CAT 9J-8734 RETAINER

CAT 9J-8734 (9J8734) is a Caterpillar hydraulic pump/motor shaft end locking retainer plate. It is primarily designed for the main hydraulic pump (e.g., 352-0616) and swing motor shaft ends of CAT 320D/323D excavators and 966H loaders. It secures the shaft end bearings, seals, and adjusting shims to prevent axial movement of components during high-speed rotation, ensuring the transmission accuracy and sealing reliability of the hydraulic system. Key information is as follows:

Key Technical Parameters
Item Details
Part Model: CAT 9J-8734 (9J8734) Shaft End Locking Retainer Plate, Circular Flange Type, Suitable for Positioning and Locking of Hydraulic Pump/Motor Shaft Ends, Used with Bolts and Anti-Loosening Shims

Core Material: Q345B Low Alloy High-Strength Steel, Integral Hardening (HRC 32–38), Surface Galvanized Passivation Treatment, Corrosion Resistance + Impact Resistance, Suitable for High-Pressure and Vibration Conditions in Hydraulic Systems

Key Dimensions: Outer Diameter 120 Dimensions: mm, inner diameter 60 mm, thickness 10 mm, flange diameter 120 mm, number of bolt holes 6, bolt hole diameter 14 mm, bolt hole distribution circle diameter 100 mm, compatible shaft diameter 60 mm, installation tolerance H7/h6
Single weight: approx. 0.8 kg
Compatible models: CAT 320D/320D2/323D/329D excavators (main hydraulic pump/slewing motor shaft end), 966H/980H loaders (gearbox hydraulic pump shaft end), 420D backhoe loader (hydraulic motor shaft end), used for axial fixing of hydraulic pump/motor, transmission system shaft end bearings and seals
Working compatibility: Maximum axial load 50 kN, working temperature -20℃ to +100℃, compatible hydraulic oil (ISO VG 46), can withstand high pressure in hydraulic systems and vibration of transmission components, preventing loosening of shaft end components
Core functions and structural features:
Axial positioning and locking: flange structure + 6. Evenly distributed bolts apply uniform axial preload to the shaft end bearings, seals, and adjusting shims, preventing axial movement of components during high-speed rotation, ensuring the transmission accuracy of the hydraulic pump/motor, and preventing seal failure and leakage.

Impact Resistance and Loosening Prevention: The Q345B material, after quenching, has a yield strength ≥345 MPa. The galvanized passivated surface provides corrosion protection. Combined with 12.9 grade high-strength bolts and anti-loosening shims, it can adapt to hydraulic system vibration and load fluctuations, preventing loosening of the retainer and extending component life.

Precise Assembly and Fit: With an inner diameter tolerance of H7, it achieves a clearance fit with the shaft diameter (0.03–0.05 mm). The flange and pump/motor housing fit accuracy ≤0.02 mm, ensuring high coaxiality after installation and reducing shaft end runout and seal wear.

Auxiliary Sealing Protection: The retainer and shaft end seal (e.g., 153-2789) work together to prevent hydraulic oil leakage and simultaneously block dust and moisture from entering the shaft end, ensuring the cleanliness of the hydraulic system and sealing reliability.