Abstract: An engine with an air vane type governor and provision for preventing overspeeding of the engine in the event the governor fails to do so, wherein a normally restrained or loaded spring acts to effect closing adjustment of the throttle valve upon release of its restraint by a tripping device actuated by a centrifugally projected plunger on the engine flywheel. In a modified embodiment, the release of the spring effects closure of an ignition grounding switch.

Abstract: A system for reducing the nitrogen oxide content of exhaust gas emitted by an internal combustion engine, by introducing exhaust gas from the engine into the fuel mixture being supplied to the engine. A valve that is adjusted by a pressure sensitive actuator responsive to changes in pressure in the engine crankcase proportions the amount of exhaust gas introduced into the fuel mixture to engine speed, and another valve that is controlled by adjustment of the throttle valve prevents introduction of the exhaust gas into the fuel mixture when the engine is idling and when it is operating at high speed and under high loads.