Development of Wheelchair-Lift Prototype for Transit Buses

This paper describes the concept, design, and prototype fabrication of an innovative four-bar mechanism-based wheelchair-lift system, which can allow a wheelchair-, scooter-, or walker-bound passenger to be lifted from ground level to the bus floor level and back again. The new lift is designed to accommodate a passenger service load of 3,300 N (750 lbf). It has relatively few components. It consists of two four-bar mechanisms, a platform, and two hydraulic actuators to raise, lower, fold, and unfold the platform. The use of restraining pins enables the lift platform to pivot normal to the ground for stowage. When stowed away, it folds into a very compact space. The lift is designed with safety, human comfort, and ride stability in mind. Under full load conditions, the angular deflection of the lift platform is 0.8°, as opposed to nearly 3° in existing lifts. The lift provides a very smooth ride to the passenger, without any uncomfortable jerking or vibrations. The device represents a sound alternative to existing lifts.