Using the force

40 years ago, Bulgarian inventor Roumen Antonov made a startling discovery – 20 years later his ideas for a redesigned automatic transmission have come to fruition.

With road congestion increasing, driving speeds dropping and gear changes per kilometre rising there’s a definite feeling in the automotive industry that automatic transmission’s the way forward.

The trouble is that most of today’s automatics are based on ideas that date back more than half a century where power- robbing hydraulics and heavily stressed housings with elaborate controls is both expensive and inefficient.

One young pretender, apparently free of these drawbacks, is the Antonov Automatic Drive (AAD), a low-cost, low-weight, fuel-efficient automatic transmission with an interesting pedigree.

Poring over the blueprints of an old Automatic transmission in his native Bulgaria, Roumen Antonov noticed that the naturally occurring axial force produced by helically cut gears, always seen having no useful role, could actually be utilised to initiate gear changes; eliminating the high-pressure hydraulic system used now, which saps power and adds weight and cost. The Antonov AAD was born.

With a number of licensing deals in place and the much talked about launch of an electronically controlled six-speed transmission at the 2002 Paris Motor Show the future looks bright for Antonov. But It was not always so.

The oppressive regime of Antonov’s native Bulgaria offered him little opportunity to develop his idea, so, after 21 years and ’17 escape attempts’, he finally made it to France in 1988 aged 44. Arriving in Paris, Antonov realised that he had to build a working prototype to ensure that his invention wasn’t ‘seen as a crazy idea coming from an immigrant without money, language or relationships.’

Fortunately, the prototype wasn’t difficult to build. Making use of a French program designed to help ex-miners enter business, Antonov built a fully working prototype from existing components. This 3 speed automatic gearbox with no external control was enough, says Antonov, to demonstrate the concept’s advantages in terms of fuel consumption, top speed, and weight.

At the heart of the transmission is a simple idea: the use of two naturally occurring forces to bring about an automatic shift of gear.

These non energy-consuming forces replace the major energy consuming components in current automatics. The first force is the axial thrust generated by meshing helical gear teeth. This seeks to disengage the gears axially along their shafts. The other is the Centrifugal force created by all rotating bodies.The axial force is proportional to engine torque, which combined with engine speed information tells the gearbox when to change gear.

Not limited to any engine torque category, the Antonov AAD uses conventional components and current manufacturing technologies, allowing existing transmission plants to produce it.

The six-speed transmission is just 250 mm long, making it suitable for the smallest of cars. Estimates show an anticipated unit cost of around 30 % less than today’s high-pressure hydraulic transmissions at comparable production volumes.

It also dispenses with the need for a high-pressure, high-flow hydraulic system without compromising smoothness, comfort, convenience or driving safety.This is in stark contrast to CVTs (continuously variable transmissions) and toroidal devices, which, says Antonov ‘require ultra-high-precision engineering and new materials’.

Asked about competing automatic technologies, Antonov is confident that his patent protection has given him something of a head start, ‘I don’t see any competitive projects on the horizon at the moment – and it’s hard to see who could offer a unit with these dimensions, this price and this efficiency’. He also sensibly refuses to enter into the arbitrary business of predicting market share, saying, half in jest, ‘I will never predict what the picture will be in 2010. Maybe there won’t be any cars because a war will destroy everything!’

Antonov has already granted production licenses to Honda, NZWL (a transmission producer that supplies DaimlerChrysler), and Gajra, an Indian transmission builder.

General Motors is currently testing the six-speed version and presentations are taking place to Peugeot, FORD, BMW and ZF.

‘Interest is huge’, says Antonov, ‘people want to see it work, and when they see it work they take it seriously.’