CAT 521-7538 BEARING-SEM

CAT 521-7538 is a Caterpillar genuine SEM (Sealed Radial Roller) bearing, suitable for travel gearboxes, final drives, or hydraulic motors in heavy equipment such as excavators and loaders. It features double-sided sealing, heavy-duty vibration resistance, and is used for radial support and power transmission, ensuring stable operation of rotating components. The following are key information.

Core Technical Parameters

Item Details
Part Model: CAT 521-7538 (SEM Sealed Radial Roller Bearing, Single Unit)

Material: Inner/Outer Ring: GCr15 Chromium Bearing Steel (HRC 60-64); Rolling Elements: High Carbon Chromium Bearing Steel; Cage: Reinforced Nylon PA66; Seal: Nitrile Rubber (NBR)

Key Dimensions: Inner diameter approx. 70mm, outer diameter approx. 125mm, width approx. 31mm, sealing lip thickness 2.5mm, radial clearance 0.012-0.022mm, suitable for 70mm shaft diameter mounting positions

Single Weight: Approx. 1.32kg (2.91 lbs)

Compatible Models: Final drive gearbox, travel motor output end, wheel end axle support position of CAT 320D, 323D excavators, 950H, 966H loaders, etc.

Performance Characteristics: Double-sided NBR Sealed, dustproof, waterproof, and leak-proof, suitable for temperatures from -40℃ to +120℃; rated dynamic load ≥85kN, rated static load ≥98kN, vibration and impact resistant, suitable for heavy-duty continuous operation.

Structure and Core Functions

Sealing Protection: Double-sided NBR sealing lip + metal skeleton, blocking dust/mud and water, preventing grease leakage, suitable for dusty and humid working conditions, extending service life.

Heavy-duty Load Bearing: Hardened chrome steel and precision-ground raceways withstand radial loads and impacts from heavy equipment, preventing premature wear failure.

Stable Rotation: Nylon cage guides even distribution of rolling elements, reducing friction and vibration, ensuring rotational accuracy and transmission efficiency.

Pre-lubricated Design: Factory-pre-lubricated, no additional grease required after installation, simplifying maintenance.

Compatible Models and Application Scenarios

Compatible Equipment: Final drive gearboxes, travel motor output ends, and wheel end axle support positions for CAT 320D/323D excavators, 950H/966H loaders, etc. Core Applications: Provides radial support for rotating shafts, absorbs vibration and shock, prevents wear between shaft and housing, suitable for heavy-duty, dusty, and humid conditions, ensuring stable operation of the travel and transmission systems.

Installation and Maintenance Points
Installation Specifications: Clean the shaft diameter and bearing housing, ensuring no burrs or rust; cold-press installation, using a dedicated press to apply pressure to the inner ring; do not strike the outer ring/seals to avoid damage.

After installation, check the radial clearance (0.012-0.022mm). The bearing housing and shaft diameter fit tolerance should be designed according to H7/h6 to ensure accuracy and stability.

Maintenance Recommendations: Check the operating temperature every 1000 hours (stop the machine if it exceeds 80℃ or there is abnormal noise), and troubleshoot lubrication and installation issues.

During assembly overhaul, replace bearings and seals simultaneously, adding the corresponding type of grease to avoid old parts affecting assembly accuracy.

Avoid overloading, reduce impact loads, and extend bearing life.