Hydrostatic propulsion system

Claim 2

A hydrostatic power transmission system for a vehicle having first and second pairs of selectively driveable wheels comprising hydraulic fluid drive means, first and second pairs of selectively driveable hydraulic motor means for driving respective pairs of said wheels and adapted to be driven by said fluid drive means, said fluid drive means also being adapted to distribute the hydraulic fluid to drive said first and second pairs of motor means when all said motor means are driving said wheels, and control means operatively connected to said fluid drive means for interrupting the flow of fluid to one pair of said motor means and redirecting it to the other pair of said motor means to effect a shift from four to two-wheel drive without interrupting the flow of traction fluid to said other pair of motor means, said control means including transition control means operative to redirect to the low pressure side of the system the fluid flow to said one pair of motor means to facilitate smooth vehicle operation during the transition from four to two-wheel drive.

Claim 3

A power transmission system as claimed in claim 1 wherein said fluid drive means includes variable displacement pump means, said pump means and motor means being reversible for driving the vehicle either in forward or reverse and for rapidly braking the vehicle, and operator control means for controlling the speed, displacement and direction of said pump means at all times during vehicle operation whereby rapid vehicle braking may be effected by a reversal of torque at the motor means.

Claim 4

A power transmission system as claimed in claim 1 wherein said control means includes means operative to direct one portion of distributed fluid selectively to said one pair of motor means or to said low pressure side of the system or to said other pair of motor means.

Claim 5

A power transmission system as claimed in claim 3 wherein said latter operative means is adjustable valve means to modulate at a selected rate the redirection of fluid flow from said low pressure side to said other pair of motor means.

Claim 6

A power transmission system as claimed in claim 1 wherein said fluid drive means includes variable displacement pump means and fluid flow divider means, and said control means includes selector valve means operative to direct the fluid flow from one side of said flow divider means either to said one pair of motor means, or to the inlet of the pump means, or to said other pair of motor means.

Claim 7

A power transmission system as claimed in claim 5 wherein a fluid cooling circuit is adapted to circulate a portion of the fluid in the circuit of said one pair of motor means to a reservoir means when said selector valve means directs the fluid flow either to the inlet of said pump means or to said other pair of motor means.

Claim 8

A transmission system as claimed in claim 6 wherein charge pump means is connected to the reservoir and to the circuit of said one pair of motor means for maintaining said latter circuit fully fluid charged when said fluid cooling circuit circulates a portion of said fluid.

Claim 9

A power transmission system as claimed in claim 5 wherein said flow divider means is adjustable to control the flow to said one pair of motor means between approximately no flow and an intermediate flow, and to control the flow to said other pair of motor means between said intermediate flow and full flow.

Claim 10

A power transmission system as claimed in claim 1 wherein at least one pair of said driveable wheels are also steer wheels, and a flow divider means in circuit with said fluid drive means with a pair of said motor means and responsive to steering of said steer wheels for proportioning between the latter pair of motor means as a function of steering angle a predetermined portion of said hydraulic fluid.

Claim 11

A power transmission system as claimed in claim 9 wherein said one pair of motor means are in a parallel hydraulic circuit for driving the steer wheels, steer linkage means connecting said steer wheels, and said other pair of motor means are in a parallel hydraulic circuit for driving the other pair of wheels, said flow divider means being operatively in circuit with said other pair of motor means and operatively connected to the steer linkage of said pair of steer wheels.

Claim 12

A transmission system as claimed in claim 1 wherein said fluid drive means includes variable displacement pump means and fluid-divider means, said fluid-divider means distributing the output of said pump means to said pairs of motor means when all said motor means are driving said wheels such that each wheel travels substantially the same circumferential distance in the same period of time as each other wheel of said pairs of wheels irrespective of variations in surface traction as between any one wheel and any other wheel.

Claim 13

A transmission system as claimed in claim 11 wherein one pair of said wheels are also dirigible wheels, and second fluid-divider means is in circuit with the first-mentioned fluid-divider means and with a pair of said motor means, said second fluid-divider means being responsive to steering angles of said dirigible wheels for dividing between the latter pair of motor means as a function of steering angle that portion of hydraulic fluid directed to said second fluid-divider means by said first fluid-divider means.

Claim 14

A transmission system as claimed in claim 1 wherein said fluid drive means includes variable displacement pump means and fluid-divider means, said fluid-divider means distributing the output of said pump means when all said motor means are driving said wheels substantially one-half pump output to the first pair of said motor means and substantially one-half pump output to the second pair of said motor means.

Claim 15

A transmission system as claimed in claim 1 wherein said fluid drive means includes a variable displacement pump means, an engine driving said pump means, said control means including first manually manipulatable operator means for controlling the displacement of said pump means, second manually manipulatable operator means controlling engine speed, said first and second operator means being adapted to directly control in combination the engine and pump for optimum operation under varying conditions of vehicle operation, and third manually manipulatable operator means for controlling the said redirection of the interrupted fluid portion.

Claim 16

A transmission system as claimed in claim 14 wherein said third manually manipulatable operator means includes adjustable valve means to modulate at a selected rate the redirection of fluid flow from said low pressure side to said other pair of motor means.

Claim 17

A hydrostatic power transmission system for a vehicle having first and second pairs of selectively driveable wheels, one pair of which are also steer wheels, comprising hydraulic fluid drive means, first and second pairs of selectively driveable reversible hydraulic motors for driving respective pairs of said wheels and adapted to be driven by said fluid drive means, said fluid drive means including distributor means in circuit with said pairs of motors adapted to distribute the hydraulic fluid to said first and second pairs of motors when all said motors are driving said wheels in one direction and irrespective of the torque required at any wheel, and for combining the return fluid from said first and second pairs of motors when all said motors are driving said wheels in an opposite direction and irrespective of the torque required at any wheel, a fluid divider-combiner means in circuit with said distributor means and with a pair of said motors and responsive to steering of said steer wheels for proportioning between the latter pair of motors as a function of steering angle in both forward and reverse drive a portion of said hydraulic fluid, first control means for controlling the displacEment and direction of said fluid drive means, and second control means operatively connected to said distributor means for interrupting the flow of fluid to one pair of said motors and for redirecting it to the other pair of motors to effect two-wheel drive without interrupting the flow of traction fluid to said other pair of motors, said second control means including transition control means operative to redirect to the low pressure side of the system the fluid flow to said one pair of motors to facilitate smooth vehicle operation during the transition from four to two-wheel drive.

Claim 18

A hydrostatic power transmission system for a vehicle having first and second pairs of selectively driveable wheels, one pair of which are also steer wheels, comprising hydraulic fluid drive means, first and second pairs of selectively driveable reversible hydraulic motors for driving respective pairs of said wheels and adapted to be driven by said fluid drive means, said fluid drive means including distributor means in circuit with said pairs of motors adapted to distribute the hydraulic fluid to said first and second pairs of motors when all said motors are driving said wheels in one direction and irrespective of the torque required at any wheel, and for combining the return fluid from said first and second pairs of motors when all said motors are driving said wheels in an opposite direction and irrespective of the torque required at any wheel, a fluid divider-combiner means in circuit with said distributor means and with a pair of said motors and responsive to steering of said steer wheels for proportioning between the latter pair of motors as a function of steering angle in both forward and reverse drive a portion of said hydraulic fluid, first control means for controlling the displacEment and direction of said fluid drive means, and second control means operatively connected to said distributor means for interrupting the flow of fluid to one pair of said motors and for redirecting it to the other pair of motors to effect two-wheel drive without interrupting the flow of traction fluid to said other pair of motors, said second control means including transition control means operative to redirect to the low pressure side of the system the fluid flow to said one pair of motors to facilitate smooth vehicle operation during the transition from four to two-wheel drive.

Claim 19

A power transmission system as claimed in claim 16 wherein a fluid cooling circuit is adapted to circulate a portion of the fluid in the circuit of said one pair of motors to a reservoir means when said second control means directs the fluid flow either to said low pressure side or to said other pair of motors, and charge pump means connected to the reservoir and to the circuit of said one pair of motors for maintaining said latter circuit fully fluid charged when said fluid cooling circuit circulates a portion of said fluid.

Claim 20

A hydrostatic power transmission system for a vehicle having an engine and first and second pairs of selectively driveable wheels comprising a reversible variable displacement engine driven hydraulic pump means, first and second pairs of selectively driveable reversible hydraulic motors for driving respective pairs of said wheels and adapted to be driven by said pump means, a fluid divider means in circuit with said pairs of motors for dividing in a predetermined manner the pumped fluid to said first and second pairs of motors when all said motors are driving said wheels, first operator control means for controlling the speed of the engine, second operator control means for controlling the displacement and direction of said pump means, and third operator control means operatively connected to said fluid divider means for interrupting the flow of fluid to one pair of said motors and for redirecting it to the other pair of motors to effect a shift from four to two-wheel drive, and for reconnecting said latter fluid flow to said one pair of motors to effect a shift from two to four-wheel drive, said system being adapted to accommodate such shifting during traction driving of the vehicle and without interrupting the fluid flow to said other pair of motors said first and second operator control means being operable singly or together in either two or four-wheel drive to brake the veicle by reversing the direct of operation of the pump means either with or without an increase in engine speed, and said third operator control means including transition control means operative to redirect to the inlet of the pump means the fluid flow to said one pair of motors to facilitate a smooth transition from four to two-wheel drive, said first and second operator control means being manipulatable to brake the vehicle also during said operative condition of said transition control means.

Claim 21

A hydrostatic power transmission system for a vehicle having an engine and first and second pairs of selectively driveable wheels comprising a reversible variable displacement engine driven hydraulic pump means, first and second pairs of selectively driveable reversible hydraulic motors for driving respective pairs of said wheels and adapted to be driven by said pump means, a fluid divider means in circuit with said pairs of motors for dividing in a predetermined manner the pumped fluid to said first and second pairs of motors when all said motors are driving said wheels, first operator control means for controlling the speed of the engine, second operator control means for controlling the displacement and direction of said pump means, and third operator control means operatively connected to said fluid divider means for interrupting the flow of fluid to one pair of said motors and for redirecting it to the other pair of motors to effect a shift from four to two-wheel drive, and for reconnecting said latter fluid flow to said one pair of motors to effect a shift from two to four-wheel drive, said system being adapted to accommodate such shifting during traction driving of the vehicle and without interrupting the fluid flow to said other pair of motors said first and second operator control means being operable singly or together in either two or four-wheel drive to brake the veicle by reversing the direct of operation of the pump means either with or without an increase in engine speed, and said third operator control means including transition control means operative to redirect to the inlet of the pump means the fluid flow to said one pair of motors to facilitate a smooth transition from four to two-wheel drive, said first and second operator control means being manipulatable to brake the vehicle also during said operative condition of said transition control means.

Claim 22

A hydrostatic power transmission system for a vehicle having a first pair of transversely spaced rotatable means and second rotatable means spaced longitudinally from the pair of rotatable means comprising fluid drive means, hydraulic motor means for driving respective ones of said first and second rotatable means adapted to be driven by said fluid drive means, said fluid drive means being adapted also to distribute the hydraulic fluid to drive said hydraulic motor means when all said motor means are driving said first and second rotatable means, and control means operatively connected to said fluid drive means for interrupting the flow of fluid to the hydraulic motor means which drives one of said first or second rotatable means and redirecting it to the motor means driving the other rotatable means to effect a shift from driving said first and second rotatable means to driving said latter other rotatable means without interrupting the flow of traction fluid to said hydraulic motor means which drives Said other rotatable means, said control means including transition control means operative to redirect to the low pressure side of the hydraulic system the fluid flow to said one of said first or second rotatable means to facilitate smooth vehicle operation during transition from driving said first and second rotatable means to driving said other rotatable means.

Claim 23

A hydrostatic power transmission system for a vehicle having a first pair of transversely spaced rotatable means and second rotatable means spaced longitudinally from the pair of rotatable means comprising fluid drive means, hydraulic motor means for driving respective ones of said first and second rotatable means adapted to be driven by said fluid drive means, said fluid drive means being adapted also to distribute the hydraulic fluid to drive said hydraulic motor means when all said motor means are driving said first and second rotatable means, and control means operatively connected to said fluid drive means for interrupting the flow of fluid to the hydraulic motor means which drives one of said first or second rotatable means and redirecting it to the motor means driving the other rotatable means to effect a shift from driving said first and second rotatable means to driving said latter other rotatable means without interrupting the flow of traction fluid to said hydraulic motor means which drives Said other rotatable means, said control means including transition control means operative to redirect to the low pressure side of the hydraulic system the fluid flow to said one of said first or second rotatable means to facilitate smooth vehicle operation during transition from driving said first and second rotatable means to driving said other rotatable means.

Claim 24

A transmission system as claimed in claim 19 wherein when said fluid drive means is driving said first and second rotatable means in non-dirigible movement the distribution of hydraulic fluid to the motor means is such that the first and second rotatable means traverse substantially the same circumferential distance in the same period of time irrespective of variations in surface or road traction as between surface or road engaging elements of any of said rotatable means.

Claim 25

A transmission system as claimed in claim 20 wherein said first and second rotatable means are wheel means, at least one of which wheel means is dirigible, and fluid-divider means in circuit with said fluid drive means and with certain of said hydraulic motor means and responsive to steering of the dirigible wheel means so that a predetermined portion of the said hydraulic fluid is proportioned between the wheels of said first pair of wheel means as a function of steering angle.

Claim 26

A transmission system as claimed in claim 20 wherein said fluid drive means comprises variable displacement pump means and fluid-divider means, said fluid-divider means distributing the hydraulic fluid to said motor means to effect said traverse of such circumferential distance.

Claim 27

A transmission system as claimed in claim 19 wherein said second rotatable means comprises a second pair of transversely spaced rotatable means, said fluid drive means including variable displacement pump means, and said control means including operator control of the displacement of said pump means.

Claim 28

A transmission system as claimed in claim 19 wherein said fluid drive means includes a variable displacement pump means, an engine driving said pump means, said control means including manually manipulatable operator means for controlling the displacement of said pump means, and other manually manipulatable operator means controlling engine speed, said operator means and other operator means being adapted to directly control in combination the engine and pump means for optimum operation under varying conditions of vehicle operation.

Claim 29

A hydrostatic power transmission system for a vehicle having a first pair of transversely spaced rotatable means and second rotatable means spaced longitudinally from the pair of rotatable means comprising fluid drive means, hydraulic motor means for driving respective ones of said first and second rotatable means adapted to be driven by said fluid drive means, said fluid drive means being adapted also to distribute the hydraulic fluid to drive said hydraulic motor means when all said motor means are driving said first and second rotatable means, and control means operatively connected to said fluid drive means for interrupting the flow of fluid to the hydraulic motor means which drives one of said first or second rotatable means and redirecting it to the motor means driving the other rotatable means to effect a shift from driving said first and second rotatable means to driving said latter other rotatable means without interrupting the flow of traction fluid to said hydraulic motor means which drives said other rotatable means, said control means which interrupts the flow of fluid being operative to redirect the interrupted fluid portion selectively from said one of said first or second rotatable means to the low pressure side of the hydraulic system and then to said other rotatable means, and in that order of succession, in order to facilitate smooth vehicle operation during transition from driving said first and second wheel-like means to driving said other rotatable means.

Claim 30

A hydrostatic power transmission system for a vehicle having a first pair of transversely spaced rotatable means and second rotatable means spaced longitudinally from the pair of rotatable means comprising fluid drive means, hydraulic motor means for driving respective ones of said first and second rotatable means adapted to be driven by said fluid drive means, said fluid drive means being adapted also to distribute the hydraulic fluid to drive said hydraulic motor means when all said motor means are driving said first and second rotatable means, and control means operatively connected to said fluid drive means for interrupting the flow of fluid to the hydraulic motor means which drives one of said first or second rotatable means and redirecting it to the motor means driving the other rotatable means to effect a shift from driving said first and second rotatable means to driving said latter other rotatable means without interrupting the flow of traction fluid to said hydraulic motor means which drives said other rotatable means, said control means which interrupts the flow of fluid being operative to redirect the interrupted fluid portion selectively from said one of said first or second rotatable means to the low pressure side of the hydraulic system and then to said other rotatable means, and in that order of succession, in order to facilitate smooth vehicle operation during transition from driving said first and second wheel-like means to driving said other rotatable means.

Claim 31

A transmission system as claimed in claim 25 wherein saiD control means which interrupts the flow of fluid includes adjustable valve means operable to modulate at a selected rate the redirection of fluid flow from said low pressure side of the hydraulic system to said other rotatable means.

Claim 32

A transmission system as claimed in claim 25 wherein said first and second rotatable means comprise wheel means at least one of which wheel means is dirigible, and fluid-divider means in circuit with said fluid drive means and with certain of said hydraulic motor means and responsive to steering of the dirigible wheel means so that a predetermined portion of the said hydraulic fluid is proportioned between the wheels of said first pair of wheel means as a function of the steering angle.

Claim 33

A transmission system as claimed in claim 27 wherein said fluid drive means when driving said first and second wheel means in non-dirigible movement effects a distribution of hydraulic fluid to the respective motor means such that all of the wheels traverse substantially the same circumferential distance in the same period of time irrespective of variations in surface or road traction as between any of said wheels.

Claim 34

A transmission system as claimed in claim 28 wherein said latter control means is operator controlled and said operative means comprises adjustable valve means to modulate at a selected rate the redirection of fluid flow from said low pressure side to said other pair of motor means.

Claim 35

A transmission system as claimed in claim 25 wherein said fluid drive means includes a variable displacement pump means and an engine driving said pump means, said control means including first manually manipulatable operator means for controlling the displacement of said pump means, second manually manipulatable operator means controlling engine speed, said first and second operator means being adapted to directly control in combination the engine and pump for optimum operation under varying conditions of vehicle operation, and third manually mainpulatuble operator means for controlling the said redirection of the interrupted fluid portion.

Claim 36

A transmission system as claimed in claim 30 wherein said first and second rotatable means comprise wheel means, at least one of which wheel means is dirigible and fluid-divider means in circuit with said fluid drive means and with certain of said hydraulic motor means and responsive to steering of the dirigible wheel means so that a predetermined portion of the said hydraulic fluid is proportioned between the wheels of said first pair of wheel means as a function of steering angle.