An apparatus for urging a person of limited physical ability from a first location to a second location includes a self-propelled type of wheelchair that has two driven wheels disposed under the chair. A pair of preferably front-disposed castors is included. Together, the pair of castors and the two driven wheels define a first plane that the wheelchair is disposed on when the wheelchair is on a level surface. A pair of additional driven wheels is provided that are elevated with respect to the first plane. The additional driven wheels can be disposed either in front of or behind the two driven wheels. Together, the two driven wheels and the pair of additional driven wheels define a second plane. When the wheelchair is disposed along a sufficient incline, it tilts from the first plane into the second plane. At that time, contact with the surface is made by the pair of additional driven wheels, whereby the pair of additional driven wheels provides an additional motive force to help propel the wheelchair.