CAT 078-1844 LOCKING COLL

CAT 078-1844 is a Caterpillar genuine locking collar, 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 lock the position of the 078-0921 adjusting screw to prevent adjustment parameter drift caused by vibration. It is often used in conjunction with the 078-0253 retainer and the 078-0776 spool valve.

Core Parameters and Information

Item Details
Part Model: CAT 078-1844 (0781844) Locking Collar

Structure Type: Split elastic collar with internal thread locking section, external hexagonal drive surface and anti-loosening gear ring, compatible with M12×1.25 thread

Material: 65Mn spring steel, galvanized and passivated surface, conforming to CAT MES B0306 specification

Key Dimensions: Inner diameter 11.8 mm, outer diameter 20 mm, width 8 mm, split groove width 1.5 mm, drive surface edge distance 16 mm, anti-loosening gear ring tooth height 0.3 mm

Performance Parameters: Operating temperature -40℃ to +120℃, locking torque 18-22 N・m, anti-loosening axial force ≥500 N, hardness HRC42-48, surface roughness Ra≤1.6 μm

Compatibility Standard: Compatible with SAE J1966 fastener standard, and… 078-0921 Adjusting Screw (M12×1.25) thread matching, compatible with 078-0253 Fixture Positioner

Compatibility: Compatible with 3044C/3054C engines, 306E/307E excavators, and 226B3/236B3/246B3 skid steer loaders; works with 078-0921 Adjusting Screw, 078-0776 Spool Valve, and 078-0253 Fixture.

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: Used for locking the adjusting screw of a hydraulic pilot valve to ensure stable valve core stroke, spring preload, and pressure threshold. Suitable for medium-high pressure and high-vibration Cat® applications.

Installation Guide: Insert the 078-0921 adjusting screw thread section, ensuring the hexagonal drive surface is coaxial with the adjusting screw drive head. The anti-loosening gear ring engages with the valve body positioning surface. After installation, coaxiality should be ≤0.1 mm with no axial movement.

Installation and Maintenance Points: Clean the collar, adjusting screw, and valve body positioning surface. Check the collar for deformation and cracks, ensure the internal threads are undamaged, and verify the anti-loosening gear ring is intact.

After setting the adjusting screw, screw the collar to the valve body positioning surface and apply 18-22 N·m of torque with a hexagonal wrench to ensure complete engagement of the anti-loosening gear ring.

Post-Installation Testing: Adjustment parameters should be stable, with no loosening or leakage of the collar. After vibration testing, the adjustment value drift should be ≤0.02 mm.

Maintenance: Check the locking condition of the collar and the wear of the anti-loosening gear every 2000 hours. Replace immediately if the wear exceeds 0.1 mm or the locking torque is insufficient.