Compression spring pre-tension during vehicle mfr. - involves tension tool, with expanding head, operated by control rod and drive

The pre-tension appliance consists of a shank-shaped tension tool. During pre-tension, the tool passes through an aperture of a vehicle body section, acting as an abutment, along the spring axis, into the spring top. It is removably fastened to a remote spring winding, by an anchor member. A drive unit displaces the tool. The anchor member consists of an expanding head, with three or more expanding levers, which are grouped around the longitudinal tool axis at even angular distances. The levers are moved into/out of working position on the spring winding, by a control rod, passing through the tension tool. The drive unit, and an actuating member for the control rod, are located on a support unit for the axial guidance of the tension tool. The support unit supports itself on the abutment opposite to the spring.