Patent ID: 7014021

Claim:
A fluid coupling comprising: a pump impeller provided on a drive shaft; a turbine impeller provided on a driven shaft; a housing fixed to said pump impeller and surrounding said turbine impeller; a multiple disc clutch provided between a drive shaft side and a driven shaft side, said multiple disc clutch being operated to couple said drive shaft and said driven shaft mechanically so that said drive shaft and said driven shaft are rotated at the same rotational speed; a pressing device for pressing clutch plates in said multiple disc clutch; said pressing device comprising: a clutch plate pressing chamber to which a fluid pressure is applied; a piston provided in said clutch plate pressing chamber for pressing said clutch plates; and a device for limiting a stroke of said piston; wherein when the amount of wear of said clutch plates exceeds a predetermined value, the stroke of said piston is limited by said device so that the frictional force for transmitting power by said clutch plates cannot be exerted to generate a differential between a rotational speed of said drive shaft and a rotational speed of said driven shaft.