CAT 521-6757 BEARING–SEM

The CAT 521-6757 SEM bearing is a Caterpillar genuine heavy-duty spherical roller bearing (self-aligning type), suitable for the drive/travel systems of loaders, excavators, and other equipment. It is used in wheel hubs, gearboxes, or final drives, and can withstand heavy radial loads and bidirectional axial loads. It is compatible with misaligned installation and shaft deflection conditions, ensuring stable system operation.

(Caterpillar 521-6757 SEM bearing is a Caterpillar genuine heavy-duty spherical roller bearing (self-aligning type), suitable for the drive/travel systems of loaders, excavators, and other equipment. It is used in wheel hubs, gearboxes, or final drives, and can withstand heavy radial loads and bidirectional axial loads. It is compatible with misaligned installation and shaft deflection conditions, ensuring stable system operation.) Core Technical Parameters

Item Details
Part Model CAT 521-6757 SEM Bearing (Self-aligning Spherical Roller Bearing)

Material: Outer ring/inner ring/rollers are made of high-carbon chromium bearing steel, hardened (HRC 60-64); cage is made of stamped steel plate/copper alloy, impact-resistant and fatigue-resistant; seals are made of nitrile rubber, dustproof and leak-proof Cat®…

Key Dimensions: Inner diameter approx. 100-120mm, outer diameter approx. 180-200mm, width approx. 50-60mm, weight approx. 8-10kg (subject to actual product/manual), radial clearance C3 grade, suitable for heavy-duty conditions

Compatible Models: Loaders 950K/966K, excavators 320D/336D, bulldozers D6N/D7E, etc., used in wheel hubs, gearbox output ends, final drives, etc. (Cat)

Performance Characteristics: Self-aligning to compensate for installation misalignment / Shaft deflection; high load capacity suitable for impact conditions; surface hardening enhances wear resistance and lifespan; sealed design prevents contamination and extends lubrication intervals. Cat Core Functions and Structure: Heavy-duty load capacity and self-aligning: The spherical roller design can withstand large radial loads and bidirectional axial loads; a single-crack outer ring can compensate for ≤2° installation misalignment or shaft deflection, preventing roller jamming and premature wear.

Shock absorption and vibration suppression: The rollers and raceway curved surfaces disperse impact loads, reduce vibration and noise, protect the shaft system and housing, and are suitable for harsh operating conditions (Cat).

Sealing protection and lubrication retention: Integrated seals/dust covers prevent dust and moisture intrusion, reduce grease leakage, and extend maintenance intervals and bearing life.

Precise positioning and assembly interchangeability: Standardized dimensions ensure assembly accuracy and interchangeability, adapting to Caterpillar equipment maintenance and replacement procedures, and reducing downtime.

Installation and Maintenance Points

Installation Specifications: Clean the journal, bearing housing bore, and bearing to remove oil, rust, and impurities; check that the roundness, cylindricity, and surface roughness of the shaft/bore meet standards, and that there are no scratches/pits.

Use hot fitting (oil temperature 80-100℃) or cold pressing processes with specialized tooling for installation. Do not directly strike the outer/inner ring to avoid deformation or cracking; after installation, check the clearance and rotational flexibility for any jamming.

Add the specified grease (such as extreme pressure lithium-based grease) according to the equipment manual to ensure sufficient lubrication of the rollers and raceways. After assembly, recheck that the axial and radial clearances meet the standard (Cat).

Maintenance Recommendations: Every 1000-1500 working hours, check for abnormal noises, abnormal temperature rise, seal leaks, and loose bolts (Cat).

If pitting, outer ring cracks, seal failure, or excessive clearance is found in the rollers/raceways, replace immediately to avoid secondary damage to critical components such as the shaft system and housing.