Carrier roller: Also called top roller / upper roller, one main part of undercarriage.
Function of Carrier Roller：It supports the upper track chain, keeps track tension, prevents track sagging and deviation, fits for excavator, bulldozer, crawler crane.
Carrier Roller – Material & Mechanical Properties
1. Main Raw Materials
Shell / Roller Body
Cast steel: ZG35Mn, ZG40Mn, ZG50Mn
Forged steel: 50Mn, 40SiMnTi, 45# steel
Shaft：
45# steel, 40Cr, 42CrMo
Bushing & Seal
Bushing: Copper alloy / high-strength iron-based alloy
Seal: Nitrile rubber (NBR) / PU / floating oil seal
2. Mechanical Properties (Standard 50Mn / 40SiMnTi Roller)
Surface quenching hardness: HRC 52–58
Depth of hardened layer: 4–8 mm
Shaft hardness: HRC 28–36
Tensile & Yield Strength
Tensile strength: ≥ 750 MPa
Yield strength: ≥ 500 MPa
Elongation: ≥ 9%
Impact Toughness
Impact value: ≥ 30 J/cm²
Good wear resistance, impact resistance, anti-fatigue
3. Key Performance Characteristics
High wear resistance for long working life
Good impact resistance for rough terrain
High surface hardness with tough core (anti-crack)
Good sealing performance, dust-proof & water-proof
Stable lubrication, low friction, no easy oil leakage
