Abstract: A valve system is provided for the hydraulic work system of a work vehicle, in particular of an industrial truck, with a elevating drive system for raising and lowering a load and a tilting drive system, each of which can be actuated by a control valve, in particular by an electrically actuated control valve, the opening width of which determines the speed of movement of the user. The elevating drive system is realized in the form of a single-action hydraulic cylinder and a check valve in the form of a seat valve that can be opened toward the hydraulic cylinder is located in a hydraulic line leading from the control valve to the hydraulic cylinder. The tilting drive system is realized in the form of a double-action hydraulic cylinder. The valve system has an improved function with low energy losses.

Abstract: A hydrostatic axial piston machine employs a swash plate construction in which the diagonal position of the swash plate can be controlled by at least one positioning piston pressurized with a control pressure. A control valve is in a line which leads to at least one positioning piston. A simple electrical-hydraulic control of the swash plate can be accomplished by the electrical actuation of the control valve. The control valve may be in the form of a rotary disk valve which can be actuated by a stepper motor.

Abstract: A control valve device controls the movement of at least one hydraulic user. Relative movement of a control spool valve of a control valve with respect to a housing controls the connection of at least one hydraulic connection that is in communication with the user with a delivery connection and with a reservoir connection. The control spool valve can be moved relative to the housing by an actuator device. The housing has a multi-layer construction consisting of plates connected with one another by soldering or another adhesive, which plates comprise intermediate plates that are located between two end plates. The thickness (D) of the end plates is greater than the thickness (d) of the intermediate plates, whereby the end plates are provided with a fastening device for the actuator device and/or of connection devices for the hydraulic lines.

Abstract: A hydrostatic drive system with an adjustable pump in the delivery flow has at least one consuming device connected to the pump. Associated with each consuming device are actuation devices that specify the direction of movement and the speed of movement. A control valve device controls the direction of movement and the speed of movement. The delivery flow of the pump can be adjusted to the hydraulic flow required by the actuated consuming devices. The hydrostatic drive system makes possible the operation of the consuming devices independently of the load and the operation of the consuming devices independently of the direction of the load, in a simple manner and with lower energy losses. Associated with each consuming device is a delivery flow sensor that measures the hydraulic flow discharged from the consuming device to a reservoir, and/or a delivery flow sensor that measures the hydraulic flow from a delivery line of the pump to the consuming device.

Abstract: A hydrostatic drive system with a pump and at least one consuming device that is connected to the pump can be actuated by a control valve. The control valve can be actuated as a function of an actuator that specifies a desired speed of movement and a direction of movement of the consuming device. The control valve in the center position, makes possible an unpressurized circulation of the pump. The control valve can be actuated electrically, and there is a sensor that measures the actual speed of movement of the consuming device. The control valve, the speed-of-movement sensor and the actuator are connected with an electronic control that controls the control valve as a function of the direction and speed of movement specified by the deflection of the actuator and of the actual speed of movement of the consuming device as measured by the speed-of-movement sensor. The speed-of-movement sensor may be a delivery flow sensor.

Abstract: A valve system is provided for the hydraulic work system of a work vehicle, in particular of an industrial truck, with a elevating drive system for raising and lowering a load and a tilting drive system, each of which can be actuated by a control valve, in particular by an electrically actuated control valve, the opening width of which determines the speed of movement of the user. The elevating drive system is realized in the form of a single-action hydraulic cylinder and a check valve in the form of a seat valve that can be opened toward the hydraulic cylinder is located in a hydraulic line leading from the control valve to the hydraulic cylinder. The tilting drive system is realized in the form of a double-action hydraulic cylinder. The valve system has an improved function with low energy losses. The check valve has a control surface that acts in the direction of the opening position and can be pressurized by the load pressure of the elevating drive system.

Abstract: A control valve device for a hydraulic user includes an electrically actuated control valve that has a sliding spool for the control of the connection of at least one user channel that is in communication with the user with a delivery channel and a reservoir channel. A shutoff valve located in the user channel blocks a return flow from the user to the control valve. A pilot control valve actuates the shutoff valve. When the user channel is connected with the reservoir channel, the pilot control valve can be actuated to move the shutoff valve into the open position by an actuator element. The control valve device has a low actuation force for the deflection of the sliding spool and for the actuation of the pilot control valve. A gear train actuates the sliding spool and the actuator element.

Abstract: A hydrostatic axial piston machine employs a swash plate construction in which the diagonal position of the swash plate can be controlled by at least one positioning piston pressurized with a control pressure. A control valve is in a line which leads to at least one positioning piston. A simple electrical-hydraulic control of the swash plate can be accomplished by the electrical actuation of the control valve. The control valve may be in the form of a rotary disk valve which can be actuated by a stepper motor.

Abstract: Hydrostatic unit for driving an industrial truck with a pump, a hydrostatic propulsion unit and additional users of hydraulic energy, wherein the pump is located on an axle body of a drive axle. A control valve for the pressurization of the propulsion unit and at least one control valve for the pressurization of an additional user are located on the axle body or at least partly integrating into the axle body. In one embodiment, the axle body is a control seat receptacle of the pump and at least one traction motor of the hydrostatic propulsion unit. The control valves can be actuated electrically or hydraulically.

Abstract: A hydrostatic drive system is provided for a vehicle, in particular an industrial truck, with a hydrostatic traction drive system (16), a hydraulic work system (13) and a hydraulic steering system (9). The invention provides a drive system that is compact and exhibits improved operating behavior during the change from traction operation to coasting operation.

Abstract: A regulating device for a hydrostatic positive displacement unit, such as an axial piston machine employing the swash plate principle, includes a control valve which pressurizes a regulating piston which determines the stroke volume or the displacement volume of the positive displacement unit. An electric-hydraulic regulating device having a simple construction is provided with the control valve in the form of a slide valve which can be actuated electrically. In one configuration of the invention, the slide valve can be actuated by a stepper motor.

Abstract: A hydrostatic drive system is provided for a vehicle, in particular an industrial truck having a hydrostatic traction drive system (16), a hydraulic work system (20) and a hydraulic steering system (8). The drive system is compact and the energy utilization in the drive system is improved by providing a hydraulic pump (1) with an adjustable delivery volume working in an open circuit to supply the traction drive system (16), the hydraulic work system (20) and the steering system (8). In one configuration of the invention, there is at least one traction drive control valve (23) in the delivery line (5b) of the pump (1), whereby upstream of the traction drive control valve (23) in the delivery line (5b) of the pump (1) there is a priority valve (18) for the hydraulic work system (20), and upstream of the priority valve (18) of the hydraulic work system (20) there is a priority valve (6) for the steering system (8).

Abstract: A track-laying vehicle has two tracks, each with a hydrostatic drive unit, where at least one drive motor 1, 2 adjustable in working volume is provided in each drive unit and to which at least one pressure medium supply line 3, 4, 5, 6 connected to a hydrostatic pump leads and which has a working volume adjusting device 9, 11, 10, 12 that can be influenced by a signal dependent on the operating pressure. To avoid unintentional changes in direction of the track-laying vehicle in the case of different resistances to the tracks, it is proposed to connect the pressure medium supply lines 3, 4, 5, 6 of all the drive motors 1, 2 to a shuttle valve circuit 32, 33, 34 which determines the highest of the operating pressures of the hydrostatic drive unit and empties in a signal line 19 that is connected to the control elements of the working volume adjusting devices 9, 11, 10, 12 of all the drive motors 1, 2.

Abstract: A hydrostatic transmission in a closed circuit which includes a hydraulic engine having a stroke-volume control device and a hydraulic pump connected to said hydraulic engine by two pressure lines. The stroke volume of the pump and/or the engine is regulated by the stroke-volume control device. The closed circuit includes a reversing valve which is connected to both pressure lines and is controlled by the prevailing pressures in the pressure lines. The reversing valve connects the pressure line carrying the lower pressure to a delivery valve and connects the pressure line carrying the higher pressure to a pressure-reducing valve so that the level of the control pressure in the stroke-volume control device is determined. A pressure-reducing valve is located in each pressure line and the pressure-reducing valves and the reversing valve are combined as a single combination valve.

Abstract: A control device for a variable displacement hydrostatic machine having a stroke-volume regulator which is responsive to an actuating pressure. The control device includes a booster pump. The delivery pressure of the machine is the actuating pressure unless the delivery pressure of the machine is insufficient in which case the actuating pressure is a feed pressure produced by the booster pump. The control device includes a plurality of delivery-pressure lines and a proportioning pressure regulator having an outlet pressure which is proportionally reduced relative to the intake pressure connected between each delivery-pressure line and the stroke-volume regulator.

Abstract: An electrohydraulic signal converter includes an armature which is movable in a magnetic field generated by field coils and is located between two inlet channel orifices that are provided with restrictors. Drain channels are connected downstream from the orifices and lead to a pressureless tank. The armature is connected to the orifices so that a pressure differential can be produced between the pair of inlet channels in the converter. In order to keep the loss of oil of the signal converter low, the orifices are closed when the armature is in its neutral or central position. When the armature is moved from its neutral position, the orifice away from the armature is opened and permits the flow of hydraulic oil from one inlet channel to a drain channel. The orifices are each formed by a borehole into which can be inserted a cylindrical projection on each front face of the armature.

Abstract: A control for working machine equipped with a continuously hydraulic drive unit and an adjusting element therefor in which the adjusting element is adjusted by control pressure, which is in turn adjusted by a control pressure adjusting element is provided having at least one restrictor in the control pressure adjusting element and a control pressure modifying element that influences the control pressure connected to the control pressure adjusting element.

Abstract: A control for a power drive assembly having a primary energy source, a hydrostatic pump driven by the energy source and a consumer of energy has a multiway valve between the pump and consumer and a control pressure dependent valve receiving fluid from the pump controlling its position and connections between a source of pressure fluid and a spring biased operating cylinder connected to a control lever on the primary energy source controlling operation thereof.

Abstract: An electromagnetic proportioning valve is provided having two coils and an armature which can be displaced by either coil in one of two possible directions, in which case a seat valve on whose valve bodies the magnetic force generated in the armature acts, is located on each side of the armature.

Abstract: An hydrostatic drive unit for driving a motor vehicle is provided including a pump, a hydraulic motor, connecting means between said pump and motor, a branch line connected to the connecting means, a shut-off means located in said connecting means, measuring means in said shut-off means for measuring the horizontal forces arising in the direction of the longitudinal axis of the vehicle, said shut-off means acting on the hydrostatic drive unit, said measuring means including a mass capable of being displaced in the direction of the longitudinal axis of the vehicle against a forcible stop, resilient means acting on said mass to position the same normally in a center position capable of movement in two directions on the longitudinal axis of the vehicle and in working connection with the shut-off element whereby during the exertion of force upon the forcible stop, said mass acts directly or indirectly on said shut-off element to control fluid flow in said connecting means.