Fluid friction clutch

A fluid friction clutch controlled as a function of rotational speed, comprising:

• a driving primary member comprising a hollow drive disk and a drive member, said drive disk comprising a reservoir and an overflow orifice in said reservoir said overflow orifice positioned on the circumferential surface of said drive disk;
• a driven secondary member surrounding said primary member;
• a working chamber formed between the primary and secondary members and in communication with the reservoir;
• and
• a centrifugally actuated retaining body for regulating flow of a working fluid, and for directing the working fluid into the reservoir, wherein the retaining body is radially displaceable within the overflow orifice between a first position within said reservoir and a second position within said working chamber.

A fluid friction clutch controlled as a function of temperature and rotational speed, comprising:

• a driving primary member which comprises a hollow drive disk and a drive member, said drive disk comprising an overflow orifice positioned on the circumferential surface of said drive disk;
• a driven secondary member surrounding said primary member and comprising a partition axially positioned from said drive disk within said secondary member;
• a three chamber working fluid system which includes:
• a first reservoir chamber within said hollow drive disk,
• a second reservoir chamber disposed between a cover of said secondary member and said partition, and
• a working chamber disposed between said primary and said secondary members;
• temperature responsive valve means positioned on said partition for controlling the flow of working fluid between said second reservoir chamber and said working chamber;
• and
• a centrifugally actuated retaining body for controlling and directing the flow of working fluid between said working chamber and said first reservoir chamber, wherein the retaining body is radially displaceable within said overflow orifice between a first position within said first reservoir chamber and a second position within said working chamber.