Rotational unit

A rotational unit, comprising:

• a compressor having a housing, wherein the housing includes a front wall;
• a rotary shaft having an end portion that protrudes from the front wall of the housing;
• an electric rotational device coaxial with the rotary shaft, wherein the electric rotational device is coupled to the end portion of the rotary shaft and functions as at least one of a motor and a generator;
• a rotational member coupled to the rotary shaft, wherein the rotational member has a power transmitting mechanism for transmitting power between the rotational unit and an external drive source;
• and
• a one-way clutch located in a power transmitting path between the rotary shaft and the rotational member, wherein the one-way clutch is located inward of the rotational member;
• wherein the electric rotational device is located on or forward of the front wall of the housing, and wherein at least part of the electric rotational device is located outside the outer dimension of the power transmitting mechanism.