Patent ID: 6224068
Filing Date: 2001-05-01
Classification: B62B

Abstract:
A pushcart for negotiating an escalator stairway of specification slope and step tread length, the pushcart comprising:a cart body;a plurality of wheel assemblies carrying wheels for running the pushcart on generally level surfaces, wherein at least two of said wheel assemblies each includesa fixed member fastened to said cart body;a pivotable wheel mount holding a wheel;a swivel joining a horizontal part of said wheel mount to said fixed member such that said wheel mount is pivotable against said fixed member about a vertical axis, whereby the at least two of said wheel assemblies are pivotable against said cart body for running the pushcart in lateral and advancing directions;a releasable pivoting-lock mechanism for releasably locking said pivotable wheel mount in the pushcart advancing direction, said releasable pivoting-lock mechanism includingan engagement member mounted on said fixed member and having a rearward notch oriented along the pushcart advancing direction, a stop formed for engagement with the rearward notch in said engagement member, and a stop retainer fixed to the horizontal part of said wheel mount for retaining said stop in contact with the wheel, whereinwhen the pushcart is pushed in the advancing direction, the stop is urged by frictional contact with the wheel into engagement with the rearward notch, and when the pushcart is reversed slightly against the advancing direction, the stop is urged out of engagement with the rearward notch by frictional contact with the wheel such that the wheel assembly is pivotable against said cart body; anddrop attenuating mechanisms fitted to each wheel assembly, said drop attenuating mechanisms including damped-swing traction members disposed at a predetermined level-surface separation for establishing adhesive friction in contacting the treads of a sloping escalator stairway with said pivotable wheel assemblies locked in the pushcart advancing direction, wherein said traction members bear the pushcart through a damped swing if said wheel assemblies are not riding on the treads of the escalator steps.