The present invention is a transmission used with a winch drum. The transmission includes a drive shaft, an output shaft, a hydraulic or pneumatic system, a cooling system, a gear coaxially mounted on the output shaft, and an electric motor for powering the gear. The drive shaft is adapted to drive the winch drum and includes a clutch disc extending generally radially outwards from the drive shaft. The clutch disc has a face. The output shaft coaxially surrounds at least a portion of the drive shaft and includes a friction surface extending generally radially inward. The friction surface has a face opposing the face of the clutch disc. The hydraulic or pneumatic system is adapted to bring the faces into contact, and the cooling system is adapted to remove heat from the friction surface via a fluid coolant.