The track roller, sometimes called a bottom roller or carrier roller, is part of the undercarriage system of an excavator. It supports the machine’s weight and guides the track as it moves over the ground. Excavators usually have two types of track rollers:
Bottom Rollers (Track Rollers) – support the weight of the excavator.
Top Rollers (Carrier Rollers) – support the upper track when it returns over the undercarriage.
Core Functions
Weight Support: Bears the entire weight of the excavator and distributes it evenly across the track chain.
Track Guidance: Guides the track chain and prevents lateral slippage (derailment).
Stability & Movement: Ensures smooth travel by reducing friction and vibration.
Wear Reduction: Minimizes wear on the track and other Undercarriage Parts.
Design & Construction
Material: Forged/cast high-strength alloy steel (e.g., 40Cr, 20CrMnTi).
Surface: Hardened to HRC 50–58 for wear resistance.
Internal: Contains precision bearings, high-performance seals, and long-life lubrication to block mud, water, and dust.
Flanges: Most are double-flanged to better handle side loads during swinging.
Location & Quantity
Position: Mounted below the track frame, in contact with the ground track.
Quantity: Typically 5–9 per side, depending on excavator size.
Difference from Carrier Roller (Top Roller)
Track Roller (Bottom): Supports the machine's weight, located at the bottom.
Carrier Roller (Top): Only supports the upper track to prevent sagging, located at the top
