Abstract: In a tractor power take-off mechanism comprising an input shaft driveable from an engine by a friction clutch and a two-speed power take-off shaft driveable from the input shaft by gearing including a disengageable toothed driving member operable by a hand lever by way of a selector fork, the disengageable toothed driving member can be difficult and noisy to engage because the input shaft tends to rotate due to inertia and drag when the friction clutch is disengaged. The input shaft is therefore provided with a band brake applied by initial movement of the hand lever in a direction to engage the disengageable toothed driving member and held applied while an operating load is being exerted on the lever in that direction. A conventional detent holding the selector fork in disengaged position provides the resistance required to cause the brake to be applied before the lever can move the fork into engaged position.