COUPLING GP-PUMP 7Y1596 - Caterpillar

Illustration 2 g00558472
Typical Example (3) Steering valve (hand metering unit) (14) Port "T" (return oil) (15) Port "P" (pressure oil)Note: Main relief valves (13) are not adjustable on the following machines: 6TL410-UP, 6WL1-UP, 7ML860-UP, 8AL1020-UP, 6ES229-UP, 8SS1-UP and 9PS1-UP.The steering valve controls the direction of travel by sending oil to the steering cylinder. This type of steering eliminates the need for a mechanical coupling between the steering wheel and tie rods. Oil flow from the steering cooling pump to the steering valve is through port "P" (15). Return oil goes through port "T" (14) to the hydraulic tank.Oil from the steering valve enters the bottom swivel in order to control the steering cylinder.The steering valve consists of the following components:Metering pump (8) - Pump that consists of external gear (9) and internal gear (10). The pump is capable of rotation in either direction.Sleeve (6) - The sleeve is moved axially.Two line relief valves (secondary pressure) - The relief valves relieve oil pressure in the lines that connect ports "L" and "R" to the steering cylinder. The valves are set at 22000 kPa (3200 psi).First check valve - When the machine is steered and the engine stopped, oil flows through this valve from the return line to the metering pump.Second check valve in the inlet passage - This valve is set to 1200 kPa (175 psi). The check valve prevents air intake if a pressure line breaks.Two makeup valves - The makeup valves prevent cavitation in the steering system.Main relief valve (primary pressure) - This valve limits the oil pressure that is coming from the steering pump to 15000 kPa (2200 psi).Check valve with a pressure relief valve - This valve prevents the wheels from automatically returning to the original position when the sleeve is deflected. The valve also reduces the pressure spikes inside the steering cylinder.Steering Valve In Neutral Position
When the steering wheel is released, sleeve (6) returns to the NEUTRAL position. This allows the oil flow from the steering cooling pump to go through the check valve, through the return oil passages and to the hydraulic tank. The oil in the other passages of the metering pump does not move. Control passages for left and right turn ports are blocked. Line relief valves (11) and (12) prevent high pressure peaks in the steering system. The pressure peaks can occur during travel.Steering Valve In Operating Position
When the steering wheel is turned, the steering column (1) is moved. The steering column is splined with drive shaft (7) and connected to metering pump (8). When the steering column rotates, metering pump (8) produces flow through the rotation of internal gear (10) inside external gear (9). The oil pressure in the steering cylinder slows the rotation of the metering pump.Steering Valve Operation (Left Turn)
When the steering wheel is turned to the left, sleeve (6) inside the steering housing moves in order to allow oil passages in the valve to open. The oil flow goes from the steering cooling pump through port "P"