with the researching, developing and manufacturing to big-sized

compressors with the flow up to 50–100 thousand M3 per minute,

the structure of the compressors has greatly changed. Varied techniqueand technology such as compact and convenience to assembly and  commissioning, easiness to manufacturing are widely used. The  complicated parts,such as impellers with curvic coupling of  transmitting big torque, also widely used. The impellers are most madeof aluminum alloy. They are forged and heat-treated. A few

centrifugal impellers of small-sized engines are cast by titanium

alloy. A impeller locates on the impeller shaft of the compressor and driven by the shaft through the curvic coupling. It automatically

secures alighning under conditions of the radial deformation of the

impeller because of being heated or acted by centrifugal load.