When the bearing seat of a large-sized generator shaft was damaged

it can be repaired by machnining on site.The installation space of cutting tool and the rotating accuracy of shaft are the necessary conditions of machining on site.A method of using false bush to support the shaft is presented in this paper

A hydraulic loop is applied to the false bush to avoid heating and burning of the bush due to contact of shaft with the false bush

providing necessary rotating accuracy for machining.The shape of the false bush

particularly the arrangement and size of the oil cavity

clearance between the false bush and the shaft

the hydraulic loop of the false bush

as well as the pressure and displacement of the shaft are analyzed and designed

the installation position and turning method of the cutting tool are determined

the material and angle of the cutting tool

as well as the cutting amount are chosen.The precautions and the possible problems during the course of shaft machining are also given.It is believed that the machining on site is an easy and low-cost way

ensuring the accuracy of the machined shaft.