Note: This arrangement can only be used with the single action hydraulic attachment circuit or the double action hydraulic attachment circuit.
When the one pump system is used, the hydraulic oil to the attachment is supplied by the left pump. The two pump system allows the attachment circuit to provide part of the right pump oil or all of the right pump oil. This oil is in addition to the oil that is supplied by the left pump. This increases the amount of oil flow that is available to the attachment while the attachment is active. This also reduces the load on the left pump while the attachment is active. The following parts are the main components of the two pump system:
- Pilot oil lines
- Front lines
 | |
| Illustration 1 | g00522028 |
Pilot oil lines (1) Port (2) Port (3) Main control valve (4) Port (5) Check valve (6) Line (7) Port (8) Two-way valve (9) Pilot oil manifold | |
When the pedal assembly for the attachment is depressed forward, pilot oil is sent through line (7). This shifts the attachment valve stem upward. At the same time, pilot oil also flows through line (6). The pilot oil that remains in the attachment control valve drains through line (2) .
The pilot oil in lines (6) and (2) flows to check valve (5). When the pilot oil pressure is greater than the force of the springs in check valve (5), the pilot oil flows to port (4) .
The pilot oil pressure in port (4) shifts a two-way valve (8). When the two-way valve shifts, the right pump oil is blocked from draining to the hydraulic tank.
The same operation occurs when the pedal assembly for the attachment is depressed backward. The pilot oil is supplied by line (1) and drains from the attachment control valve through line (6).
 | |
| Illustration 2 | g00660248 |
Front lines (10) Tee (11) Line (12) Check valve | |
The right pump supply oil goes through tee (10) and line (11) to check valve (12) instead of draining to the hydraulic tank. This allows right pump oil to flow into the attachment control valve. In the attachment control valve, the right pump oil combines with the left pump oil.