CAT 521-9963 BEARING–SEM

CAT 521-9963 is a Caterpillar single-row cylindrical roller SEM bearing, suitable for transmission components such as gearboxes and final drives in loaders and excavators. It is primarily designed to withstand pure radial loads under high-speed, heavy-load conditions and is suitable for impact and high-speed applications. It features high rigidity, low friction, and impact resistance, making it a key component for ensuring the efficient and stable operation of transmission systems. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 521-9963, Type: Single-row cylindrical roller bearing (SEM, with cage, separable inner ring), Material: Bearing steel (GCr15SiMn, quenching hardness HRC 60-64), Cage: Integral brass, Weight: Approximately 2.3 kg, Operating temperature: -40℃ to +120℃, Lubrication method: Grease lubrication (Recommended: Cat 5P-0960 extreme pressure lithium-based grease), Design life: ≥15000 hours (normal operating conditions)

Key Dimensions
Inner diameter: 90 mm (tolerance 0/+0.015 mm), Outer diameter: 160 mm (tolerance 0/-0.018 mm), Width: 30 mm (tolerance 0/-0.02 mm), Roller diameter: 14 mm, Number of rollers: 18, Radial clearance: C3 grade (0.025-0.045) (mm), chamfer size r2=2 mm, installation fit is shaft interference fit (0.01-0.02 mm), seat transition fit (0-0.01 mm)

Compatible Models and Parts: Compatible with Cat 966M, 972M loaders (transmission intermediate shaft), 320D2, 330D2 excavators (final drive input shaft), M320F wheeled excavators (drive axle half shaft), with matching 203-0711 retainer, 103-8329 elastic retaining ring, 5P-0960 grease, 4T-0512 oil seal

Performance Parameters: Basic rated dynamic load 128 kN, basic rated static load 152 kN, limiting speed (grease lubrication) 4500 r/min, allowable radial load ≥100 kN, coefficient of friction ≤0.0012, impact load ≥50 kN, recommended lubrication cycle 1000 hours (500 hours for heavy load conditions) (Hours)

Structural and Performance Advantages:
Single-row cylindrical roller structure, line contact load bearing, strong pure radial load bearing capacity, suitable for high-speed, heavy-duty components such as gearboxes and final drives. The separable inner ring design facilitates installation and maintenance, suitable for assembly scenarios with limited space.

Integral brass cage, even roller distribution, smooth operation, suppressing vibration and noise, suitable for high-speed conditions. The good thermal conductivity of brass effectively dissipates heat, preventing bearing overheating.

Bearing steel is hardened, balancing surface hardness and core toughness, providing strong fatigue and impact resistance, suitable for frequent start-stop and large load fluctuation conditions, extending service life.

Installation and Maintenance Points:
Before installation, clean the inner and outer rings, journal, and bearing housing, checking for rust and burrs. Measure the journal and inner diameter, and the bearing housing and outer diameter to ensure the interference fit meets requirements. Use specialized tooling for press-fitting. Do not strike the inner ring to prevent cage deformation and roller damage.

After installation, rotate the shaft system to check for any jamming or abnormal noise. Adjust the radial clearance to the C3 range, and add sufficient grease (filling 1/2 to 2/3 of the bearing cavity). Install the oil seal and retainer to ensure reliable sealing.

Maintenance: Check the bearing temperature, clearance, and lubrication condition every 1000 hours. If the temperature exceeds 80℃, the clearance exceeds 0.06 mm, or the grease deteriorates, replace the bearing immediately. When replacing bearings, they must be replaced in pairs at the same shaft end; mixing bearings of different models or brands is prohibited.