Q + A with Roger Stone, Torotrak’s engineering director

Q. After a long and distinguished career in the motor industry including roles with Ricardo, Lotus, Ford, Rover Group and more recently Gates Corporation, what attracted you to Torotrak?

A great deal of time, money and high quality engineering have been invested in Torotrak’s technology over recent years and this has converted potential that was once merely promising, into proven capability. Torotrak’s change of strategy towards non-automotive applications, placing less emphasis on passenger car transmissions and exploring other opportunities, especially in the Commercial Vehicle and Agricultural sectors, is, to my mind, precisely the right strategy. I believe there are also very significant opportunities in the field of mechanical hybrids which offer cost, weight, efficiency, package and durability advantages over battery-electric solutions. I see very significant opportunities for the technology by pursuing such applications and the CO2 imperative effectively means that the toroidal transmission’s time has come.

Q. How does the Torotrak transmission actually work?

At the heart of our system is a full-toroidal traction drive, called a variator, that transmits torque using a specially developed traction fluid between loaded rollers and discs, giving a simple and robust Continuously Variable Transmission (CVT). When configured with an epicyclic gear train, we convert the simple CVT into an IVT or Infinitely Variable Transmission providing a smooth, seamless spread of ratio from forward to reverse, including the unusual geared neutral condition – where we can provide output torque at zero speed.

Q. In which sectors do you feel Toroidal IVT and CVT transmissions offer the greatest opportunities?

One of the fascinating things I have discovered since joining Torotrak is the sheer range of potential applications for this technology – from those mentioned above to forklifts, auxiliary drives, industrial applications; the list is far longer than we have the capacity to explore!

Q. Would you agree that it’s the technology’s environmental benefits which are sparking renewed interest in alternative transmissions?

Certainly CO2 emissions reductions are a driving force for the commercial vehicle applications and the engine downsizing opportunities created by our supercharger and turbocompounding ideas are of very significant environmental benefit. The huge potential for flywheel hybrids is also important – these are much more efficient than battery-electric technology and will offer dramatically better environmental advantage not only on a “well to wheels” basis but, to an even greater extent, on the more stringent “dust to rust” analysis.

Of course, it hardly needs saying that CO2 emissions reductions also mean fuel consumption improvements so there is not only the environmental advantage but, for industry, real, hard-nosed commercial benefit too!

In other markets, the attraction of a toroidal transmission may be based more on functional performance – for example, the seamless shuttling capability or geared neutral/hill hold feature can be of tremendous advantage in some applications, such as forklift trucks, tractors and dump trucks.

Q. Hybrids are receiving increasing interest from the media, but some have questioned the ability of Torotrak’s transmission technology to work effectively in this field. Can you respond to that?

It is perfectly possible to integrate Torotrak’s technology into today’s hybrids and produce better CO2 emissions by so doing. However, far more cost effective results can be obtained by using Torotrak’s technology – a KERS-CVT, to be precise – in an entirely mechanical hybrid using a flywheel as the energy storage device. This will produce a much “greener” all round product! I say this because the fuel consumption advantage in an urban driving cycle will be at least as good as battery-electric vehicles while under motorway cruise conditions we avoid the CO2 penalty incurred by battery-electric systems. This is because efficiency levels of up to double those of an electrical approach can be achieved. Furthermore, the environmental load relating to the manufacture and end-of-life disposal of a mechanical hybrid system is dramatically less than that of the electric hybrid.

Q. In that case, how long will it be before this technology becomes a feature on road cars?

Torotrak is working on the application of this technology to road cars as part of two, part-government funded consortia which include vehicle OEMs. I am confident that the idea will be demonstrated as both feasible and attractive. This done, the implementation timing is in the hands of the vehicle manufacturers; application engineering of the units to integrate them with the target vehicles will be required, along with all the other work necessary to take a new product from the drawing board to the car showroom.

Q. As with all new technology there are obvious concerns about reliability and durability. Does the metal to metal disc and roller system not suggest a greater likelihood of wear?

The disc and roller system, in common with practically all moving, lubricated “contacts” in mechanical applications (between gear teeth, cam and tappet, piston ring to cylinder bore, etc) does not normally run with metal to metal contact. The surfaces are actually separated by a very thin layer of oil, or traction fluid in our case, and this film prevents metal to metal contact and wear. We actually transmit substantial forces through this fluid layer which becomes almost glass-like under the pressures applied. Dry contact only occurs (in any of these mechanisms) as a transient phenomenon, typically under start-up conditions. A correctly designed toroidal drive, in normal operation, will never experience failure due to metal to metal contact.

Q. Do you feel there are other potential markets where Torotrak’s technology could be invaluable?

As I mentioned earlier, I see a wealth of potential new markets, including wind turbines, two-wheelers, marine drives, industrial machines and a variety of automotive auxiliary drives.

Q. Tell me about the benefits for auxiliary drives? How would they be improved? 

There are several levels of benefit; reducing the parasitic losses incurred in driving the alternator, power steering, air-con compressor and other auxiliaries can certainly provide worthwhile savings in fuel consumption and may even show cost benefits by enabling downsizing to smaller units but running them faster when engine speed is low. We are very actively investigating these opportunities now. However, the opportunities for fuel saving become even wider if we consider supercharger drives and the opportunity that these might present for engine downsizing – leading to very significant fuel consumption savings. Furthermore, and perhaps more a heavy duty opportunity, turbocompounding is a technology currently of limited application in the truck world, but a toroidal CVT could transform it into a CO2 reduction tool of much wider benefit.

Q. Looking into the future, where would you like Torotrak to be in ten years time?

In ten years time, I hope that Torotrak’s extensive development work will have paid off, and that Torotrak’s technology has reached the stage of mass commercialisation and is being used extensively not only in our current target markets (commercial vehicles, off-highway, outdoor power equipment and automotive), but also in the new markets we want to address – marine, industrial, mining etc . I would also like Torotrak to be a recognised supplier of leading edge, ”green” technology especially in the form of mechanical hybrids – with Torotrak’s KERS-CVT playing a key role in the system being adopted as a viable alternative alongside electric hybrids.

About Torotrak

Torotrak is the world’s foremost developer of full-toroidal traction drive technology. The company designs and develops Continuously Variable (CVT) and Infinitely Variable (IVT) transmissions which deliver outstanding levels of performance, functionality and refinement along with improved fuel economy and reduced emissions. Torotrak develops main drive transmissions as well as variable ratio transmissions for application in flywheel-based mechanical hybrid systems and for use as auxiliary drives.

Torotrak operates in the automotive, truck, bus, off-highway and agricultural markets, in motor sport and in outdoor power equipment.  Its customers are widely spread across Europe, North America, India and Japan, and include major vehicle makers and tier one transmission manufacturers.

Torotrak plc is fully listed on the London Stock Exchange.


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