Poppet configuration for counterbalance valve

DETAILED DESCRIPTION It is a feature of the present invention to provide an improvement in counterbalance valves which compensates for backpressure erroneously introduced from a hydraulic control unit.
In view of this feature and other features, the present invention provides a passage through or around a spring-biased poppet used in a counterbalance valve, wherein the passage transmits hydraulic operating fluid from one end of the poppet to the other to compensate for erroneous, unintended increases in operating fluid pressure against the poppet which might interfere with the pressure relief function of the poppet.
In accordance with a preferred embodiment of the invention, the passage is configured as a bore through the poppet and includes an internal valve.
The valve blocks the bore when pilot pressure is applied to the poppet and allows hydraulic operating fluid to flow through the bore to the pilot side of the poppet when there is backpressure holding the poppet in a blocking position.