Negative Factors

A couple of cautions, but neither one is a deal-breaker.


Sprag bearings


There is one part, called a sprag bearing, of which each transmission requires two, which will wear in use and will have to be periodically replaced. This part is also the limiting factor on the speed of the input. (This limit does not significantly affect the practicability of the transmission). Sprag bearings are a common and readily available item, but the uses to which they have been put so far have not been as demanding as what we are asking them to do. Their technology has barely improved in the last few decades. They have always been good enough for the market. There is every reason to suppose that given a new and potentially very large market that demanded higher performance, this would certainly be forthcoming. 

In any case, wear in this part is inevitable, and even better ones will have to be regularly replaced. Fortunately their position in the mechanism makes it simple to design units for easy replacement, and when returned to the factory as cores, they can be easily refurbished and resold. We do not view this as a major drawback; in fact since we will supply regenerative braking, we will eliminate the need to change brake pads, so we are simply replacing one maintenance task with another, probably cheaper one. 

The bottom line is that what is available right now is adequate to the task, but this is the single component where improving it will improve the performance of the transmission.


User Acceptance


This factor really only applies to automotive use, and specifically to gasoline powered cars. The issue is that use of an infinitely variable transmission in a gasoline car (if one is going to use it to its best advantage) results in the engine going at a single speed (or one of two or three defined speeds), with the transmission taking care of the conversion to the required road speed. For some kinds of drivers (those who consider driving a sport rather than a chore) this lacks what one may term the “vroom-vroom” effect. It just sounds and feels boring to them, no matter that the performance is actually improved. It is similar to the reason that electric cars are excluded from drag racing: they would win all the prizes, but nobody would want to watch them without the smoke, flames and deafening roar.

Although this is mentioned frequently in articles about vehicles with continuously variable transmissions as a reason why acceptance has been slow, we do not consider it a significant factor, for the following reasons. First, we do not see gasoline powered cars as a high priority market. They are a shrinking market segment, and are a notoriously slow adopter of new technology. Although the benefits would be immense, they also require some radical rethinking of what the proper function is of the engine in the power train. Radical rethinking is not a common Detroit phenomenon.

Secondly the people who suffer from this reaction are also a shrinking market segment. They are from the days when motoring was still fun, and that is getting to be a long time ago. Younger drivers have no great expectation that their cars will be fun to drive, and those who do can get a lot of thrills in a Tesla, so “muscle cars” and their fans are literally a dying breed.