A self-contained clutch having no external conrols comprising, in combination: a first member (14); a second member (38,62) rotatably mounted with respect to the first member (14); a drive disc (22) for rotation with the first member; a piston (80) mounted for reciprocation within a cylinder (C) carried by the secondmember (38;62); friction facing means (86) engaged by the piston (80) for engagement contact with the drive disc (22) for providing rotation of the second member (38,62) with the first member (14); and environment sensing means (104,126) carried by the second member (38,62) for moving the piston (80) within the cylinder (C) to cause the friction facing (86) to engage and disengage with the drive disc (22) so that when the condition of the environment sensed by the environment sensing means (104,126) is within a first range, the friction facing (86) is disengaged from the drive disc (22) and thus the first (14) and second (38,62) members are not rotably interrelated buty when the condition of the environment sensed by the environment sensing means (104,126), is within a second range, the friction facing (86) is engaged with the drive disc (22) and the first (14) and second (38,62) members are rotatably interrelated, characterized in that the piston (80) divides the cylinder (C) into a high pressure cavity side (Cb) and a low pressure cavity side (Ca), and that means (113, 116, 136) are provided which are actuated by the environment sensing means (104,126) for movingfluid between the high pressure cavity side (Cb) and the low pressure cavity side (Ca) of the cylinder (C). - (13pp) EPAB- EP-163797 B A self-contained clutch having no external conrols comprising, in combination: a first member (14); a second member (38,62) rotatably mounted with respect to the first member (14); a drive disc (22) for rotation with the first member; a piston (80) mounted for reciprocation within a cylinder (C) carried by the second member (38;62); friction facing means (86) engaged by the piston (80) for engagement contact with the drive disc (22) for providing rotation of the second member (38,62) with the first member (14); and environment sensing means (104,126) carried by the second member (38,62) for moving the piston (80) within the cylinder (C) to cause the friction facing (86) to engage and disengage with the drive disc (22) so that when the condition of the environment sensed by the environment sensing means (104,126) is within a first range, the friction facing (86) is disengaged from the drive disc (22) and thus the first (14) and second (38,62) members are not rotably interrelated buty when the condition of the environment sensed by the environment sensing means (104,126), is within a second range, the friction facing (86) is engaged with the drive disc (22) and the first (14) and second (38,62) members are rotatably interrelated, characterized in that the piston (80) divides the cylinder (C) into a high pressure cavity side (Cb) and a low pressure cavity side (Ca), and that means (113, 116, 136) are provided which are actuated by the environment sensing means (104,126) for moving fluid between the high pressure cavity side (Cb) and the low pressure cavity side (Ca) of the cylinder (C). - EP-163797 B A self-contained clutch having no external conrols comprising, in combination: a first member (14); a second member (38,62) rotatably mounted with respect to the first member (14); a drive disc (22) for rotation with the first member; a piston (80) mounted for reciprocation within a cylinder (C) carried by the secondmember (38;62); friction facing means (86) engaged by the piston (80) for engagement contact with the drive disc (22) for providing rotation of the second member (38,62) with the first member (14); and environment sensing means (104,126) carried by the second member (38,62) for moving the piston (80) within the cylinder (C) to cause the friction facing (86) to engage and disengage with the drive disc (22) so that when the condition of the environment sensed by the environment sensing means (104,126) is within a first range, the friction facing (86) is disengaged from the drive disc (22) and thus the first (14) and second (38,62) members are not rotably interrelated buty when the condition of the environment sensed by the environment sensing means (104,126), is within a second range, the friction facing (86) is engaged with the drive disc (22) and the first (14) and second (38,62) members are rotatably interrelated, characterized in that the piston (80) divides the cylinder (C) into a high pressure cavity side (Cb) and a low pressure cavity side (Ca), and that means (113, 116, 136) are provided which are actuated by the environment sensing means (104,126) for movingfluid between the high pressure cavity side (Cb) and the low pressure cavity side (Ca) of the cylinder (C). (13pp) USAB- US4456110 A The self-contained fan clutch includes a housing, in which is contained a rotatable drive disc driven by a source of power connected to the housing and the drive disc. Also mounted within the housing is an annular piston having an annular piston reciprocable within a cylinder member. The piston portion carries a friction facing engageable with the driven drive disc when the piston is actuated within the cylinder. - The piston divides the cylinder into a high pressure side and a low pressure side with the piston, piston portion and cylinder carried by the housing, with the housing having a series of fan blades mounted on it. The cylinder mounts a reciprocal pump plunger actuated by a cam mounted on the driven drive disc for pressurising the high pressure side of the cylinder, which causes the friction facing of the piston portion to engage the drive disc and be rotated together with the housing and fans. The pump plunger is actuated by a thermal sensor pill.