SCREW-TRUSS HEAD 2500908 - Caterpillar

(7FR386-Up) Compactors;
5110 (8HN1-Up, 7GN1-Up) Excavators;
24H (7KK67-Up) Motor Graders;
69D (9SS1-Up),
73D (1GW1-Up),
769D (5TR1026-Up, 5SS75-Up),
771D (6JR302-Up, 6YS72-Up),
773D (7ER948-Up, 7CS76-Up),
775D (6KR374-Up, 8AS81-Up) Off-Highway Trucks;
PM565 (3TK113-Up),
PM565B (8GS151-Up) Cold Planers;
D9R (8BL1368-Up, 7TL1080, 7TL1083-Up),
D10R (3KR11212-Up) Track-Type Tractors;
988F (2ZR1572-Up),
990 (4FR372-Up) Wheel Loaders;
834B (7BR662-Up),
844 (2KZ1-Up) Wheel Tractors;
631E Series II (1AB1842-Up, 1NB1433-Up),
633E Series II (2PS314-Up),
637E Series II (1FB776-Up),
651E (4YR221-Up),
657E (5YR283-Up, 6PR103-Up, 6TR215-Up, 7KR232-Up) ScrapersThe 144-0835 Unit Injector Hydraulic Pump that provides the actuation energy for the fuel system on the 3408E and 3412E engines has had several incremental improvements to its robustness. These changes have significantly increased the durability of the pump.
A through hardened control piston replaces the case hardened design. Once the case was broken on the former design, the piston would wear rapidly and pump control would be lost. The new piston is hardened completely through the entire piston.
The pump now has a full-support spherical washer which prevents debris from entering into the interface between the washer and the pump's shoe plate. Debris in this interface often lead to early wear out of the washer and the shoe plate.
The pump compensator group has changed in order to eliminate the adjusting screw that was retained with a patch lock insert. The new design is now a single solid screw that provides a positive adjustment. Engine starting failures were sometimes experienced with the previous screw when it allowed the compensator pressure setting to shift below the value needed for the engine start sequence.
The 166-5985 Compensator Kit and the 154-6732 Pump Kit are available. Disassembly and assembly instructions are detailed in Special Instruction, REHS0192. The pump may be bench tested following Test Procedure, NEHT6160.