| 摘要 |
A pair of endless belt track assemblies attach to the frame of a hand truck and extend backwards from the ground wheels for a distance to facilitate travel on stairs or the like during the intervals when the ground wheels are out of contact with the stair treads. Rollers are situated between the front, back, lower and upper regions of a pair of spaced apart side plates and are spaced from the edges of the plates to define a continuous belt guideway between the peripheral regions of the side plates. An endless belt is seated in the guideway in continuous contact with each of the rollers and functions as a crawler track when the truck wheels are out of contact with the stairs. The construction reduces resistance to belt movement from friction and inhibits jamming of the rollers and snagging of the belt.
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