Hydrostatic transmission with acceleration control

Claim 2

A hydrostatic transmission, comprising, a. a pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the output of the pump to cause operation of the output shaft, and f. an acceleration control valve including: means providing a bypass passage between the first and second conduits, a valve member responsive to pressure buildup in said first conduit for closing the bypass passage, yieldable means urging the valve member toward open position establishing, said bypass passage, means providing a restricted passageway for supplying fluid under pressure from the first conduit to move the valve member to closed position, and check valve means for bypassing the restricted passageway on return movement of the valve member to open position when pressure drops in the first conduit.

Claim 3

A hydrostatic transmission, comprising, a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump to cause operation of the output shaft, and f. an acceleration control valve including: a valve bore having a first port communicating with the first conduit, a second port communicating with the second conduit and an annular abutment providing a valve seat, a valve member movable in the valve bore to a valve closed position engaging said abutment responsive to pressure buildup in said first conduit, a longitudinal groove on the valve member providing restricted bypass communication between the first and second ports with the valve member in open position, and yieldable means urging the valve member toward open position establishing said bypass communication.

Claim 4

A hydrostatic transmission, comprising, a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump to cause operation of the output shaft, and f. an acceleration control valve including: a valve bore having a first port communicating with the first conduit, a second port communicating with the second conduit and an annular abutment providing a valve seat, a valve member movable in the valve bore to a valve closed position engaging said abutment responsive to pressure buildup in said first conduit, a longitudinal groove on the valve member providing restricted bypass communication between the first and second ports with the valve member in open position, and yieldable means urging the valve member toward open position establishing said bypass communication.

Claim 5

A hydrostatic transmission, comprising, a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump to cause operation of the output shaft, and f. an acceleration control valve including: a first port communicating with said first conduit, a second port communicating with said second conduit, a valve member having means providing restricted bypass communication between the first and second ports with the valve member in open position, yieldable means urging the valve member toward open position establishing said bypass communication, means on the valve member providing a restricted passageway for supplying fluid under pressure from the first port to move the valve member to closed position, and a check valve in the valve member for bypassing the restricted passageway on return movement of the valve member to open position when pressure drops in the first conduit.

Claim 6

A hydrostatic transmission, comprising, a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump to cause operation of the output shaft, and f. an acceleration control valve including: a first port communicating with said first conduit, a second port communicating with said second conduit, a valve member having means providing restricted bypass communication between the first and second ports with the valve member in open position, yieldable means urging the valve member toward open position establishing said bypass communication, means on the valve member providing a restricted passageway for supplying fluid under pressure from the first port to move the valve member to closed position, and a check valve in the valve member for bypassing the restricted passageway on return movement of the valve member to open position when pressure drops in the first conduit.

Claim 7

A hydrostatic transmission, comprising, a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump in opposite directions from neutral, and f. acceleration control valve means including, a first valve communicating with said first conduit, a second valve communicating with said second conduit, means providing a restricted bypass passage between the first and second conduits through both valves, each valve including a valve member normally biased to an open position establishing said bypass passage, and means for supplying fluid under pressure from each conduit to the associated valve for moving the valve member to a closed position blocking the bypass on increase of pressure in the associated conduit.

Claim 8

A hydrostatic transmission, comprising, a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump in opposite directions from neutral, and f. acceleration control valve means including, a first valve communicating with said first conduit, a second valve communicating with said second conduit, means providing a restricted bypass passage between the first and second conduits through both valves, each valve including a valve member normally biased to an open position establishing said bypass passage, and means for supplying fluid under pressure from each conduit to the associated valve for moving the valve member to a closed position blocking the bypass on increase of pressure in the associated conduit.

Claim 9

A hydrostatic transmission as defined in claim 4, including a valve bore having a first port communicating with said first conduit and said first valve member, and a second port communicating with said second conduit and said second valve member, and spring means acting between the valve members urging both toward valve open position.

Claim 10

A hydrostatic transmission as defined in claim 4, including means on each valve member providing a restricted passageway for supplying fluid under pressure from the associated conduit to move the valve member to closed position.

Claim 11

A hydrostatic transmission as defined in claim 6, including a check valve in each valve member for bypassing the restricted passageway on, return movement of the valve member to open position on pressure drop in the associated conduit, and spring means urging the check valve to closed position.

Claim 12

A hydrostatic transmission, comprising a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump in opposite directions from neutral, and f. acceleration and deceleration control valve means including a valve bore having a first port communicating with the first conduit and a second port communicating with the second conduit, a first valve member in the bore communicating with the first port and a second valve member in the bore communicating with the second port, means providing a restricted bypass passage between the first and second ports through both valve members, spring means urging both valve members toward valve open position establishing said bypass passage, means on each valve member providing a restricted passageway for supplying fluid under pressure from the associated port to move the valve member toward a closed position blocking the bypass passage on pressure increase in the associated port, and a check valve in each valve member for bypassing the restricted passageway on return movement of the valve member to open position responsive to pressure drop in the associated conduit.

Claim 13

A hydrostatic transmission, comprising a. a variable displacement pump, b. a motor having an output shaft, c. a first conduit connecting the pump outlet and the motor inlet, d. a second conduit connecting the motor outlet and the pump inlet, e. means for varying the displacement of the pump in opposite directions from neutral, and f. acceleration and deceleration control valve means including a valve bore having a first port communicating with the first conduit and a second port communicating with the second conduit, a first valve member in the bore communicating with the first port and a second valve member in the bore communicating with the second port, means providing a restricted bypass passage between the first and second ports through both valve members, spring means urging both valve members toward valve open position establishing said bypass passage, means on each valve member providing a restricted passageway for supplying fluid under pressure from the associated port to move the valve member toward a closed position blocking the bypass passage on pressure increase in the associated port, and a check valve in each valve member for bypassing the restricted passageway on return movement of the valve member to open position responsive to pressure drop in the associated conduit.