STRIP 2H9730 - Caterpillar

Location and Function
Illustration 1 g00954138
The access panels for the pump compartment are on the left side of the machine.
Illustration 2 g00954139
Upper and Lower Pump Stacks (1) Upper pump stack (2) Lower pump stack (3) Charge pump (4) Electronic displacement control valve (EDC valve)EDC valve (4) is for the right auger conveyor piston pump that is on upper pump stack (1). There is an EDC valve for the left auger conveyor piston pump that is on lower pump stack (2). The following text will only explain the operation of EDC valve (4). Each EDC valve has two 12 volt solenoids.Components
Illustration 3 g00954144
Upper Pump Stack (4) EDC valve (5) Solenoid (forward) (6) Solenoid (reverse) (7) Port "M4" (8) Port "M5"Ports "M4" and "M5" can be used to monitor the oil pressure that goes to the swashplate piston.
Illustration 4 g00954149
Hydraulic Schematic (4) EDC valve (5) Solenoid (forward) (6) Solenoid (reverse) (9) Servo control cylinder (10) Linkage (11) Servo control valve (12) Swashplate piston (13) Piston pump (auger conveyor) (14) Forward combination valve (15) Charge pump (16) Reverse combination valveOperation and Oil Flow
Note: Illustration 5 shows the upper pump stack. The upper pump stack contains the EDC valve that controls the piston pump for the right auger conveyor motor. The lower pump stack contains the EDC valve that controls the piston pump for the left auger conveyor motor. The only difference between the upper and lower pump stacks is that the upper pump stack contains the charge pump. The charge pump provides charge pressure oil for the upper and lower pump stacks. The lower pump stack is not shown in this section.
Illustration 5 g00954151
Hydraulic Schematic (4) EDC valve (5) Solenoid (forward) (6) Solenoid (reverse) (9) Servo control cylinder (10) Linkage (11) Servo control valve (12) Swashplate piston (13) Piston pump (auger conveyor) (14) Forward combination valve (15) Charge pump (16) Reverse combination valve (17) Valve envelope (18) Valve envelope (19) Valve envelope (20) Valve envelope (21) Line from charge filter (22) Line to auger conveyor motor (23) Line from charge filter (24) Line from auger conveyor motor (25) Valve envelope (26) Valve envelope (27) Valve envelope (28) Valve envelope (AA) System pressure (AB) Charge pressure (AC) Sump (AD) Activated components (AE) First pressure reduction (AF) Reduced charge pressureReference: See Systems Operation, "Piston Pump (Auger Conveyor)" for information about the forward and reverse combination valves.Note: The auger conveyors can be run in reverse. Both solenoids on the EDC valve are used. One solenoid controls the piston pump so that system pressure oil will flow in the forward direction. The other solenoid controls the piston pump so that system pressure will flow in the reverse direction.Charge Pressure Oil
When the machine is started, hydraulic oil is drawn through a suction screen in the hydraulic tank by charge pump (15). The charge pump sends charge pressure oil to the upper pump stack through the line from charge filter (21). The charge pressure oil is filtered before going to the pump stack. Charge pressure oil supplies EDC valve (4) and servo control