Several new and useful concepts for a manually propelled vehicle such as a wheel chair are provided. In one concept, the vehicle is configured to be selectively placed in an automatic lock condition in which (i) the wheel chair can move in a conventional manner while an occupant is seated in the wheel chair, and (ii) the wheel chair is automatically locked against movement when an occupant begins to rise from a seated position on the wheel chair. In another concept, a particularly secure structure is provided for locking the wheel of the wheel chair against movement. In yet another concept, important components of the wheel chair are formed in a manner that facilitates assembly of those components into the wheel chair, by an internal fastening system and in a modular fashion.
