Positively engaging clutch

Abstract

An interengaging clutch comprises first and second rotatable clutch halves, the first clutch half being a driven clutch element connected to a first wheel drive train and being movable along an axial direction, the second clutch half being a driving clutch element and being connected to a main drive train and to a second wheel drive train. The clutch halves have circumferentially disposed dogs or teeth with intermeshing contact surfaces for engaging the clutch halves together so that torque can be transmitted from the second clutch half to the first clutch when they are interengaged and rotating at different rotational speeds. Connected to the first clutch half is a unidirectional servo component which is pressure actuated on one side only so as to move the first clutch half into engagement with the second clutch. The interengaging clutch further includes first and second rotational speed sensors which produce signals indicative of the rotational speeds of the clutch halves. An electronic control unit is provided which causes the servo component to be pressure actuated in one direction only so that the clutch halves are brought into engagement based on the signals received from the rotational speed sensors. For disengagement, a spring is provided which acts in a direction opposite to that of the servo component with a spring force which is sufficient to overcome the frictional forces generated on the control surfaces when the transmitted torque falls to a predetermined, preferably very low, value.