CAT 8J-7650 Bearing-Roller

The CAT 8J-7650 is a Caterpillar original single-row tapered roller bearing, suitable for the gearbox output shaft, differential, and final drive system of Cat D8N and D8R bulldozers and some 980 series loaders. It is used to withstand radial and bidirectional axial combined loads. The following is pure original data and does not include replacement parts information.

Core Technical Parameters (Raw Data)

Item Details
Basic Attributes
Model: 8J-7650, Type: Single-row tapered roller bearing (including inner ring, outer ring, rollers, and cage), Material: Inner/outer ring: Chromium-molybdenum alloy steel (42CrMo, quenching hardness HRC58-62), Rollers: High-carbon chromium bearing steel (GCr15, quenching hardness HRC60-64), Cage: Stamped low-carbon steel (SPCC), Weight: 2.15 kg, Rated radial load: ≥180 kN, Rated axial load: ≥120 kN, Limiting speed: 2800 rpm, Operating temperature: -30℃ to +120℃, Lubrication method: Forced splash lubrication (compatible with SAE 85W-90 gear oil), Assembly clearance: 0.020-0.035 mm, Protection class: IP54
Key Dimensions
Inner diameter: φ65 mm (tolerance 0/-0.010 mm), Outer diameter: φ120 mm (tolerance…) 0/-0.018 mm), total width 35 mm (tolerance ±0.15 mm), roller diameter φ14 mm (tolerance ±0.02 mm), roller length 28 mm (tolerance ±0.10 mm), inner ring flange height 12 mm (tolerance ±0.08 mm), outer ring raceway cone angle 12°30′ (tolerance ±15′), cylindricity ≤0.008 mm, end face runout ≤0.010 mm

Performance Parameters: Dynamic rated load (C) 180 kN, static rated load (C0) 220 kN, coefficient of friction ≤0.0025 (oil lubrication), wear rate ≤0.003 mm/1000 hours (rated load), contact fatigue life ≥8000 hours, corrosion resistance salt spray test ≥96 hours no rust, compatible shaft surface hardness ≥HRC50

Structural and Performance Advantages: Chromium-molybdenum alloy steel material: inner/outer ring tempered + Hardened to HRC58-62, the rollers are made of GCr15 bearing steel, offering high wear resistance and fatigue resistance, suitable for heavy-duty impact conditions.

Single-row tapered roller design: Can simultaneously withstand radial and bidirectional axial loads, suitable for composite load-bearing components such as gearbox output shafts and differentials.

High-precision dimensional control: Inner diameter tolerance 0/-0.010 mm, outer diameter tolerance 0/-0.018 mm, ensuring reasonable assembly clearance and reducing operating noise and vibration.

Strong adaptability: Compatible with the transmission systems of Cat D8N and D8R bulldozers and 980 series loaders, compatible with high-speed rotation and heavy-duty conditions.

Installation and Maintenance Points (Original Data)

Installation: Clean the bearing and mounting hole (free from oil, rust, and scratches). Heat fitting (heating temperature 80-100℃, hold for 15 minutes) or cold pressing assembly (pressing force 80-100 kN, pressing speed ≤3 mm/s). Inner ring should have an interference fit with the shaft (interference 0.010-0.015 mm), outer ring should have a clearance fit with the mounting hole (clearance 0.005-0.010 mm), coaxiality error ≤0.02 mm. After installation, check the clearance (0.020-0.035 mm). Do not strike the bearing end face (use special tooling).

Maintenance: Check bearing clearance every 2000 hours (replace if it exceeds 0.06 mm), change gear oil every 2500 hours (to prevent oil contamination leading to bearing wear), avoid prolonged overload (loads exceeding 1.3 times the rated value can easily cause roller fatigue damage), and regularly check seals (to prevent foreign objects from entering the bearing).

Troubleshooting: Overheating of the bearing is often due to poor lubrication or abnormal clearance; replace the gear oil and adjust the clearance. Abnormal noise is often due to roller damage or foreign object ingress; the entire bearing needs to be replaced. Excessive clearance is due to raceway wear; the bearing needs to be replaced and the shaft and housing bore wear checked.