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| Illustration 1 | g00567807 |
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(1) Secondary steering pump
(2) Unloader valve | |
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| Illustration 2 | g00950394 |
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(3) Diverter valve
(4) Relief valve (5) Check valve (R) Inlet port (S) Outlet to the accumulator (T) Outlet to the combination valve (PS) Port for pressure signal | |
The unloading valve contains the following main components: check valve (5), diverter valve (3) and relief valve (4).
When the engine is running, oil from the primary pump flows through the port for pressure signal (PS) into diverter valve (3). The primary oil closes the spool in the diverter valve. The secondary pump oil passes through the diverter valve to the combination valve.
Under normal operation, check valve (5) separates the primary steering oil from the secondary system.
When pressure oil from the primary pump is not present in the port for the pressure signal (PS), the spool in diverter valve (3) is shifted by an internal spring to the open position. The diverter valve (3) will now send secondary pump oil through outlet port (S) to the steering system.
Relief valve (4) limits the maximum secondary system pressure that is delivered to the steering system when diverter valve (3) is open. Any bypassed oil is returned to the tank through the combination valve.