CONTROL MECHANISM FOR TENSIONING UNIT

摘要

The invention concerns a control mechanism designed for manipulation with a stressing rod of a stressing unit which is used for fastening and prestressing of bolts, e.g. for flange joints of large pressure vessels, especially for flange joints of nuclear reactor vessels. The drive of the control mechanism of the stressing unit is a pseudo-planetary system of a gear mechanism which has the ability of both manual and mechanical control. A crown gear wheel is equipped with outer teeth and inner teeth. An inserted gear wheel of a driving pinion mates with the outer teeth. Only three planet gear wheels are inserted between the inner teeth of the crown gear wheel and the outer spur teeth of a central gear wheel. The central gear wheel is formed into the shape of a cylindrical shell which is bedded by its lower side, having a certain radial move possibility, on a wire bearing placed on a carrying body. A further part of the control mechanism forms a joint between the central gear wheel and the stressing rod which is equipped in its lower part with an inner thread corresponding to an auxiliary thread of a flange bolt, is relieved by a compensating spring leaning against the face of a supporting nut which revolves together with the stressing rod on a suspension bolt which has the same lead as the auxiliary thread of the flange bolt.