CAT 3B-3911 12.7mm Bore Diameter Needle Roller Bearing

The CAT 3B-3911 is a Caterpillar genuine single-row tapered roller bearing, suitable for small to medium power engines and engineering machinery transmission components. It can withstand combined radial and unidirectional axial loads, ensuring stable operation of gearboxes, drive shafts, and other similar components. The following are key information.

Core Technical Parameters

Item Details
Part Model: CAT 3B-3911 (includes inner ring/outer ring/roller/cage; some applications require matching bearing housing rings)

Material: High-carbon chromium bearing steel; inner and outer rings and rollers are quenched and tempered; surface is coated with an anti-rust coating; cage is made of stamped steel plate.

Key Dimensions: Inner diameter approx. 50.8mm (2.00in), outer diameter approx. 112.71mm (4.4375in), width approx. 29.37mm (1.156in); tapered angle adaptable to combined load transmission.

Single Weight: Approx. 1.45kg (3.2 lbs)

Compatible Models: CAT 3054 engine camshaft, 307 excavator slewing gearbox, 904B loader gearbox second axle, small road roller drive axle, and other small to medium power transmission components.

Performance Characteristics: Single-row tapered roller design, capable of withstanding radial and unidirectional axial loads, suitable for small to medium load conditions; operating temperature… -40℃ to +120℃, impact and vibration resistant, long fatigue life.

Structure and Core Functions

Combined Load Transmission: The tapered rollers and inner and outer raceways form a tapered contact, enabling simultaneous transmission of radial and unidirectional axial loads. Suitable for complex stress conditions in engineering machinery transmission systems, preventing axial movement of components.

High-Precision Stable Transmission: Made of carburized and quenched bearing steel with a surface hardness of HRC 60-64, the rollers and raceways have line contact, ensuring uniform load distribution, reducing vibration and noise, and guaranteeing power transmission accuracy.

Compact Design: The cage is made of stamped steel plate, with a compact structure suitable for space-constrained small to medium power transmission components, while ensuring stable roller operation and extending bearing life.

Suitable Scenarios and Installation/Maintenance Points

Suitable Scenarios: Primarily used in small to medium power transmission components such as the camshaft support of the 3054 engine, the slewing gearbox of the 307 excavator, the second axle of the 904B loader gearbox, and the drive axle of a small road roller. Suitable for small to medium loads and low to medium speed operation, ensuring smooth component operation.

Installation Specifications

Before installation, clean the journal and bearing housing bore to ensure there are no burrs or rust. The journal tolerance should be controlled within f6, and the housing bore tolerance within H7. The fit clearance should conform to the machine model specifications.

Use a dedicated press to smoothly press in the bearing. Do not strike the inner or outer rings to prevent damage to the rollers and raceways. During installation, pay attention to the bearing orientation, ensuring the large end of the roller faces the load direction to guarantee load-bearing capacity.

Adjust the preload according to the machine model requirements. Avoid over-tightening, which can cause overheating; avoid under-tightening, which can cause vibration, affecting bearing life and transmission accuracy.

Maintenance Recommendations
Check the bearing’s operating condition every 1500-2000 working hours. Monitor temperature and noise to determine if there are any problems such as wear or poor lubrication. Replenish or replace grease/oil as needed.

Replace the bearing immediately if roller peeling, raceway pitting, or excessive clearance is found to prevent transmission failure due to component failure. Spare parts must be stored in a sealed container to prevent moisture or impurities from entering.