US4067193A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Combined hydrostatic transmission implement system
Assignee: Caterpillar Inc
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Filing: 1976-11-22
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Granted: 1978-01-10
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Expires: 1996-11-22
Abstract
Abstract A hydraulic system is disclosed which combines hydrostatic and implement motors and includes a plurality of hydraulic motors with a variable displacement pump supplying fluid for the motors and a plurality of directional control valves for selectively directing fluid from the pump to the respective motors and includes pressure varying means connected to each of the directional control valves for varying a pilot pressure communicated to vary the displacement of the variable displacement pump in direct relationship to the shifting of the directional control valves.
Inventors
- 👤 William B. Norick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:14
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/438; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/2053; F15B2211/20538; F15B2211/20546; F15B2211/20553; F15B2211/20576; F15B2211/20584; F15B2211/25; F15B2211/30; F15B2211/31; F15B2211/3144; F15B2211/355; F15B2211/40; F15B2211/405; F15B2211/40515; F15B2211/455; F15B2211/50; F15B2211/505; F15B2211/50509; F15B2211/50518; F15B2211/515; F15B2211/5156; F15B2211/5157; F15B2211/55; F15B2211/555; F15B2211/60; F15B2211/605; F15B2211/6058; F15B2211/62; F15B2211/635; F15B2211/6355; F15B2211/70; F15B2211/71
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
140 words
A hydraulic system comprising a plurality of hydraulic motors, a variable displacement pump for supplying pressurized fluid for operation of said motors and a plurality of directional control valves for selectively directing pressurized fluid from said variable displacement pump to said hydraulic motors, the improvement comprising: pressure responsive variable displacement means for varying the displacement of said pump; a source of pressurized fluid communicating with said variable displacement means; and, pressure varying means connected to at least one of said directional control valves for varying the pressure of said source of pressurized fluid in response to movement of said one of said directional control valves for varying the displacement of said variable displacement pump, wherein said pressure varying means comprising separate and discrete throttling means for variably restricting the flow of said fluid via said conduit means to said sump.
Claim 2
Dependent Claim
140 words
A hydraulic system comprising a plurality of hydraulic motors, a variable displacement pump for supplying pressurized fluid for operation of said motors and a plurality of directional control valves for selectively directing pressurized fluid from said variable displacement pump to said hydraulic motors, the improvement comprising: pressure responsive variable displacement means for varying the displacement of said pump; a source of pressurized fluid communicating with said variable displacement means; and, pressure varying means connected to at least one of said directional control valves for varying the pressure of said source of pressurized fluid in response to movement of said one of said directional control valves for varying the displacement of said variable displacement pump, wherein said pressure varying means comprising separate and discrete throttling means for variably restricting the flow of said fluid via said conduit means to said sump.
Claim 3
Dependent Claim
37 words
The hydraulic system of claim 1 wherein: said source of pressurized fluid comprises a fixed displacement pump; and, conduit means communicating the outlet of said pump with said pressure responsive variable displacement means and with a sump.
Claim 4
Dependent Claim
46 words
The hydraulic system of claim 1 comprising timing means between said throttling valve means and said directional control valve to provide that the directional control valve opens said pump to said actuator prior to said throttling valve means restricting the flow of said fixed displacement pump.
Claim 5
Dependent Claim
25 words
The hydraulic system of claim 3 wherein said timing means includes lost motion connecting means for connecting said throttling valve means to said one valve.
Claim 6
Dependent Claim
45 words
The hydraulic system of claim 1 wherein said variable displacement pump is a swash plate pump; said variable displacement means includes spring means for biasing said swash plate to a minimum displacement position; and, piston means for biasing said plate to a maximum displacement position.
Claim 7
Dependent Claim
37 words
The hydraulic system of claim 5 wherein said plurality of valves are connected in a true series connection wherein the outlet from one of said valves is communicated to the inlet to the next valve downstream thereof.
Claim 8
Dependent Claim
32 words
The hydraulic system of claim 6 wherein said system comprises a pair of linear hydraulic motors and a rotary hydraulic motor, and said rotary hydraulic motor is downstream of said linear motors.
Claim 9
Dependent Claim
20 words
The hydraulic system of claim 5 wherein said throttling valve means is connected to each of said directional control valves.
Claim 10
Dependent Claim
15 words
The hydraulic control system of claim 8 wherein said throttling valve means is infinitely variable.
Claim 11
Dependent Claim
18 words
The hydraulic control system of claim 9 including manual control lever means for shifting said directional control valves.
Claim 12
Dependent Claim
47 words
The hydraulic control system of claim 10 comprising timing means between said throttling valve means and said directional control valves to provide that the directional control valves open said pump to said actuator prior to said throttling valve means restricting the flow of said fixed displacement pump.
Claim 13
Dependent Claim
22 words
The hydraulic control system of claim 11 including lost motion means for connecting said throttling valve means to said directional control valves.
Claim 14
Dependent Claim
35 words
The hydraulic control system of claim 12 including pilot controlled unloading valve means for controlling the maximum pressure of said fixed displacement pump in response to a first predetermined pressure of said variable displacement pump.
Claim 15
Dependent Claim
24 words
The hydraulic control system of claim 13 including a pilot actuated relief valve for maintaining a second predetermined pressure of said variable displacement pump.
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) | 1981-01-09 | 1981-07-11 | 1982-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-09 | 1985-07-11 | 1986-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-09 | 1989-07-11 | 1990-01-10 | $7700.00 | Window Closed / Lapsed |