CAT 171-9421 BEARING

CAT 171-9421 (1719421) is a tapered roller bearing for Caterpillar’s travel mechanisms, suitable for the final drive/travel reduction gears of mini excavators. The following is purely accurate information (without additional description):

Core Parameters and Information

Item Details
Part Model: CAT 171-9421 Bearing

Part Type: Single-row tapered roller bearing (including inner ring, outer ring, rollers, and cage), used for radial and axial combined load support in the final drive/travel reduction gears

Material: Bearing steel (GCr15SiMn), inner and outer rings and rollers integrally hardened (HRC 60–64), cage is stamped steel plate, seals are nitrile rubber

Key Dimensions: Inner diameter approx. 40.00 mm (1.575 in), outer diameter approx. 80.00 mm (3.150 in), width approx. 22.00 mm (0.866 in), contact angle 12°

Structural Features Separable structure, the inner ring is separable for easy installation and clearance adjustment; features a contact-type double-lip seal to prevent dust and moisture intrusion.

Compatible Structures: Matches the final drive shaft and gearbox housing; used for the output end of the travel motor and the planetary gear support area.

Suitable Working Conditions: Heavy-duty, low-to-medium speed; suitable for dusty, muddy, and high-vibration outdoor working environments.

Compatible Models:
CAT 307B/307C/308C Mini Excavators (Travel final drive, gearbox support area)
CAT 305.5E/306E Mini Excavators (Travel mechanism, swing gearbox area)
CAT 247B/257B Compact Tracked Loaders (Travel drive shaft support area)

Installation and Fitting Points: The inner ring and shaft have a transition fit (interference 0–0.015 mm), and the outer ring and bearing housing have a clearance fit (clearance 0.012–0.028 mm) to ensure smooth and unobstructed operation.

Use a dedicated press-fit tool for cold pressing assembly; do not directly strike the inner and outer rings. Adjust the axial clearance to 0.02–0.04 mm during installation.

Before installation, clean the journal and bearing housing bores, removing burrs, rust, and impurities. Check the integrity of the seals.

Axially position the bearings using the end cap/lock nut to prevent movement. After installation, check for smooth rotation, no abnormal noise, and no axial movement.

Add the specified extreme pressure grease according to the model manual. After initial lubrication, check the lubrication status and replenish grease every 1000 working hours.