Shift of emphasis

An automatic gearbox that allows gears to be changed without torque interruption promises smoother rides and better fuel efficiency in everything from passenger cars to heavy trucks, motorcycles, boats and buses, its developers claim.

The technology, from UK automotive company Zeroshift, works by replacing the synchromesh within a manual transmission with a pair of interlocking rings. These allow the next gear to be pre-engaged while retaining drive in the existing gear. This means that gearshift takes place in zero time and engine torque is not interrupted.

The gearbox gives users the freedom of driving an automatic car with all the benefits of a manual. When comparing vehicles with conventional manual and automatic transmissions, manuals lead to lower fuel consumption and convert more of an engine's power to moving the vehicle. However, every gear change wastes energy and causes a 'vrooming' engine surge that increases fuel emissions.

The Zeroshift gearbox not only has the efficiency of a manual, but also produces instantaneous gear changes, which eliminates the vroom, reduces fuel emissions and wastes less energy.

The company estimates that, in a typical mixed drive cycle, the system should generate a fuel economy saving of at least two per cent compared with a manual transmission, and seven per cent compared with a six-speed planetary automatic.

It also reckons that the reduction of emissions between a Zeroshift automatic and any other kind of automatic is about 10 per cent.