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An expander device for anchoring in a hole to secure a castor to a part which forms the hole, comprises a conical expander engaged in a sleeve having a conical interior. The expander and the sleeve are mouldings of reinforced plastics material. The expander is screwed onto a coaxial bolt with a 3-st

An expander device for anchoring in a hole to secure a castor to a part which forms the hole, comprises a conical expander engaged in a sleeve having a conical interior. The expander and the sleeve are mouldings of reinforced plastics material. The expander is screwed onto a coaxial bolt with a 3-start thread. The sleeve is axially slotted from either end, the slots from one end being angularly spaced from one another by 90°as are the other slots with which they are assymetrical so that alternate major and minor sleeve portions are formed between adjacent slots. Deformation takes place predominantly in the minor portions as the sleeve is expanded by axial movement of the conical expander into the internal taper of the sleeve which is caused by rotation of the bolt.

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An expander device for anchoring a castor in a hole by expansion therein, said device comprising: a radially expansible sleeve formed of a plastics material and having a conical inner surface which extends over at least a major portion of the axial extent of the sleeve; an expander member formed of

An expander device for anchoring a castor in a hole by expansion therein, said device comprising: a radially expansible sleeve formed of a plastics material and having a conical inner surface which extends over at least a major portion of the axial extent of the sleeve; an expander member formed of a plastic material, engageable in the sleeve and having an outer surface at least a major portion of which is conical; the conical surface portions of the sleeve and the expander member being adapted for sliding interengagement over a major portion of the axial extent of the sleeve such that axial movement of one of the expander member and the sleeve relative to the other causes radial expansion of the sleeve; an elongated externally-threaded member having a multi-start thread engaged in a complementary, axially extending tapped bore in the expander member, the multi-start thread acting to limit the applied torque to avoid overtightening; and means for rotating the externally-threaded member relative to the expander member so as to move the expander member relative to the sleeve and thereby to expand the sleeve into contact with a surface defining said hole and to anchor it therein.