TANK & MTG GP-FUEL 1295571 - Caterpillar

Steering Cylinder Location
(7) Steering cylinder.When the steering wheel is turned, two double acting steering cylinders (7), receive oil from SCU (2) so that the compactor can make the desired turn. When the steering wheel is not being turned, oil goes through SCU (2) and return line (13) to filter (14). From the filter, the oil flows through line (11) to the vibration and propulsion charge systems. Spring loaded check valve (15) prevents a total loss of charge pressure when the filter bypass valve opens.If filter (14) becomes plugged a pressure drop is created across the filter. When the pressure drop reaches 350 kPa (50 psi), the filter bypass valve opens and oil flows through the bypass valve to the spring loaded check valve. When the pressure reaches 1220 kPa (175 psi) in the passage between the bypass and check valves, the spring loaded check valve opens and the oil flows to tank. The spring loaded check valve prevents the charge circuit pressure from ever dropping below 1220 kPa (175 psi).Steering Pump
Steering Pump
(1) Rotor and vane cartridge. (2) Inlet port. (3) Outlet port.The steering pump is a fixed displacement vane pump driven off of the back of the tandem propulsion pumps. The pump turns clockwise when the engine is running.Oil from the hydraulic tank enters the steering pump at inlet port (2), and is ported to rotor and vane cartridge (1). As the rotor and vanes rotate, high pressure oil is sent through outlet port (3) to the steering priority valve.Steering Pump Flow Diagram
Steering Pump Flow DiagramThe components of the rotor and vane cartridge are inlet and outlet support plates, seal packs, flex plates, rotor ring, rotor, vanes and inserts. For more information on vane pumps see, Special Instruction Form No. SMHS7047.The rotor is driven inside the cartridge by the shaft. As the rotor speed increases, centrifugal force causes the vanes to follow the cam shape (outline with a curve) of the rotor ring. System pressure behind the vanes and inserts keep them pushed out to make sure there is no leakage around the rotor ring surface during normal operation.The rotor ring has a shape (contour) with two chambers opposite each other that are made (formed) to prevent any hydraulic loads on the bearings. Rotation of the vanes and the rotor cause the chamber area between the vanes to increase in size at the inlet (large diameter) section of the rotor ring. This causes a low pressure or vacuum in the chamber. This pressure difference causes oil to flow in the inlet, where it is stopped between vanes while in rotation. It is now sent with force, through passages in the pressure plate, to the outlet and into the system as chamber size decreases at the pressure (small diameter) section of the ring.Steering Priority Valve
Steering Priority Valve
(1) Passage. (2) Load sensing port. (3) Tank port. (4) Steering signal relief valve. (5) Excess flow port. (6) Spring. (7) Spool. (8) Inlet port. (9) Control flow port (to SCU). (10) Passage.