Position responsive valve for controlling the retraction rate of a lower boom in an articulated boom assembly
US4146998A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 16, 1977 |
| Grant date | Apr 3, 1979 |
| Priority date | — |
| Expiry date | Feb 16, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/0753
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
In an articulated boom having a platform and comprised of upper and lower booms respectively, there are hydraulic actuators controlling the movements of the upper and lower booms. Control means are necessary in association with the lower boom to control its rate of movement, slowing such rate of movement as the lower boom approaches its retracted, or full rest, position. A position responsive valve permits unimpeded fluid pressure access to the actuator for lowering the lower boom at its regular rate until the lower boom reaches a critical angle as it approaches horizontal position, at which time the valve prevents further fluid access to its associated hydraulic actuator. Thereafter, a position responsive valve and a pressure reducing valve reduce the rate of descent of the lower boom until the lower boom is fully retracted to its rest position. The described hydraulic control is in a single package which can be retrofitted into existing hydraulic systems and is independent of the pilot operated check valve and cylinder, being located between the main control valve and the power cylinder and does not interfere with existing hydraulic controls.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.