Forward reverse drive control providing automatic braking

Claim 2

In means to reduce the change-direction-shock in a vehicle equipped with a signal responsive power brake system which, in response to a brake apply signal, arrests movement of the vehicle in forward and rearward directions of actual movement, which releases in response to a brake voiding signal, and which has two sensing points each for receiving a different one of the respective apply signal and voiding signal communicated thereto, a fluid circuit, a source of high pressure and low pressure fluid for supplying fluid to said circuit, controllable torque transmission means drivable to change the vehicle to a forward or rearward direction of movement desired and operatively receiving fluid of said circuit, and a shift control in said circuit which is forwardly and rearwardly shifted to control direction of drive of the transmission: the improvement of first valve means (220, 2CD) forming part of said shift control effective to be correspondingly forwardly and rearwardly shifted thereby, and to assume no fewer (N, FN, RN) than one intermediate position of neutral, said first valve means effective to communicate a brake apply signal (208) to one of the sensing points of the brake system; and second valve means forming part of the first valve means effective to communicate (214) a brake voiding signal (N) to the other sensing point of the brake system, when the first valve means assumes at least one neutral position aforesaid.

Claim 3

In means to reduce the change-direction-shock in a vehicle equipped with a pressure signal responsive power brake system responsive to a brake apply signal to arrest movement of the vehicle in forward and rearward directions of actual movement and releasable in response to a brake voiding signal, said power brake system having two sensing points each for receiving a different one of the respecting apply signal and voidinG signal communicated thereto, a fluid control circuit, a source of high and low pressure for supplying fluid to said circuit, torque transmission means receiving said fluid from the circuit shiftable to change the vehicle to a forward or reverse direction of movement desired, and a shift control in said circuit forwardly and rearwardly shifted to cause the torque transmission means to change the vehicle direction: the improvement of first valve means (220) forming part of said shift control effective to be correspondingly forwardly and rearwardly shifted thereby, and to assume no fewer (N, FN, RN) than one intermediate position of neutral; second valve means (2CD) forming part of said shift control hydraulically disposed between the first valve means and said brakes to communicate a brake apply signal to one of the sensing points of said brake system; and third valve means forming part of the first valve means (220) effective to communicate (214) to one point of the brake system a brake voiding signal (N) when the first valve means assumes at least one neutral position aforesaid.

Claim 4

In means to reduce the change-direction-shock in a vehicle equipped with a pressure signal responsive power brake system responsive to a brake apply signal to arrest movement of the vehicle in forward and rearward directions of actual movement and releasable in response to a brake voiding signal, said power brake system having two sensing points each for receiving a different one of the respecting apply signal and voidinG signal communicated thereto, a fluid control circuit, a source of high and low pressure for supplying fluid to said circuit, torque transmission means receiving said fluid from the circuit shiftable to change the vehicle to a forward or reverse direction of movement desired, and a shift control in said circuit forwardly and rearwardly shifted to cause the torque transmission means to change the vehicle direction: the improvement of first valve means (220) forming part of said shift control effective to be correspondingly forwardly and rearwardly shifted thereby, and to assume no fewer (N, FN, RN) than one intermediate position of neutral; second valve means (2CD) forming part of said shift control hydraulically disposed between the first valve means and said brakes to communicate a brake apply signal to one of the sensing points of said brake system; and third valve means forming part of the first valve means (220) effective to communicate (214) to one point of the brake system a brake voiding signal (N) when the first valve means assumes at least one neutral position aforesaid.

Claim 5

The invention of claim 2, the sensing points of the brake system characterized by: a spring-released brake cylinder with head and rod ends forming the two ends thereof; means (258) of introducing the communicated brake apply signal to one of said ends against the force of the brake release spring; and means of introducing the communicated brake voiding signal to the other end of the cylinder, augmenting the release spring to provide a combined force overcoming the brake apply signal.

Claim 6

In combination: a control valve assembly comprising a housing having a high, transfer 210, and low pressure chambers; a common bore intersecting the chambers; individual valve bores in communication with the transfer and low pressure chambers and with plural service passages in said housing; first and second range selector valve elements (F1F2, R2R1) each shiftably disposed in a different one of the individual valve bores, said valve elements being movable selectively from a position interconnecting the low pressure chamber and the service passages to discrete operating positions at once interconnecting the transfer chamber and selected service passage and interconnecting the low pressure chamber and the unselected service passages; a dump valve element (CD) shiftably disposed in said common bore and having an undisplaced, satisfied position interconnecting the transfer and high pressure chambers and a displaced, dump position interconnecting the transfer and low pressure chambers; means including pressure movable control means carried by the dump valve element for shifting same selectively to make available high pressure to, or to dump the pressure from, the transfer passage and the selected service passage; utilization means for said control valve assembly comprising a vehicle supported for rolling movement on a horizontal surface; a run detector pump (22) connected to the vehicle to sense its direction of rolling movement and having a directionalized pump output; application means including a desired direction selector (20) for controlling application of the pump output in two paths to said pressure movable means carried by the dump valve element each opposing and balancing the other so that said element takes an undisplaced, satisfied position when the direction in which the vehicle is rolling as sensed by the pump is the desired direction; said application means including the desired direction selector comprising valving including a neutralizable operator operated valve (20, 220) effective to communicate pump output to an unopposed, valve element displacing, pressure movable means carried by the dump valve element when the direction in which the vehicle is rolling as sensed by the pump is undesired; said dump valve element having means including a control device therefor (138 or 122) effective to restore the Dump valve element to the undisplaced, satisfied position, when the pump output falls to or below a predetermined reduced value indicative that rolling of the vehicle in the undesired direction has reached a substantial standstill; a brake operating cylinder for brakes carried by the vehicle; a first communication between the brake operating cylinder and said pressure chamber to make available high pressure to, or to dump the pressure from, one end of the cylinder for automatically holding the brakes set with a brake apply pressure when the direction in which the vehicle is rolling as sensed by the pumped is the undesired direction, or for automatically holding the brakes released both when the direction in which the vehicle is rolling as sensed by the pump is the desired direction ann also when the direction in which the vehicle is rolling as sensed by the pump is the undesired direction in the event that the pump output is at or below said predetermined reduced value; and a second communication between the other end of the brake operating cylinder and the operator operated valve (220) to make available a brake voiding signal to the cylinder overcoming said brake apply pressure for automatically holding the brakes released in response to said operator operated valve (220) being in neutral.

Claim 7

In combination: a control valve assembly comprising a housing having a high, transfer 210, and low pressure chambers; a common bore intersecting the chambers; individual valve bores in communication with the transfer and low pressure chambers and with plural service passages in said housing; first and second range selector valve elements (F1F2, R2R1) each shiftably disposed in a different one of the individual valve bores, said valve elements being movable selectively from a position interconnecting the low pressure chamber and the service passages to discrete operating positions at once interconnecting the transfer chamber and selected service passage and interconnecting the low pressure chamber and the unselected service passages; a dump valve element (CD) shiftably disposed in said common bore and having an undisplaced, satisfied position interconnecting the transfer and high pressure chambers and a displaced, dump position interconnecting the transfer and low pressure chambers; means including pressure movable control means carried by the dump valve element for shifting same selectively to make available high pressure to, or to dump the pressure from, the transfer passage and the selected service passage; utilization means for said control valve assembly comprising a vehicle supported for rolling movement on a horizontal surface; a run detector pump (22) connected to the vehicle to sense its direction of rolling movement and having a directionalized pump output; application means including a desired direction selector (20) for controlling application of the pump output in two paths to said pressure movable means carried by the dump valve element each opposing and balancing the other so that said element takes an undisplaced, satisfied position when the direction in which the vehicle is rolling as sensed by the pump is the desired direction; said application means including the desired direction selector comprising valving including a neutralizable operator operated valve (20, 220) effective to communicate pump output to an unopposed, valve element displacing, pressure movable means carried by the dump valve element when the direction in which the vehicle is rolling as sensed by the pump is undesired; said dump valve element having means including a control device therefor (138 or 122) effective to restore the Dump valve element to the undisplaced, satisfied position, when the pump output falls to or below a predetermined reduced value indicative that rolling of the vehicle in the undesired direction has reached a substantial standstill; a brake operating cylinder for brakes carried by the vehicle; a first communication between the brake operating cylinder and said pressure chamber to make available high pressure to, or to dump the pressure from, one end of the cylinder for automatically holding the brakes set with a brake apply pressure when the direction in which the vehicle is rolling as sensed by the pumped is the undesired direction, or for automatically holding the brakes released both when the direction in which the vehicle is rolling as sensed by the pump is the desired direction ann also when the direction in which the vehicle is rolling as sensed by the pump is the undesired direction in the event that the pump output is at or below said predetermined reduced value; and a second communication between the other end of the brake operating cylinder and the operator operated valve (220) to make available a brake voiding signal to the cylinder overcoming said brake apply pressure for automatically holding the brakes released in response to said operator operated valve (220) being in neutral.

Claim 8

The invention of claim 4, the first communication including: orifice means (258) communicating the brake apply pressure to said one end of the cylinder with resistance so as to restrict the rate of brake application; and a check valve (200) communicating the overcome brake apply pressure from said one end of the cylinder and unseating in a direction for immediate brake release.

Claim 9

Process to reduce the change-direction-shock in a vehicle which has first means comprising brakes to arrest movement of the vehicle in each of the forward and rearward directions of actual movement, second means comprising a shift-control and disengageable-transmission means having a transmission-disconnect condition preceding each direction change and engageable to drive the vehicle in corresponding directions of movement desired when the control is forward shifted and rearward shifted through or from the control being in neutral, said first means having first and second sensing points controlling operation of the brakes, and signal comparison means (2CD) having first and second comparator points for receiving and comparing signals, said process comprising: producing a vehicle direction signal comprising a forward vehicle signal when the vehicle is moving forwardly, or a rearward vehicle signal when the vehicle is moving rearwardly, and producing a vehicle control signal comprising a forward control signal when the transmission selector is in forward or a rearward control signal when the transmission selector is in reverse; simultaneously applying one of said direction signals to one of said comparator points and opposite one of said control signals to one of said comparator points to disconnect the transmission and brake the vehicle with a brake apply force communicated to one sensing point when the vehicle is moving in a direction opposite to the selected transmission drive direction; production and application of a separate overcoming force to the other sensing point of the first means, corresponding to the control being in neutral in the shift-control and disengageable-transmission means; and operation of the first means to release the brakes responsive to coincidence of said brake apply force and the brake overcoming force in the brakes.

Claim 10

Process to reduce the change-direction-shock in a vehicle which has first means comprising brakes to arrest movement of the vehicle in each of the forward and rearward directions of actual movement, second means comprising a shift-control and disengageable-transmission means having a transmission-disconnect condition preceding each direction change and engageable to drive the vehicle in corresponding directions of movement desired when the control is forward shifted and rearward shifted through or from the control being in neutral, said first means having first and second sensing points controlling operation of the brakes, and signal comparison means (2CD) having first and second comparator points for receiving and comparing signals, said process comprising: producing a vehicle direction signal comprising a forward vehicle signal when the vehicle is moving forwardly, or a rearward vehicle signal when the vehicle is moving rearwardly, and producing a vehicle control signal comprising a forward control signal when the transmission selector is in forward or a rearward control signal when the transmission selector is in reverse; simultaneously applying one of said direction signals to one of said comparator points and opposite one of said control signals to one of said comparator points to disconnect the transmission and brake the vehicle with a brake apply force communicated to one sensing point when the vehicle is moving in a direction opposite to the selected transmission drive direction; production and application of a separate overcoming force to the other sensing point of the first means, corresponding to the control being in neutral in the shift-control and disengageable-transmission means; and operation of the first means to release the brakes responsive to coincidence of said brake apply force and the brake overcoming force in the brakes.

Claim 11

The invention of claim 6, the brake apply force with and without said overcoming force having an operation character zed by: restricted application of the brake apply force alone causing brake-setting at a low rate; and relatively uninhibited concerted action of the brake apply force in being overcome by said overcoming force for brake release at a high rate.

Claim 12

The invention of claim 6 the process Further comprising: maintaining a transmission engaged and brake released condition by simultaneously applying one of said direction signals to one of said points and a corresponding one of said control singals to one of said points to keep the transmission engaged and brakes released when the vehicle is moving in the same direction as the selected transmission direction.