초록 ▼

A trolley comprising a pair of vertical bars, a pair of linking bars, and a wheel assembly operable by the linking bars to pivotally move between an extended and a retracted positions. A movable block slidable on the vertical bars is connected with the linking bars. A positioning plate is fixedly mo

A trolley comprising a pair of vertical bars, a pair of linking bars, and a wheel assembly operable by the linking bars to pivotally move between an extended and a retracted positions. A movable block slidable on the vertical bars is connected with the linking bars. A positioning plate is fixedly mounted on the movable block and a sliding movement of the movable block relative to the vertical bars is controlled by a biasing unit in cooperation with the positioning plate. A respective compression spring is additionally provided on the vertical bars to facilitate the sliding movement of the movable block when the movable block is released to move.

대표청구항 ▼

For use in a trolley comprising a pair of vertical bars, wheel means connected to the pair of vertical bars, and a pair of linking bars for effectuating a pivotal movement of a pair of wheels of the wheel means relative to the pair of vertical bars, the improvement comprising the provision of an act

For use in a trolley comprising a pair of vertical bars, wheel means connected to the pair of vertical bars, and a pair of linking bars for effectuating a pivotal movement of a pair of wheels of the wheel means relative to the pair of vertical bars, the improvement comprising the provision of an actuation device between the pair of linking bars and the pair of vertical bars, said actuation device comprising: a movable block linked to the linking bars and slidable on the pair of vertical bars; a stationary block fixedly mounted on the pair of vertical bars; a positioning plate fixedly attached on said movable block, said positioning plate having at least two lateral holes therein; a longitudinal slot disposed on said stationary block and permitting said positioning plate to pass through; and a biasing unit mounted on said stationary block, said biasing unit having a pin protruding into said stationary block, said pin being engageable with each of said holes on said positioning plate, said biasing unit being manually laterally operable to effectuate a lateral movement to thereby engage and disengage said protruding pin with and from said holes.