CAT 258-7574 BEARING AS

CAT 258-7574 is a tapered roller bearing assembly for Caterpillar loader/grader steering knuckles/drive axles. It integrates the inner and outer rings, rollers, and cage, and is suitable for heavy-duty articulations and transmission components. It is used to withstand combined loads and ensure rotational accuracy. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 258-7574, Type: Double-row tapered roller bearing assembly, Material: Bearing steel (GCr15SiMn), Outer/inner ring: integrally hardened, Cage: stamped steel plate, Single weight: approximately 3.8 kg, Operating temperature: -40℃ to +120℃, Suitable operating conditions: heavy-duty, medium-speed rotation, withstands radial and bidirectional axial loads.

Key Dimensions
Inner diameter: 100 mm, Outer diameter: 150 mm, Width: 42 mm, Roller large end diameter: 12 mm, Number of rollers: 28, Contact angle: 15°, Radial clearance: 0.10-0.15 mm, end face runout ≤0.02 mm, surface roughness Ra≤0.4 μm, tolerances conform to ISO 355 standard.

Compatible Models and Parts: Compatible with Cat 950K/966K loader axle hub bearings, 140M grader steering knuckle main bearings, and D7E bulldozer drive axle end bearings. One bearing per wheel, used for drive axle hub support, steering knuckle rotation positioning, and bearing radial and braking axial loads transmitted by the wheels.

Performance Parameters: Rated radial dynamic load 280 kN, rated radial static load 450 kN, rated axial dynamic load 100 kN, rated axial static load 200 kN, limiting speed 800 rpm, fatigue life ≥8000 hours, grease lubrication, Cat 2C-9600 recommended. Grease

Structural and Performance Advantages

Combined Load Bearing: Double-row tapered roller design simultaneously bears radial and bidirectional axial loads, suitable for composite stress components such as drive axles and steering knuckles. High overall component integration eliminates the need for additional inner/outer ring matching during installation, reducing assembly errors.

Precision and Durability: Overall quenching process ensures a hardness of HRC 60-64. A stamped steel cage improves roller guiding accuracy and reduces friction loss. A 15° contact angle optimizes load distribution and extends fatigue life, suitable for high-frequency start-stop and impact conditions in engineering machinery.

Easy Installation: Pre-adjusted clearance; radial clearance is set at the factory. Direct press-fit installation eliminates the need for on-site adjustments, saving maintenance time. Modular design reduces spare parts management costs and is compatible with common parts in various machine models.

Sealing Compatibility: A pre-drilled sealing groove on the outer ring accommodates 140×5 mm nitrile rubber oil seals, preventing grease leakage and the intrusion of dust and moisture, suitable for long-term use under harsh conditions.

Installation and Maintenance Points
**Before installation, clean the bearing housing and shaft diameter, removing burrs and oil stains. Check the dimensional tolerances of the mating surfaces (bearing housing inner diameter tolerance H7, shaft diameter tolerance k6). Use a hydraulic press-fitting tool to press the assembly into the bearing housing with a pressure ≤50 kN to avoid impact loads that could deform the assembly.**

Lubrication Specifications: Before installation, apply sufficient grease between the rollers and the cage, filling to 1/2-2/3 of the bearing volume. Replenish every 1000 hours, adding 1/3 of the initial fill amount. Do not mix different types of grease.

Tightening and Pre-tightening: Use M48×2 compatible nuts. Pre-tighten to a torque of 350-400 N·m. After pre-tightening, check the bearing’s rotational flexibility; ensure there is no jamming or abnormal noise, and the axial movement is ≤0.05 mm. Recheck the pre-tightening torque during the initial 20 hours of operation.