End of shift for small cars?

IT IS HARDLY surprising that conventional automatic transmissions are too heavy for small cars - they were invented for Second World War tanks. What is surprising is that a simpler version, thought up by a schoolboy in Bulgaria in the 1960s, is only now being tested in prototype cars.

Roumen Antonov, the schoolboy in question, later trained as a quantum physicist but became a political dissident after clashing with his country's military in the early 1970s. After escaping to Paris in 1988, he set about developing his gearbox, backed up with £7m from the French government and Dutch venture capitalists. Next month he will float his company in Britain.

Antonov Automotive Technology hopes to raise £3.3m in a float on the matched bargain market under the London Stock Exchange's Rule 4.2, this to be followed by a quick move to the Alternative Investment Market when it opens in June.

The group will be valued at just under £20m, which, according to Mike Emmerson, the company's managing director, will lend it credibility in negotiating with motor manufacturers. He conceded, however, that the key to the company's credibility is its technology, which is being evaluated by 19 unidentified car makers. Its claims are impressive. The company says its gearbox is 20 per cent cheaper, 25 per cent lighter, 30 per cent smaller and 12.5 per cent more fuel-efficient than conventional automatic transmissions.

Ordinary four-speed automatic transmissions use complex hydraulic systems with high-pressure pumps and metres of pipe to measure the rotational speed of a car's wheels and the torque on its drive shaft, and thus determine when to change gears. The teenage Antonov realised that he could dispense with this external equipment by using natural forces operating within the transmission.

The cogs on automotive gear wheels are set at a slant to reduce the noise and vibration they make when they mesh. As a result they act like a screw, pushing along their axis of rotation in proportion to the amount of torque. In conventional gearboxes this movement is blocked by ball bearings. In the Antonov transmission it is balanced against a bob weight, a simple lever mechanism that moves due to centrifugal force as the axle changes speed. This in turn determines when the engine changes gear. "It's so obvious I couldn't understand why it hadn't been done," said Mr Antonov.

The principal competition Antonov faces in the small car market is the Continuously Variable Transmission marketed by a Dutch company, Vehicle Components Sint Truiden, which was spun off from the former Daf, now called NedCar. The CVT is an updated version of the Variomatic transmission, using steel belts in an oil bath rotating on pulleys that are thicker at one end than the other. Although the CVT is used by some car makers, including Rover and Ford, the lack of a clear distinction between gears has proven to be a marketing disadvantage with many potential customers.

Edo Boer, manager of NedCar's driveline and chassis development department, still thinks his company's CVT gearbox is superior, but admits that the Antonov is far better than conventional automatics. The only technical problem it faces is refinement of the drive train suspension - a relatively simple matter. "We expect the shift quality can reach the same level as standard automatics," he said, adding that "the reliability should be good".

The potential market for the Antonov is huge - only 40 per cent of the world's vehicles currently have automatic transmissions, mostly in the US and Japan. In Europe, only 7 per cent of cars are automatics, partly because there are fewer large cars and partly because the price of fuel is higher.

Rather than manufacture the transmission itself in competition with the car makers' own gearbox divisions, Mr Antonov plans to license the technology.

He says prototypes have been well received by the industry, particularly because they can be made using standard techniques and components. The company believes it can have production vehicles on the road with its gearbox as early as 1996. It will then be up to motorists to decide whether they want to shift to the new technology.