HARNESS AS-ENGINE 6T6074 - Caterpillar

Illustration 1 g00628510
Illustration 2 g00935214
924G
Illustration 3 g00935216
928G and IT28GThe metering pump (1) controls the flow of oil from the steering pump to the steering cylinders. The metering pump is located under the operator platform above the articulation joint. Access to the metering pump is underneath the operator's platform.
Illustration 4 g00929783
The metering pump contains a control valve section (D) and a metering section (E). The two sections send oil to the steering cylinders. The control valve section contains the cylinder relief valves (1) and the anticavitation valves (2). Access to the anticavitation valves is through the metering section. The control valve section of the metering pump connects to the steering wheel through the column assembly.The metering pump controls the direction of a turn and the speed of a turn. By turning the steering wheel faster, the flow of oil to the steering cylinders increases. The increase in the flow of oil turns the machine faster.When the steering wheel is not being turned, the control section (D) is in the NEUTRAL position. The metering pump is a closed center valve. The oil grooves in the spool (3) and the oil holes in the sleeve (4) are not aligned in the NEUTRAL position.A small amount of oil flows through the metering pump in the NEUTRAL position. The small flow of oil keeps the spool open slightly. By being open slightly, the metering pump can respond quickly to steering movements.When the steering wheel is turned for a right turn, oil from the steering pump flows into the metering pump through inlet (5). The oil flows from inlet (5) through passage (6) into passage (7). The oil flows into gerotor (8). When the steering wheel is turning, the gerotor is turning and the gerotor is pumping oil. The oil flows from the gerotor through internal passages into the sleeve and into the spool. The holes in the sleeve and the grooves in the spool align. Then, the oil flows to port (9). From port (9), the oil flows to the right steering cylinder.When the steering wheel starts to turn, spool (3), pin (10) and drive (11) start to turn. The sleeve (4) did not start to turn at the same time as the spool. The diameter of the holes in the sleeve are slightly larger than the diameter of the pin.The larger holes allow the spool (3) to turn. As the spool turns, the small holes in the sleeve (4) align with the grooves in the spool (3). The alignment of the holes and the grooves provides the paths for the oil flow to gerotor (8) and to the steering cylinders.The centering spring (12) is compressed when the spool moves in relation to the sleeve. When you no longer turn the steering wheel, the centering spring will move the spool to the NEUTRAL position. The wheels will stay in position when you stop turning the steering wheel. In order to straighten the machine, you turn the steering wheel to the left.For a right turn, oil flows