CAT 539-2448 BEARING-NEED

CAT 539-2448 is a Caterpillar genuine single-row needle roller bearing with an inner ring (with cage, no seal), suitable for the gearboxes, travel motors, or hydraulic pumps of mini excavators and loaders. It is designed for high radial load capacity and impact resistance in confined spaces, and is suitable for medium-to-low speed heavy-duty applications. The following are the key specifications.

Core Technical Parameters

Item Details
Part Model: CAT 539-2448 (Single-row needle rollers with inner ring, stamped steel cage, no seal/dust cover)

Material: Inner ring + needle rollers are made of 52100 high-carbon chromium bearing steel, integrally hardened (HRC 60-64), hardened layer depth ≥ 1.0 mm; suitable for -40℃ to +120℃, compatible with oil/grease lubrication

Key Dimensions: Inner diameter 35 mm (1.378 in), outer diameter 52 mm (2.047 in), width 17 mm (0.669 in), needle roller diameter 3.5 mm, number of needle rollers 18, chamfer 0.5 mm

Single Weight: Approx. 0.185 kg (0.408 lbs)

Tolerances and Geometric Positions: Inner diameter tolerance m6 (+0.010/+0.002 mm), outer diameter tolerance… h6 (0/-0.016 mm), radial clearance C2 (0.005-0.012 mm), rotational accuracy P0
Load capacity: Radial rated dynamic load 28.5 kN, radial rated static load 42.8 kN, limiting speed 7500 rpm (oil lubrication) / 5200 rpm (grease lubrication)
Structure and core functions:
High-density load capacity: The slender needle roller line contact design minimizes radial space, providing high radial load capacity in confined areas such as the gearbox secondary shaft and the input shaft of the travel reduction gearbox, with strong resistance to impact and vibration.

Inner ring reinforcement: Features a built-in hardened inner ring, preventing direct wear of the journal, suitable for maintenance scenarios where journal hardness is insufficient or quick replacement is required, reducing shaft repair costs.

Easy assembly: The stamped steel cage evenly positions the needle rollers, eliminating the need for additional positioning fixtures during installation, suitable for batch maintenance, and shortening assembly time.

Stable and wear-resistant: Made of 52100 bearing steel with integral quenching, resistant to pitting and deformation. Suitable for continuous low-to-medium speed (≤3000 rpm) operation with oil/grease lubrication.

Compatible Models and Application Scenarios

Compatible Equipment: CAT 305.5E2/306E2 mini excavators, 906M/907M loaders, 420F2 backhoe loaders, and hydraulic pumps/motors for C3.6 engines.

Core Applications: Used for gearbox synchronizer support, travel motor reduction mechanism, hydraulic pump drive shaft bearings, and boom cylinder pin support. Suitable for confined spaces and radial heavy loads (≤25 kN).

Installation and Maintenance Points

Installation: Clean the journal and bearing housing bore, ensuring no burrs or oil contamination. The inner ring should have an interference fit with the shaft (0.010-0.018 mm). It can be heat-fitted to 70-90℃. Do not directly strike the end face.

The outer ring and bearing housing have a clearance fit (0.008-0.015 mm), and the coaxiality after press fitting is ≤ 0.04 mm to ensure uniform force on the needle rollers.

Maintenance
Lubrication: Use CAT HYDO 10 hydraulic oil for oil lubrication and NLGI Grade 2 lithium-based grease for grease lubrication. Add grease/change oil every 400-600 hours, with the oil level reaching the center of the bearing.

Inspection: Regularly monitor vibration and temperature. Stop the machine and inspect if the vibration speed exceeds 4.0 mm/s or the temperature exceeds 80℃. Replace the bearing immediately and inspect the journal/seat bore for wear if the clearance exceeds 0.12 mm.