Abstract: A cargo drive unit which, as part of an array of several such units, it disposed in the hold of a vehicle to permit cargo to be moved within the hold. The drive unit derives power from an electric motor to first erect a drive a roller into contact with a load and then to move the load. A hysteresis coupling is disposed between the motor and the roller and functions to limit the force of the roller against the load to be driven by adjusting the excitation current thereto. The hysteresis coupling allows the roller to retract when the current to the coupling is removed and limits shock loading to drive gearing and the motor when excessive loads are applied to the roller.

Abstract: A gear arrangement includes two coaxial output bevel gears having a common pitch axis and rigidly coupled each to the other. Two coaxial bevel pinions, each of which meshes with a corresponding output bevel gear, are flexibly coupled together via a quill shaft. The quill shaft is used to adjust the preload of one of the pinions against the other, whereby the load capacity of the gear drive is substantially equal to the sum of the load capacity of the two pinion/gear pairs.