In order to achieve its target speeds of 60mph on the road and a speedy 30 knots on the water, the vibration and noise emanating from the transmission was a major problem which had to be solved.

Any solution had to address and overcome the complexities caused by the amphibious nature of a machine which was also a passenger carrying road vehicle. For land use, any transmission sounds had to be removed for passenger comfort as well as the elimination of wider environmental noise pollution.

Centa's innovative solution called for the use of their Centax CX-16VFA coupling, which isolated the torsional vibrations of the diesel engine from the driveline. High torsional vibrations in the driveline will 'ring' the thin wall section of a cardan shaft and create rumbling noises in the gearbox which will generally reduce the life of the entire transmission.

The Centax-16VFA also supports the cardan shaft it protects, providing a dynamically stable drive line at an economic cost. As in many marine drive situations, space was at a premium and Centa's design used a minimum length coupling and shaft solution to meet those demands.

David Royle, managing director of Covelink Marine said, 'The Jet Bus is an entirely new vehicle that does not use conventional bus or truck engineering but was designed and built from scratch. It's only when all is put together that you find out exactly where the problems are. The result is that the Jet Bus is very quiet, lovely and smooth running and we are pleased with Centa's solution to the noise problem.'

MJ Information No: 20515