Abstract: A hydraulic arrangement for lifting and/or lowering at least one implement carrying arm on an agricultural machine. The arrangement comprises an inlet hydraulic line and an outlet hydraulic line connecting a fluid pump (18) and a fluid reservoir (26) respectively to a first valve means (12), said arrangement comprising at least one dual acting hydraulic cylinder (15) for lifting/and or lowering the implement carrying arm. The at least one cylinder is connected to the first valve means (12) allowing the cylinder (15) to be switched between a single acting mode wherein the arm can be lifted and a double acting mode wherein the arm can be lifted and lowered.

Abstract: A hydraulic circuit for a working machine includes hydraulic actuators which respectively drive a plurality of kinds of working devices and which are driven by a drive circuit having circuit states that correspond to the working devices, a directional control valve unit which, when one of the working devices is attached to the attachment, switches in response to a signal from a controller to select one of the circuit states, a detection sensor that detects the actual circuit state, and a display operated by the controller. The controller activates the display when the detected actual circuit state and the selected circuit state do not match.

Abstract: A hydraulic steering system for turning two mutually articulated vehicle-halves (13, 14) relative to one another with the aid of two hydraulic piston-cylinder devices (11, 12) includes a control valve (17) which will normally connect the piston-cylinder devices in a manner such that the devices operate as single-acting piston-cylinder devices. When abnormally high steering torque prevails, however, and the oil pressure rises correspondingly above a pre-determined value, the setting of the control valve is adjusted by these oil pressures so that the valve connects the piston-cylinder devices in a manner which causes the devices to operate as double-acting piston-cylinder devices.

Abstract: A valve with four passages controls a piston (15) disposed in a cylinder (16). Between the body (1) of the valve and the cylinder (16) is disposed a plate (23) having passages (24, 25) which are used and a passage (26) which is not used in FIG. 1. By turning plate (23) 180.degree., the passage (24) is located in the non-use position, while the passage (26) connects the conduits (19 and 13) in such a way as to cause the space (21) of the cylinder (16) to communicate continuously with an exhaust orifice (6).