SCISSOR LIFT LOAD SENSING SYSTEMS AND METHODS

A lift device (10, 310) includes a base, a retractable lift mechanism (20,320), a work platform (22), and a lift controller. The retractable lift mechanism is moveable between an extended position and a retracted position. The work platform is configured to support a load and is coupled to and supported by the retractable lift mechanism. The linear actuator (26, 326) is configured to selectively move the retractable lift mechanism between the extended position and the retracted position. The linear actuator has an electric motor (34) and an electromagnetic brake (50). The lift controller is in communication with the linear actuator. First an actuator force applied by the linear actuator to the work platform is determined based on the motor torque. Then, the load supported by the work platform is determined based on actuator force and height of the platform. In another embodiment, the linear actuator includes a push tube (38) assembly and the load supported by the work platform is further determined based on a monitored compression of the inner push tube. The lift mechanism could be a scissor lift or a boom lift. A fully electric scissor lift, devoid of hydraulic systems is also claimed.