Hydrostatic control system

Claim 2

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle, the drive unit comprising: a pair of output pumps axially aligned, each of the output pumps having an infinitely variable swash plate operatively connected thereto to control the output of the respective pumps; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor without intervening valves or other flow control devices; operative means to control the output of the drive motor; and the improvement comprising a lost motion connecting means provided between the swash plates of the aligned drive pumps, such lost motion connecting means including a single operator control device to sequentially control the output of one or both pumps.

Claim 3

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 1 wherein the lost motion connection between the swash plates of the axially aligned output pumps includes a connecting member pivotally mounted on both pumps, the forward connecting member including an elongated slot which permits movement of one swash plate of the vehicle independently of the second swash plate of the vehicle.

Claim 4

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 1 or 2 wherein a dampener is disposed between the rear swash plate and an anchor adjacent the front swash plate of the vehicle, the dampener fully extended when the swash plates are aligned in the neutral position and a compression spring disposed between the rod end and the cylinder end of the dampener to maintain the rear swash plate in the neutral position when the dampener is fully extended.

Claim 5

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 1 wherein the operative means to control the output of the drive motor includes a pedal linkage arrangement cooperatively connected between a foot pedal of the vehicle and a servo control valve controlling the output of a cylinder which is operatively coupled to the forward swash plate of the pair of axially aligned drive pumps whereby activation of the servo control valve through the foot pedal activates the cylinder to urge the front swash plate forward, the lost motion connection permitting the second motor to engage when the front swash plate has been sufficiently extended in a forward or reverse direction.

Claim 6

An improved method for controlling the output of a hydrostatic drive unit, wherein the drive unit comprises: a pair of output pumps axially aligned, each of the output pumps having an infinitely variable position swash plate operatively connected thereto to control the output of the respective pumps; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor; operative means including a pedal member to control the output of the drive motor; and the improved method comprises providing a lost motion connection between the swash plates of the axially aligned output pumps including providing a connecting member pivotally mounted on both pumps, the forward connecting member including an elongated slot which permits movement of one swash plate of the vehicle independently of the second swash plate of the vehicle.

Claim 7

An improved method for controlling the output of a hydrostatic drive unit, wherein the drive unit comprises: a pair of output pumps axially aligned, each of the output pumps having an infinitely variable position swash plate operatively connected thereto to control the output of the respective pumps; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor; operative means including a pedal member to control the output of the drive motor; and the improved method comprises providing a lost motion connection between the swash plates of the axially aligned output pumps including providing a connecting member pivotally mounted on both pumps, the forward connecting member including an elongated slot which permits movement of one swash plate of the vehicle independently of the second swash plate of the vehicle.

Claim 8

An improved method for controlling the output of a hydrostatic drive unit for a front end loader as claimed in claim 5 wherein providing the cooperative connecting means includes providing a dampener disposed between the rear swash plate and an anchor adjacent the front swash plate of the vehicle, the dampener fully extended when the swash plates are aligned in the neutral position and a compression spring disposed between the rod end and the cylinder end of the dampener to maintain the rear swash plate in the neutral position when the dampener is fully extended.

Claim 9

An improved method for controlling the output of a hydrostatic drive unit for a front end loader as claimed in claim 5 wherein the operative means to control the output of the drive motor includes a pedal linkage arrangement cooperatively connected between a foot pedal of the vehicle and a servo control valve controlling the output of a cylinder which is operatively coupled to the forward swash plate of the pair of axially aligned drive pumps whereby activation of the servo control valve through the foot pedal activates the cylinder to urge the front swash plate forward, the lost motion connection permitting the second motor to engage when the front swash plate has been sufficiently extended in a forward or reverse direction.

Claim 10

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle, the drive unit comprising: a pair of hydrostatic output pumps axially aligned, each of the hydrostatic output pumps having an infinitely variable position swash plate mounted thereon; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor; operative means to control the output of the drive motor; and the improvement comprising a lost motion connecting means cooperatively connected between the swash plates of the aligned hydrostatic drive pumps, the lost motion connecting means including a lost motion connecting member pivotally mounted at each end to respective front and rear swash plates of the front and rear drive pumps, the lost motion connecting member having an elongated slot in which the connection between the front swash plate and the lost motion connecting member is disposed, said operative means including a servo control valve controlling the horizontal forward and reverse output of a cylinder rigidly coupled to the frame whereby selective control of the servo control valve controls the output of the cylinder operatively connected to the front swash plate of the pair of axially aligned drive pumps, and activation of the servo control valve causes the cylinder to rotate the front swash plate until it engages the forward edge portion of the slot provided on the lost motion connecting member whereupon further rotation of the front swash plate forces rotation of the rear swash plate to selectively couple the output of both drive pumps to the drive motor.

Claim 11

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle, the drive unit comprising: a pair of hydrostatic output pumps axially aligned, each of the hydrostatic output pumps having an infinitely variable position swash plate mounted thereon; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor; operative means to control the output of the drive motor; and the improvement comprising a lost motion connecting means cooperatively connected between the swash plates of the aligned hydrostatic drive pumps, the lost motion connecting means including a lost motion connecting member pivotally mounted at each end to respective front and rear swash plates of the front and rear drive pumps, the lost motion connecting member having an elongated slot in which the connection between the front swash plate and the lost motion connecting member is disposed, said operative means including a servo control valve controlling the horizontal forward and reverse output of a cylinder rigidly coupled to the frame whereby selective control of the servo control valve controls the output of the cylinder operatively connected to the front swash plate of the pair of axially aligned drive pumps, and activation of the servo control valve causes the cylinder to rotate the front swash plate until it engages the forward edge portion of the slot provided on the lost motion connecting member whereupon further rotation of the front swash plate forces rotation of the rear swash plate to selectively couple the output of both drive pumps to the drive motor.

Claim 12

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 8 wherein the cooperative connecting means between the aligned drive pumps includes a dampener having a rod end and a cylinder and mounted between the rear swash plate and an anchor mounted to the frame adjacent the front swash plate, the dampener being fully extended when the front and rear swash plates are disposed in a neutral position, the dampener being compressed when the rear swash plate is moved forwardly, and a compression spring mounted on the dampener between the rod end and the cylinder end of the dampener to return the rear swash plate to a neutral position when the operative means controlling the output of the drive motor is released.

Claim 13

An improved hydrostatic control system for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 9 wherein the operative means to control the output of the drive motor includes a cooperative pedal linkage disposed between the servo control valve and an operator foot pedal for controlling the output of the drive motor.

Claim 14

An improved method for controlling the output of a hydrostatic drive unit for a vehicle, the drive unit comprising: a pair of hydrostatic output pumps axially aligned, each of the hydrostatic output pumps having an infinitely variable position swash plate mounted thereon; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor; operative means to control the output of the drive motor; and the improvement comprising providing a lost motion connecting means cooperatively connected between the swash plates of the aligned hydrostatic drive pumps, the lost motion connecting means including a lost motion connecting member pivotally mounted at each end to respective front and rear swash plates of the front and rear drive pumps, providing the lost motion connecting means with an elongated slot wherein which the connection between the front swash plate and the lost motion connecting member is disposed, said operative means including a servo control valve controlling the horizontal forward and reverse output of a cylinder rigidly coupled to the frame, whereby selective control of the servo control valve controls the output of the cylinder operatively connected to the front swash plate of the pair of axially aligned drive pumps and activation of the servo control valve causes the cylinder to rotate the front swash plate until it engages the forward edge portion of the slot provided on the lost motion connecting member whereupon further rotation of the front swash plate forces rotation of the rear swash plate to selectively couple the output of both drive pumps to the drive motor.

Claim 15

An improved method for controlling the output of a hydrostatic drive unit for a vehicle, the drive unit comprising: a pair of hydrostatic output pumps axially aligned, each of the hydrostatic output pumps having an infinitely variable position swash plate mounted thereon; a drive motor; cooperative means between the drive motor and the output pumps to couple the output pumps to the drive motor; operative means to control the output of the drive motor; and the improvement comprising providing a lost motion connecting means cooperatively connected between the swash plates of the aligned hydrostatic drive pumps, the lost motion connecting means including a lost motion connecting member pivotally mounted at each end to respective front and rear swash plates of the front and rear drive pumps, providing the lost motion connecting means with an elongated slot wherein which the connection between the front swash plate and the lost motion connecting member is disposed, said operative means including a servo control valve controlling the horizontal forward and reverse output of a cylinder rigidly coupled to the frame, whereby selective control of the servo control valve controls the output of the cylinder operatively connected to the front swash plate of the pair of axially aligned drive pumps and activation of the servo control valve causes the cylinder to rotate the front swash plate until it engages the forward edge portion of the slot provided on the lost motion connecting member whereupon further rotation of the front swash plate forces rotation of the rear swash plate to selectively couple the output of both drive pumps to the drive motor.

Claim 16

An improved method for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 11 wherein the cooperative connecting means between the aligned drive pumps is provided with a dampener having a rod end and a cylinder end mounted between the rear swash plate and an anchor mounted to the frame adjacent the front swash plate, the dampener being fully extended when the front and rear swash plates are disposed in a neutral position, the dampener being compressed when the rear swash plate is moved forwardly, and providing a compression spring mounted on the dampener between the rod end and the cylinder end of the dampener to return the rear swash plate to a neutral position when the operative means controlling the output of the drive motor is released.

Claim 17

An improved method for controlling the output of a hydrostatic drive unit for a vehicle as claimed in claim 12 wherein the operative means to control the output of the drive motor includes a cooperative pedal linkage disposed between the servo control valve and an operator foot pedal for controlling the output of the drive motor.

Claim 18

A hydrostatic drive comprising a hydraulic motor, two variable displacement pumps driven jointly by a common prime mover, conduit means connecting the outlets of both said pumps to the inlet of said motor without intervening valves or other flow control devices, an operator controlled infinitely variable operating means having two ranges, one range for varying the displacement of one of said pumps for operating said motor in one operating range, the other range for varying the displacement of both said pumps simultaneously for operating said motor in another operating range in the same direction, and said operator controlled infinitely variable operating means providing transfer from said one operating range to said other operating range without any separate action required by the operator.

Claim 19

A hydrostatic drive comprising a hydraulic motor, two variable displacement pumps driven jointly by a common prime mover, conduit means connecting the outlets of both said pumps to the inlet of said motor without intervening valves or other flow control devices, an operator controlled infinitely variable operating means having two ranges, one range for varying the displacement of one of said pumps for operating said motor in one operating range, the other range for varying the displacement of both said pumps simultaneously for operating said motor in another operating range in the same direction, and said operator controlled infinitely variable operating means providing transfer from said one operating range to said other operating range without any separate action required by the operator.

Claim 20

A hydrostatic drive as in claim 14 wherein said one operating range is a lower speed range and said other operating range is a higher speed range.

Claim 21

A hydrostatic drive as in claim 15 wherein said operating means includes a foot pedal, and wherein said foot pedal moves farther in operating said operatine means through said one operating range than it does in operating said operating means through said other operating range.

Claim 22

A hydrostatic drive as in claim 14 wherein said operating means includes a third operating range in which said motor operates in the reverse direction from said other two operating ranges.

Claim 23

A hydrostatic drive as in claim 17 wherein said operating means includes a neutral position between said first operating range and said third operating range.

Claim 24

A hydrostatic drive as in claim 18 wherein said operating means includes means for selectively changing the displacement of said one pump from either said one or said other operating range back to neutral.

Claim 25

A hydrostatic drive as in claim 19 wherein said other pump is returned to neutral from said other operating range by a spring which continuously urges said other pump toward neutral.

Claim 26

A hydrostatic drive as in claim 17 wherein reverse drive is achieved by changing the displacement of said one pump in the opposite sense to said first operating range.