A hydrokinetic torque converter in the power train between the engine and the wheels of a motor vehicle has a rotary engine-driven housing which is of one piece with a pump and contains a rotary turbine having a hub which drives the input shaft of a transmission. A lockup clutch can be engaged, either entirely or with slip, to transmit torque from the housing or from the pump to the hub of the turbine. Such clutch can employ flat or conical friction linings and/or friction surfaces, for example, a friction lining on the shell of the turbine and a friction surface on a wall of the housing. The shell of the turbine in the torque converter employing such clutch is movable axially to advance the friction lining into or from engagement with the friction surface. Alternatively, the lockup clutch can be installed in a torus which is defined by the turbine and the pump of the torque converter, and such clutch can be cooled by one or more streams of a hydraulic fluid.