Abstract: A winch assembly (10) includes a first transmission assembly rotatably connecting a motor (11) to a winch drum (20) comprising clutches (12, 16) adapted to rotatably engage an output shaft (13) of the motor (11) to a winch drum shaft (19) of the winch drum (20) to wind in cable (22) onto the winch drum (20) and to payout cable (22) from the winch drum (20) by disengagement of motor drive shaft (13) from winch drum shaft (19).The winch assembly (10) further includes a second transmission assembly comprising an overrun clutch (23) rotatably connecting winch drum shaft (19) to motor drive shaft (13) if and when the payout speed of cable (22) from drum (20) exceeds a predetermined value.The winch assembly (10) is particularly suited to control conveyor belt tension in relatively large conveyor belts by simple on/off control of the clutches (12, 16) in response to sensed conveyor belt tension.