US3910369A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic transmission system for articulated vehicle
Assignee: Doosan Bobcat North America Inc
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Filing: 1974-04-12
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Granted: 1975-10-07
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Expires: 1994-04-12
Abstract
Abstract A hydrostatic transmission drive system for an articulated vehicle in which an operator controlled reversible variable displacement pump effects through flow divider means positive traction at one wheel under full pump pressure irrespective of a loss of traction on any other wheel, such that during straightahead steering each drive wheel operates continuously at a fixed proportion of total fluid volume and at pump discharge pressure. During articulation of the vehicle for steering the flow is proportionalized to the inside and outside wheels to effect differential wheel speeds at front and rear pairs thereof as required for non-scrub steering at all available steering angles. under particularly adverse circumstances, such as deep mud, the vehicle is capable of ''''snaking'''' its course by zig-zag steering under traction.
Inventors
- 👤 Willard L Chichester
- 👤 Donald A Holtkamp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:00
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/44; F16H61/456; B; B60; B60K; B60K17/00; B60K17/34; B60K17/356; B62; B62D; B62D53/00; B62D53/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
260 words
In a hydrostatic power transmission system for a four-wheel drive articulated vehicle having first and second pairs of longitudinally spaced drive wheels and first and second pairs of hydraulic motors for driving respective pairs of said wheels, a fluid drive system comprising a closed loop drive circuit connecting said pairs of hydraulic motors including an engine driven variable displacement pump means, operator control means for controlling said engine and pump, and other control means in said drive circuit operatively connecting said pump to each of said motors including a main fluid flow divider means for dividing continuously in straight-ahead operation of the vehicle the fluid discharge of said pump means by volume substantially one-half each to said first and second pairs of motors at substantially pump discharge pressure, a first fluid flow divider means for dividing continuously under all conditions of straightahead vehicle operation the said first one-half fluid volume between the motors of said first pair of motors in a predetermined fixed proportion by volume and at substantially pump discharge pressure, and a second fluid flow divider means for dividing continuously under all conditions of straight-ahead vehicle operation the said second one-half fluid volume between the motors of said second pair of motors in a predetermined fixed proportion by volume and at substantially pump discharge pressure, whereby each drive wheel operates continuously for straight-ahead vehicle operation at a predetermined substantially fixed proportion of total fluid volume and substantially at pump discharge pressure irrespective of variations in surface traction as between any one of said wheels and any other wheel.
Claim 2
Dependent Claim
260 words
In a hydrostatic power transmission system for a four-wheel drive articulated vehicle having first and second pairs of longitudinally spaced drive wheels and first and second pairs of hydraulic motors for driving respective pairs of said wheels, a fluid drive system comprising a closed loop drive circuit connecting said pairs of hydraulic motors including an engine driven variable displacement pump means, operator control means for controlling said engine and pump, and other control means in said drive circuit operatively connecting said pump to each of said motors including a main fluid flow divider means for dividing continuously in straight-ahead operation of the vehicle the fluid discharge of said pump means by volume substantially one-half each to said first and second pairs of motors at substantially pump discharge pressure, a first fluid flow divider means for dividing continuously under all conditions of straightahead vehicle operation the said first one-half fluid volume between the motors of said first pair of motors in a predetermined fixed proportion by volume and at substantially pump discharge pressure, and a second fluid flow divider means for dividing continuously under all conditions of straight-ahead vehicle operation the said second one-half fluid volume between the motors of said second pair of motors in a predetermined fixed proportion by volume and at substantially pump discharge pressure, whereby each drive wheel operates continuously for straight-ahead vehicle operation at a predetermined substantially fixed proportion of total fluid volume and substantially at pump discharge pressure irrespective of variations in surface traction as between any one of said wheels and any other wheel.
Claim 3
Dependent Claim
36 words
A hydrostatic transmission system as claimed in claim 1 wherein said other control means connects said first and second pairs of motors for operation in series, and further connects the motors of said pair in series.
Claim 4
Dependent Claim
121 words
A hydrostatic transmission system as claimed in claim 1 wherein the vehicle is articulated for steering about a vertical axis, said main flow divider means being responsive to the steering angle between articulated sections of the vehicle for increasing the volume fluid flow to the pair of motors of the outside wheels of said first and second pairs of wheels above said, one-half volume an amount which is proportional to the steering angle and for decreasing the volume fluid flow to the pair of motors of the inside wheels below said one-half volume an amount which is proportional to steering angle to differentiate the wheel speeds of the inside and outside pairs of wheels as a function of the steering angle.
Claim 5
Dependent Claim
41 words
A hydrostatic transmission system as claimed in claim 3 wherein articulating the vehicle in a zig-zag pattern for steeriNg effects vehicle drive by rotary traction driving under continuous series operation of said first and second motors at said pump discharge pressure.
Claim 6
Dependent Claim
55 words
A hydrostatic transmission system as claimed in claim 1 wherein said variable displacement pump and said motors are reversible to operate the vehicle in a reverse direction, said main and first and second flow divider means functioning also as flow divider means as aforesaid during operation of said pump and motors in a reverse direction.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |