Abstract: An electronic transmission control system is provided 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: 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: 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: 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: 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 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: 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 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: 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: 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.

Abstract: A control device apparatus for a proportionally adjustable hydraulic pump of a closed hydraulic circuit, including an axial piston pump adjustable from a zero position in two pivoting directions, with an electro hydraulic valve configuration for the activation of a piston of the hydraulic pump from both sides and with a feedback device, connected to the piston and whereby the angular pivoting position of the piston can be fed back to the valve configuration as a control signal, the valve configuration having a valve for each pivoting direction of the piston, and the feedback device comprising two mechanical feeler elements, each connected to one of the valves and in sliding engagement with the piston in such a way that the feeler elements are actuated when it leaves the zero position.

Abstract: A bent axis hydrostatic module, comprising:

Abstract: A hydrostatic module is disclosed, including a pair of shafts rotatably supported by a frame. Two yokes are pivotally mounted on the frame, each having complimentary surfaces to the other yoke and to the frame, minimizing the space occupied by the yokes. Stop means are provided on the yokes and on the frame to limit the pivotal movement of the yokes. A hydrostatic power unit is carried by each yoke, each connected to one of the shafts. A control system, having a single piece control housing containing servo pistons, pivots the yokes. The servo pistons independently determine the orientation of the yokes. A single piece fluid control porting plate is secured to the control housing to route hydraulic fluid to multiple locations within the control housing. A fluid manifold serves as a main structural element, with intimate proximity between the manifold and the control housing allowing simplified fluid exchange therebetween.

Abstract: A transmission has an HMT which is in parallel with an HST both driving two planetaries which are used for forward/reverse and for differential steer. A two or three mode HMT is created by having a first HST in parallel with two or three mechanical power paths defined by separate clutches. One clutch has a speed reversing gear to produce reverse output speed. A four-element planetary sums the parallel flow and delivers variable speed and torque to two output shafts. The differential steer is created by two planetaries connected with the outputs of the HMT and a second HST. The planetaries have a speed reversing gear on one power path connection. The second HST controls the differential speed between the output shafts by adding speed to one and subtracting speed from the other.

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: A hydraulic power unit in a housing has a power shaft associated with the power unit. A transducer adapted for measuring torque is mounted in the housing. A stationary portion of the transducer is mounted in non-contact relation to the shaft. A method for measuring torque in the power unit involves placing the transducer in the position described.

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 selectable detent relief valve of this invention is used to operate a hydraulic detent mechanism on a manually operated spool valve. This design has three modes of operation, no-detent, continuous detent and kick-out detent. The no-detent position allows flow to pass through the relief valve, from a first port to a second port and bypass the relief function. The pressure created, disengages the detent mechanism in the spool valve. The spool always returns to neutral position as long as pressure is present. The continuous detent position blocks the flow from a first port to a second port. The kick-out detent position allows flow to pass from the first port to the second port to override (kick-out) the detent mechanism in the spool when the pressure is greater than 2600 psi.