| 摘要 |
A common relief valve circuit for controlling or monitoring two or more pumps. The circuit includes two fixed displacement pumps with the pumps being connected to at least two valve bodies or sections that supply fluid to hydraulic cylinders for operating earth-working buckets or the like. A main relief valve is connected to the inlet of a first valve section, and a check valve is connected in a parallel cavity line in the first valve section. The check valve remains closed under conditions where a valve spool in the first valve section is shifted but a valve spool in the second valve section is not shifted or when a valve spool in the second valve section is shifted and a valve spool in the first valve section is not shifted. If a valve spool in the first valve section is actuated at the same time as a valve spool in the second valve section, fluid pressure downstream of the first valve section is communicated through the check valve and parallel cavity line to the main relief valve, thereby permitting the relief valve to monitor both valve sections and eliminating the need for a separate main relief valve for each valve section.
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