Tuning Out Greenhouse Gas

Ottawa's buses are becoming green machines, thanks to a new diagnostic tool that enables mechanics to detect and correct engine, drive train and brake problems that cause excessive fuel consumption and emissions of greenhouse gases and other pollutants. Developed by engineers at Environment Canada's Environmental Technology Centre, the Multi-Dynamometer Simulator^TM could reduce the fleet's fuel consumption by two to three per cent, and save 4000 tonnes of carbon dioxide per year.

The dynamometer allows technicians to assess the performance of a vehicle under actual driving conditions—without ever having to leave the garage. The unit is installed in a pit in the garage floor, and consists of two pairs of motorized rollers attached to a computer. The front wheels of the bus sit still while the rear wheels spin on the rollers, which simulate road resistance at speeds of up to 108 kilometres per hour. By comparing the expected power output of the bus with the amount of power that is measured at the wheels, the dynamometer can be used to determine whether or not the vehicle is operating at peak performance. If it is not, a technician can run a barrage of diagnostic tests to determine where the power drain is taking place and correct it.

Based on similar devices used for in-lab emission tests, the Centre's engineers began developing the dynamometer two years ago, after OC Transpo—the region's public transit company--approached them to create a driving simulator that was more flexible and less costly than existing models. What makes their invention unique is that, unlike other dynamometers, it is made up of two independent devices, so readings can pinpoint which side of the vehicle is experiencing power loss due to brake or drive train problems. The dynamometer's computer can also record and store data on the vehicle's performance, rather than simply indicating readings on a gauge, and can be programmed to vary speeds, loads and other parameters automatically.

At the end of 1998, a prototype was installed at OC Transpo headquarters to pilot the equipment under operating conditions. Used on a daily basis to service the 800-vehicle fleet, the dynamometer has undergone minor adjustments over the past several months, and is now ready to be taken to market. Environment Canada has applied for patent protection for the technology, and has already attracted interest from several firms interested in manufacturing it under licence.

OC Transpo is piloting the use of the new Multi-Dynamometer Simulator^TM (on its fleet of 800 buses).

The Department's engineers have also developed a smaller, portable version of the dynamometer for use with cars or light-duty trucks, and believe that the single-axle model currently used for buses could eventually be adapted for use with dual- or multi-axle vehicles such as transport trucks. As the Multi-Dynamometer Simulator becomes more widely used, it will make vehicles safer and less expensive to operate, improve air quality, reduce human impact on the climate change and conserve our fossil fuels.

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