Main Drive Transmissions

Torotrak’s main drive infinitely variable transmissions (IVTs) combine our full toroidal traction drive variator with other conventional transmission components.The IVT enables the engine to operate under optimum conditions, improving performance and fuel economy.

Our IVTs can make a significant difference to the economy of vehicles equipped with existing internal combustion engines as well as those fitted with new, more efficient models. Transmissions incorporating our technology have demonstrated fuel savings of 20 per cent in a city bus and delivery truck.

We are currently focused on commercialisation of our main drive technology for our commercial vehicle transmission licensees: Allison Transmission Inc; Tata Motors; and an undisclosed major European truck and bus manufacturer.

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Technology Background

The need to improve fuel economy in commercial vehicles has never been greater. Fuel now represents over one third of operators’ costs in this sector, while legislation is forcing down noxious gas emissions worldwide.

The car industry has had access to different forms of fuel saving variable gearbox technology for years, but the high powers and torques of commercial vehicle engines have made these variable technologies impracticable – until now.

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How our Transmissions Deliver

Enabling an internal combustion engine to run at its most efficient operating point is key to maximising fuel economy. Conventional fixed ratio gearboxes, whether manual, automated manual or full automatic, cannot maintain this optimum because the engine and vehicle speed must follow a fixed relationship, defined by the gear in which the vehicle is operating. In order to achiever the optimum operating point, the engine speed and vehicle speed need to be decoupled by employing a variable transmission, such as our IVT.

With no torque convertor or starting clutch in an IVT configuration, fuel efficiency is further enhanced in vehicles with high levels of ‘stop/start’ driving, such as city buses and distribution trucks. Emissions can be further reduced by removing the discontinuities during gear shifts in a conventional fixed ratio transmission.

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Transmission Features

  • Infinitely Variable - the engine is always operating at its most efficient condition, maximising fuel economy. Uninterrupted power delivery to the wheels avoids emissions spikes during gearshifts, ensures maximum comfort for passengers or goods, and removes shock loads to the driveline, minimising wear
  • Geared Neutral - allows exceptional low speed control of commercial vehicles and effortless vehicle launch in both forwards and reverse directions
  • Multiple Regimes – enables power-splitting, whereby only a small portion of the engine power is routed via the variator. These regimes also allow very high overdrive ratios to be achieved, which can minimise engine speed and associated pumping losses when low drive powers are required

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Transmission Benefits

  • Improved Fleet Average Fuel Economy - harmonises fuel usage across all vehicles and minimises the variability introduced by differing driver skill levels
  • Refined Drive Experience – smooth and seamless power delivery creates an exceptionally comfortable and refined ride for passengers or goods. Driver fatigue is reduced and safety for bus passengers may be further enhanced by deletion of gear shifts and actively controlling vehicle acceleration away from rest
  • Reduced Lifetime Cost – our IVTs are cost comparable with current Automated Manual Transmissions (AMTs), and cheaper than conventional fixed ratio automatic transmissions. Complete integration of the IVT and engine ensures optimum operation of the driveline, maximising service life and protecting against possible abuse conditions to minimise maintenance costs
  • Optimised Engine Braking - allows the engine speed to be varied independently of vehicle speed, enabling accurate control of engine braking and reducing brake wear
  • Exceptional Low Speed Control – enables precise vehicle manoeuvring and positioning. When integrated with parking sensors, our IVT can also help prevent collisions

 

In a typical urban bus or delivery truck, our IVT can deliver fuel economy improvements of around 20 per cent

A Torotrak IVT can significantly improve manoeuvrability and control in OPE vehicles, such as wheeled loaders

Our IVTs can be applied in agricultural tractors