Advancing transmissions
Page 14
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• Torotrak Holdings, the company developing the Leyland/Perbury continuously variable transmission system (CVT), claims to have made a number of major advances in the design, which is being fitted to a Rover 800 series car. An example will be available to drive next year, claims the company.
The gearbox, which was fitted to the 1986 Leyland TX 450 concept truck, uses vertical concave plates with a variable-angle roller between them to transmit the rotation, which gives an infinitely variable transmission system.
Special oils, working in shear between the plates and the rol lers, actually transmit the power.
Torotrak claims to have reduced the number of parts in the gearbox by 50%. The latest design uses hydraulicallycontrolled carriers for the rollers, which are claimed to be inherently stable and quicker to react than the older design.
While the new gearbox is slightly wider than the old, it weighs 60kg, and its 400mm length should endear it to manufacturers of front-wheeldrive vehicles.
Torotrak (Holdings) is owned by the British Technology Group (BTG), which in turn owns the licences from Perbury, Leyland, and the Rover Group to manufacture and develop the CVT.
The company is negotiating with seven major manufacturers and parts suppliers, who have an interest in taking out licences to produce the gearbox: "1990 should see the first deal," says Torotrak, "with more during the year."
1:1 Work on the Ricardo Automatic Layshaft Transmission (ALT) is nearing completion, and an announcement on the future of the automatic gearbox is expected in January.
It first broke cover as the Avon/Maxwell bus transmission, which used layshafts and wet clutches to activate the gears hydraulically. Ricardo's ALT (CM 7-13 January 1988) is a similar system but uses electronics to 'read' the engine and road speed as well as the throttle angles.
The company says it is almost satisfied with the control systems, which determine the shift timing, and that the fully automatic gearbox is ready for production applications. It claims to have a waiting list of interested Manufacturers ready to help develop the gearbox.