Combined unloading and relief valve for pump unloading circuit
US4017221A · kind A · utility
11Cited by
7References
12Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 27, 1976 |
| Grant date | Apr 12, 1977 |
| Priority date | — |
| Expiry date | Feb 27, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/87177
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A hydraulic fluid circuit comprises an engine-driven pump for communicating pressurized fluid through a combined unloading and relief valve and to an implement control circuit of a construction vehicle. Actuating means are provided for selectively opening the valve during engine start-up to reduce fluid pressure in the valve and implement control circuit to a first predetermined level. An override means is operatively connected to the actuating means for preventing the valve from opening when the fluid pressure exceeds a second predetermined and operating level which is higher than the first predetermined level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.