초록

In a conventional hand truck, a stair tread engaging device having reduced friction and improved mobility provided by a plurality of rollers each rotating freely in its own socket and only on its own axis without forward movement.

대표청구항 ▼

In a hand truck assembly having a wheel and handled frame, including side members, a tread engaging device secured to one of the side members of the frame, said tread engaging device including an endless V-belt for engaging the tread of a stairs and roller means thereon, the improvement which compri

In a hand truck assembly having a wheel and handled frame, including side members, a tread engaging device secured to one of the side members of the frame, said tread engaging device including an endless V-belt for engaging the tread of a stairs and roller means thereon, the improvement which comprises: said roller means including a plurality of barrell-shaped rollers having flat end walls and a bulging sidewall, each of said rollers being mounted in an individual cavity in said device and rotatable about their own axes, said rollers being generally linearly aligned and non-linearly movable with respect to said device, with said V-belt making full contact with more than one of said rollers only when said V-belt abuts against a generally flatsurface and said rollers, and making contact with only one of said rollers when a portion of said V-belt engages the edge of a stair and impacts against said only one of said rollers, said tread engaging device further including flange means at each of the two ends thereof to maintain said V-belt on said device.