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| Illustration 1 | g01189444 |
Left Side of Machine (1) Front upper pump stack (2) Pump control valve (3) Front lower pump stack (4) Rear upper pump stack (5) Rear lower pump stack | |
The hydraulic pumps are located on the left side of the machine, behind the front access door.
The machine is equipped with the following four pump stacks:
- Front upper (1)
- Rear upper (4)
- Front lower (3)
- Rear lower (5)
The configuration of the pumps in each stack is as follows:
- Front upper stack (right material feed pump)
- Rear upper stack (left material feed pump and vibratory pump)
- Front lower stack (right propulsion pump and auxiliary pump)
- Rear lower stack (left propulsion pump and generator pump)
The auxiliary pump is an axial piston pump. The pump is variable displacement and pressure compensating. Pump control valve (2) maintains an auxiliary pump supply pressure at 13780 ± 172 kPa (2000 ± 25 psi).
The ports on the auxiliary pump are marked for identification. The pump draws oil from the hydraulic tank through port "S". The case drain line delivers oil from port "L1" to the return manifold.
Port "B" supplies oil to the following components:
- Auxiliary pressure manifold
- Screed extension manifolds (right and left)
- Auxiliary control manifold (port "P")
Note: The auxiliary pump supplies oil in order to release the parking brake. The auxiliary pump also supplies the oil which is used in order to shift the two-speed final drive.
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| Illustration 2 | g01192570 |
Auxiliary Hydraulic Pump | |
Note: The colors on the cross sections and the colors on the hydraulic schematics throughout this presentation signify various conditions within the system. The legend is as follows:
- Red (pump supply pressure, or pressure in the high pressure side of the loop)
- Red and white stripe (reduced pump supply pressure, or oil in the low pressure side of the propel loop)
- Red and white hatch (further reduced pump supply pressure oil)
- Orange (charge pressure)
- Orange and white stripe (reduced charge pressure)
- Orange and white hatch (further reduced charge pressure)
- Green (line open to tank)
- Blue (blocked oil)
- Yellow (moving part, or active valve envelope.)
This cross-sectional view of the auxiliary pump shows the major pump components. When the auxiliary pump is at rest, the bias spring forces the swashplate to the maximum angle. Engine rotation turns the pump input shaft, which then rotates the rotating group. The rotating group contains a cylinder block and pistons. The pistons in the groups rotate with the cylinder block. The piston slipper pads allow the pistons to follow the angle of the swashplate.
As the slipper pads follow the angle of the swashplate, the pistons move in and out of the cylinder block. As a piston moves out of the cylinder block, oil from the hydraulic tank is drawn into the piston chamber. As a piston moves into the cylinder block, oil is forced out of the piston chamber.
The pressure compensator spool maintains pump output at a constant pressure.