HANDRAIL AS 2828888 - Caterpillar

Illustration 1 g00297397
(1) Steering piston pump (2) Pressure compensator valve (3) Pump drive shaft (4) Swashplate (5) Outlet opening (6) Piston (7) Barrel (8) Inlet opening (9) Actuator piston (10) Spring
Illustration 2 g00297398
(2) Pressure compensator valve (11) Spool (12) Spring (13) Shims (14) Passage from steering piston pump outlet (15) Passage to actuator piston (16) Passages to steering pump case drain line
Illustration 3 g00301290
(1) Steering piston pump (2) Pressure compensator valve (17) Pump driveSteering piston pump (1) is a variable displacement axial piston pump. The steering piston pump is fastened to pump drive (17). Pump drive (17) is located on the inside right hand frame rail near the torque converter. Steering piston pump (1) only operates when the engine is running.When the engine is started, the pump drive (17) turns pump drive shaft (3) and barrel (7) with nine pistons (6). The ends of pistons (6) connect to a retraction plate and slippers. The retraction plate and slippers turn with barrel (7). The retraction plate and slippers are against swashplate (4). Swashplate (4) does not turn. Swashplate (4) can pivot in order to change the angle.When pump drive shaft (3) and barrel (7) turn with swashplate (4) at the maximum angle position, pistons (6) move in and out of barrel (7) as the slippers follow the angle of the swashplate. As pistons (6) move out of barrel (7), oil is pulled from the steering hydraulic tank through inlet opening (8) and into the piston cylinder in the barrel. As barrel (7) turns farther, pistons (6) are moved back into barrel (7). This pushes the oil from the piston cylinder in barrel (7). The oil flows through the outlet opening (5) and into the steering hydraulic system.When the pressure of the oil from the steering piston pump is less than the pressure setting of the pressure compensator valve (2), oil from outlet opening (5) that is in passage (14) will not move spool (11). The pressure of the oil from the steering piston pump will increase as the steering accumulators are charged.The pressure of the oil from the steering piston pump will increase until the oil in outlet opening (5) and passage (14) has more force on the spool (11) than the force of spring (12). This will move the spool (11). The pressure of the oil that can move the spool (11) is the pressure setting of the pressure compensator valve (2) .When the spool (11) is moved, the oil in passage (14) now flows through passage (15) to actuator piston (9)