ENGINE AR-COMPLETE 1695262 - Caterpillar

Illustration 1 g02908223
Steering Hydraulic System "STRAIGHT TRAVEL"
(1) Steering cylinders
(2) Line relief valve
(3) Makeup valve
(4) Steering control spool
(5) Anticavitation valve
(6) Main relief valve
(7) Line relief valve
(8) Makeup valve
(9) Steering control unit
(10) Metering pump
(11) Line to charge filter
(12) Line to fan motor
(13) Fan pump
(14) Steering pump
(15) Suction strainer
(16) Hydraulic tank When the steering wheel is in the center position, the center envelope of steering control spool (4) is active. Pump supply oil enters steering control unit (9) through port "P". This oil flows across the steering control spool to port "T". Oil leaving the outlet of the steering control unit is directed into the line to charge filter (11).Line relief valves (2) and (7) limit the maximum pressure in steering cylinders (1). These relief valves act as shock valves for the steering system. The valves are set at the factory to open when the pressure in the steering cylinder reaches 28500 kPa (4130 psi). The line relief valves are not adjustable. If the steering system does experience a shock load, makeup valve (3) or (8) in the low-pressure side of hydraulic cylinders (1) opens. This action allows oil to enter the low-pressure side of the hydraulic cylinders, preventing cylinder cavitation.
Illustration 2 g02908230
Steering Hydraulic System "LEFT TURN"
(1) Steering cylinders
(2) Line relief valve
(3) Makeup valve
(4) Steering control spool
(5) Anticavitation valve
(6) Main relief valve
(7) Line relief valve
(8) Makeup valve
(9) Steering control unit
(10) Metering pump
(11) Line to charge filter
(12) Line to fan motor
(13) Fan pump
(14) Steering pump
(15) Suction strainer
(16) Hydraulic tank Pump supply oil enters steering control unit (9) through port "P". When the steering wheel is rotated to the left, the top envelope of steering control spool (4) is active. In this case, oil flows across the steering control spool to the metering pump.Metering pump (10) rotates when the steering wheel is turned. The metering pump directs flow back through steering control spool (4). This oil flows to the head end of the right steering cylinder and to the rod end of the left steering cylinder. Oil flowing into the steering cylinders causes the machine to turn left. Oil in the head end of the left steering cylinder and in the rod end of the right steering cylinder flows out the steering control unit through port "T". This oil is directed into the line to charge filter (11).As the operator turns the steering wheel faster, metering pump (10) increases the flow to steering cylinders (1). This action causes the machine to turn faster. Metering pump (10) directs flow to steering cylinders (1) until the operator stops turning the steering wheel. When the steering wheel stops turning, the centering springs center steering control spool (4) inside a sleeve. This action blocks the oil passages to the steering cylinders. In this case, the steering angle does not change until the operator moves the steering wheel again.If the operator continues to turn the steering wheel after steering cylinders (1) reach the end of their stroke, main relief valve (6) opens. The main relief valve maintains pressure in the