CAT 629-4085 Seawater Pump Ball Bearing

CAT 629-4085 is a Caterpillar original single-row deep groove ball bearing specifically designed for seawater pumps. It is compatible with Cat C18 marine generator auxiliary seawater pumps and Cat 3516B/3512C marine main propulsion engine seawater cooling pumps. It is used to withstand radial loads and isolate seawater corrosion. The following is raw data and does not include information on replacement parts (Cat® Parts).

Core Technical Parameters (Raw Data)

Item Details Basic Attributes Model 629-4085, Type Single Row Deep Groove Ball Bearing (with Metal Dust Cover + Fluororubber Seal), Material Inner/Outer Ring Martensitic Stainless Steel (440C, Seawater Corrosion Resistant), Rolling Element Ceramic Ball (Si₃N₄, Density 3.2 g/cm³, Low Coefficient of Thermal Expansion), Cage PA66+GF30, Seal Ring Fluororubber (FKM, Seawater/Oil/Chemical Media Resistant), Single Weight 0.28 kg, Applicable Shaft Diameter φ35 mm, Rated Radial Load ≥42 kN, Rated Axial Load ≥12 kN, Limiting Speed ​​3600 rpm (Grease Lubrication), Operating Temperature -30℃ to +180℃, Lubrication Method Lifetime Sealed Lubrication (Filled with Polyurea Grease, Dropping Point ≥250℃), Protection Rating IP68 (Seawater Immersion Depth ≤10 m, No Leakage for 24 Hours), Assembly Clearance 0.008-0.015 mm

Key Dimensions: Inner diameter φ35 mm (tolerance +0.008/+0.002 mm), outer diameter φ72 mm (tolerance 0/-0.015 mm), width 17 mm (tolerance ±0.10 mm), sealing lip thickness 1.2 mm (tolerance ±0.1 mm), dust cover thickness 0.8 mm (tolerance ±0.05 mm), ball diameter φ8 mm (tolerance ±0.003 mm), clearance C2 group (0.005-0.012 mm), roundness ≤0.005 mm, cylindricity ≤0.008 mm

Performance Parameters: Hardness: Inner ring/outer ring HRC 58-62, ceramic ball HV 1500-1800, coefficient of friction ≤0.0015 (grease lubrication), rated life ≥30000 Hours (rated load cycles), corrosion resistance: ≥500 hours salt spray test with no rust, impact resistance ≥300 g (11 ms pulse), insulation resistance ≥100 MΩ (500 V DC)

Structural and performance advantages

440C stainless steel + ceramic ball combination: Double resistance to seawater corrosion; ceramic balls reduce frictional heat, suitable for high-speed and corrosive conditions of seawater pumps.

FKM seal + metal dust cover: Double protection to prevent seawater and sediment from entering the bearing, suitable for harsh marine environments.

Lifetime sealed lubrication: Polyurea-based grease is anti-emulsifying, preventing seawater ingress and lubrication failure, reducing maintenance frequency.

PA66+GF30 cage: High strength + aging resistance, suitable for high-frequency start-stop conditions of seawater pumps, preventing cage breakage.

Installation and Maintenance Points (Original Data)

Installation: Clean the pump shaft and bearing housing bore (free from salt scale/oil/impurities). Assemble using the cold pressing method (pressing force ≤ 20 kN, pressure head coaxiality ≤ 0.01 mm). Press-fit the inner ring (stainless steel material to prevent deformation of the outer ring under stress). After assembly, check the radial clearance to be 0.005-0.012 mm. Do not heat (temperature > 80℃ can easily cause aging of the seal). The coaxiality error between the pump shaft and bearing should be ≤ 0.02 mm.

Maintenance: Check the bearing temperature every 2000 hours (normal ≤ 75℃; abnormally high temperatures often indicate grease failure). Check the seal every 3000 hours (if leakage occurs, replace the entire bearing; do not replace only the seal). Check the vibration value every 5000 hours (replace if vibration speed > 2.8 mm/s). Avoid dry running of the pump chamber (dry running for ≥ 5 minutes can easily cause ceramic balls to crack). Prevent seawater crystals from adhering to the bearing surface (periodically rinse the pump body with fresh water). Troubleshooting: Abnormal bearing noise is often caused by damage to the ceramic balls, requiring replacement of the entire bearing; abnormal temperature is often caused by grease emulsification, requiring replacement of the bearing; seal leakage is often caused by aging of the FKM lip, requiring replacement of the entire bearing.