CAT 8T-1989 69.84mm Inner Diameter Roller Bearing

CAT 8T-1989 is a Caterpillar genuine single-row tapered roller bearing (inner ring + roller assembly, outer ring not included), suitable for the gearbox output shaft, drive axle differential, and other components of CAT 330C/336D excavators and 966H loaders. Its core function is to withstand radial and bidirectional axial combined loads, ensuring smooth operation of transmission components and extending their service life (Cat®…).

Core Technical Parameters

Item Details
Part Model: CAT 8T-1989 Tapered Roller Bearing (Inner Ring Assembly), original part number 8T1989, requires matching with the corresponding outer ring (e.g., 8T-1990), no official direct replacement model

Material: High carbon chromium bearing steel (chromium content 1.5%), carburized and quenched, hardness HRC 60-64, roller surface ultra-precision ground to reduce friction and wear

Key Dimensions: Inner diameter 88.9mm (3.5in), outer diameter 120mm, width 35mm, number of rollers 16, cone angle 15°, suitable for corresponding output shaft and bearing housing

Compatible Models: CAT 330C/336D excavators, 966H/972H loaders, D7R bulldozers, etc., used in gearbox output shafts, drive axle differentials, steering knuckles, etc., subjected to heavy loads and impact conditions

Performance Characteristics: Rated radial load 120kN, rated axial load 65kN, limiting speed 3000r/min, operating temperature -40℃ to 120℃, possessing excellent impact resistance and wear resistance.

Core Functions and Structure

Combined Load Bearing: The tapered roller bearing design can simultaneously withstand large radial loads and bidirectional axial loads, adapting to complex stress conditions during equipment operation, such as torque transmission and axial movement control of gearbox output shafts.

Precise Positioning: Through the interference fit between the inner ring and the shaft, and the outer ring and the bearing housing, precise positioning of transmission components is achieved, reducing vibration and noise during operation and ensuring the stability of the transmission system.

High-Efficiency Friction Reduction: The line contact design between the rollers and the raceways reduces the coefficient of friction, reduces energy loss, improves transmission efficiency, and extends the service life of the bearings and related components.

Installation and Maintenance Points

Installation Specifications: Clean the surfaces of the bearing, shaft, and bearing housing, removing oil and metal filings. Check that the bearing is undamaged, the rollers rotate freely, and the fit tolerance between the shaft and bearing housing meets the requirements (interference between the inner ring and the shaft 0.01-0.02mm). Install the inner ring using the heat-fit method (heating temperature 80-100℃) to avoid bearing deformation caused by impact. After installation, check the bearing clearance (0.05-0.10mm) to ensure it meets the standard.

When installing the outer ring, ensure it fits tightly against the bearing housing. Tighten the bearing cap bolts in a diagonal sequence, and the preload torque should be as required by the machine model manual.

Maintenance Recommendations: Every 1000 working hours, check for abnormal noises, excessive temperature rise, and sufficient grease. If the bearing is worn or has excessive clearance, replace the inner and outer ring assemblies promptly.

Regularly replace the grease with CAT-specific lithium-based grease to ensure adequate bearing lubrication and prevent damage caused by dry friction.