Infinitely Variable Transmission

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The Infinitely Variable Transmission (IVT) is a specific type of continuously variable transmission (CVT) that has an infinite range of input/output ratios in addition to its infinite number of possible ratios; this qualification for the IVT implies that its range of ratios includes a zero output/input ratio that can be continuously approached from a defined 'higher' ratio. A zero output implies an infinite input, which can be continuously approached from a given finite input value with an IVT. [Note: remember that so-called 'low' gears are a reference to low ratios of output/input, which have high input/output ratios that are taken to the extreme with IVT's, resulting in a 'neutral', or non-driving 'low' gear limit.]

Most (if not all) IVT's result from the combination of a CVT with an epicyclic gear system (which is also known as a planetary gear system) that facilitates the subtraction of one speed from another speed within the set of input and planetary gear rotations. This subtraction only needs to result in an continuous range of values that includes a zero output; the maximum output/input ratio can be arbitrarily chosen from infinite practical possibilities through selection of extraneous input or output gear, pulley or sprocket sizes without affecting the zero output or the continuity of the whole system. Importantly, the IVT is distinguished as being 'infinite' in its ratio of high gear to low gear within its range; high gear is infinite times higher than low gear. The IVT is always engaged, even during its zero output adjustment.

The term 'Infinitely Variable Transmission' does not imply reverse direction, disengagement, automatic operation, or any other quality except ratio select-ability within a continuous range of input/output ratios from a defined minimum to an undefined, 'infinite' maximum. This means continuous range from a defined output/input to zero output/input ratio.

A UK company, Torotrac Plc, IVT are currently endevouring to develop a commercially viable IVT. Their gearbox utilises a patented lubrication oil that develops a high co-efficient of friction between the pressure surfaces of a CVT type variator.

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