PLATFORM GP-CAB 2372233 - Caterpillar

Stationary Steering Wheel
Illustration 1 g01013960
Piston pump (3) supplies oil to the steering system. The piston pump is a variable displacement pump.Oil flows from piston pump (3) through steering check and combiner valve (6). The oil is then blocked at metering pump (1). The steering system is at standby pressure. This standby pressure holds the contacts of pressure switch (7) open.Pressure is maintained in the load sensing line by an orifice in metering pump (1). This pressure ensures a rapid response to a steering input. Check valve (8) maintains the pressure in the tank line. The check valve also maintains the same pressure in the load sensing line.Rotating Steering Wheel
Illustration 2 g01014005
Oil from piston pump (3) flows to metering pump (1) and through steering check and combiner valve (6). The metering pump supplies oil to steering cylinders (2). The metering pump contains a rotary spool and a gerotor pump. The system pressure holds the contacts of pressure switch (7) open.As the steering wheel is rotating, the rotary spool of metering pump (1) is offset. This opens up a flow path to the gerotor pump within the metering pump. The gerotor pump rotates with the steering wheel.As the gerotor pump rotates, the gerotor pump transfers oil to steering cylinders (2). Return oil flows from the steering cylinders to the tank.Pressure is transmitted into the load sensing line through an orifice in metering pump (1). This load sensing pressure is proportional to the rotational speed of the steering wheel and the load sensing pressure is also proportional to the resistance to the turn. The load sensing pressure causes the output of piston pump (3) to increase in order to match the requirements of the steering system.Note: Check valve (5) prevents oil flow from the load sensing line to the pressure and flow compensator valve (3a) when the engine has stopped and the electric drive pump (9) is activated. Check valve (4) prevents oil flow from the load sensing line to the electric drive pump (9) under normal operating conditions. As the rotational speed of the steering wheel is increased, a greater flow rate from piston pump (3) causes a greater flow rate of oil to bypass the gerotor pump and flow directly to the steering cylinders. This reduces the amount of rotations that are required to articulate the machine.The Illustration shows oil flow from the left turn port of metering pump (1). Oil flows to the piston side of steering cylinder (2) on the right side of the machine. Oil flows to the rod side of steering cylinder (2) on the left side of the machine. This will articulate the machine to the left.The system pressure is limited by pressure and flow compensator valve (3a) which is part of piston pump (3) .On earlier machines, relief valves (2a), which are part of steering cylinders (2), provide damping for the steering cylinders when the steering cylinders are retracted.Component location
Illustration 3 g00776755
Metering pump (1) is located at the front of the cab and beneath the windshield.
Illustration