A number of new and unique features have been optimised in the course of the 'Pivotal' engine project. These features combine to make a device well suited to future engine requirements.
The piston movement is now controlled by pivot bearings and this eliminates piston rocking and the wear associated with the cold startup phase in a conventional two/stroke engine. The exceptionally low level of mechanical noise is immediately apparent. The pivoted piston also ensures that the compression seals are held at normal orientation to the surface of the chamber and do not protrude into the port openings. The pivot shaft also provides access for water cooling which circulates through the piston to directly cool the piston crown. These features are important because the piston is no longer at risk of being damaged when the engine is cold or from over heating during sustained periods of high load.
In a 'Pivotal' engine the only components subject to wear are the chamber surfaces, the compression seals and the bearings. Modern surface coating technology provides a wide range of material choices making it possible to achieve the service life required in almost any engine application. By pivoting the piston we have removed the high lubrication demand that is associated with the sliding piston of a conventional two/stroke engine (the cause of excessive oil loss out of the exhaust). Oil can be metered by the engine management system directly to the surfaces of parts where it is needed. The 'Pivotal' engine oil usage is only 10% of the level required by a conventional two/stroke engine. This rate of oil consumption is comparable with the oil consumption of a four/stroke engine before the additional saving from not having oil changes is factored in. Click to view working Pivotal Engine: Pivotal Engine - Flash Animation Version (1.39mb, requires Flash Player) Note: this animation will appear in a new browser window

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