US 6,131,936 AGranted

Luggage or shopping cart having a self-locking front caster wheel assembly

AssigneeExedy Corporation

InventorsYasuhiko Eguchi, Heiji Fukutake

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Abstract

In the front wheel assembly of a luggage or shopping cart, a sensor wheel is supported by a wheel bracket between a pair of caster wheels so as to be rotatable around a common horizontal wheel shaft and moveable downward from a neutral position coaxial with the caster wheels. Thus, even when the cart is tilted sideways, one of the caster wheels always support the load of the cart, and serves as a center of pivotal movement of the front wheel assembly which allows the sensor wheel to be safely lifted out of the slot in the floor. Therefore, the sensor wheel is prevented from being wedged in the slot, and would not be damaged substantially under any circumstances. Additionally, a first locking arrangement allows the cart to be stationary on the conveyor surface, and a second locking arrangement allows the front wheel to remain in the straight ahead position even when the front wheel assembly hangs from an edge of a step of an escalator. These features of the present invention allow the cart to be maneuvered freely on a stationary smooth surface, and to stay stationary in a stable fashion on a moving slotted surface.

Claims5

Dependent claims

A cart adapted to be pushed by hand, comprising:

a frame, a front wheel assembly centrally attached to a lower front part of said frame, and a pair of rear wheels attached to lower rear parts of said frame, wherein said front wheel assembly includes a support bracket supported in a lower front part of said frame so as to be pivotable about a single substantially vertical pivot center line, a pair of caster wheels supported by said support bracket so as to be rotatable around a common horizontal wheel shaft, a sensor wheel supported by said support bracket between said caster wheels so as to be rotatable around said horizontal wheel shaft and moveable vertically relative to the wheel shaft between a neutral position in which the sensor wheel is coaxial with said caster wheels, when the wheel assembly is traversing a planar surface, and a lowered position in which a bottom surface of the sensor wheel is positioned below bottom surfaces of the pair of caster wheels, a first locking arrangement for blocking rotation of said pair of caster wheels as said sensor wheel drops into a longitudinal slot formed in a floor of a conveying system and into said lowered position, and a second locking arrangement for blocking swiveling movement of said support bracket around said vertical pivot center as said sensor wheel drops into the longitudinal slot formed in the floor and into said lowered position.

Dependencies are inferred from the claim text.