In a power take-off a spring engages a hydraulically actuated clutch-activating pressure plate to force the same into a neutral position. In one embodiment of the invention a hydraulically operated spring-loaded piston for arresting the rotational motion of an output shaft engages the pressure plate upon shifting thereof into its neutral position and consequent uncoupling of the output shaft from an input or drive shaft. In another embodiment of the invention an annular friction disk slidably connected or splined to the output shaft for stopping the same is clamped between a brake housing and a hydraulically actuated piston. The pistons automatically retract under the action of respective springs upon shut-off of the vehicle engine driving the input shaft and energizing the hydraulic system actuating the plates and the pistons, whereby the angular position of the output shaft may be manually adjusted.