| 摘要 |
A lift system for mounting on a vehicle comprises a main platform [30, Fig. 4], a platform extension [32, Fig. 4] slidable relative to the main platform, lifting arms [18, Fig. 4] arranged to connect the platform to a vehicle, and a fluid actuation system comprising a pump 124, a first cylinder 22 arranged to control raising and lowering of the lift on the lifting arms, a second cylinder 91 arranged to control movement of the platform extension relative to the main platform, and valve means arranged to control the flow of fluid between the pump and the two cylinders 22,91 thereby to control raising and lowering of the lift and movement of the platform extension relative to the main platform. The valve means may be arranged to direct fluid to the first cylinder 22 to raise the lift and, when the lift reaches its upper limit of travel, to direct fluid the second cylinder 91. The fluid actuation system may further comprise a third cylinder 98 arranged to control movement of a roll-off ramp [94, Fig. 4] and the valve means is further arranged to control the flow of fluid between the pump and the third cylinder 98. The valve means may include a closable valve, e.g. depressurizing valve 130 and/or cartridge valves 136,142, that can be closed to isolate the second cylinder 91, thereby allowing the lift to be raised and lowered while the platform extension is maintained in a deployed position relative to the main platform. |
