CAT 552-4639 Sleeve Bearing

CAT 552-4639 is a Caterpillar genuine straight-tube steel-backed bronze sleeve bearing, suitable for the swing motor, hydraulic pump drive end, and gearbox planetary carrier of Cat 320D and 330D series excavators. It is used to withstand radial loads and low-speed oscillation conditions. The following is pure raw data and does not include replacement parts information.

Core Technical Parameters (Raw Data)

Item Details
Basic Attributes
Model 552-4639, Type: Straight cylindrical oil-free groove bushing (steel backing + bronze alloy liner), Material: Low carbon steel (SPCC, thickness 1.2 mm), Liner: Tin bronze (CuSn8P, thickness 2.0 mm, oil content 15%-20%), Single weight: 0.45 kg, Applicable shaft diameter: φ65 mm, Rated radial load: ≥60 kN, Limiting speed: 1500 rpm (oil-free self-lubricating), Operating temperature: -30℃ to +120℃, Lubrication method: Self-lubricating (can be supplemented with lithium-based grease), Assembly clearance: 0.015-0.025 mm, Protection level: IP54

Key Dimensions
Inner diameter: φ65 mm (tolerance +0.012/+0.008 mm), Outer diameter: φ75 mm (tolerance 0/-0.015 mm), Total length: 45 mm (tolerance…) ±0.15 mm), steel backing thickness 1.2 mm (tolerance ±0.05 mm), bronze liner thickness 2.0 mm (tolerance ±0.08 mm), end face perpendicularity ≤0.01 mm, cylindricity ≤0.01 mm, surface roughness Ra≤0.4 μm (liner inner surface)

Performance Parameters: Liner hardness HB85-95, coefficient of friction ≤0.12 (oil-free condition), wear rate ≤0.005 mm/1000 hours (rated load), compressive strength ≥250 MPa, shear strength ≥60 MPa, corrosion resistance salt spray test ≥72 hours without rust, compatible shaft surface hardness ≥HRC45

Structural and Performance Advantages: Steel backing + bronze liner composite structure: The steel backing provides high-strength support, and the bronze liner has self-lubricating properties, suitable for low-speed, heavy-load conditions where lubrication is inconvenient, reducing journal wear (Cat® Parts).

Oil-free design: Suitable for swinging applications such as rotary motors, preventing grease leakage. The bronze liner contains oil to meet short-term oil-free lubrication needs.

High-precision dimensional control: Inner diameter tolerance +0.012/+0.008 mm ensures reasonable assembly clearance, reducing operating noise and vibration.

Strong adaptability: Compatible with the rotary and hydraulic systems of excavators such as Cat 320D and 330D, compatible with various shaft diameter matching requirements.

Installation and maintenance points (raw data)

Installation: Clean the journal and bearing housing bore (free from oil, rust, and scratches). Cold press assembly (pressing force 30-40 kN, pressing speed ≤3 mm/s). The gap between the bushing end face and the housing end face should be ≤0.03 mm. After assembly, check the inner diameter (ensuring a gap of 0.015-0.025 mm). The coaxiality error should be ≤0.02 mm. Do not strike the bushing end face (use a special tooling for pressing).

Maintenance: Check assembly clearance every 800 hours (replace if exceeding 0.05 mm), replenish grease every 1500 hours (0.03-0.05 kg each time), avoid prolonged dry friction (continuous operation without oil ≤2 hours), and prevent foreign objects from entering the mating surfaces (clean the surrounding area regularly).

Troubleshooting: Overheating of the bushing is often due to insufficient assembly clearance; replace the bushing and adjust the clearance. Abnormal noise is often due to journal wear or foreign object ingress; clean the journal and replace the bushing. Excessive clearance is due to liner wear; the entire bushing needs to be replaced.