US3918546A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic assist drive for vehicles
Assignee: Doosan Bobcat North America Inc
•
Filing: 1973-11-21
•
Granted: 1975-11-11
•
Expires: 1993-11-21
Abstract
Abstract A hydrostatic motor assist vehicle drive system operative at the operator''s option to provide intermittent drive to vehicle wheels which are normally idler wheels and which may be dirigible or non-dirigible. Separate propulsion means of any suitable kind is adapted to drive normally operative drive wheels. A vehicle speed responsive control operates independently of an auxiliary drive pump and includes an adjustable flow divider operating between the auxiliary drive pump and assist drive motors to direct fluid drive to the assist drive motors so as to maintain equal rpm of the main and assist drive wheels or equal circumferential distance travelled by such wheels for any increment of time. In one embodiment of a lift truck the auxiliary drive system is operated from the lift cylinder pump with a vehicle speed responsive control operative to control and divide pump discharge between the auxiliary drive system and the lift cylinder.
Inventors
- 👤 Willard L Chichester
- 👤 Donald A Holtkamp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:21
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/44; F16H61/456; B; B60; B60K; B60K17/00; B60K17/04; B60K17/10; B60K17/34; B60K17/356; F16H61/4078
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
167 words
Propulsion means for a vehicle having front and rear drive wheel means comprising a main drive train for operating one of said wheel means, and an auxiliary drive train for operating the other of said wheel means, said auxiliary drive train including hydraulic motor means for operating said other wheel means, auxiliary drive pump means adapted to drive said hydraulic motor means, vehicle speed responsive means independent of said pump means and operatively connected to said auxiliary drive train to control the speed of said motor means such that said other wheel means is driven at an effective speed which is substantially equal to the driven effective speed of said one wheel means, and an operator control for selectively disengaging said auxiliary drive train, said independent vehicle speed responsive means including an adjustable fluid flow divider means operatively intermediate said pump and motor means for controlling the volume of fluid flowing to said hydraulic motor means to effect said driven effective speed of said other wheel means.
Claim 2
Dependent Claim
167 words
Propulsion means for a vehicle having front and rear drive wheel means comprising a main drive train for operating one of said wheel means, and an auxiliary drive train for operating the other of said wheel means, said auxiliary drive train including hydraulic motor means for operating said other wheel means, auxiliary drive pump means adapted to drive said hydraulic motor means, vehicle speed responsive means independent of said pump means and operatively connected to said auxiliary drive train to control the speed of said motor means such that said other wheel means is driven at an effective speed which is substantially equal to the driven effective speed of said one wheel means, and an operator control for selectively disengaging said auxiliary drive train, said independent vehicle speed responsive means including an adjustable fluid flow divider means operatively intermediate said pump and motor means for controlling the volume of fluid flowing to said hydraulic motor means to effect said driven effective speed of said other wheel means.
Claim 3
Dependent Claim
53 words
Vehicle propulsion means as claimed in claim 1 wherein said pump means is a fixed displacement pump, and said flow divider means is adjusted to separate that volume of fluid in excess of that required to maintain said effective speed and direct said excess volume of fluid out of the hydraulic motor circuit.
Claim 4
Dependent Claim
45 words
Vehicle propulsion means claimed in claim 1 wherein said vehicle speed responsive means includes also a hydraulic servo system controlling said flow divider means comprising a vehicle speed responsive hydraulic pump and actuator operatively connected to said flow divider means for adjusting the latter means.
Claim 5
Dependent Claim
203 words
In a vehicle having front and rear drive wheel means and work means supported from the vehicle, a main drive train including a prime mover for operating one of said wheel means, an auxiliary drive train operating the other of said wheel means and adapted to be coordinated with the operation of said work means, said auxiliary drive train including hydraulic motor means for operating said other wheel means, auxiliary drive pump means adapted to drive said motor means, vehicle speed responsive means operatively connected to said auxiliary drive train to control the speed of said motor means such that said other wheel means is driven at an effective speed which is substantially equal to the driven effective speed of said one wheel means, and an operator control for selectively operating said hydraulic motor means, said vehicle speed responsive means including means operative in said auxiliary drive train and receiving the discharge of said pump means for controlling the volume of fluid Flowing to said hydraulic motor means to effect said driven effective speed of said other wheel means, the volume of pump discharge in excess of that required to thus drive said other wheels means being available to operate said work means.
Claim 6
Dependent Claim
203 words
In a vehicle having front and rear drive wheel means and work means supported from the vehicle, a main drive train including a prime mover for operating one of said wheel means, an auxiliary drive train operating the other of said wheel means and adapted to be coordinated with the operation of said work means, said auxiliary drive train including hydraulic motor means for operating said other wheel means, auxiliary drive pump means adapted to drive said motor means, vehicle speed responsive means operatively connected to said auxiliary drive train to control the speed of said motor means such that said other wheel means is driven at an effective speed which is substantially equal to the driven effective speed of said one wheel means, and an operator control for selectively operating said hydraulic motor means, said vehicle speed responsive means including means operative in said auxiliary drive train and receiving the discharge of said pump means for controlling the volume of fluid Flowing to said hydraulic motor means to effect said driven effective speed of said other wheel means, the volume of pump discharge in excess of that required to thus drive said other wheels means being available to operate said work means.
Claim 7
Dependent Claim
62 words
A vehicle as claimed in claim 4 wherein said vehicle is a lift truck and said work means is elevatable load handling means mounted from the one end of said truck, and a second operator control for directing said excess fluid volume either to the work means to elevate the load handling means or to the inlet side of said pump means.
Claim 8
Dependent Claim
90 words
A vehicle as claimed in claim 5 wherein said vehicle speed responsive means includes an adjustable fluid flow divider means which is selectively operable to direct fluid flow to said motor means in a volume to maintain said effective speed or to direct the entire fluid discharge of said pump means to elevate said load engaging means at the operator''s selection under which latter condition the said other wheel means is idler wheel means and the said one wheel means is operable in traction drive by said main drive train.
Claim 9
Dependent Claim
30 words
A vehicle as claimed in claim 6 wherein said vehicle speed responsive means includes hydraulic servo control means including vehicle speed responsive pump means for adjusting said flow divider means.
Claim 10
Dependent Claim
28 words
A vehicle as claimed in claim 6 wherein said vehicle speed responsive means includes electrical servo control means responsive to vehicle speed for adjusting said flow divider means.
Claim 11
Dependent Claim
34 words
A vehicle as claimed in claim 4 wherein said one wheel means is a pair of front wheels and said main drive train includes a transmission and transverse drive axle driving said front wheels.
References Cited (Backward Citations)
US2604109A
Cited
US3053043A
Cited
US3099098A
Cited
US3209850A
Cited
US3303901A
Cited
US3485315A
Cited
US3430722A
Cited
US3480099A
Cited
US3612202A
Cited
US3747722A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |