Pump Stacks
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| Illustration 1 | g01166994 |
(1) Front upper pump stack (2) Front lower pump stack (3) Rear upper pump stack (4) Rear lower pump stack | |
The hydraulic pumps are located on the left side of the machine, and behind the front access door.
The machine is equipped with the following four pump stacks:
- Front upper pump stack (1)
- Rear upper pump stack (3)
- Front lower pump stack (2)
- Rear lower pump stack (4)
The material feed pumps are located in the following pump stacks:
- Front upper stack (1) (right material feed pump)
- Rear upper stack (3) (left material feed pump and vibratory pump)
Material Feed Pumps
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| Illustration 2 | g01166997 |
(5) Vibratory pump (rear upper pump stack) (6) Pump neutral adjustment (auger conveyor) (7) Port "M4" (8) Electric displacement control valve (drag conveyor) (9) Reverse electric displacement control valve (auger conveyor) (10) Forward electric displacement control valve (auger conveyor) (11) Charge relief valve (12) Control neutral adjustment (drag conveyor) (13) Port "M5" (14) Reverse combination valve (auger conveyor) (15) Forward combination valve (auger conveyor) (16) Reverse combination valve (drag conveyor) (17) Forward combination valve (drag conveyor) (18) Pump neutral adjustment (drag conveyor) (19) Port "M4" (20) Control neutral adjustment (auger conveyor) (21) Port "M5" | |
The machine is equipped with two tandem material feed pumps. Each pump contains two rotating groups which are inside a single housing. The first rotating group in the housing provides flow to the drag conveyor motors. The second rotating group provides flow to the auger conveyor motors. The two rotating groups are faced to each other. Therefore, the associated components of the rotating groups are on opposite sides of the pump housing.
Vibratory Pump
A gear pump is splined to the output shaft of the rear upper pump stack. This gear pump provides the flow in order to operate the vibratory motors. The gear pump also provides charge oil to the material feed system for both pump stacks.
Direction Control Valve and Electric Displacement Control Valve
Each rotating group contains a direction control valve and a servo piston. Each direction control valve is mechanically connected to a sensing piston which is controlled by the electric displacement control valves. The rotating group for the auger conveyor is equipped with two electric displacement control valves. One of the electric displacement control valve (auger conveyor) controls the forward operation of the auger. The second electric displacement control valve (auger conveyor) controls the reverse operation of the auger conveyor. The rotating group for the drag conveyor is also equipped with two electric displacement control valves. However, only the forward electric displacement control valve is used on the rotating group for the drag conveyor.
Charge Relief Valve
Each pump housing is equipped with a charge relief valve. The charge relief valve limits the pressure in the charge system to 2240 ± 172 kPa (325 ± 25 psi). This valve is mechanically adjustable.
Note: Charge pressure can be measured at the pressure tap which is located in the base of the charge filter. However, since charge oil is supplied from a single source, and both pump stacks contain charge relief valves, the relief pressure for the charge oil will be controlled by the relief valve with the lowest setting. Therefore, the two charge relief valves must be set at the same pressure in order to ensure that oil flows through the case drain of each pump.
Combination Valve
Each rotating group in each material feed pump is equipped with two combination valves. One combination valve controls the pressure in the forward circuit. The second combination valve controls the pressure in the reverse circuit.
The combination valves act as makeup valves and relief valves. The combination valve in the auger conveyor circuit limits the pressure in that circuit to 35970 to 40450 kPa (5221 to 5871 psi). The combination valve in the drag conveyor circuit limits the pressure in that circuit to 35970 to 40450 kPa (5221 to 5871 psi). The makeup section of the valves allows charge oil to flow into the low pressure circuit in order to replenish the oil which is lost to internal leakage.
The reverse combination valve and the forward combination valve in the rotating group for the drag conveyor are located near the port "A" and near the port "B", which are in the pump housing. The forward combination valve and the reverse combination valve in the rotating group for the auger conveyor are located near port "C" and near port "D", which are in the pump housing.
Port "M4" and Port "M5"
Each rotating group is equipped with the following:
- Port "M4"
- Port "M5"
- Adjustment screw (pump neutral adjustment)
- Adjustment screw (control neutral adjustment)
Port "M4" and port "M5" can be used in order to measure the pressure on either side of the servo pistons.
Pump Neutral Adjustment
The adjustment screw for the pump neutral adjustment is used to adjust the mechanical zero setting of the swashplate. When this screw is rotated, the center location of the servo piston is moved. As a result, the center location of the swashplate in the rotating group is moved. The position of the servo piston must be adjusted so that the pressure in the forward and reverse circuits of the closed loop is 0 psi. This will occur when the pressure on both sides of the servo piston is equal. This adjustment should be made after the pump has been disassembled. If the drag conveyor or the auger conveyor creeps in either direction, when the material feed system is not operating, you should make this adjustment.
Note: When the pump neutral adjustment is made, a line must be installed between port "M4" and port "M5" of the rotating group which is being adjusted. Gauges must be installed in the forward pressure tap and in the reverse pressure tap in order to monitor the forward and reverse circuit pressures.
Control Neutral Adjustment
The adjustment screw for the control neutral adjustment is used to adjust the hydraulic zero setting of the rotating group. This adjustment aligns the swashplate and the direction control valve. This adjustment will make sure that the swashplate in each rotating group is set at zero degrees when the material feed system is not operating. The control neutral adjustment should be performed after the pump neutral setting is adjusted.
Note: When this adjustment is made, pressure gauges must be installed in port "M4" and port "M5" of the rotating group which is being adjusted. When the control neutral adjustment is done correctly, the pressure on either side of the servo piston will be equal when the material feed system is not operating.
Cross Section of Material Feed Pump
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| Illustration 3 | g01167003 |
(22) Rotating group (drag conveyor) (23) Slipper pads (24) Swashplate (25) Input shaft (26) Servo piston (27) Feedback link (28) Displacement control valve (29) Displacement control valve (30) Feedback link (31) Servo piston (32) Vibratory pump shaft (33) Swashplate (34) Slipper pads (35) Rotating group (auger conveyor) | |
The material feed pump is a tandem pump with two rotating groups inside one housing. Each rotating group contains a direction control valve and a servo piston. The direction control valves are controlled by the machine ECM through electric displacement control valves.
Pump Operation
Engine rotation turns the pump input shaft. The pump input shaft then rotates the rotating group for the drag conveyor and the pump input shaft rotates the rotating group for the auger conveyor. The rotating groups contain a piston and barrel assembly. The pistons in the groups rotate with the barrel assembly. The piston slipper pads allow the pistons to follow the angle of the swashplate. The rotating groups only generate flow when the swashplates are not at zero angle.
When the machine ECM sends an output signal to an electric displacement control valve, the corresponding servo piston moves. As the servo piston moves, the action of the control linkage causes the angle of the swashplate to change. The swashplate angle is proportional to the signal from the machine ECM.
The slipper pads in each rotating group follow the angle of the swashplate. This action causes the pistons to move in and out of the barrel assembly as the input shaft rotates. As a piston moves out of the barrel assembly, oil in the low pressure circuit is drawn into the piston chamber. As a piston moves into the barrel assembly, oil is forced out of the piston chamber and into the high pressure circuit.