CAT 078-0921 ADJ SCREW

CAT 078-0921 is a Caterpillar genuine Adjustment Screw, compatible with the hydraulic pilot valve assembly and fuel injection control module of 3044C/3054C engines, 306E/307E excavators, and 226B3/246B3 skid steer loaders. It is used to precisely set valve spool travel, spring preload, or pressure threshold. It is often used with the 078-0253 retainer and 078-0776 spool valve for Cat® installation…

Core Parameters and Information

Item Details
Part Model: CAT 078-0921 (078921) Adjusting Screw

Structure Type: Slotted/Hexagonal drive head with threaded adjustment section, positioning step and locking groove, tail with ejector pin/flat top structure

Material: 40Cr alloy steel, blackened surface, conforms to CAT MES B0305 specification

Key Dimensions: Overall length 42 mm, drive head diameter 8 mm, thread specification M12×1.25, effective adjustment stroke 10 mm, positioning step diameter 15 mm, tail ejector pin diameter 3 mm

Performance Parameters: Adjustment accuracy ±0.02 mm, maximum adjustment force 500 N, operating temperature -40℃ to +120℃, thread locking torque 15-20 N・m, hardness HRC45-50

Compatibility Standard: Complies with SAE J1966 fastener standard, compatible with 078-0253 retainer positioning, and… 078-0776 Spool Valve, 078-0653 Check Seat Matching Adjustment

Matching Relationship: Compatible with 3044C/3054C engines, 306E/307E excavators, 226B3/236B3/246B3 skid steer loaders; compatible with 078-0253 Fixing Device, 078-0776 Spool Valve, and 077-8727 Bearing.

Compatible Models and Application Scenarios

Compatible Equipment: Hydraulic pilot valve assembly and fuel injection control module for CAT 3044C/3054C engines, 306E/307E mini excavators, and 226B3/236B3/246B3 skid steer loaders.

Application Scenarios: Pressure setting of hydraulic pilot valves, spool valve stroke limit, and spring preload adjustment to ensure stable system pressure and precise operation, suitable for medium-high pressure and medium-temperature continuous operation conditions.

Installation Instructions: Screw the adjusting screw into the valve body adjustment hole. The positioning step engages with the 078-0253 retainer for limiting movement. The tail end rests against the valve core/spring seat. After installation, the adjustment stroke error should be ≤0.03 mm.

Installation and Maintenance Points: Clean the adjusting screw, valve body adjustment hole, and matching parts. Check for thread damage, slippage of the drive head, and deformation of the positioning step.

Manually screw the screw into the top position, then retract/tighten according to the set stroke. Lock with the 078-0253 retainer. Thread installation torque is 15-20 N·m.

Post-Installation Testing: The adjusting screw setting should conform to the system parameters. Pressure/stroke should be stable, with no loosening or leakage.

Maintenance: Check the adjustment value and locking status every 2000 hours. If loosening or out-of-tolerance adjustment accuracy is found, recalibrate and tighten. Replace if necessary.