Gyrobus. Flywheel-Powered Public Transport

Antwerp Tram Museum has the world’s only surviving “Gyrobus” This unusual system runs on electricity, but it’s not permanently connected to a power source. The bus has a large electric motor that runs a heavy flywheel, mounted horizontally under the floor. It collects power from a special 3 pole connector at bus stops or charging points and the flywheel then powers the road wheels by means of electric motors, which also acted as brakes and employed regenerative braking, helping to spin up the flywheel. At full speed the 1.5 tonne flywheel spins at 3000 rpm.

The system was developed by Oerlikon of Switzerland in the late 1940’s, with the idea of using them as alternatives to trolleybuses. The first commercial service began in October 1953, between the Swiss towns of Yverdon-les-Bains and Grandson. The 4.5km route had 4 charging points, and although technically successful, the route was not commercially viable and ended in 1960. Both the vehicles used and the demonstrator were scrapped. The buses had shown they were capable of travelling up to 10km before needing to be recharged.

The next system was developed in the then Belgian Congo (now Kinshasa in the Democratic Republic of the Congo) which had 12 vehicles operating on four routes, with recharging facilities around every 2 km (1.2 mi) These were much larger vehicles, at 10.4 m (34 ft) in length, weighing 10.9 tonnes and carrying up to 90 passengers. They developed major problems with excessive wear and tear, mainly caused by drivers taking shortcuts along unpaved roads, which often became quagmires. This caused damage to the bearings mounting the flywheels amongst other issues, and the high tropical humidity resulted in traction motor overload. Eventually the system’s demise came because of high energy consumption. The operator decided that 3.4 kWh/km per gyrobus was unaffordable, so the entire fleet was abandoned in 1959 and replaced with diesel buses.

The third commercial endeavour for the system was in Gent, Belgium. Eighteen vehicles were built, again by Oerlikon, 35 seater buses weighing in at 11.5 tons. One has survived and is on display in the Antwerp Tram Museum. They ran between Gent and Merelbeke, a distance of about 7km, with charging points around every 2km. The system had quite high energy demands, higher than trams, and the vehicles were much heavier than regular diesel powered buses, resulting in more road surface wear. The increasing amout of road traffic was a contributory factor in their demise, being sat in traffic with the flywheel spinning and losing energy resulted in them being stranded on several occasions. The trial finally ended in 1959.

There is today a similar system in use on the UK rail network. The “Stourbridge Shuttle” is Britain’s shortest service, 1280 metres between the stations at Stourbridge Junction and Stourbridge Town, near Birmingham. The Shuttle, known as a Class 139 and built by a company called Parry, utilises a Ford LPG engine to run a large flywheel at 2600 RPM in one direction and, along with regenerative braking, uses the flywheel for the other direction. The incredibly popular shuttle service has been featured in many railway blogs and films, such as All The Stations.

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