Patent ID: 8484802

Claim:
A combination castor, comprising: a linking device; and a plurality of castor assemblies connected with the linking device; wherein each of the castor assemblies comprises: an operation unit; a braking unit connected with the operation unit; and at least one roller connected with the braking unit; the operation unit of each of the castor assemblies includes: a mounting seat having an interior provided with a slideway; a slide slidably mounted in the slideway of the mounting seat and having a first end provided with a pivot portion pivotally connected with the linking device and a second end provided with a guide ramp and a guide slot; and a driven block abutting the slide and having a bottom provided with a pressing lug pressing the guide ramp of the slide; the braking unit of each of the castor assemblies includes: a bushing mounted on and extending downward from the mounting seat of the operation unit; a housing rotatably mounted on the bushing; a top cap mounted on the bushing; a control shaft movably mounted in the bushing and having an upper end secured on the driven block of the operation unit to move in concert with the driven block of the operation unit and a lower end extended into the housing; and a braking member secured on the lower end of the control shaft to move in concert with the control shaft and having an end provided with a locking portion; the control shaft of the braking unit is in turn extended through the driven block of the operation unit, the guide slot of the slide, the mounting seat of the operation unit and the bushing and is extended into an inner space of the housing; the guide slot of the slide is slidable on the control shaft of the braking unit; the roller of each of the castor assemblies is rotatably mounted on the housing of the braking unit and has an inner periphery provided with a plurality of locking grooves which are arranged in an annular manner; the locking portion of the braking member is movable into and releasably locked in one of the locking grooves of the roller.