Abstract: A disc valve assembly includes a disc element housed within a housing, the disc element having an inlet facing side and a second side opposite to the inlet facing side, and flow pathways configured as a plurality of different pressure zones with the flow pathways extending axially along a longitudinal axis of the disc element from at or adjacent to the inlet facing side to the second side. The valve housing that houses the disc element includes porting configured as part of the plurality of different pressure zones respectively in fluid communication with the flow pathways of the disc element. The disc element is configured to rotate to control a flow of hydraulic fluid through the disc valve assembly. The different pressure zones are isolated from each other using a plurality of annular sealing rings located on the inlet facing side of the disc element.

Abstract: An example pump includes: (i) a swash block having (a) a first trunnion arm on a first side of the swash block, and (b) a second trunnion arm on a second side of the swash block; and (ii) a housing including (a) a through-hole disposed on a respective first side of the housing, (b) a blind hole disposed on a respective second side of the housing opposite the respective first side thereof, and (c) an internal chamber. The swash block is supported within the internal chamber of the housing by the first trunnion arm being positioned in the through-hole of the housing and the second trunnion arm being positioned in the blind hole of the housing.

Abstract: An axial piston pump including a housing, a cylinder block, and a swash block. The cylinder block is rotatable within the housing about a vertical axis and includes an array of openings in the cylinder block distributed about the vertical axis and an array of pistons reciprocatably movable within the respective openings. The swash block is rotatable about an axis of rotation that is transverse to the vertical axis, and the degree of rotation is configured to control the extent of reciprocation of the pistons as the cylinder block rotates. The swash block has arc shape conical bearing surfaces tilted relative to the axis of rotation that are configured to guide movement of the swash block rotationally about the axis of rotation and prevent movement of the swash block axially along the axis of rotation.

Abstract: A disc valve assembly for control of a flow of hydraulic fluid in a hydraulic fluid system may include a disc element comprising an inlet facing side and a second side opposite to the inlet facing side, and flow pathways configured as a plurality of different pressure zones with the flow pathways extending axially along a longitudinal axis of the disc element from at or adjacent to the inlet facing side to the second side. A valve housing houses the disc element and includes porting configured as part of the plurality of different pressure zones respectively in fluid communication with the flow pathways of the disc element. The disc element is configured to rotate to control a flow of hydraulic fluid through the disc valve assembly. The different pressure zones are isolated from each other using a plurality of annular sealing rings located on the inlet facing side of the disc element.

Abstract: An axial piston pump including a housing, a cylinder block, and a swash block. The cylinder block is rotatable within the housing about a vertical axis and includes an array of openings in the cylinder block distributed about the vertical axis and an array of pistons reciprocatably movable within the respective openings. The swash block is rotatable about an axis of rotation that is transverse to the vertical axis, and the degree of rotation is configured to control the extent of reciprocation of the pistons as the cylinder block rotates. The swash block has arc shape conical bearing surfaces tilted relative to the axis of rotation that are configured to guide movement of the swash block rotationally about the axis of rotation and prevent movement of the swash block axially along the axis of rotation.

Abstract: An elective down pressure system for cutting units of a grass mowing machine with lift and lower mechanisms connected to the lift arms with lost motion couplings that may be set to either a downforce position in which the lift and lower mechanisms urge the lift arms to apply downforce to the cutting units while they are on the ground surface, or a no downforce position in which the lift and lower mechanisms discontinue urging the lift arms to apply downforce once the cutting units are on the ground surface.

Abstract: A shift mechanism for trim mower cutting units includes a pair of slidable carriers. Each slidable carrier can slide along a pair of guide rods mounted to a mower frame. A hydraulic extension cylinder is connected to each slidable carrier and independently extends to move the slidable carrier laterally outward from the mower frame or retracts to move the slidable carrier laterally inward in relation to the mower frame. A hydraulic shifting cylinder is mounted between the two extension cylinders and extends to shift both slidable carriers laterally inward toward a center position, and retracts to move both slidable carriers laterally outward toward an extended position.

Abstract: A hydraulic system for limited wheel slip of a traction drive system includes first and second pilot directional valves between a hydraulic pump and first and second hydraulic wheel motors. If a wheel slips, the first or second pilot directional valves moves to a first position directing some hydraulic fluid through a restricted passage to the slipping motor and the remainder through an unrestricted passage to the opposite motor. Absent wheel slip, the pilot directional valve is in a second position directing all of the hydraulic fluid through an unrestricted passage to the corresponding motor. The first and second pilot directional valves detect wheel slippage and move between the first and second positions based on a first pilot signal corresponding to the pressure sensed entering the respective pilot directional valve, which is balanced against a biased spring and a second pilot signal from the opposite motor.

Abstract: A trim mower includes a frame supported by a plurality of wheels to travel over a ground surface, at least two front reel-type cutting units and at least one rear reel-type cutting unit. A separate lift arm is attached between the frame and each reel-type cutting unit. Each lift arm can pivot to move a reel-type cutting unit between a mowing position on a ground surface and a transport position raised above the ground surface. The lift arm for at least two of the cutting units, and preferably at least one front cutting unit and one rear cutting unit, can extend to selectively move the cutting units attached thereto laterally while the cutting units are in the mowing position. The lateral movement of a front cutting unit may be proportionately further than the lateral movement of a rear cutting unit.

Abstract: A reverse over-ride system is provided for a mower traction drive having a front pair of hydraulic traction motors and a rear pair of hydraulic traction motors. Each motor is operable in a forward direction or a reverse direction, and each front motor is in series with a rear motor. The system includes a solenoid operated valve connected to each rear motor. Each solenoid operated valve has a first position in which a check valve opens to allow recirculation through the rear wheel motors while the mower operates in a forward turn, and closes to disallow recirculation so the rear wheel motors may build pressure and drive during hill climbing. Each solenoid operated valve has a second position allowing free rotation of the rear motor while the machine operates in a reverse direction. A mechanical or electronic linkage is provided between the reverse pedal and solenoid operated valves.

Abstract: A shift mechanism for trim mower cutting units includes a pair of slidable carriers. Each slidable carrier can slide along a pair of guide rods mounted to a mower frame. A hydraulic extension cylinder is connected to each slidable carrier and independently extends to move the slidable carrier laterally outward from the mower frame or retracts to move the slidable carrier laterally inward in relation to the mower frame. A hydraulic shifting cylinder is mounted between the two extension cylinders and extends to shift both slidable carriers laterally inward toward a center position, and retracts to move both slidable carriers laterally outward toward an extended position.

Abstract: A shift mechanism for trim mower cutting units includes a pair of slidable carriers. Each slidable carrier can slide along a pair of guide rods mounted to a mower frame. A hydraulic extension cylinder is connected to each slidable carrier and independently extends to move the slidable carrier laterally outward from the mower frame or retracts to move the slidable carrier laterally inward in relation to the mower frame. A hydraulic shifting cylinder is mounted between the two extension cylinders and extends to shift both slidable carriers laterally inward toward a center position, and retracts to move both slidable carriers laterally outward toward an extended position.

Abstract: A series hydraulic circuit for permitting motorized operation and independent control of a plurality of cutting decks of a mower. The circuit allows separate operation of one of the decks while enabling operation of one or more of the other decks associated with the mower to simultaneously occur.

Abstract: A shift mechanism for trim mower cutting units includes a pair of slidable carriers. Each slidable carrier can slide along a pair of guide rods mounted to a mower frame. A hydraulic extension cylinder is connected to each slidable carrier and independently extends to move the slidable carrier laterally outward from the mower frame or retracts to move the slidable carrier laterally inward in relation to the mower frame. A hydraulic shifting cylinder is mounted between the two extension cylinders and extends to shift both slidable carriers laterally inward toward a center position, and retracts to move both slidable carriers laterally outward toward an extended position.

Abstract: An elective down pressure system for cutting units of a grass mowing machine with lift and lower mechanisms connected to the lift arms with lost motion couplings that may be set to either a downforce position in which the lift and lower mechanisms urge the lift arms to apply downforce to the cutting units while thy are on the ground surface, or a no downforce position in which the lift and lower mechanisms discontinue urging the lift arms to apply downforce once the cutting units are on the ground surface.

Abstract: A hydraulic system for limited wheel slip of a traction drive system includes first and second pilot directional valves between a hydraulic pump and first and second hydraulic wheel motors. If a wheel slips, the first or second pilot directional valves moves to a first position directing some hydraulic fluid through a restricted passage to the slipping motor and the remainder through an unrestricted passage to the opposite motor. Absent wheel slip, the pilot directional valve is in a second position directing all of the hydraulic fluid through an unrestricted passage to the corresponding motor. The first and second pilot directional valves detect wheel slippage and move between the first and second positions based on a first pilot signal corresponding to the pressure sensed entering the respective pilot directional valve, which is balanced against a biased spring and a second pilot signal from the opposite motor.

Abstract: A series hydraulic circuit for permitting motorized operation and independent control of a plurality of cutting decks of a mower. The circuit allows separate operation of one of the decks while enabling operation of one or more of the other decks associated with the mower to simultaneously occur.