Abstract: A motor-vehicle drive engine has a cooling system to which it is connected via a transmission so that it can drive its own cooling system. A controller responsive to various parameters of the engine, particularly load power requirements, operates the cooling-system transmission through a cutout circuit so as to disconnect the cooling system from the engine when the engine temperature is below a predetermined level so that the full engine output power can be applied to a load. Thus the engine loading, engine output speed, engine heat, accelerator-pedal setting, and/or similar parameters are detected and fed to the controller which automatically cuts the cooling system off for a predetermined fixed interval (controlled by a timer) whenever it is possible for the engine to operate for this interval without the cooling system and the work produced by the engine is otherwise needed. A temperature sensor may reconnect the engine and the fan when the engine temperature rises impermissibly.

Abstract: A driving and a driven spur gear, lying in a common plane, are operatively coupled with each other through the intermediary of an idler gear in mesh therewith, the idler gear being radially shiftable against a resilient force in the common plane of rotation. The tangent to any tooth flank of both the driving and the driven gear at its point of contact with a tooth of the idler gear includes a pressure angle .alpha. with the common diameter of the meshing gears; the angle .delta. between the two common diameters should be so chosen that the two tangents are substantially perpendicular to each other, with .delta. - 2.alpha. = 90.degree. for rotation in one direction and .delta. +2.alpha. =90.degree. for rotation in the opposite direction.