US3901339A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic drive-steer system
Assignee: Doosan Bobcat North America Inc
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Filing: 1974-04-15
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Granted: 1975-08-26
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Expires: 1994-04-15
Abstract
Abstract A hydrostatic control for a vehicular dual path hydrostatic reversible drive-steer wheel assembly in which a pair of wheels is mounted for dirigible movement which may be mounted from a common rotatable shaft, the wheels being drivable and steerable by controlling the differentiation of wheel speed in either direction during transition between steering angles. A flow divider-combiner unit controls the volume flow to the wheels in one direction of travel and from the wheels in the other direction, the steering control being functionally intermediate the flow divider-combiner and the wheel assembly for transferring one or more units of fluid volume or pressure from one wheel circuit to the other wheel circuit to effect transitory wheel speed differentiation and thereby turning of the steer wheel assembly to a different steering angle. The hydrostatic control is also operative with independently mounted drive-steer wheels connected by the usual steering control rod.
Inventors
- 👤 William A Williamson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:41
CPC Classifications
B; B62; B62D; B62D11/00; B62D11/02; B62D11/06; B62D11/10; B62D11/14; B62D11/18; B62D11/183
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
154 words
In a hydrostatic drive-steer system for vehicles having first and second dirigible drive wheels mounted for dirigible movement about a common vertical axis, hydraulic first and second motors for driving respective ones of said wheels, a first hydraulic drive circuit connected to the first motor and a second hydraulic drive circuit connected to the second motor, means for supplying pressure fluid to said first circuit in a volume substantially equal to and independent of the pressure fluid which it supplies to said second circuit, and means for transferring a unit volume of fluid from said first circuit to said second circuit to effect a differential wheel speed whereby to cause the wheels to turn about said vertical axis, said latter means comprising a conduit connecting said first circuit to said second circuit and an operator operated device in said conduit for transferring said fluid unit volume from said first circuit to said second circuit.
Claim 2
Dependent Claim
154 words
In a hydrostatic drive-steer system for vehicles having first and second dirigible drive wheels mounted for dirigible movement about a common vertical axis, hydraulic first and second motors for driving respective ones of said wheels, a first hydraulic drive circuit connected to the first motor and a second hydraulic drive circuit connected to the second motor, means for supplying pressure fluid to said first circuit in a volume substantially equal to and independent of the pressure fluid which it supplies to said second circuit, and means for transferring a unit volume of fluid from said first circuit to said second circuit to effect a differential wheel speed whereby to cause the wheels to turn about said vertical axis, said latter means comprising a conduit connecting said first circuit to said second circuit and an operator operated device in said conduit for transferring said fluid unit volume from said first circuit to said second circuit.
Claim 3
Dependent Claim
22 words
The system as claimed in claim 1 wherein said wheels are also mounted for rotational tractive movement about a common horizontal axis.
Claim 4
Dependent Claim
76 words
The system as claimed in claim 2 wherein said wheel mounting includes a generally inverted Y-shaped yoke, the upper leg of which supports the wheels in the vehicle chassis and which is rotatable on said vertical axis, said first and second wheels being mounted from the lower spaced legs of said yoke for tractive movement about said horizontal axis, said first and second motors being also mounted from the respective lower spaced legs of said yoke.
Claim 5
Dependent Claim
25 words
The system as claimed in claim 3 wherein said first and second circuits include conduit means connecting said first and second motors through said yoke.
Claim 6
Dependent Claim
38 words
The system as claimed in claim 1 wherein said pressure fluid supply means comprises an enGine driven pump connected to a flow divider, said flow divider dividing the output of said pump to said first and second circuits.
Claim 7
Dependent Claim
70 words
The system as claimed in claim 5 wherein said fluid pressure supply means is reversible to supply pressure fluid in a reverse direction in said first and second circuits to reverse the direction of rotation of the first and second motors and of the direction of rotation of the drive wheels, said flow divider functioning as a flow combiner in the fluid return conduits of said first and second circuits.
Claim 8
Dependent Claim
72 words
The system as claimed in claim 6 wherein said operator operated device is functionally upstream of said flow combiner during such travel in a reverse direction and functions to change the pressure levels as between said first and second circuits in such a manner as to effect a change in fluid volume to said first and second motors so as to cause a differential wheel speed in reverse for turning the wheels.
Claim 9
Dependent Claim
49 words
The system as claimed in claim 1 wherein said operator operated device comprises a steering pump operated by a steering wheel or the like for transferring a fluid unit volume from said first circuit to said second circuit which is proportional to the steer angle demand by the operator.
Claim 10
Dependent Claim
94 words
The system as claimed in claim 1 wherein said pressure fluid supply means includes a flow divider-combiner for dividing the volume flow to the first and second motors in one direction of travel and combining the volume flow from the said motors in the opposite direction of travel, said operator operated device being adapted to transfer a fluid unit volume from said first circuit to said second circuit as a function of the operator steer angle demand, thereby effecting speed differentiation as between the first and second wheels causing dirigible movement of the wheels.
Claim 11
Dependent Claim
107 words
The system as claimed in claim 1 wherein said operator operated device comprises a gear pump, a steering wheel or the like connected to said gear pump for operating it to displace a volume of fluid from said first circuit to said second circuit which is proportional to the degree of turning of the steering wheel or the like, which in turn effects a differential wheel speed as between said first and second wheels which is proportional to the fluid volume so transferred, which in turn causes dirigible movement of said first and second wheels to establish a steering angle proportional to the fluid volume so transferred.
Claim 12
Dependent Claim
190 words
In a hydrostatic drive-steer system for vehicles having first and second dirigible drive wheels mounted for dirigible movement about a common vertical axis, hydraulic first and second motors for driving respective ones of said wheels, a first hydraulic drive circuit connected to the first motor and a second hydraulic drive circuit connected to the second motor, a variable displacement drive pump, a flow divider connected to said pump and to said circuits for dividing the pump output substantially half and half to said first and second motors for driving said motors in one direction, an operator''s operated steering device intermediate said flow divider and said motors and a conduit connecting said steering device to said first and second drive circuits, said steering device being adapted to transfer a volume of fluid from one of said circuits to the other of said circuits to effect a differential speed between said motors and wheels whereby to turn said wheels to a steering angle which is proportional to the volume of fluid transferred and in a direction dependent upon the fluid volume transfer from said circuit to said second circuit, or vice versa.
Claim 13
Dependent Claim
190 words
In a hydrostatic drive-steer system for vehicles having first and second dirigible drive wheels mounted for dirigible movement about a common vertical axis, hydraulic first and second motors for driving respective ones of said wheels, a first hydraulic drive circuit connected to the first motor and a second hydraulic drive circuit connected to the second motor, a variable displacement drive pump, a flow divider connected to said pump and to said circuits for dividing the pump output substantially half and half to said first and second motors for driving said motors in one direction, an operator''s operated steering device intermediate said flow divider and said motors and a conduit connecting said steering device to said first and second drive circuits, said steering device being adapted to transfer a volume of fluid from one of said circuits to the other of said circuits to effect a differential speed between said motors and wheels whereby to turn said wheels to a steering angle which is proportional to the volume of fluid transferred and in a direction dependent upon the fluid volume transfer from said circuit to said second circuit, or vice versa.
Claim 14
Dependent Claim
124 words
The system as claimed in claim 11 wherein said pump and motors are reversible for reversing the direction of travel, a flow combiner controlling during such reversal of travel the return flow of fluid from said first and second motors in substantially half and half relation and combining and directing the flow to the pump inlet, said steering device operable upstream of said flow combiner and betWeen the return fluid lines of said first and second circuits to cause a differential pressure as between said first and second circuits whereby to cause a differential volume flow to said motors to drive the latter at a differential speed in a reverse direction whereby to steer the wheels in one direction or the other in reverse.
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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |