are uniquely constructed to enable access to be gained to the shaft 16 and the interior of the housing for repair purposes without need of withdrawing the shaft axially out of the housing and the bearings as a result complete air cycle machine overhaul may be performed on location without sending the machine to a repair depot specifically the foregoing is achieved by forming the housing 15 as a split assembly having two housing sections 15a and 15b fig3 the two housing sections are formed with mounting flanges 75 having holes 76 for receiving fasteners such as screws 77 when the housing sections are assembled on the shaft 16 the mounting flanges 75 of the housing section 15a are disposed in face to face engagement with the mounting flanges 75 of the housing section 15b and the interface between the mating flanges lies in a plane which substantially coincides with a plane containing the axis of the shaft the housing sections are held in assembled relation by virtue of the screws 77 extending through the holes 76 in the flanges 75 by removing the screws either housing section may be removed from the shaft by pulling the housing section radially away from the shaft thus the housing sections are like a clam shell and may be opened up to afford access to the shaft without need of withdrawing the shaft axially from the housing 15 the bearings 40 and 60 and the bushings 70 also are of a clamshell nature in that the bearings and.