Hydraulic control system for a dockboard
US4641388A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 1, 1984 |
| Grant date | Feb 10, 1987 |
| Priority date | — |
| Expiry date | Aug 1, 2004 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB65G69/2823
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A hydraulically operated dockboard comprising a ramp which is hinged at its rear edge to the frame of the dockboard, and a lip is hinged to the forward edge of the ramp. A main hydraulic cylinder unit connects the frame and the ramp, and by operating the cylinder unit the ramp can be pivoted upwardly from a horizontal cross traffic position to an upwardly inclined position. A lip cylinder interconnects the ramp and the lip and acts to pivot the lip from a downwardly hanging pendant position to an extended position. A hydraulic line is connected to the lip cylinder, and a control valve interconnects the hydraulic line to either a supply line or a return line that is connected to the reservoir of the hydraulic system. The control valve is normally biased to a first position where the lip cylinder is connected to the return line. When it is desired to extend the lip, fluid is supplied through the supply line to pressurize the control valve and move the control valve to a second position where it connects the supply line to the lip cylinder to thereby introduce fluid to the lip cylinder to pivot the lip to the extended position. When the lip is subsequently lowered into engagement with…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.