US3946560A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic transmission control
Assignee: Danfoss Power Solutions Inc
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Filing: 1975-03-17
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Granted: 1976-03-30
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Expires: 1995-03-17
Abstract
Abstract A hydrostatic transmission control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor including pressure-responsive displacement control means for the pump and motor with a displacement control valve for each of the pump and motor and positionable by a control pressure to set the displacement of the pump or motor with which it is associated. In dual path control of two hydrostatic transmissions, a master circuit has a first valve for setting a control pressure to determine the speed of operation of the transmissions and a second valve for determining the direction of operation of the transmissions, with operation of both valves by a single control handle. The master circuit connects into two branch circuits, each leading to the displacement controls for one of the hydrostatic transmissions and with each branch circuit having its own steering control valve. The steering operation is controlled by an additional pair of handles associated one with each of the pair of steering control valves. Each of the steering control valves provides for a reduction in a control pressure for reduced speed of the associated hydrostatic transmission or reversal of flow of control pressure fluid to obtain the reverse direction of operation of one of the transmissions.
Inventors
- 👤 Donald J. Mac Intosh
- 👤 Edward L. Stout
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:47
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/423; B; B62; B62D; B62D11/00; B62D11/02; B62D11/06; B62D11/10; B62D11/14; B62D11/18; B62D11/183; F16H61/433
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
135 words
A dual path hydrostatic transmission control for two hydrostatic transmissions each having a pump, a motor, and pressure-responsive displacement control means for one of the pump and motor comprising a first valve for establishing a control pressure for said two transmissions, a second valve for setting a direction of operation of said two transmissions, a single control member for operating both said first and second valves, a fluid circuit including said first and second valves and having two branch circuits downstream of said first and second valves with each branch circuit having one of said pressure-responsive displacement control means for the pump and motor, and a pair of steering control valves positioned one in each of said branch circuits for modifying the control pressure to affect action of said hydrostatic transmissions relative to each other.
Claim 2
Dependent Claim
135 words
A dual path hydrostatic transmission control for two hydrostatic transmissions each having a pump, a motor, and pressure-responsive displacement control means for one of the pump and motor comprising a first valve for establishing a control pressure for said two transmissions, a second valve for setting a direction of operation of said two transmissions, a single control member for operating both said first and second valves, a fluid circuit including said first and second valves and having two branch circuits downstream of said first and second valves with each branch circuit having one of said pressure-responsive displacement control means for the pump and motor, and a pair of steering control valves positioned one in each of said branch circuits for modifying the control pressure to affect action of said hydrostatic transmissions relative to each other.
Claim 3
Dependent Claim
75 words
Apparatus as defined in claim 1 wherein said first valve includes a control spring and movable cam follower for setting said control spring, said single control member being rotatable and a cam thereon coacting with said cam follower, said cam having a cam surface with a pair of inclined sections one to each side of a central section whereby said control spring may be set in either direction of rotation of said single control member.
Claim 4
Dependent Claim
78 words
Apparatus as defined in claim 1 including a third valve for horsepower control positioned in the fluid circuit ahead of said branch circuits and having a connection to tank, a control pump for generating control fluid under pressure for delivery to said first valve, a conduit leading from the control pump to said third valve, and means associated with the third valve responsive to an excessive pressure generated by the control pump to connect said conduit to tank.
Claim 5
Dependent Claim
60 words
Apparatus as defined in claim 3 including a variable orifice means connected to the outlet of the control pump to set a pressure differential dependent on the throttle setting of a prime mover, and said third valve includes a valve spool exposed at opposite ends to the differential pressures with one end thereof exposed to fluid pressure in said conduit.
Claim 6
Dependent Claim
182 words
A dual path hydrostatic transmission control for two hydrostatic transmissions each having a pump, a motor, and pressure-responsive displacement control means for one of the pump and motor comprising, variable means for establishing a control pressure, means for setting a direction of operation of said two transmissions, a single control member for operating both said variable means and said setting means, a fluid circuit including said variable means and said setting means and having two branch circuits downstream of said last-mentioned means with each branch circuit having one of said pressure-responsive displacement control means for the pump and motor, and a pair of steering control valve means positioned one in each of said branch circuits for modifying the control pressure to affect the action of said hydrostatic transmissions relative to each other, each steering control valve having a first pair of lines defining said branch circuit and a second pair of lines connectable one to said variable means and the other to tank, and a valve operable to meter flow between said second pair of lines and obtain a reduced control pressure.
Claim 7
Dependent Claim
182 words
A dual path hydrostatic transmission control for two hydrostatic transmissions each having a pump, a motor, and pressure-responsive displacement control means for one of the pump and motor comprising, variable means for establishing a control pressure, means for setting a direction of operation of said two transmissions, a single control member for operating both said variable means and said setting means, a fluid circuit including said variable means and said setting means and having two branch circuits downstream of said last-mentioned means with each branch circuit having one of said pressure-responsive displacement control means for the pump and motor, and a pair of steering control valve means positioned one in each of said branch circuits for modifying the control pressure to affect the action of said hydrostatic transmissions relative to each other, each steering control valve having a first pair of lines defining said branch circuit and a second pair of lines connectable one to said variable means and the other to tank, and a valve operable to meter flow between said second pair of lines and obtain a reduced control pressure.
Claim 8
Dependent Claim
25 words
Apparatus as defined in claim 5 wherein the steering control valve means includes means to reverse the direction of flow of the control pressure fluid.
Claim 9
Dependent Claim
95 words
Apparatus as defined in claim 5 wherein the steering control valve means includes a housing with said valve having a spool movable therein, a manually operable handle connected to said valve spool for positioning thereof at either of or between two limit positions, grooves on said valve spool for metering the flow of control pressure fluid to tank as said valve member is moved from one limit position, and a flow path in said valve spool for reversing flow of control pressure fluid therethrough when the valve spool is shifted to the other limit position.
Claim 10
Dependent Claim
158 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means including a pair of lines extending to the valve of the pump displacement control for applying the control pressure to the valve for shift thereof in a direction dependent upon which of said lines has the control pressure, circuit means connecting said pair of lines to the opposite ends of the valve of the motor displacement control, and said circuit means including a shuttle valve to always apply the highest control pressure existing in either of said lines to the same end of the motor displacement control valve.
Claim 11
Dependent Claim
158 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means including a pair of lines extending to the valve of the pump displacement control for applying the control pressure to the valve for shift thereof in a direction dependent upon which of said lines has the control pressure, circuit means connecting said pair of lines to the opposite ends of the valve of the motor displacement control, and said circuit means including a shuttle valve to always apply the highest control pressure existing in either of said lines to the same end of the motor displacement control valve.
Claim 12
Dependent Claim
148 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means for applying the control pressure to each of the displacement control valves, and feedback means for each of the displacement control valves and responsive to the displacement position of the pump and motor to set the control valves at a null position, said feedback means for the motor displacement control valve including a cam to establish a certain non-linear relation between motor displacement and transmission speed to obtain a desired relation between transmission speed and said control pressure.
Claim 13
Dependent Claim
148 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means for applying the control pressure to each of the displacement control valves, and feedback means for each of the displacement control valves and responsive to the displacement position of the pump and motor to set the control valves at a null position, said feedback means for the motor displacement control valve including a cam to establish a certain non-linear relation between motor displacement and transmission speed to obtain a desired relation between transmission speed and said control pressure.
Claim 14
Dependent Claim
76 words
A control as defined in claim 9 wherein said motor includes a swashplate, said feedback means for the motor includes an arm connected to the control valve for the motor, a pair of springs acting oppositely on the arm, said cam being pivotally mounted and in engagement with one of the springs, and a linkage connected to said motor swashplate and engageable with the cam to convert motor swashplate movement into forces on said one spring.
Claim 15
Dependent Claim
155 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, means for applying a control pressure to the valves of the pump and motor displacement controls, feedback means for each of said valves and each of said means including, an arm connected to the valve, a pair of springs acting oppositely on said arm, a linkage for indicating displacement and for varying the force applied to one of said springs, and means for adjusting the force on one of said springs to provide a null position for the valve when the swashplate of the associated pump or motor is at a predetermined position.
Claim 16
Dependent Claim
155 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, means for applying a control pressure to the valves of the pump and motor displacement controls, feedback means for each of said valves and each of said means including, an arm connected to the valve, a pair of springs acting oppositely on said arm, a linkage for indicating displacement and for varying the force applied to one of said springs, and means for adjusting the force on one of said springs to provide a null position for the valve when the swashplate of the associated pump or motor is at a predetermined position.
Claim 17
Dependent Claim
156 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, each of said control valves being subjectable to a control pressure for positioning thereof, a pressure setting valve for setting a desired control pressure, and a steering control valve for modifying the control pressure set by the pressure setting valve, said steering control valve having a first pair of lines extending to said displacement controls and a second pair of lines connectable one to the pressure setting valve and the other to tank, and a valve spool manually operable to meter flow between said second pair of lines and obtain a reduced control pressure.
Claim 18
Dependent Claim
156 words
A control for a hydrostatic transmission having a variable displacement pump and a variable displacement motor, a pair of displacement controls associated one with each of the pump and motor and each control including a valve connected to a source of operating fluid under pressure and a pair of operating cylinders subjected to operating fluid dependent upon the position of the valve, each of said control valves being subjectable to a control pressure for positioning thereof, a pressure setting valve for setting a desired control pressure, and a steering control valve for modifying the control pressure set by the pressure setting valve, said steering control valve having a first pair of lines extending to said displacement controls and a second pair of lines connectable one to the pressure setting valve and the other to tank, and a valve spool manually operable to meter flow between said second pair of lines and obtain a reduced control pressure.
Claim 19
Dependent Claim
46 words
A control as defined in claim 12 wherein said valve spool has first and second limit positions with means to reverse the flow connections to the first pair of lines by movement of the valve spool from the first limit position to the second limit position.
Claim 20
Dependent Claim
129 words
A control for a hydrostatic transmission having a pump and a variable displacement motor, a displacement control associated with said motor and including a valve connected to a source of operating fluid under pressure and an operating cylinder subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means for applying the control pressure to the displacement control valve, and feedback means for the displacement control valve and responsive to the displacement position of the motor to set the control valve at a null position, said feedback means for the motor displacement control valve including a cam to establish a certain non-linear relation between motor displacement and transmission speed to obtain a desired relation between transmission speed and said control pressure.
Claim 21
Dependent Claim
129 words
A control for a hydrostatic transmission having a pump and a variable displacement motor, a displacement control associated with said motor and including a valve connected to a source of operating fluid under pressure and an operating cylinder subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means for applying the control pressure to the displacement control valve, and feedback means for the displacement control valve and responsive to the displacement position of the motor to set the control valve at a null position, said feedback means for the motor displacement control valve including a cam to establish a certain non-linear relation between motor displacement and transmission speed to obtain a desired relation between transmission speed and said control pressure.
Claim 22
Dependent Claim
76 words
A control as defined in claim 14 wherein said motor includes a swashplate, said feedback means for the motor includes an arm connected to the control valve for the motor, a pair of springs acting oppositely on the arm, said cam being pivotally mounted and in engagement with one of the springs, and a linkage connected to said motor swashplate and engageable with the cam to convert motor swashplace movement into forces on said one spring.
Claim 23
Dependent Claim
161 words
A control for a hydrostatic transmission having a pump and a variable displacement motor having a swashplate, a displacement control associated with said motor and including a valve connected to a source of operating fluid under pressure and an operating cylinder subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means for applying the control pressure to the displacement control valve, and feedback means for the displacement control valve and responsive to the displacement position of the motor to set the control valve at a null position, said feedback means for the motor displacement control valve including a spring, a linkage movable by the swashplate, and means operable by the linkage to apply varying rates of compression to said spring dependent on the displacement range of the motor to establish a certain nonlinear relation between motor displacement and transmission speed to obtain a desired relation between transmission speed and said control pressure.
Claim 24
Dependent Claim
161 words
A control for a hydrostatic transmission having a pump and a variable displacement motor having a swashplate, a displacement control associated with said motor and including a valve connected to a source of operating fluid under pressure and an operating cylinder subjected to operating fluid dependent upon the position of the valve, a circuit for establishing a control pressure, means for applying the control pressure to the displacement control valve, and feedback means for the displacement control valve and responsive to the displacement position of the motor to set the control valve at a null position, said feedback means for the motor displacement control valve including a spring, a linkage movable by the swashplate, and means operable by the linkage to apply varying rates of compression to said spring dependent on the displacement range of the motor to establish a certain nonlinear relation between motor displacement and transmission speed to obtain a desired relation between transmission speed and said control pressure.
Claim 25
Dependent Claim
73 words
Apparatus as defined in claim 1 including a third valve for horsepower control positioned in the fluid circuit ahead of said branch circuits and having a connection to tank, a control pump for generating control fluid under pressure for delivery to said first valve, a conduit leading from the control pump to said third valve, and means responsive to an excessive pressure generated by the control pump to connect said conduit to tank.
Claim 26
Dependent Claim
96 words
Apparatus as defined in claim 1 including a control pump for generating control fluid under pressure for delivery to said first valve, a third valve for horsepower control positioned in the fluid circuit ahead of said branch circuits and having a connection to tank, said third valve having a valve spool controlling flow to said branch circuits and said connection to tank, and means for applying a pressure signal to said valve spool of the third valve representative of engine speed whereby a reduction of engine speed below rated speed will open said connection to tank.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-30 | 1979-09-29 | 1980-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-30 | 1983-09-29 | 1984-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-30 | 1987-09-29 | 1988-03-30 | $7700.00 | Window Closed / Lapsed |