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Geared for Success

Six-speed automatic transmissions are beginning to hit the market, hot on the heels–almost literally–of yesterday’s tech leader, the five-speed automatic.

Six-speed automatic transmissions are beginning to hit the market, hot on the heels–almost literally–of yesterday’s tech leader, the five-speed automatic. But the greater cost, package size and weight of six-speeds often stand in the way of their adoption. However, there’s one competitor out there that claims its six-speed automatic technology is simpler, less expensive, lighter, smaller, and offers greater efficiency than its peers: Antonov Automotive Technologies. Never heard of them? Chances are, you will.

This is the second attempt at an automatic gearbox by Antonov (Rotterdam, Netherlands). The first was a four-speed that used actual force to hold the clutches on the planetary gearbox open, and centrifugal force to close them at different torque and speed combinations. As an almost fully mechanical device (i.e. there were no electronics, and little help from hydraulics), the gearbox was extremely simple, reliable, and out-of-touch with an industry moving rapidly toward greater electronic powertrain control and coordination. “It was a good starting point,” says Antonov managing director Mike Emmerson, “but we were headed in a direction not being followed by the car makers.” Rather than adapt electronic controls to the existing system, Roumen Antonov, the Bulgarian-born creator of the Antonov Automatic Transmission (AAT), started over from scratch. Strong interest in the prototype gearbox and requests to tie it into powertrain control systems lead him to use actual force to close the clutches, and low-pressure hydraulics or electronic actuation to open them. “It was a big move forward for us,” says Emmerson. “We now have a six-speed gearbox that’s about 10-in. long [actual measurement for the transverse front-drive gearbox: 250 mm], with a projected production weight of less than 50 kg.”

The AAT six-speed’s two planetary gearsets create the six ratios. (An animation can be found at: www.antonov-transmission.com.) “With a planetary gearset,” explains Emmerson, “you have three elements that can move at different speeds relative to each other. By braking them individually or together, you can get each gear module to produce three ratios.” Emmerson says the addition of another three-ratio module–which he insists wouldn’t increase length, but would require another clutch–would provide nine gear ratios. “We’re just not sure anyone would want it,” he says, though he does admit that a couple of “name-brand” sports car makers have inquired about the gearbox.

They’re not the only ones interested. The estimated per unit cost of an Antonov six-speed in volume production is $650. This compares favorably to the $900 to $1,000 per unit price of a conventional four-speed automatic, the estimated $1,100 per unit of a CVT, or the approximately $900 per unit for an automated, dual-clutch six-speed manual transmission. A Le Pelletier-style six-speed automatic–like the ZF transmission found in BMW’s 7-Series sedan–is estimated to cost $1,600 per unit, though Emmerson believes this number reflects the transmission’s current low-volume status. “I’d expect it to be in the $1,100 to $1,200 range in economic quantities,” he says.

The price advantage comes along with a 20% improvement in fuel economy (when compared to a conventional four-speed automatic), and a size and weight advantage. In addition, the gearbox can be driven in manual mode, and offers a pre-selector option. “It’s not a sequential box,” explains Emmerson. “You don’t have to go through each gear, because it’s a one clutch operation to go from, say, sixth to second. And with a normal ‘H’ gate, you can drive it like a manual.” Not unexpectedly, the electronics package doesn’t let the user abuse the transmission, so that sixth to second shift–a “pre-selector” shift–won’t take place until road speed matches the speed necessary to safely engage that gear.

Honda has a non-exclusive global production license for the AAT that covers all products. But they’re not the only ones interested in the technology. “The last few months have been crazy,” says Emmerson, “to the point where we’re having to tell car company executives we can’t fit them in for six months.” Considering the AAT’s estimated benefits, and that Antonov’s R&D center is in Paris, chances are good they’ll wait.

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