US3823558A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic transmission
Assignee: Robert Bosch GmbH
•
Filing: 1973-03-15
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Granted: 1974-07-16
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Expires: 1993-03-15
Abstract
Abstract A driven main pump drives a hydraulic motor through high pressure and low pressure conduits, while a feed pump supplies pressure fluid through a check valve to the low pressure conduit. A control conduit connects the feed pump with a pressure maintaining valve opening into a low pressure container, and includes a shiftable control valve operated by fluid from the high pressure conduit, but connecting in all positions the feed pump with the pressure maintaining valve. In the control conduit portion between the control valve and the feed pump, a throttle is provided whose pressure differential is greater than the pressure differential of the check valve between the feed pump and the low pressure conduit.
Inventors
- 👤 E Tittmann
- 👤 W Romeisch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:24
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/472; F16H61/4078; F16H61/4104
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
191 words
Hydrostatic transmission comprising a driven main pump, a hydraulic motor, high pressure conduit means, and low pressure conduit means connecting said main pump with said motOr so that said motor is driven by said main pump; a driven feed pump having outlet conduit means with check valve means connecting said feed pump with said low pressure conduit means, and inlet conduit means connected with a low-pressure area; pressure maintaining valve means opening into a low pressure area for cooling a pressure fluid; a control conduit means connecting said outlet conduit means with said pressure maintaining valve means; control valve means in said control conduit means having a plurality of positions, and connecting said outlet conduit means with said pressure maintaining valve means, and connecting in one of said positions also said low pressure conduit means with said pressure maintaining valve means so that heated pressure fluid from said low pressure conduit means is cooled; and throttle means in said control conduit means between said outlet conduit means and said control valve means, producing in said control conduit means a pressure differential greater than the pressure differential of said check valve means.
Claim 2
Dependent Claim
191 words
Hydrostatic transmission comprising a driven main pump, a hydraulic motor, high pressure conduit means, and low pressure conduit means connecting said main pump with said motOr so that said motor is driven by said main pump; a driven feed pump having outlet conduit means with check valve means connecting said feed pump with said low pressure conduit means, and inlet conduit means connected with a low-pressure area; pressure maintaining valve means opening into a low pressure area for cooling a pressure fluid; a control conduit means connecting said outlet conduit means with said pressure maintaining valve means; control valve means in said control conduit means having a plurality of positions, and connecting said outlet conduit means with said pressure maintaining valve means, and connecting in one of said positions also said low pressure conduit means with said pressure maintaining valve means so that heated pressure fluid from said low pressure conduit means is cooled; and throttle means in said control conduit means between said outlet conduit means and said control valve means, producing in said control conduit means a pressure differential greater than the pressure differential of said check valve means.
Claim 3
Dependent Claim
28 words
Hydrostatic transmission as claimed in claim 1 wherein said control valve means connects in all said positions thereof said outlet conduit means with said pressure maintaining valve means.
Claim 4
Dependent Claim
138 words
Hydrostatic transmission as claimed in claim 1 wherein said main pump includes means for reversing the flow therethrough so that said high pressure conduit means becomes a low pressure conduit means, and said low pressure conduit means becomes a high pressure conduit means; wherein said check valve means connect said outlet conduit means of said feed pump with the respective low pressure conduit; and wherein said control valve means has a normal position connecting only said outlet conduit means with said pressure maintaining valve means, and two control positions for connecting also the respective high pressure conduit with said pressure maintaining valve means; and comprising shifting conduits connected with said low pressure and high pressure conduit means for shifting said control valve means between said normal position and the control position associated with respective high pressure conduit means.
Claim 5
Dependent Claim
57 words
Hydrostatic transmission as claimed in claim 3 wherein said control valve means includes a valve slide movable between said normal position and two outer control positions; springs at the ends of said valve slide urging said valve slide to said normal position; and wherein said valve slide closes one of said shifting conduits before opening the other.
Claim 6
Dependent Claim
33 words
Hydrostatic transmission as claimed in claim 3 wherein said control valve means connects in said normal position and in said two control positions, said outlet conduit means with said pressure maintaining valve means.
Claim 7
Dependent Claim
24 words
Hydrostatic transmission as claimed in claim 1 comprising a filter in said outlet conduit means of said feed pump upstream of said throttle means.
Claim 8
Dependent Claim
78 words
Hydrostatic transmission as claimed in claim 1 wherein said outlet conduit means of said feed pump include a first outlet conduit connecting said feed pump with said control conduit, and second and third outlet conduits connecting a point of said first outlet conduit upstream of said throttle means with said high pressure conduit means and said low pressure conduit means, respectively, and wherein said second and third outlet conduits contain check valves, respectively, opening toward said main pump.
Claim 9
Dependent Claim
57 words
Hydrostatic transmission as claimed in claim 7 wherein said main pump includes hydraulic adjusting means; comprising a shifting valve means operated by the pressure fluid in said low pressure and high pressure conduit means to connect said high pressure conduit means with said hydraulic adjusting means for varying the amount of fluid pumped by said main pump.
Claim 10
Dependent Claim
87 words
Hydrostatic transmission as claimed in claim 1, wherein said outlet conduit means of said feed pump include a first outlet conduit connecting said feed pump with said control conduit, and second and third outlet conduits connecting a poinT of said first outlet conduit upstream of said throttle means with said high pressure conduit means and said low pressure conduit means, respectively, and wherein said second and third outlet conduits contain check valves, respectively, opening toward said main pump; and comprising a filter in said first outlet conduit.
Claim 11
Dependent Claim
27 words
Hydrostatic transmission as claimed in claim 9 wherein said control valve means connects in all said positions thereof said throttling means with said pressure maintaining valve means.
References Cited (Backward Citations)
US2255783A
Cited
US3175354A
Cited
US3230699A
Cited
US3360934A
Cited
US3429123A
Cited
US3650108A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-15 | 1978-01-14 | 1978-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-15 | 1982-01-14 | 1982-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-15 | 1986-01-14 | 1986-07-16 | $7700.00 | Window Closed / Lapsed |