A wheelchair lift for supporting a wheelchair bound passenger and for moving the passenger between ground level and an opening in a vehicle. The wheelchair lift includes a platform and pivotal mechanism engaging the platform as well as a bridge plate for assuming a horizontal orientation to enable the passenger to proceed through the vehicle opening and a vertical orientation to act as a roll stop as the platform proceeds between the ground and the vehicle opening. The bridge plate includes a non-linear channel configured within its side which engages a pivotal mechanism which includes an upper parallelogram structure and hydraulic apparatus to move the upper parallelogram structure to move the platform. Also included is a lower parallelogram structure which is in sliding engagement with the upper parallelogram structure during at least a portion of the motion when the platform is moved between the ground and the vehicle opening. The lower parallelogram also is provided with a saddle bolt for sliding engagement with the non-linear channel such that movement of the lower parallelogram acts to raise and lower the bridge plate upon movement of the platform.