PURPOSE: To promote the low-unit cost of production by supporting another spherical surface free of slide motion with a spherical surface supporting means attached to one side of two rotating members, while making a cam body and a cam surface come into spherically contact with each other so as to enable both these rotating members to be aligned, thereby dispensing with the conventional universal joint.

CONSTITUTION: A torque transferrer A being used as a driving force distributor for a 4WD vehicle is constituted as a piston type flow generating means. In addition, it is provided with a drive housing 30 as each of both first and second rotating members, a driving piston 50 as a rotor 40 and a cam body, a cylinder chamber 60 as a fluid chamber snf the others. In this case, a spherical surface supporting means 110 is attached to the drive housing 30, spherically supporting the rotor 40. In addition, a cam surface 31 of the drive housing 30 and a spherical surface 50a of the driving piston 50 are made spherically contact with each other. With this constitution, both these rotating members 30, 40 are aligned, thereby having both input shaft and output shaft sides aligned with each other.