PURPOSE: To freely install a center bearing between a propeller shaft by accommodating a transmission shaft for driving a compressor into the upper part of a casing and accommodating an input shaft joined with the propeller shaft into the lower part and installing an installation stay into the upper part of the casing.

CONSTITUTION: A transmission shaft for driving a compressor which is connected and disconnected by a clutch is accommodated into the upper part of a casing, and an input shaft onto which a center bearing 17 joined with a propeller shaft (a) at the both shaft edges is accommodated into the lower part, and a chain is laid onto the sprockets on the both shafts. In the upper part of the casing, installation stays 47 are installed at the right and left edges in the width direction through a mounting bush 46, and a frame installation metal fitting 49 having a U-shaped section which is joined with a car body frame 48 is installed integrally at the other edge of each stay 47. Therefore, a turbo-retarder can be installed onto the propeller shaft (a), securing a proper interval between the upper surface of the ground and the undersurface of an oil pan 44 in a vehicle, etc.