| 摘要 |
A hydraulic lock valve assembly (10) includes a valve body (16) having an axially extending main bore (18) and first and second axially spaced pump ports (20, 22). A tank passage (23) is in communication with said main bore (18) and first and second valve chambers (24, 26). The assembly (10) includes a spool valve (74) for opening either of the first and second check valve (36, 38) to allow fluid flow from the cylinder ports (28, 30) through the check valve (36, 38) and the inner passage (32, 34) to the pump ports (20, 22) to define a first return flow passage and for opening either of the first and second return ports (84, 86) to allow fluid flow to and from the tank passage (23) to and from the pump port (20, 22) through the return port (84, 86) to define a second return flow passage, whereby the spool valve (74) opens either of the first and second check valves (36, 38) in response to a predetermined delivery pressure in the delivery flow passage in opposite check valve chamber. The check valve (36, 38) includes an outer poppet (40, 56) and an inner popper (42, 58) slidably disposed within the outer popper (40, 56) to delay return flow through the first return flow passage to allow the spool valve (74) to open the second return flow passage prior to the inner poppet (42, 58) opening a restricted flow passage via orifices (54, 72) but before opening a large area passage via ports (41, 47) by outer poppets (40, 56).
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