Abstract: A hydraulic system includes a selective control valve and a cam member movable to selected positions for controlling a hydraulic cylinder powered by a pump. A follower is urged to a locking relationship with the cam by a hydromechanical mechanism to releasably hold the control valve in the selected positions. The hydromechanical mechanism includes a bore exposed to sump pressure and to pressure upstream and downstream from a metering valve in a passage interconnecting the pump and the control valve. A hollow apertured sleeve is movably mounted in the bore. An apertured piston is slidably received by the sleeve. A rod, engageable with the follower, extends through the piston and sleeve apertures. A first spring interconnects the rod and the piston and a second spring interconnects the piston and the sleeve. The sleeve moves to a preload position in response to a no-flow differential pressure between the sump and the passage to urge the follower via the rod towards its locking position.