CAT 521-9956 BEARING-SEM

CAT 521-9956 SEM is a Caterpillar genuine single-row tapered roller bearing assembly (SEM is the specification/batch identifier) ​​used in the drive axle differential/wheel end of loaders, excavators, and other equipment to withstand heavy radial and unidirectional axial loads. The following is pure raw data and does not include replacement parts information for Cat®…

Core Technical Parameters (Raw Data)

Item Details
Basic Attributes Model 521-9956 SEM, Type Single Row Tapered Roller Bearing, Material High Carbon Chromium Bearing Steel (GCr15), Weight 3.2 kg, Operating Temperature -30℃ to +120℃, Fitting Shaft Diameter 90 mm, Rated Radial Load 58 kN, Rated Axial Load 32 kN, Limiting Speed ​​2200 rpm, Lubrication Method Grease/Oil Lubrication Compatible

Key Dimensions (Metric/Imperial) Inner Diameter 90.0 mm (3.54 in), Outer Diameter 150.0 mm (5.91 in), Width 35.0 mm (1.38 in), Number of Rollers 22, Roller Taper Angle 15°, Inner and Outer Ring Fit Tolerance P5, Radial Clearance C2 Group

Performance Parameters Inner and Outer Ring Hardness HRC 61-65, Roller Hardness HRC 62-66, Surface Roughness Ra≤0.04 μm, cage material is stamped steel plate, suitable for working pressure 0-25 MPa, impact load capacity ≥120 kN.
Structure and Adaptability Characteristics:
Heavy Load Bearing: The tapered roller structure can simultaneously withstand radial and unidirectional axial loads, suitable for heavy-duty parts such as drive axle differentials and wheel ends, distributing shaft loads, avoiding local stress concentration, and improving operational stability.

Precision Adaptation: Factory pre-adjusted clearance and tolerances, directly adaptable to specific machine drive axles without additional adjustments, ensuring assembly accuracy and operational reliability, suitable for dusty and vibrating conditions.

Wear Resistance and Sealing: High-carbon chromium bearing steel is quenched, with high surface hardness and wear resistance. The stamped steel plate cage has high strength, suitable for harsh working conditions, preventing contaminant intrusion and extending bearing life.

Compatible Machine Models and Application Scenarios:
Loaders: 950M, 966M, 972M, etc.

Excavators: 320GC, 323D2, 336GC, etc.

Application Scenarios: Drive axle differential, wheel end supports, adapted to the travel system, ensuring efficient power transmission during equipment travel and operation, and withstanding complex loads during vehicle travel and operation.

Installation and Maintenance Points (Original Data)

Installation: Clean the shaft diameter and bearing housing bore, ensuring no scratches or rust on the surface. Shaft diameter fit tolerance k5, bearing housing bore fit tolerance H6.

Use the hot-fit method (oil temperature 80-100℃) to avoid impact that could deform the bearing. After installation, check the end face runout to ≤0.04 mm.

After installation, add lithium-based grease (NLGI 2) as specified, ensuring sufficient lubrication. Run under no-load for 5-10 minutes; check for any jamming or abnormal noise.

Maintenance: Check the bearing’s operating condition every 2000 hours. Replace immediately if the temperature rise exceeds 45℃ or abnormal noise occurs.

Check the grease condition every 500 hours. Clean the grease filler nozzle before adding grease to prevent contaminants from entering the bearing.