Relief valves and mine props incorporating the same
US4237769A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 3, 1978 |
| Grant date | Dec 9, 1980 |
| Priority date | — |
| Expiry date | Apr 3, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/87241
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A relief valve assembly particularly in combination with yieldable pit posts is provided having an elongate housing, a first load chamber at one end of said housing, an inlet aperture into said housing, a non-return valve in said inlet aperture for admitting fluid non-returnably into said load chamber, a first valve seat in said housing communicating with said load chamber, a spring loaded relief valve movable lengthwise of the housing and normally engaging said seat to close the load chamber, a second valve seat in said housing spaced lengthwise from said first valve seat and relief valve and forming therebetween a balancing load chamber, a spring loaded pilot relief valve movable lengthwise of the housing and normally engaging said second seat to close the same, and a regulated orifice means in said relief valve connecting the first load chamber and the balancing load chamber whereby said balancing load chamber is normally pressurized to the pressure of the load chamber.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.