CAT 077-9931 RETAINER

CAT 077-9931 is a Caterpillar original equipment retainer, compatible with 3044/3054 engines, 306/307 excavators, 226B/246B skid steer loaders, etc. It is used for positioning the rotor shaft end of the generator/starter motor and is often used in conjunction with the 077-8727 bearing and the 077-9360 rotor retainer.

Core Parameters and Information

Item Details
Part Model: CAT 077-9931 (0779931) Fixture

Structure Type: Annular with locating edge, central shaft hole + 3 mounting holes, compatible with rotor shaft end flange positioning, bolt fastening

Material: 42CrMo alloy steel, blackened anodized surface treatment, conforms to CAT MES J4203 specification

Key Dimensions: Outer diameter 82 mm, inner diameter 25 mm, thickness 10 mm, locating edge height 3 mm, mounting hole diameter 6 mm, hole spacing circle diameter 60 mm, compatible with M6 bolts

Performance Parameters: Axial locking force 5 kN, operating temperature -40℃ to +180℃, radial runout ≤0.05 mm, hardness HRC35-40

Compatibility Standard: Compatible with SAE J1926 rotor connection standard, central hole compatible with 077-8727 bearing inner ring

Matching Relationship: Compatible with 3044/3054 Engines, 306/307 excavators, 226B/246B skid steer loaders, compatible with 077-8717 retaining rings and 077-9360 rotor retainers.

Compatible Models and Application Scenarios

Compatible Equipment: CAT 3044/3054 engines, 306/307 mini excavators, 226B/236B/246B skid steer loaders, and generator/starter motor rotors for some small scrapers.

Application Scenarios: Rotor shaft end anti-motor shifting, drive component positioning, vibration displacement suppression, and stable power output.

Installation: Secure to the rotor shaft end flange with M6 bolts, torque 12-15 N·m. Matches bearings and drive plates. Axial clearance ≤0.1 mm after installation.

Installation and Maintenance Points: Clean the shaft end, retainer, and bolts. Check for deformation and cracks. Ensure the shaft end diameter matches the center hole and the mounting hole is undamaged.

Align the positioning edge with the rotor flange surface, align the mounting holes, and tighten the bolts in a crisscross pattern, ensuring no misalignment.

Post-installation inspection: Ensure there is no looseness or wobble; the rotor rotates without interference; and the rotor resistance measured with a multimeter shows no abnormalities.

Maintenance: Check the bolt torque and retainer wear every 800 hours. Replace immediately if deformed or with damaged threads.