Patent ID: 7921879

Claim:
A control valve for a hydraulic motor used to lift loads, wherein the control valve is a directional control valve comprising: a valve body having a longitudinal bore and a plurality of transverse bores leading to said longitudinal bore, said transverse bores comprising a first working connection bore, a second working connection bore, a pump connection bore, and a tank connection bore; and a control slide installed in the longitudinal bore with freedom to move axially, the control slide having a first working connection bore to tank groove, a first control groove, a pump groove, and a second control groove, the control slide further comprising: an auxiliary control groove located between the first control groove and the first working connection bore to tank groove, the auxiliary control groove being limited on both sides by cylindrical sealing surfaces; a longitudinal bore in the control slide; a first transverse bore connecting the auxiliary control groove to the longitudinal bore in the control slide; a second transverse bore connecting the first working connection bore to tank groove to the longitudinal bore in the control slide; and a spring-loaded check valve in the longitudinal bore in the control slide, wherein the check valve can be opened by flow from the first working connection bore via the auxiliary control groove and the first transverse bore in the control slide.