Ermentrout-Kopell canonical model

An emergency device for bringing a lift car (10) to a level in the event of an unwanted stoppage in a different position from a normal stop level (Ln) comprises an auxiliary hydraulic motor (30) with a reversible sense of rotation arranged to operate the winch (20) of the lift through a control system which may be manual or automatic. The control system includes a hydraulic accumulator (38) connected to the hydraulic motor (30) through valve means (54) and selector means (69) for controlling the sense of rotation of the hydraulic motor (30), actuator means (54; 152; 184) for controlling the opening of the valve means (54), and means (86; 164) for indicating the position of the lift car (10) and position sensor means (128; 176) which are displaceable relative to each other in synchronism with the movement of the lift car (10) and cooperate with the selector means (69) to bring the lift car (10) to a level by moving it in the more convenient direction to reach one of the normal stop levels (Ln).