folvo's flywheel bus could lead the way
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iWEDEN'S Volvo Bus Corporation has developed a 'evolutionary bus that uses 15 to 25 per cent less fuel than the lquivalent bus today, reports NOEL M ILLI ER.
The bus, which is the result of 3 development programme ;tarted in 1975, uses an entirely lew power train concept. Ori)inally, the whole concept was 3roved by mounting it on a :railer which was used to propel conventional Volvo B59 city 3(.15 with its original power units 'emoved.
This experiment has led to he building of a complete new )us based on the Volvo B10R rvith local specification aodywork. This prototype is a aractical vehicle suitable for iormal service and is to be the ;ubject of an intensive prolramme of tests.
The bus propulsion system is lybrid and consists of a diesel .ngine, a regenerative flywheel Ind a hydraulic transmission nstalled under the floor line )ehind the rear axle.
Initial power is provided by a ;mall Volvo TD60 engine nodified to operate between 600rpm and 2000rpm and to give the best possible fuel consumption with low exhaust emission.
Starting power is provided by the engine which produces 100kW and activates the regenerative flywheel which in turn produces 125kW and allows 225kW of power to provide the vehicle's acceleration.
Retardation braking returns 170kW to the flywheel which can be stored and allow the bus to operate in certain areas with the conventional power unit switched off.
The vehicle gearbox is replaced by a hydrostatic drive produced by Volvo subsidiary Volvo Flygmotor, The power to and from the flywheel is transmitted by a hydraulic pump and hydraulic motor.
The hydraulic arrangement allows exceptionally smooth gear changes and means that bus braking system comes into use only in cases of emergency.
The bus is therefore likely to need far less maintenance than conventional buses and should be more economic, reliable and environmentally acceptable.
If the bus entered production now it would be more expensive than conventional vehicles, but Volvo stresses that no immediate plans exist to put the concept into production as much development work has still to be done, The performance of the prototypes is undeniably impressive, however, and suggests that it has a bright future.