Hydraulic cyliner systems with safeguarded float action
US4018350A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 17, 1975 |
| Grant date | Apr 19, 1977 |
| Priority date | — |
| Expiry date | Mar 17, 1995 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE02F9/2004
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The invention may be used with a boom or the like which is raised and lowered by double-acting hydraulic cylinder means provided with a pilot-actuated safety valve at its bottom such that the boom can only go down when pilot pressure (normally from the downthrust line) is applied to this safety valve. The main manual valve has a four-position spool which provides a float position reached by moving through the lowering position. As the main valve is moved to the float position, its manual actuation mechanism actuates an auxiliary valve to supply pilot pressure to the safety valve to open the safety valve to allow the cylinder to achieve the desired floating action. This pilot pressure supply is through a shuttle valve which alternatively lets pilot pressure be applied to this safety valve as here stated or, from the downthrust, without ever connecting the two sources.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.