Expanding dowel driven into wall - has cams with interengaging convex and concave wedge sections for automatic friction engagement in three-stage fitting action.

摘要

The dowel core (1) and dowel sleeve whose relative movement expands the dowel each have at least one cam (6,8) each projecting radially over an imaginary cylinder face (5). The cams have matching wedge sections rising in opposite directions in the sleeve and on the core with convex wedge section on the core cam and concave wedge section on the sleeve cam. The wedge sections engage automatically with each other in friction engagement through expansions of the dowel during a three phase fitting movement wherein first the core is inserted to the required depth in the sleeve and a gap is left between the wedge sections. The concave wedge faces of the cam on the sleeve slide on the convex faces of the cam on the core and widen out the outer face of the sleeve until it adjoins the dowel hole wall. Further turning between core and sleeve ensures resilient deformation and friction engagement. USE/ADVANTAGE - Expanding dowel driven into wall is simple to mfr. and does not come loose during use but can be easily released when required.