Torotrak develops new generation transmission

Torotrak, a Leyland-based high-tech engineering company, has developed a new generation transmission using its patented technology which can slash CO2 emissions, improve fuel efficiency, boost performance and offer drivers the world’s most refined motoring experience. What’s more, as one of the leading technology providers for flywheel-based Kinetic Energy Recovery systems (KERS), Torotrak could also be bringing technology developed for F1 Grand Prix racing to a car near you sooner than you might think.

The company’s technology for Continuously Variable Transmissions (CVTs) and Infinitely Variable Transmissions (IVTs) uses innovative steel discs and rollers rather than conventional toothed gears. When used in place of a conventional gearbox the new transmission offers completely seamless acceleration from standstill to cruising speed and back again. Harmful exhaust gases are reduced because there are no “emission spikes” caused by gear changes, and fuel efficiency is increased because, even at motorway speeds, the transmission ensures that the engine operates at low speed and at optimum efficiency, generating around half the normal fuel-burning revs.

Torotrak’s win-win technology has already captured the imagination of one of the world’s largest manufacturers of gearboxes, America’s Allison Transmission Inc., which recognises how IVT could revolutionise the commercial vehicle market. The British company’s technology is also attracting heightened interest from mainstream car manufacturers and their component suppliers faced with meeting ever tighter emissions legislation and volatile fuel costs.

Meanwhile, the firm’s variable drive technology also looks set to transform the way many of the everyday features on current cars are powered. By fitting small, low-cost variable drive units, which also use the company’s technology, to components such as superchargers, turbochargers and alternators, as well as engine cooling and air conditioning systems, they can be made to operate more efficiently.

Currently, these systems are usually driven, directly or indirectly, from the engine. But, governed and constrained by engine speed, they often have to meet peak demand when the power unit is only turning slowly or, conversely, are unnecessarily driven at excessive, wasteful speeds when the engine is turning faster. For example, air conditioning is usually in demand during standing traffic on a hot day, just when an engine is operating at close to tick-over and is producing little power. A variable drive allows the air-con system to operate at peak output and efficiency even if the car’s engine is only at idling speed.

However, the automotive revolution doesn’t end there. Torotrak, which has already helped to develop a mechanical Kinetic Energy Recovery system (KERS) for use in F1 Grand Prix racing, is part of a Government-backed consortium creating a similar system to work on road cars. KERS technology allows kinetic energy, generated and usually lost during vehicle braking, to be captured and stored for re-use when accelerating. Applied to a road car, it offers a new greener route to enhanced performance, fuel saving and reduced emissions.

How does Torotrak’s transmission work?

The core of any transmission using Torotrak’s technology (whether CVT or IVT) is the traction drive “toroidal variator”. Unlike conventional manual or automatic gearboxes, with their toothed gears, this variator incorporates smooth, saucer-shaped discs and circular rollers. The variator allows the transmission to deliver a stepless range of ratios to meet all driving conditions.

The simplest form of transmission using a toroidal variator is a CVT. This offers a ratio spread of approximately 7 and requires a starting device such as a clutch or torque converter to launch the vehicle from rest.

An IVT is a more sophisticated form of transmission where the variator is used in conjunction with an epicyclic gear set to provide a “geared neutral” function with a seamless transition from reverse to forwards motion. A typical IVT is configured to provide a ratio spread in excess of 7 and provides high levels of overdrive gearing. With an IVT, no starting device is required.

A specially-developed oil-like fluid, with unusual lubricating and traction properties, ensures grip between the rotating rollers and discs to transfer torque through the transmission from the engine to the driven wheels. The result is smooth power delivery, faster acceleration, improved fuel economy and reduced emissions.