GB1407233A - Powerless lift with automatic balance and differential action - Google Patents

Abstract

1407233 Lifts K S SMART 10 Jan 1973 [29 Jan 1972] 4284/72 Heading B8L A powerless lift comprising a lift car with two platforms which form a step at a lower level and a reverse step at an upper level, the two platforms being suspended respectively from the larger and smaller barrels of a differential drum whereby when a person steps on to the lower platform, the remote end of the platform suspension rope rises to pick up weights until the person is counterbalanced, whereafter the person steps up on to the other platform and descends if the other platform is suspended on the larger diameter barrel or ascends if its on the smaller diameter barrel. In the latter case, a carrier with the counterbalance weights thereon is transferred to the smaller diameter barrel at the mid-point of travel whereby the ascending person is counterbalanced to retard his progress and is eventually halted. The counterweight carrier is similarly transferred during descent of a person. When a passenger steps on to the lower platform at the lower level, latches on the carrier at the remote end of that platform suspension cable rise to lift and accumulate weights from latches on a fixed structure, until balance is reached. As the passenger steps on to the upper platform, it descends slightly against springs to operate a control rope causing retraction of all the unloaded latches on the fixed structure so that movement of the picked up weights is not impeded as the car ascends. The car starts to decelerate once the cable supporting the weight carrier is transferred on to the small barrel of the drum at mid travel and the car is finally stopped by deposition of the balance weights on to latches at the lower level and by a damper arrangement for the car at the upper level. As the car approaches the lower level, the balance weight carrier picks up more weights at the top of its travel, to halt the car, after which the weights are deposited on to the fixed upper level latches as the carrier settles when the passenger steps from the platform. In a second embodiment, the system comprises two elevator cars and a separate weight carrier is not required.