Abstract: A control means for a hydraulic motor connected to an external load comprises a directional valve (10) for selectively feeding hydraulic fluid to the motor from a pressure source and including load pressure sensing means (24, 25) connected to a load compensating valve (15) located upstream of the directional valve (10) for adjusting automatically the feed pressure in relation to the actual load pressure. The load compensating valve (15) includes a valve spindle (28) with opposite end surfaces (29, 30), one of which is exposed to the load pressure whereas the other is exposed to the feed pressure, and a selectively activatable feed pressure reducing means (38, 43; 50-57) for increasing the bias force acting on the load compensating valve spindle (28) in the closing direction of the latter in relation to the bias force acting in the closing direction of said valve spindle (28).

Abstract: Device in a hydraulic power system connected to a load driving hydraulic motor (18; 32), comprising a pilot controlled flow regulating directional valve (1; 29) for alternative connection of the service ports of the motor (18; 32) to a pressure medium source and a tank. The directional valve (1; 29) comprises two opposite and by a pilot pressure activatable activating means (3, 4), and a pilot pressure means (84) is arranged to pressurize and activate the activating means (3, 4), alternatively, and drain one of the activating means to the tank through a flow restriction (5, 7) at activation of the other activating means (3, 4).

Abstract: A hydraulic drive system for one or more hydraulic motors, comprising a pump (1), a tank (25) for hydraulic fluid, one or more control valve sections (10, 11, 12) each being provided with a shunt passage and each being coupled to a respective hydraulic motor, a first shunt conduit (4) including the shunt passages of said control valve sections (10, 11, 12) connected in series for leading off of the tank (25) the temporarly surplus flow of hydraulic fluid from the pump (1), and a feed conduit (3) for connecting the control valve sections (10, 11, 12) in parallel to the pump (1).