Aerial lift with safety device

摘要

A safety device for an aerial lift (10 fig. 1) having a basket or cage with operator controls 23 for manoeuvring the basket to a desired location and a foot operable safety switch 24 which provides a switch-closed signal to the controls 23 before the controls become operable, the safety device comprising a load sensitive bar 160 extending across the basket proximate to controls 23 and an auxiliary safety switch 26 connected in series with the foot switch 24 with its contacts (C1 fig. 4) normally in a closed condition (switch on) and in the event that the bar 160 is subject to a preset minimum load, the switch 26 is operated to change the contacts to a open condition (switch off) thereby cutting off the switch-closed signal. The minimum load may be preset for the load sensitive bar 160 by spring means (166 fig. 3). The load sensitive bar may be a fixed bar (173 fig. 6) having a pressure sensitive safety edge or bumper (175 fig. 6). Auxiliary safety switch 26 may be connected to an alarm such as a flashing beacon or an audible warning device. Auxiliary safety switch 26 may include a signal filter to prevent switch off of power until a desired time period has elapsed and thus prevent switch off due to inadvertent loads on the bar 160.