Abstract: A method is disclosed for starting heavy machinery driven by an internal combustion engine. The method comprises starting the engine and cyclically operating a clutch to couple the engine to the machinery intermittently. The transmission of torque to the machinery through the clutch is briefly interrupted or reduced when the engine risks stalling.

Abstract: A method is disclosed for starting heavy machinery driven by an internal combustion engine. The method comprises starting the engine and cyclically operating a clutch to couple the engine to the machinery intermittently. The transmission of torque to the machinery through the clutch is briefly interrupted or reduced when the engine risks stalling.

Abstract: An air filtering mechanism for use on crop harvesting machinery having a generally cylindrical, rotary, perforate filter element, a fan operable to draw air therethrough, drive means operable rotatably to drive the filter element, and blanking off means mounted within the filter element for blanking off the perforations thereof over a predetermined region, is disclosed wherein a duct having an open portion is provided exteriorly of the filter element opposite to the blanking off means, A pressurized flow of air from the fan is directed through the duct in the form of a cleaning air blast in a direction parallel to the external surface of the filter element to clean foreign matter collected on the filter element in the region of the blanking off means by virtue of the filter element being exposed to the pressurized air in the duct along the open portion thereof.