PLATE AS-MOUNTING 4983532 - Caterpillar

Illustration 1 g00856578
Metering Pump (Steering) (A) Control section (B) Metering section (1) Tank port (2) Pump port (3) Left turn port (4) Load sense port (5) Right turn port (6) Check valve (7) Relief valve (8) Shock valve (9) Rotary spool
Illustration 2 g00856092
Location of Metering PumpThe metering pump is located behind a panel at the front of the cab.The metering pump directs oil to the steering cylinders from the fixed displacement pump.The steering metering pump consists of two sections, control section (A) and metering section (B). Section (A) contains a rotary control valve. Metering section (B) is a gerotor pump. These two sections work together in order to send oil to the steering cylinder.The metering pump also includes check valve (6), pressure relief valve (7) and shock valves (8) .
Check valve (6) prevents pressurized oil from flowing back into the pump line from the steer cylinders.
Pressure relief valve (7) protects the pump and the metering unit against excessive pressures. The pressure relief valve also limits the system pressure while the machine is being steered by limiting the load signal to the priority valve that is located in the accumulator charging valve.
Shock valves (8) protect the metering pump. The shock valves also limit the maximum external forces on the steering cylinders. The shock valves are direct acting valves that react very quickly.Refer to Testing and Adjusting, "General Information Table" for more information.Both the direction of a turn and the speed of a turn are controlled by the metering pump. As the steering wheel is turned faster, there is an increase in the flow of oil to the steering cylinders. The increased flow of oil to the steering cylinders causes the steering cylinder rods to move faster. This causes the machine to make a faster turn.When the steering wheel is turned, oil is directed from the main pump through the metering pump to the rear steering cylinder. The metering pump meters the oil flow to the steering cylinder in proportion to the rotation of the steering wheel.The gerotor pump is coupled to the steering wheel. As the steering wheel rotates, the gerotor pump inside the metering pump transfers oil to the rotary spool which directs oil to the steering cylinder.Rotary spool (9) is infinitely variable. The rotary spool is offset when the steering wheel is rotated. The rotary spool is spring centered when the steering wheel is stationary. The oil flow past the rotary spool increases as the rotational speed of the steering wheel increases. The rotary spool has the following functions.
The rotary spool divides the flow from pump port (2) between the gerotor pump and the left turn port (3) or the right turn port (5) .
The rotary spool allows a load sensing signal to flow from load sensing port (4) into the load sensing line to the accumulator charging valve when the steering wheel is turning. The magnitude of the load sensing pressure depends on the rotational speed of the steering wheel and on the resistance to the turn.
The rotary