Abstract: A lift mechanism having vertical columns and including manually positionable load supporting arms which may be manipulated so as to engage a raised load thus permitting lowering of the lift. The lift mechanism is further characterized by a safety system which prevents operation of the lift unless the load supporting arms are all fully retracted from the path of the lift or all fully extended under the load. The safety system includes kinematically coupled latch members which move with the lift and engage apertures of vertically spaced arrays located in each support column of the lift.