Abstract: The invention concerns a hydraulic valve arrangement with locking function. It has a control valve (9), which in two operating positions (11, 12) connects one motor connection (A) with a pump connection and a second motor connection (B) with a tank connection and vice versa, and in a locking position (10) separates both motor connections (A, B) from pump and tank connection. Further, there are two lock valves (16, 17), each connected between the control valve (9) and one of the motor connections (A, B).

Abstract: The invention concerns a hydraulic valve arrangement with a control valve (3), which, in a first operating position (5), connects a motor connection (21) with a pump connection, in a second operating position (6), connects a motor connection with a tank connection, and, in a locking position (4), disconnects the motor connection (21) from the pump and tank connection. A locking valve (19) is coupled between the control valve (3) and the motor connection (21), dividing the motor line (22) into a first section (23) allocated to the control valve (3) and a second section (24) allocated to the motor connection (21). For the locking valve (19), a pressure release valve (20) in the shape of a seated valve is provided. The operating element (32) of said pressure release valve (20) is loaded in the closing direction by the pressure in the first section (23) and a spring (36) and in the opening direction by a constant control pressure (V) acting in dependence of the position of the control valve (3).

Abstract: The invention concerns a hydraulic line coupling arrangement of a consumer, with a pump line, a tank line and a safety valve in the pump line, the valve element of the safety valve being acted upon in the opening direction by an opening pressure from the pump line and in the closing direction by a closing pressure of a closing pressure connection.

Abstract: The invention concerns a hydraulic dual circuit steering system with

Abstract: A hydraulic valve arrangement with locking and floating function, with a control valve (9), which, for two operating positions (11, 12) connects one motor connection (A) with a pump connection and a second motor connection (B) with a tank connection and vice versa, in a floating position (13) connects both motor connections (A, B) with the tank connection and in a locking position (10) separates both motor connections (A, B) from the pump and tank connections. Further, there are two closing valves (16, 17), each being connected between the control valve (9) and a motor connection (A, B) and each having a piston loaded by a spring and limiting a spring chamber, the spring chambers being pressure releasable. Characteristic of this valve arrangement is that lifting valves (18, 19) are provided for the pressure release, which valves are operated by a control pressure depending on the position of the control valve (9). This improves the operating reliability.

Abstract: A three-way or multi-way valve is provided, which is built up of a plurality of two-way valves, each of which has a high pressure connection and a low pressure connection which are separated from each other by means of a valve seat with which a closure element co-operates, the two-way valves being arranged to be operated in pairs or in groups by means of a control pressure fluid by way of a control pressure line opening into a pressure chamber, and one of the two-way valves of each group being arranged in a connection between a pressure source and a load, and another two-way valve of the same groups being arranged in a connection between the load and a pressure sink. With a valve of this type, it is desired to obtain improved closing behavior with simple construction. For this purpose, at least one of the connections, especially the high pressure connection, of at least one valve of each group communicates with the control pressure line by way of a throttle channel.

Abstract: A two-way seat-type valve is provided, having a valve seat which is arranged between a first and a second connection, and having a closure element which co-operates with the valve seat, is arranged in a guide so as to be movable towards the valve seat or away from the valve seat, and which is subjected to a control pressure prevailing in a pressure chamber on the side, remote from the valve seat, of the closure element. A valve of this type should also be able to exhibit good reaction characteristics with water as hydraulic fluid. For this purpose, the closure element is guided seallessly in the guide.

Abstract: A control valve is disclosed, having a housing which has an input port and an output port that are connected to one another by a flow path in which a throttling device is arranged. It is desirable for such a control valve to be able to hold a volume flow constant, irrespective of the load pressure at the output port. For that purpose, the throttling device comprises a series connection of a first throttle, the passage of which is externally adjustable, and a second throttle, the passage of which is adjustable in dependence on pressure.

Abstract: A pressure control valve of the type having pump, tank and load-sensing connections used in conjunction with one or more proportional type valves. In this type of system a load-sensing signal is tapped off from the output side of the proportional valves and conveyed to the load-sensing connection of the pressure control valve. A pressure control valve of the type herein has load-sensing and pressure chambers at opposite ends thereof with a slide valve therebetween which is spring biased towards the pressure chamber and controls the internal flow from the pump connection to the tank connection. The slide valve has an auxiliary change-over type valve which selectively connects the pressure chamber to the pump and load-sensing connections in response to a pressure differential between the pump and load-sensing connections to achieve a pressure balance between the load-sensing chamber and the pressure chamber.

Abstract: A hydraulic circuit for a backhoe loader having two double-acting cylinders for the arm and bucket of the loader and respective directional valves for the cylinders. There are heavy demands on the oil pump of the system when the two cylinders are moved simultaneously from one extreme position to another which requires substantially two whole cylinder volumes of oil. The cylinders are arranged in parallel relative to the pump. A first source of pressure medium displaced from one cylinder is used to perform work in the other cylinder and the other cylinder is also supplied with a second source of pressure medium directly from a pump. The line section through which the first source of pressure medium is supplied is shunted to a tank by valving apparatus upon a predetermined pressure being reached to freely accommodate the simultaneous movements of the cylinders.

Abstract: There is provided control apparatus for controlling fluid flow between a bidirectional motor, a pump and a container, and includes a control valve that has a slide operative between neutral and first and second operative positions. A compensating valve is provided in the supply conduit that holds the upstream pressure drop at the control valve substantially constant and is controlled by load pressure sensing circuitry. The load pressure circuitry includes two branches that are connected through a change over valve to the compensating valve. There is provided an over pressure valve and a throttle point in each branch, each branch being connected to a load pressure sensing orifice of the control valve housing and fluidly connected through the slide to one of the housing motor orifices, the one depending upon whether the slide is in its first or in its second position.

Abstract: A hydraulic control valve and sensing mechanism for controlling flow between a motor and a pump and container that includes a slide mounted in a housing bore for movement between a neutral position and two operative position. The slide has a central collar separated from end collars by slide grooves, profilings on diametric opposite sides of the slide grooves intersecting each groove. The housing bore has a pump groove supplied with pressure medium, axially opposite motor grooves connectable to motor conduits, and axially opposite the motor grooves from the pump grooves there are container grooves connectable to the container. The pressure sensing mechanism includes at least one pressure sensing orifice that is connected to the pressure to be sensed in an operative position of the slide but not being fluidly connected thereto when the slide is in its neutral position.

Abstract: A damping arrangement for damping the oscillations of valves which are controlled by pressure fluid and the control pressure conduits of which contain a throttle. A characteristic is that initial oscillations can be rapidly stabilized independently of the operating temperature of the pressure fluid. This is accomplished by the throttle having a throttle gap of which the height varies oppositely to the temperature of the pressure fluid so as to compensate fully or partially for changes in the hydraulic resistance that are occasioned by the temperature. The throttle gap is mostly traversed by laminar flow and consequently there is a high hydraulic throttling resistance even at low speeds of flow. The throttle is therefore also adapted effectively to damp small oscillations of the valve element so that the initial oscillations are rapidly stabilized.