Banned! Continuously Variable Transmission (CVT)

Posted on | Author Keith Collantine

Alain Prost, Damon Hill, Williams-Renault, 2007Williams unleashed one of the greatest technological blows the sport has ever seen in 1992 when their computer-controlled active suspension FW14B stormed the championship.

The technological onslaught continued in 1993 as traction control and anti-lock braking became commonplace and Williams’ rivals up and down the pit lane grappled with active suspension.

Astonishingly even as the FIA sought to ban the expensive innovations, several teams concocted radical new technologies even though they knew they would be illegal in 1994. Benetton’s four-wheel steer (discussed in an earlier ‘Banned!’) was one.

Another was Williams’ Continuously Variable Transmission – which could have revolutionised the way F1 cars sound, had it not been banned.

Great engineering innovations often start with an inspired logical observation. Here’s one:

If a car’s engine is constantly decelerating and accelerating, it is not operating at maximum efficiency. To do that it should rev constantly at the optimum point of power and torque.

This point was well understood by car engineers outside of Williams long before 1993. One solution was to do away with a conventional gearbox and instead use a system of pulleys to adapt the engine’s power in line with what the driver required.

The system – continuously (or “continually”) variable transmission – existed in various different forms. DAF had produced a road car in 1958 called the 600 (or “A-Type”) which featured a “Variomatic” gearbox – which was essentially a CVT.

The problem for using such technology in racing cars was the difficulty of finding a strong enough belt to transit the power from an F1 engine.

In 1993 Williams cracked it and David Coulthard tested the car on a wet July day at Pembrey in Wales. It was later driven by touring car racer Alain Menu (his Renault 19 race car was prepared by Williams at the time).

At first it was feared that a ban on electronically controlled gearboxes would do away with the CVT before it could race. But in the end the FIA came up with something much more direct to get rid of it.

They stipulated that, from 1994, F1 cars had to have between four and seven fixed gears – and for good measure added a sub-clause specifically banning CVT.

Williams’ CVT car sounded revolutionarily different to contemporary (and modern) F1 cars because of the different way it used the engine. Instead of the revs rising and falling with each corner they remaining constant through each bend – a wholly unusual sound for spectators.

There was also speculation that it had instantly proved several seconds per lap quicker than the conventional Williams – which was already streets ahead of its rivals.

Although the technology and offshoots of it have been used in road cars it remained too exotic for the increasingly stringent demands of Formula One. A lone, unraced Williams-Renault CVT sits in a DAF museum somewhere.

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