US Patent 8342544 Utility cart

An adjustable cart, comprising in combination a base supported by wheels at least one of which is swiveled to allow cart steering travel, two frames carried by the base to pivot from active upright positions to stored down positions, one above the other, there being upright supports carried by the cart at or proximate cart corners, there being mechanism associated with the frame and certain of the supports to releasably lock the frames in upright extended positions relative to the supports in response to frame pivoting to upright positions, and there being lengthwise adjustable means, associated with each frame, whereby said mechanism is un-blocked to allow frame folding.