What term describes the condition where, during reversing, all ports are briefly closed against one another while pressure is maintained, making forward movement difficult?

• A. Positive switching overlap
• B. Negative switching overlap
• C. Check valve hold
• D. By-pass

Answer: (A)

During switching of a directional control valve, there is a brief window where the connections inside the valve overlap in how they link the ports to the actuator. When that overlap is positive, the transition causes all the ports that feed the actuator to be closed to one another while pressure is still held somewhere in the circuit. That creates a momentary deadlock: the actuator has no path for fluid to move, so forward motion becomes difficult or stalls as the system holds pressure on both sides. This is why the term describes a hold during reversing.

Other options describe different situations. A bypass would give an alternate path for flow, preventing a stall. A check valve hold references a one-way valve feature, not the transient closing of all ports during a position change. Negative switching overlap implies a different timing effect that doesn’t produce a full port closure with maintained pressure.