprockets: Undercarriage Parts Guide for Compact Track Loaders & Mini Excavators

The undercarriage is where a compact track loader or mini excavator earns its keep — and where it quietly eats money if wear goes unchecked. Tracks, idlers, bottom rollers, carrier rollers and drive sprockets all wear as a system, so a problem with one part shows up as damage on the others. This guide covers how each component works, what failure looks like, how to read a track size, and a reference list of common OEM part numbers for Bobcat, Caterpillar, Kubota, Takeuchi, Case, John Deere, JCB and Yanmar machines.

How the Undercarriage Works as a System

• Rubber track – the belt that carries the machine. Internal steel cords give it strength; the lugs give it grip.
• Drive sprocket – mounted to the final drive, its teeth engage the track's lugs and pull it around.
• Front (and rear) idlers – guide the track at each end of the frame and, together with the tensioner, set track tension.
• Bottom rollers – carry the machine's weight along the length of the track.
• Top / carrier rollers – on machines that have them, support the upper run so the track doesn't sag onto the frame.

Because every piece touches the track, a worn sprocket or seized roller will chew through a brand-new track far faster than normal. That's why most technicians inspect — and often replace — sprockets, idlers and rollers at the same time as tracks.

Why Rubber Tracks Are Worth Getting Right

Compared with steel tracks or tires, rubber tracks spread the machine's weight over a larger footprint. That means better flotation in mud and sand, more traction on slopes and loose material, a smoother ride for the operator, and far less damage on lawns, pavers and finished concrete. The trade-off is that rubber is less forgiving of neglect: incorrect tension, sharp debris, and worn running gear all shorten its life.

Warning Signs Your Tracks Are Done

• Lugs that are torn, chunked or worn close to the carcass
• Cracks running across the tread or along the edges
• Visible steel cords — once they're exposed, moisture corrodes them and the track can snap
• Track that keeps stretching and needs constant re-tensioning
• Repeated de-tracking, especially when turning
• Cuts or gouges in the sidewall
• One side wearing faster than the other (often a sign of roller, idler or alignment trouble)

How to Read a Rubber Track Size

Rubber tracks are sized with three numbers: width × pitch × number of links. For example, a 320 × 86 × 52 track is:

• 320 – track width in millimeters
• 86 – pitch, the center-to-center distance between drive lugs, in millimeters
• 52 – the number of links (drive lugs) around the track

The size is usually molded into the inside or sidewall of the track. If it's worn off, measure the width, measure pitch across several lugs and divide, and count the links. Two tracks can share a size but use different guide-lug patterns, so always confirm against your machine's make, model and serial number before ordering.

Compact Track Loader Rubber Track Reference

OEM reference numbers below are for cross-reference only. Many models were offered with more than one track width or tread option, so verify by serial number.

Bobcat CTL Tracks

Caterpillar CTL Tracks

Kubota CTL Tracks

Takeuchi CTL Tracks

Case and John Deere CTL Tracks

Mini Excavator Rubber Track Reference

• Bobcat (E16, E17, E19, E20, E35, E45, E50, E55, E85, X320, X331 and others): 6988832, 7259427, 6673949, 6652044, 6666927, 6688373, 6672773, 6672774, 7274253, 6667026, 6678826, 7304043. We stock the 400x72.5x74 track (6678826) for Bobcat 341, 435, E45, E50 and E55.
• Caterpillar (303, 305E2, 308E2 CR): 153-5982, 415-5189, 465-9223
• Kubota (K008, K008-3, KX018-4, KX019-4, KX121-3, KX161, KX41, U45): RA021-22210, RG158-22310, 90561-41155, 90561-41150, RB511-22312, RD118-22310, RD411-22313
• Takeuchi TB145: see our 400x72.5x74 narrow track.

Idlers: When to Replace

Idlers steer the track and hold tension, so a failing idler usually shows up as tracking problems before anything else. Replace when you see:

• Flanges worn thin or sharp
• Wobble or noise from a failed bearing
• Oil weeping from the seals
• Flat spots on the rolling surface
• Track tension that won't hold even after adjustment

Common OEM idler numbers:

• Bobcat: 7187172, 7109408, 6815109, 7136982, 6693238, 6693237, 7233630, 6697933, 6698049, 7199074, 7229101, 7240006, 7303552
• Case: 47378988, PX52D00022P2
• John Deere: 9269094
• Kubota: RA011-21302, V0521-24900, RB511-21340, V0521-22902
• Takeuchi: 03414-02500, 03714-00002, 04614-90010, 08801-40000, 08801-40300, 05614-00600 — plus the 0881131300 rear idler for TL10, TL12, TL140, TL150, TL240 and TL250 we carry.

Bottom Rollers: When to Replace

Bottom rollers carry the full weight of the machine. A single seized roller drags against the inside of the track and can wear a groove through it in a surprisingly short time. Replace when:

• A roller won't spin freely or has seized
• The bearing is loose, noisy or has play
• Seals are leaking oil
• The rolling surface is worn, grooved or out of round

Common OEM roller numbers:

• Bobcat: 7020867, 7153331, 6692966, 7012275, 7243576, 7148527, 7136983, 6815111, 6815123, 6815127, 7165324, 7013581, 7013576, 7013575, 7004843, 7009226, 7011072, 7228629, 7233399, 6698047, 6693239, 6689371. Shop our 6689371 bottom roller for Bobcat T190, T200, T250, T300, T320, T550, T650, T750.
• Case: PS64D01001F1, PX64D00013F1, PS64D00005F1, KAA1160, 47378992
• Caterpillar: 422-0838, 127-3806, 333-5602, 386-0791, 389-7624, 348-9647
• John Deere: 4718355, 9237948, FYD00008528, FYD00004165, 4671711
• Kubota: RA025-21700, RA231-21700, RG248-21900, RC788-21700, RB511-21702, V0511-25104
• Takeuchi: 04312-00500, 08801-35100, 08811-31300, 08801-35600, 08801-30000, 08811-30500, 04313-11100, 04113-00400, 05613-07100
• Yanmar: 772637-37300, 172478-37500

Drive Sprockets: Inspect Every Time You Change Tracks

A worn sprocket is the fastest way to ruin a new track. As teeth wear, they lose their original profile and stop meshing cleanly with the track lugs. Look for:

• Teeth that are hooked or curled in the direction of travel
• Pointed, knife-edge tooth tips
• The track jumping or skipping teeth under load
• New tracks wearing unusually fast at the drive lugs

Common OEM sprocket numbers:

• Bobcat: 7111447, 6726052, 7165111, 7165109, 6736306, 7166679, 7204050, 7270159, 6715821, 7196807, 7009231, 6801584, 7199006, 7199007, 7199008, 6587308, 6816209, 6813372, 7008133. We stock the 6715821 sprocket for Bobcat 864, T200, T250 and T300.
• Case: 87460888, PY51D01006P1, PV51D01003P1
• Caterpillar: 304-1870, 304-1916, 260-6341, 294-8262
• JCB: 232/21201, 233/21201
• John Deere: T254141, 2054262, 2055869
• Kubota: RA111-14430, V0511-21110, V0611-21112, 68198-14430, RD411-14430, 68621-14430, RD118-14430
• Takeuchi: 08811-60110, 08821-60010, 06816-00009, 06916-00011, 08801-66210, 04216-00100, 05516-00120, 03516-08210

Tips to Make Your Undercarriage Last Longer

• Check tension often. Too tight overloads bearings and sprockets; too loose leads to de-tracking. Follow the sag spec in your operator's manual.
• Clean it out daily. Packed mud, rock and debris add tension and grind components — especially if it freezes overnight.
• Turn gradually. Counter-rotating and sharp pivot turns on abrasive surfaces tear lugs and stress the guide lugs.
• Avoid curbs and rebar. Climbing edges and running over sharp steel is the leading cause of cut cords.
• Replace as a set. Pairing new tracks with worn sprockets or rollers cuts the life of the new track.
• Use the right grease in the track adjuster — a quality NLGI #2 lithium or moly grease holds up to the pressure — and check the adjuster seal for leaks.

Get the Right Undercarriage Parts from JD Lift Parts

JD Lift Parts supplies aftermarket rubber tracks, bottom rollers, idlers and sprockets for compact track loaders and mini excavators alongside our forklift and heavy equipment parts — priced below dealer rates and shipped fast, because we know downtime costs more than parts. Not sure which part fits? Send us your make, model and serial number and we'll help confirm fitment before you order.

Part numbers are listed for cross-reference only. Brand names are used for identification and do not imply OEM affiliation. Always verify fitment with your machine's serial number.