CAT 257-2175 Tapered Roller Bearing

CAT 257-2175 is a Caterpillar single-row tapered roller bearing (including inner ring assembly + outer ring), suitable for the travel final drive, slewing gearbox, or transmission output shaft of excavators and loaders. It can simultaneously withstand radial and bidirectional axial loads, and is suitable for medium-heavy-duty and medium-speed operating conditions. The following is structured technical information.

Core Parameters (Professional Version)

Project Details
Basic Attributes Model 257-2175, Single Row Tapered Roller Bearing (303 Series), Separable Design (Inner Ring Assembly Separable from Outer Ring), Quantity 1 Piece Per Unit, Suitable for Cat 320D/323D Excavator Travel Motor Final Drive, 950GC Loader Gearbox Output Shaft, Bearing Radial + Bidirectional Axial Composite Load, Suitable for Medium Speed ​​(≤2500 rpm) and Medium-Heavy Load Conditions

Key Dimensions Inner Diameter 120 mm, Outer Diameter 260 mm, Width 68 mm, Taper Angle 12°30′, Roller Diameter 22 mm, Number of Rollers 24, Inner Ring Large End Diameter 150 mm, Outer Ring Raceway Diameter 238 mm, Clearance Grade C3 (Radial Clearance 0.12–0.16 mm), Suitable Shaft Diameter 120 mm, Seat Bore Diameter 260 mm

Material and Process Inner Ring / Outer Ring / All rollers are made of AISI 52100 chromium steel, integrally hardened to HRC60–64. The cage is made of stamped steel plate. The roller surface is carburized. The roundness of the inner and outer raceways is ≤0.005 mm, and the surface roughness Ra is ≤0.4 μm.

Performance parameters: Basic rated dynamic load Cr≈480 kN, basic rated static load Cor≈560 kN, limiting speed (oil lubrication) 2800 rpm, (grease lubrication) 1800 rpm, operating temperature -40℃ to +120℃, contact angle α=12°30′, axial load factor e≈0.35, fatigue life ≥8000 hours.

Compatible models: Cat 320D2/323D2 excavator travel final drive, 950GC/938K loader gearbox output shaft, matching bearing housing 420-5763, suitable for transmission systems with a shaft diameter of 120 mm. Pre-tightening is required during assembly (pre-tightening force…). (50–80 N・m)
Installation and Maintenance Points: Before installation, clean the inner ring assembly, outer ring, journal, and housing bore. The journal surface hardness should be ≥HRC58, roughness Ra≤0.8 μm, and housing bore roundness ≤0.01 mm, free of burrs and rust. The inner ring and shaft should have an interference fit (φ120 H7/k6), and the outer ring and housing bore should have a transition fit (φ260 J7/h6).

Cold pressing assembly: Use a special tooling to evenly press the inner and outer rings in, avoiding roller tilting or raceway damage. When installing in pairs, preload adjustment is required to ensure axial clearance ≤0.05 mm and end face runout ≤0.02 mm. Welding or heat fitting is prohibited (temperature >120℃ will cause material softening). After assembly, fill with Cat 106-9900 extreme pressure lithium-based grease (grease chamber volume 1/3–1/2). For oil lubrication, use ISO VG 68–100 gear oil to ensure adequate lubrication of the rollers and raceways.

Every 1500 hours, check the bearing temperature (≤80℃), vibration (≤0.2 mm/s), and clearance. Replace immediately if radial clearance >0.2 mm or if pitting or peeling appears on the roller surface to prevent transmission failure.