CAT 7U-9291 90mm Self Aligning Bearing

CAT 7U-9291 is a Caterpillar single-row deep groove ball bearing, suitable for hydraulic pumps and slewing reducers in excavators such as Cat 320 and 336. It is used to bear radial loads and allows a certain amount of axial clearance. It is a key rotating support component in transmission and hydraulic systems and has high wear resistance and impact resistance. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 7U-9291, Type: Single-row deep groove ball bearing (with dust cover), Material: High carbon chromium bearing steel (GCr15, quenched HRC60-64), Weight: Approx. 0.85 kg, Applicable Temperature: -40℃ to +120℃, Lubrication Method: Grease lubrication (recommended Cat DEO-ULS 15W-40), Sealing Type: Double-sided stamped steel dust cover, Mounting Method: Journal interference fit (interference 0.010-0.020 mm)

Key Dimensions
Inner Diameter: 65 mm (Tolerance k6, +0.021/+0.002 mm), Outer Diameter: 120 mm (Tolerance P6, -0.019/-0.039 mm), Width: 23 mm (Tolerance ±0.05 mm), Ball Diameter: 12.7 mm (Quantity: 10) (Number of pieces), cage material phenolic resin, chamfer at both ends r=1.5 mm (tolerance ±0.10 mm), radial clearance C3 (0.015-0.035 mm), surface roughness Ra≤0.4 μm
Compatible Models and Applications: Compatible with Cat 320GC/336GC excavator main hydraulic pump input shaft and swing reducer output shaft, 950GC loader gearbox secondary shaft, radial load ≤180 kN, permissible speed ≤3600 rpm, compatible seal 437-2808
Performance Parameters: Rated dynamic load 86.5 kN, rated static load 56.8 kN, fatigue life ≥10⁶ cycles, limiting speed (grease lubrication) 4500 rpm, impact load ≥300 kN, coefficient of thermal expansion 11.5×10⁻⁶/℃, cylindricity ≤0.003 mm
Structural and Performance Advantages
Deep Groove Ball Bearing Structure: Capable of simultaneously withstanding radial loads and bidirectional slight axial loads, suitable for rotating shafts in hydraulic pumps, reducers, and other applications. Compared to ordinary needle roller bearings, it has a wider applicable speed range and is suitable for high-speed rotation scenarios.

Dustproof Sealing Design: Double-sided dust covers effectively prevent hydraulic oil impurities and dust from entering the raceway, reducing wear between the steel balls and the raceway. The seal life is approximately twice that of open bearings, making it suitable for harsh working conditions in engineering machinery.

Precision Dimensions and Materials: GCr15 bearing steel undergoes quenching treatment, resulting in uniform raceway hardness. Combined with a phenolic resin cage, it reduces operating noise (≤65 dB), minimizes steel ball friction loss, and improves rotational efficiency.

C3 Clearance Adaptation: Radial clearance adapts to thermal expansion under high-temperature conditions, preventing bearing seizure while ensuring rotational accuracy, meeting the high-speed rotation requirements of hydraulic pump input shafts.

Installation and Maintenance Points
**Before installation, clean the bearing and journal. Heat the bearing to 80-100℃ using a bearing heater, then quickly press-fit it. After pressing, check that the bearing end face and shaft shoulder fit is ≤0.02 mm, and the radial runout is ≤0.005 mm. Do not strike the bearing outer ring to prevent damage to the raceway.**

Every 2500 hours of maintenance, check the bearing temperature (normally ≤80℃). If the temperature rises abnormally or abnormal noise occurs, disassemble and inspect the raceway and steel balls. Replace the bearing immediately if scratches or peeling are found. At the same time, replenish grease, each time filling 1/3-1/2 of the bearing cavity.

Prioritize original equipment manufacturer (OEM) parts. Aftermarket parts must match the radial clearance and dimensional accuracy. Inferior bearings can easily cause shaft vibration, seal failure, and lead to decreased hydraulic pump efficiency or wear on reducer gears.