Abstract: A cylinder block for a hydrostatic transmission has a rotatable piston housing with a plurality of piston bores arranged in a circular pattern in the housing. A piston element is slidably mounted in each bore. Each of the piston elements has an outer end extendible out of an open end of each of the bores. A well or socket having a rounded bottom portion is in the outer end of each of the pistons. A piston slipper element comprising an arcuate base (a ball) is rotatably mounted in the socket. An arm extends outwardly from the ball and has a laterally extending flat planar surface at the other end. The flat planar surface slidably engages a swashplate having a planar control surface. The distance from the center of the ball to the flat planar surface is greater than the diameter of the piston element.

Abstract: A device for varying the displacement of a variable displacement bent axis unit includes a one-piece yoke having a bucket portion adapted to carry a cylinder block kit of the bent axis unit, a trunnion bearing portion for swing control on one side of the bucket portion, and a trunnion portion for fluid porting on the other side of the bucket portion. The bucket portion has a bottom wall, a continuous side wall, and an open top. Inside the yoke is a pair of fluid passages intersecting the interior of the bucket portion and extending separately and entirely within the bottom wall and the side wall before opening onto the trunnion portion for fluid porting.

Abstract: A vehicle having a hydrostatic drive and a hydraulic control apparatus, in which the hydrostatic drive has a variable displacement hydraulic pump and a hydraulic motor in a closed circuit, an internal combustion engine for driving the hydraulic pump and a variable displacement pump, producing a volumetric output flow, of an open circuit, and a retarder valve arranged in the open circuit and intended for the hydraulic absorption of braking energy. The retarder valve has a valve and a pressure-limiting valve, connected thereto, for throttling the volumetric output flow of the variable displacement pump. The variable displacement hydraulic pump, the variable displacement pump and the retarder valve are controlled by a digital electronic unit for the respective driving and working functions.

Abstract: A hydrostatic transmission includes a hollow one-piece cast housing having an internal compartment and an outer shell with opposite sides and opposite ends; a central wall in the housing dividing the compartment into separate sub-compartments and being integrally cast with the housing; first and second hydrostatic power units mounted one each in the sub-compartments on opposite sides of the central wall; and high pressure fluid conduits extending through the central wall and hydraulically connecting the hydrostatic power units. The hydrostatic power units can include a pump and a motor, each having respective rotating groups which are easily insertable into the respective sub-compartments through access openings in the housing. Although the main shafts of the pump and motor are capable of rotating in different directions from each other and at different speeds, the shafts have axes of rotation which are coincidental to each other.

Abstract: The multiple pump apparatus includes first and second variable displacement closed circuit pumps. The multiple pump apparatus pressurizes fluid to be subsequently supplied to drive load devices. The first and second pumps each have fluid communication lines connected to load devices through flow control valves. Each of the pumps has a swashplate for varying its displacement. The swashplates are of the over-center type, enabling each pump to supply pressurized fluid in either direction, thus providing both forward and reverse function to the load devices. The first pump has its fluid communicating lines connected to fluid communicating lines between first and second two-position four-way flow control valves. The opposite side of the first flow control valve has fluid communicating lines connected to a load device which drives a harvesting mechanism, in this case a rotor motor.

Abstract: A hydraulically propelled vehicle has a vehicle body with a pair of forward wheels and a pair of rearward wheels. A single fluid displacement pump is operatively connected to each wheel. A fluid displacement motor is connected to each wheel. The pump is fluidly connected to each motor. A steering angle sensor is located adjacent each wheel to sense the angular position of each wheel. The speed sensor is on each motor to measure its rotational speed output. A fluid displacement actuator is on each motor to set the fluid displacement thereof. A fluid displacement computer controller is operatively connected by electronic impulse to the speed sensors. The fluid displacement actuators and the steering angle sensors are operatively connected to the controller so that the controller can obtain information therefrom to calculate the expected speeds for the motors.

Abstract: A mobile work vehicle with at least one driven axle assembly is connected to and driven by just one integrated hydraulic motor. The hydraulic motor is a low-speed radial-piston motor which has a hollow shaft of which the axis of rotation is concentric with respect to the longitudinal axis of the axle assembly.

Abstract: A displacement control device for a hydraulic unit includes: an actuator for applying operator input force to a movable member for varying displacement of the unit; a control valve having a spool and a sleeve displaceable with respect to each other, one of these being coupled with the movable member and the other being coupled with the actuator, the control valve being capable of generating a control signal based upon the relative displacement of the spool and sleeve; a servo which is operatively connected to the movable member and receives the control signal so as to move the movable member and change the fluid displacement of the unit in response to the control signal; and a bias coupling connecting the spool and the sleeve of the control valve. Thus, a preload force is interposed between and the spool and the sleeve such that relative displacement between the spool and the sleeve takes place when the feedback force exceeds the preload force.

Abstract: A ganged pumping apparatus includes first and second variable displacement open circuit pumps, each having a load sensing control and a servo actuator together for changing the fluid displacement of each pump respectively. The load sensing controls being adjusted so that the setting of the control on the second pump is lower than the setting of the control on the first pump. The servo actuator of the first pump having over-center capability, allowing the first pump to operate with negative fluid displacement, and the servo actuator of the second pump having a stop to limit minimum displacement to non-negative or zero displacement. A single pressure compensating pilot valve disposed in the first pump provides the pressure compensation function of both pumps. A pilot signal line interconnects the pressure compensating pilot valve, the load sensing controls, and a load such that the flow output of the pumps is combinable into a single output and functions as a single large displacement pump.

Abstract: A plug for a threaded port is formed of resilient elastomeric material and has upper and lower ends. A smooth non-threaded outer cylindrical wall is disposed between the ends. The outer cylindrical wall has an outer diameter sufficient to frictionally engage the threads of the port. An outwardly protruding collar is disposed between the upper end and the outer cylindrical wall. An annular bead is integrally formed on the collar and is adapted to sealingly engage an inner peripheral surface of the port.

Abstract: A pump system includes a variable fluid displacement pump having a pressure line which is connected to a pressure load and connected to a load sensing control. A variable orifice is located downstream from the load sensing control. The variable orifice is fluidly connected to the load sensing control in a servo pressure conduit such that the margin pressure varies proportionally with respect to the fluid displacement Of the pump. The variable orifice can take many different forms, including a variable cross sectional area gap between the housing and an elongated servo piston longitudinally slidable therein. A longitudinal slot having uniformly increasing depth along the length of the servo piston gives the servo piston a cross sectional area which varies along its length. Thus, a variable orifice results.

Abstract: A sliding bearing, particularly for slippers of hydrostatic piston machines, with a support having a supporting surface on which slides a sliding piece having a sliding and sealing surface. Between the supporting surface and the sealing part of the sliding and sealing surface is a bearing gap height (h.sub.2) and in the sliding and sealing surface at least one shallow recess with a depth (h) bordered by the sealing part of the sliding and sealing surface. At least one connecting channel is connected to a pressure source of the lubricating fluid so that a lubrication gap with a height (h.sub.2 +h) is formed. The lubrication gap is in accordance with the invention designed in such a way that a self-adjusting load bearing capacity dependent on the gap height (h.sub.2) is achieved, whereby in the gap such a flow is created, under the influence of which the velocity of the lubricating fluid is positive (greater than zero) in all directions and the pressure gradient is declining in the flow direction.

Abstract: A hydraulic slipper includes a slipper body having first and second ends and a central portion therebetween. The first end terminates in a spherical-shaped head. The second end terminates in a round base portion with a hub protruding outwardly therefrom in the direction away from the head. The hub terminates in a planar surface and has a diameter less than the diameter of the round base portion. The slipper includes a washer element having a center opening extending around the hub and having first and second opposite planar surfaces. The first surface engages the base portion, and the second surface extends beyond the planar surface of the hub to create a running face for the slipper. The washer element can be a bi-metal ring formed of steel and bronze.

Abstract: A kit for converting a base transmission having a mid PTO shaft and a detachable original equipment rear cover into an optional configuration transmission having a rotatable mid PTO shaft and a rotatable rear PTO shaft that are both selectively drivable such that they can be commanded by the operator to rotate simultaneously or individually. The kit includes a conversion rear cover for replacing the original equipment rear cover, a rear PTO cover with an aperture therein mounted to the conversion rear cover, a rear PTO shaft rotatably supported in the aperture and extending into the conversion rear cover, and a three position selector assembly mounted on the conversion rear cover and the PTO rear cover. When installed on the base transmission, the selector assembly of the kit allows the operator to cause the rotation of the mid PTO shaft only, both the mid and rear PTO shafts simultaneously, or the rear PTO shaft only.

Abstract: An integrated hydrostatic transmission has a housing comprised of two separable elements detachably joined together along a substantially horizontal parting plane. A hydrostatic transmission including a hydrostatic pump, a hydrostatic motor, and a center section is separately mounted within the housing. The center section comprises a generally L-shaped member having a hydrostatic pump and motor mounting surfaces thereon disposed at right angles to each other. A pair of fluid ports is on each of the mounting surfaces, and internal passageways are in the L-shaped member connecting each of the fluid ports on one of the mounting surfaces with one of said fluid ports being on the other of the mounting surfaces. The L-shaped member comprises first and second legs integrally joined and extending at right angles to each other, with the first leg normally extending in a horizontal direction, and the second leg normally extending in a vertical direction.

Abstract: A vehicle transmission assembly includes a power means, a clutch connected to the power means and having an output power shaft, and a plurality of gears and substantial alignment. The gears include a first gear on the power shaft meshed with a second gear mounted on a first idler shaft. The second gear driving a third gear mounted on another idler shaft. The third gear drives a fourth gear mounted on a first PTO shaft. A second PTO shaft is operatively connected to the first shaft. A three position selector assembly on the first shaft selectively powers the PTO shafts simultaneously or individually. The method of connecting a single PTO shaft transmission assembly includes adding a second PTO shaft to said power means, and imposing a multi-position selector assembly to the gears to permit said PTO shafts to be operated together or individually.

Abstract: A joystick mechanism includes a housing, a substantially spherical magnetic ball rotatably mounted on the housing, a joystick shaft attached to the magnetic ball, and a pair of magnetic effect sensors operatively positioned adjacent the magnetic ball. The sensors, which are positioned along the x and y axes, are aimed perpendicular to each other and the z axis. Thereby, movement of the joystick and the ball causes a change in the magnetic field which is measured and indicated by the sensors.

Abstract: A holddown pin mechanism for hydraulic power units has a cylindrical flat base washer having a central opening and opposite sides, a plurality of spaced elongated holddown pins have one end rigidly secured to one side of said base washer and an outer end. The pins extend outwardly at right angles from the side of said washer to which they are secured. The holddown pin mechanism is placed in a hydraulic cylinder block having a center bore, with the pins extending into holes in the block. A guide member on a shaft extending through the block engages the free ends of the pins.

Abstract: A control system for a variable pump and a process to control the variable pump with a circuit connected to a hydraulic motor by working lines, controlled by an electronic controller, having check valves in the circuit to allow oil flow from a charge pump going into the circuit and further consisting of high pressure relief valves to allow oil flow out of the working lines to limit maximum pressure. A temperature sensor is placed between the high pressure relief valves and the connected check valves. A signal is processed in an electronic control to control the displacement of a variable pump, depending on temperature measure of the fluid flowing across the high pressure relief valves.

Abstract: A speed sensor for sensing the speed and direction of a hydrostatic motor or pump measures the speed, monitors an operator input, processes this information and generates a high power output to drive a solenoid valve or electrical displacement control. The sensor is housed in a single package mounted directly on the hydrostatic motor or pump. The function of the sensor can be easily modified with software changes.