Stair ascending or descending cart

Claim 1

A stair ascending or descending cart comprising a. a frame, b. two rear wheels, c. means mounting said rear wheels on said frame adjacent the rearward portion thereof for rotation about an axis operatively fixed with respect to said frame, d. front wheel means, e. means for mounting said front wheel means on said frame for (1) rotational movement about an axis of rotation generally parallel to the axis of rotation of said rear wheels and (2) movement of said front wheel means axis between a forward position and a backward position relative to said rear wheels so that the wheel base of said cart is varied in response to the movement of said front wheel means axis, f. spring means biasing said front wheel means into said forward position, and g. stair descent facilitating means disposed in a position of convenient engagement by an operator stationed rearwardly of said cart and extending therefrom into operative relation with said front wheel mounting means for effecting movement of said front wheel means toward said backward position against the bias of said spring means in response to operator engagement after said cart has been moved pivotally backward about said rear wheel axis of rotation to effect clearance of said front wheel means of an upper step so that upon forward pivotal movement of said cart about said rear wheel axis of rotation said front wheel means will engage a lower step and upon release of said stair descent facilitating means said spring means is operable to facilitate manually controlled movement of said rear wheels into engagement with a lower step.