METHOD OF FIXING A RAIL ON A SUPPORT OF TIMBER OR CAST OR MOULDED MATERIAL

摘要

A method and a device for attaching a rail on a timber support. The device includes a helically threaded fastener adapted to be screwed into a helically threaded borehole in the support after a rectangular metal insert is positioned in a rectangular opening at the periphery of the borehole. The borehole is sufficiently large that the fastener only contacts the timber support via contact with the insert. The rectangular opening is longer than the insert so that there is radial play between the insert and one end of the insert. The other end of the insert is adapted to contact a sloped side of the thread of the fastener. As the fastener is screwed into the borehole, the sloped side of the fastener presses the insert parallel to and perpendicular to the screwing axis of the fastener. As a result, the insert elastically expands parallel to and perpendicular to the screwing axis. Because the expansion perpendicular to the screwing axis is less than the radial play, no radial forces act on the timber support. Rather the timber support is only compressed parallel to the screwing axis thereby preventing the timber support from splintering.