Abstract: A control system that can be used on a hydrostatic pump has a feedback sensor to detect the angle of a swashplate. From the information gathered by the feedback sensor about the swashplate and another set command, this information is sent to a microprocessor. The microprocessor then uses an algorithm to create an output signal and also sends out a superimposed dither signal. This dithered output signal is then received by a pressure control that causes a dither servo pressure in a servo system. Because of the dither pressure the servo system adjusts the position of the swashplate.

Abstract: The invention concerns a hydraulic valve arrangement with a working connection arrangement having a first working connection and a second working connection, both working connections being connectable with a hydraulic consumer, a supply connection arrangement having a pressure connection and a tank connection, a first valve arrangement, which closes the pressure connection or connects it in a controlled manner with the first working connection or the second working connection, a second valve arrangement, which closes the tank connection or connects it in a controlled manner with the first working connection or the second working connection, and a control device, which controls the first valve arrangement and the second valve arrangement. It is endeavoured to enable a simple manner of exact controlling the consumer.

Abstract: An open circuit system that uses a two-position three-way logic valve that automatically compensates for remote pressure in the system. The system has a pump that sends a pump supply through an orifice to the two-position three-way logic valve. Then depending on the load sense signal, the valve either allows the flow of the pump supply to the compensation relief valve or alternatively, the logic valve prevents the flow from the pump supply. The load sensing signal determines whether the valve will allow flow from the pump supply.

Abstract: A joystick device is provided that is in electronic communication with a remotely located main electronic controller used to control heavy machinery and the like. The joystick device includes a base assembly having a first microprocessor in electronic communication with the main electronic controller. The joystick device also includes a grip assembly pivotally connected to the base assembly. The grip assembly includes a plurality of input buttons and a second microprocessor in electronic communication with the first microprocessor. The joystick device further includes sensing elements that detect movement of the joystick device.

Abstract: An open circuit system that uses a two-position three-way logic valve that automatically compensates for remote pressure in the system. The system has a pump that sends a pump supply through an orifice to the two-position three-way logic valve. Then depending on the load sense signal, the valve either allows the flow of the pump supply to the compensation relief valve or alternatively, the logic valve prevents the flow from the pump supply. The load sensing signal determines whether the valve will allow flow from the pump supply.

Abstract: In an axial-piston machine of the swashplate or oblique-axis type of construction, a contact face of the cylinder head (1) is pressed against a stationary sealing face. The contact face has located in it transition orifices (15a) for the exchange of hydraulic fluid between the cylinder head (1) and the stationary part. The transition orifices (15a) are located on a raised annular collar (13) of the end face (11) of the cylinder head (1). Microgrooves (21) are recessed in the annular collar (13) between the individual transition orifices (15a), so that, of the supporting face, only two edge webs (13a, 13b) remain. The depth of the microgrooves (21) is only a few hundredths of a millimeter. This design prevents a hydrodynamic carrying effect between the cylinder head and the stationary part.

Abstract: A hydrostatic variable displacement unit is provided having a swash plate which serves to adjust the stroke of displacement pistons in a cylinder block and can be pivoted in its angular position by means of a servo system, the servo system having at least one servo piston with two servo-piston end surfaces which are in each case assigned a servo cylinder and a servo-piston rear surface, and the servo cylinders, by means of the assigned servo-piston end surfaces, in each case bounding a servo-cylinder pressure space. The servo piston is acted upon by a spring arrangement having at least one spring arranged outside the servo-cylinder pressure space and clamped between two spring plates. The two spring plates are acted upon by the springs in the direction of a stop of the particular servo cylinder that is situated on its side such that in the neutral position, the spring plates bear against the servo-piston rear surfaces and against the stop of the particular servo cylinder.

Abstract: A swing speed compensation device is provided for use with a flow sharing hydraulic system. The present invention is mounted within the metering spool of a flow sharing valve and includes a poppet that is attached to a spring retainer. The spring retainer encases a compression spring which pushes against a plug and has a drain hole that, depending upon the position of the spring retainer and poppet combination, can vent excess pressure within the present invention to a hydraulic pump tank. When a flow sharing hydraulic system starts or stops, there is a rush in the fluid flow that can cause a spike in the system pressure. The present invention absorbs this pressure spike, allowing for the fluid flow to gradually increase or decrease as the system starts or stops.

Abstract: The invention concerns a pressure reduction valve (1) with a housing (2a, 2b), a valve element (6) being displaceable in the housing and acted upon in one direction by a pressure in a low-pressure chamber connected with an outlet (11) and in the opposite direction by the force of a spring (16), which is arranged in a spring chamber (17) in the housing (2a). It is endeavoured to improve the dynamic behaviour of the pressure reduction valve. For this purpose, a pilot flow path (7, 23, 21) connects the low-pressure chamber (5) and the spring chamber (17) with each other.

Abstract: In the stationary part (1) of an axial piston machine, a first flow duct (2) and second flow duct (5) intersect with the central axes (3) and (6). A valve body (20) having a valve cone (21) and a tubular guide piston which can be displaced in relation to the valve cone is situated in the extension of the central axis (3) of the first flow duct (2). The valve body (21) bears against a first valve seat (4) which is surrounded by an expanded section (7). The entire valve body (20) moves in a tubular partial housing (9) which is connected to the stationary part (1) in a sealed manner via a seal (11), a screw connection (10) and a flange (12) which rests on a shoulder (13) of the stationary part (1). A first compression spring (27) and a second compression spring (28) serve to support the valve body (20) and its parts in relation to one another. An extension stem (22) passes through the tubular guide piston and guides the second compression spring (28).

Abstract: A hydraulic control system (1) has a hydraulic motor (10), which is connected with a control valve (2) via two working lines (8, 9), the control valve (2) being connected with a low-pressure connection (T) and, via a compensation valve (4), with a high-pressure connection (P), to ensure that a return compensation valve (14, 15) is arranged in each working line, each return compensation valve (14, 15) having a nominal flow line (29), which extends unintersectedly in relation to the nominal flow line (28) of the compensation valve (4).

Abstract: The invention concerns a valve arrangement for controlling a hydraulic drive, the supply and the outflow of the hydraulic drive being separately controllable. It is endeavoured to improve the valve arrangement in such a manner that it is intrinsically tight, at the same time having a relatively simple design. For this purpose, a pump pipe and a tank pipe are connected with a first control valve, the first control valve being connected by separate pipes with a second control valve and a third control valve connected in parallel with the second control valve, the second control valve being connected with a first working connection of the hydraulic drive and the third control valve being connected with a second working connection of the hydraulic drive, backflow preventers for preventing the flow from the hydraulic drive in the direction of the tank being connected in parallel with the second control valve and/or the third control valve.

Abstract: The invention concerns a valve arrangement for controlling a hydraulic drive, the supply to and the outflow from the hydraulic drive being separately controllable. It is endeavoured to realise separate controls of the speed and the hydraulic pressure of the hydraulic drive. For this purpose, a pump pipe is connected with a first control valve, the first control valve is connected through a pipe with a first working connection and a second working connection of the hydraulic drive, and the first working connection is connected with a second control valve and the second working connection is connected with a third control valve, the second control valve and the third control valve opening into a tank (T).

Abstract: The invention concerns a valve arrangement for controlling a hydraulic drive having a first working connection (A) and a second working connection (B), and being connectable with or separable from a pressure source (P), the supply and the outflow of the hydraulic drive being separately controllable. It is endeavoured to improve the energetic efficiency of the valve arrangement. For this purpose, the first working connection (A) is connected with a first control valve and the second working connection (B) is connected with a second control valve, the first and the second control valves being connected with each other and with a third control valve, which is connected with a tank.

Abstract: A fixed displacement pump includes a housing having a cavity, an inlet, and an end cap with alignment portions therein. A cam ring pivotally associated within the cavity includes adjustment portions. The cam ring is aligned in a fixed position via a pin inserted through both a select adjustment portion and a corresponding alignment portion. The adjustment portion selected determines both rotational direction and displacement of the pump. The cam ring also includes recesses positioned adjacent the inlet to facilitate porting of fluid through the pump. A rotor mounted within the cam ring includes roller slots having groove segments. The groove segments are positioned in an arcuate arrangement about the rotor to facilitate porting of fluid through the pump. The rotor also includes undercut portions positioned between the roller slots in an arcuate arrangement on an outer edge of the rotor to facilitate porting of fluid through the pump.

Abstract: A hydraulic valve system (1) has a supply connection arrangement having a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement, having two working connections (A, B) connectable with a motor (2), with a directional valve (4), which is arranged between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and with a compensation valve (8), which is acted upon in a first operation direction by a spring (22) and a pressure in a pressure chamber (23), which is connected with a load-sensing line (LS), and in a second operation direction, which is opposite to the first operation direction, by a pressure at the directional valve (4).

Abstract: An electronic transmission control system that can achieve a transmission ratio based on the operator inputs and the current vehicle operating conditions. The transmission constantly connects the engine to the load, and the transmission ratio is only varied by a change in command from the present invention. The transmission's mechanical function is solely to vary the ratio between its input and output. In using the present invention, an operator must select an operating mode, either automatic or manual, using a two-position switch. While in the automatic mode, the present invention determines the vehicle speed by considering the position of the throttle and the operator's use of brakes. In the manual mode, the present invention further considers the operator's selection of a gear condition.

Abstract: The invention concerns a hydraulic steering arrangement with a steering motor, a supply path between a pressure source and the steering motor, in which supply path a throttling device and a measuring motor are located, a return path between the steering motor and a pressure sink, in which return path a return throttle is located, and a bypass path, which connects the supply path and the return path on the pressure source end or the pressure sink end, respectively, and which has a bypass throttle. It is endeavoured to make such steering arrangements suitable for fast motorboats. For this purpose it is ensured that with a load on the steering motor the pressure drop over the bypass throttle is larger than the sum of the pressure drops between a point before the first throttle and a point after the last throttle of the throttling device.

Abstract: An HMT apparatus (T) is mounted on a vehicle (A). In the HMT apparatus (T), input rotational force from an engine (13) is once divided into two systems which are then transmitted by an MT device (23) and by an HST device (24) respectively and are re-synthesized for transfer toward wheels (12) and (16). The HMT apparatus (T) is disposed on the vehicle-body right side of the engine (13) which is sideways-mounted on a vehicle body (1), and its input and output shafts (25) and (26) are disposed in parallel with a crank shaft (13a) of the engine (13) and are disposed to run parallel with each other. The input shaft (25) is coupled directly to the crank shaft (13a) and an input gear (27) of the MT device (23) is mounted on the input shaft (25), and a hydraulic piston pump (30) of the HST device (24) is connected to the right side end of the input shaft (25).

Abstract: A loop flushing circuit in a closed circuit hydraulic system has a variable displacement hydraulic pump that is fluidly connected to a hydraulic motor. The flushing flow in the closed circuit is controlled by an electronically proportional flow control valve. The electronically proportional flow control valve is controlled by a control that ensures that the control valve being used is connected to a low pressure side of the closed loop flushing circuit.