Abstract: The disclosure embraces a manure disposal installation including an electric motor having a fixed stator and a rotor which is attached to a hollow cylinder on the interior of which is fixedly secured a threaded nut; a threaded shaft passes through the center of the cylinder that is fixed to the rotor whereby rotation of the rotor will effect linear translation of the shaft; to one end of the shaft is attached a coupling means for coupling the shaft to a manure shovel rod to which is secured a manure shovel; the shaft is provided adjacent its ends with non-threaded, reduced diameter portions so that in the event that the direction of rotation of the rotor, upon the shovel reaching its limit of travel, is not automatically changed, damage to the associated mechanisms will be avoided since the reduced diameter portion of the shaft will come into juxtaposition with the nut fixed on the hollow cylinder whereby further movement of the shaft is prevented.