Abstract: A method of making a cylinder block for a rotatable hydrostatic power member by separating the cylinder block into its four geometries and joining them together. The geometries include a base plate having a center opening and a arcuate kidney-shaped openings uniformly spaced radially around the center opening. The second geometrical item is a grooved drive shaft that fits into the center opening of the base plate. The third member is a group of tubular bore elements that fit in the base plate and mate with the drive shaft. The final member is a torque ring that matingly fits over the tubular piston bore elements.

Abstract: A decoupled check-relief valve for use in a hydraulic fluid circuit is provided that has a cylindrical guide housing which travels during the check function of the valve. The cylindrical guide housing has a clearance parameter, allowing for the selection of an optimal check response time. A dampening disk is provided inside the cylindrical guide housing, traveling within the guide during the relief function of the valve. The dampening disk has a separate clearance parameter, allowing for the selection of an optimal dampening capacity and fluid circuit stability. As such, the check and relief clearance parameters are independent of each other to allow both the check and relief functions of the valve to be optimized.

Abstract: A current sampling half-bridge output driver capable of driving a wide range of loads using an accurate selection of current sensing resistors. Pluralities of stages are connected in series with the current sensing resistors from each stage connected in series. A range selector selects the stage appropriate for each current load. The reference resistors for a selected stage includes the current sensing resistor associated with that stage added in series to all current sensing resistors electrically connected between the selected stage and the load. The disclosed circuit avoids switching resistors in and out of the circuit and thereby increases the accuracy of the sensing resistor circuit.

Abstract: The present invention discloses a system for non-contact measurement of vibrational motion in a vibratory compacting machine. The system includes a vibrating element such as a roller drum adapted for vibrational motion and a non-contact sensor positioned a distance from the vibrating element and adapted for sensing the vibrational motion of the vibrating element. The present invention also discloses a method for non-contact measurement of vibrational motion of a vibrating element in a vibrating element that includes sensing position information of the roller drum with a non-contact sensor positioned a distance from the vibrating element and determining at least one vibration characteristic based on the position information sensed with the non-contact sensor.

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 piston for use in the cylinder block of a hydraulic power unit. The piston has an elongated cylindrical body with one end configured to connect with a slipper element. The second end of the piston is open with an annular cavity in the piston body defining an elongated stem extending from the head end of the piston and slightly protruding through the open end. The stem is concentrically located within the longitudinal axis of the annular cavity and has an elongated fluid conduit that extends longitudinally through the stem and completely through the piston. The fluid conduit traverses the piston body along the center axis, providing a path for pressurized fluid. The piston is composed of a unitary cast construction.

Abstract: A variable displacement hydraulic power unit has a housing and a rotating piston block with a rotatable axis and a servo piston bore having a reciprocal piston therein with the bore extending in a direction parallel to the rotatable axis of the rotating piston block. The housing and servo piston each have adjacent open ends. A single integral cover is attached to the housing to cover close and close the open ends of both the housing and the piston bore.

Abstract: An extended male slipper servo pad provides an improved connection between the swashplate and a positioning mechanism in a variable displacement hydraulic unit. The swashplate assembly includes a swashplate having a socket formed therein and a male slipper servo pad pivotally attached to the swashplate at the socket. The male slipper servo pad has a ball end secured in the socket and a pad end having a substantially flat planar surface thereon directed away from the ball end.

Abstract: A method of securing a cap on a piston body includes forming a first annular V-shaped surface at an open end of a cylindrical piston body; forming a second annular V-shaped surface on an annular surface of an oil conduit in the interior center of the piston body; forming a cap to close the open end of the piston body and forming a pair of annular surfaces therein which are flat in shape and in contact with first and second annular V-shaped surfaces on the piston body; placing the cap over the open end of the piston body and thereby placing the annular surface on the cap and the body in close intimate contacting relation; and welding the respective annular surface of the cap and the piston body together by subjecting the cap and body to an extreme high current density to fuse respective contacting annular surfaces together.

Abstract: A pump housing assembly includes a housing, a hub portion, and a flange. The housing has an end cowling defining a transition from a central portion of the housing to a transverse end portion. The hub portion extends longitudinally outwardly from the transverse end portion of housing. The flange extends radially outwardly from the outward end of the hub and is in spaced longitudinal relation to the end of the cowling to create a space to receive a head of a mounting bolt. The flange has an outer periphery with a pair of tangentially extending slots having an open end. The space for receiving a head of a mounting bolt is less than the length of a shank of a mounting bolt, to minimize the length of the housing. The slots have a width sufficient to receive the movement of a shank into and out of the open ends of the slots.

Abstract: A pump housing assembly includes a housing, a hub portion, and a flange. The housing has an end cowling defining a transition from a central portion of the housing to a transverse end portion. The hub portion extends longitudinally outwardly from the transverse end portion of housing. The flange extends radially outwardly from the outward end of the hub and is in spaced longitudinal relation to the end of the cowling to create a space to receive a head of a mounting bolt. The flange has an outer periphery with a pair of tangentially extending slots having an open end. The space for receiving a head of a mounting bolt is less than the length of a shank of a mounting bolt, to minimize the length of the housing. The slots have a width sufficient to receive the movement of a shank into and out of the open ends of the slots.

Abstract: An integrated wheel hub assembly includes a hydrostatic spindle assembly that has a spindle with a hydrostatic rotational power unit and integral high-pressure passageways therein, a wheel hub rotatably supported by the spindle assembly, and an axle shaft extending through the spindle for transmitting power from the hydrostatic unit to the wheel hub through a planetary gear set reducer. For radial compactness, the swashplate of the hydrostatic power unit resides outside the wheel hub.

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 swing cylinder oscillation control circuit and valve for oscillating booms connects two hydraulic cylinders with a shuttle valve and two check valves to provide the higher cylinder pressure to a fluid inlet and a lower cylinder pressure to a fluid outlet of a fast-opening and a slow-closing check valve. The fast-opening and slow-closing check valve uses a poppet and spring to set a valve opening pressure and uses internal flow connections to a large diameter piston that works with mechanically adjustable piston and poppet strokes to control the time for valve closing.

Abstract: A method of securing a cap on a piston body includes forming a first annular V-shaped surface at an open end of a cylindrical piston body; forming a second annular V-shaped surface on an annular surface of an oil conduit in the interior center of the piston body; forming a cap to close the open end of the piston body and forming a pair of annular surfaces therein which are flat in shape and in contact with first and second annular V-shaped surfaces on the piston body; placing the cap over the open end of the piston body and thereby placing the annular surface on the cap and the body in close intimate contacting relation; and welding the respective annular surface of the cap and the piston body together by subjecting the cap and body to an extreme high current density to fuse respective contacting annular surfaces together.

Abstract: A non-feedback proportional system is provided to achieve desired operating characteristics which will allow the control of a hydrostatic transmission to closely approximate the control performance of a displacement feedback control system by establishing certain parameters relating to (1) the servo spring rate; (2) the valve plate index; (3) valve plate crossport/trap; (4) valve plate porting geometry; (5) swashplate offset; and (6) piston bore volume.

Abstract: A hydromechanical transmission has a housing with a planetary gear system. A power output is operatively connected to the gear system for deriving power therefrom. A control is provided for operating the gear system in either a hydromechanical or a hydrostatic mode.

Abstract: A swing cylinder oscillation control circuit and valve for oscillating booms connects two hydraulic cylinders with a shuttle valve and two check valves to provide the higher cylinder pressure to a fluid inlet and a lower cylinder pressure to a fluid outlet of a fast-opening and a slow-closing check valve. The fast-opening and slow-closing check valve uses a poppet and spring to set a valve opening pressure and uses internal flow connections to a large diameter piston that works with mechanically adjustable piston and poppet strokes to control the time for valve closing.

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: The neutral override circuit of this invention includes a variable displacement pump controlled by a servo fluidly connected to a displacement control that is biased to a neutral position. A charge pump is connected to the pump and the displacement control. A solenoid-operated neutral override brake control valve is connected to the charge circuit upstream of the displacement control valve and is normally biased to an open position. However, the solenoid urges the valve to a closed position in a response to a signal indicating that the brake has been released. In the open position, the valve dumps charge flow to the pump case until the supply pressure to the displacement control is inadequate to overcome the centering bias of the displacement control. The characteristics of the brake control valve can be set so that some minimum charge pressure and lubricating flow are still provided to the rotating elements of the pump.