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Gyrobus: The Incredible 1950s Flywheel Powered Bus

Written by Kevin Jennings

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            As global climate change becomes more and more of a concern, a lot of attention is being placed on how to reduce fossil fuel usage. Cars are one of the largest sources of the damage that has been done. Globally, automobile emissions account for roughly 10% of all greenhouse emissions. In the United States, where public transportation leaves a bit to be desired, to put it rather charitably, that number rises to 29% of greenhouse gases. Both electric cars and increased use of public mass transit systems are emphasized as important steps to reduce future climate change. With that in mind, let’s go back 70 years to a time when this problem may have already been solved.

            It’s October of 1953. You step onto the brand new Swiss gyrobus, a remarkable electric bus powered by a flywheel. You immediately notice that, unlike electric trolleys, there are no wires overhead, meaning that the bus is free to take whatever route it wants, rather than following the rails. It is also both the quietest and smoothest ride you have ever taken. You think that surely this must be the technology of the future, that this new gyrobus will revolutionize public transportation not just in Switzerland but around the world. And yet, seven years later, the gyrobus would be extinct.

What is a Flywheel?

            Seeing as the flywheel is the mechanism that powered the gyrobus, it’s probably important that we understand how such a device actually works. As the name implies, a flywheel is a large wheel or disc, usually made of steel or other metals. Energy is applied externally to the wheel to make it spin on its axis of symmetry, which is fixed in place. Because of the conservation of angular momentum, the wheel will store kinetic energy in the form of rotational energy for later use.

            Flywheels have a number of uses, and as such they date back thousands of years. The potters’ wheel, invented around 3500 B.C. and the spindle dating back to around 10,000 B.C. are both early examples of the flywheel. It’s no surprise that the origins of the object would date back so long ago; at its core, it really is just a wheel. The use of flywheels as a more general mechanical device goes back to the 11th century.

            Once rotating, the flywheel can serve multiple purposes simultaneously. Most relevant to the gyrobus, the flywheel is a means of storing energy. Because of its consistent rate of rotation, it can also be used to smooth out the energy output of a less consistent energy source. The wheel will act as an intermediary, storing the energy as it is generated and outputting it at a constant rate. It can also be used to output more energy than a generator would normally be able to produce. The flywheel can collect energy over time and then release it at a greater rate of output than the energy source was capable of. Finally, and also relevant to the gyrobus, a flywheel can be used to control the orientation of a mechanic system because of its gyroscopic properties. The Greek word for “flywheel” is “gyros”, hence the bus’s name.

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Origins of the Gyrobus

            Bjarn Storsand, the head engineer of Swiss engineering company Maschinenfabrik Oerlikon identified a problem with the contemporary public transportation system of Switzerland. Electric trolleybuses were common for public transit, but they were only able to operate on the rails that were built for them, and installing new overhead lines to power them was too expensive. Many of the routes these buses needed to cover simply didn’t have enough riders to justify the cost, but there still needed to be a solution to service these routes. Strorsand wanted to build a type of bus that was less bulky and less likely to interfere with the existing electrical lines, but that was also not confined in its route the way trolleybuses were.

https://commons.wikimedia.org/wiki/File:Gyrobus_G3-engine.jpg

            The immediate solution that comes to mind may be a diesel or gas burning bus, but motor buses at the time were loud, uncomfortable, and reliable. Switzerland was also seeking to gain energy independence following two world wars, so electrical power was much more appealing than fossil fuel. The next consideration would be a battery operated bus, but this also posed issues. Batteries were rather heavy for the amount of energy they provided, to the point that much of their efficiency was lost simply trying to move their own weight. The technology just wasn’t there yet, and battery powered electrical buses are only now potentially becoming commercially viable.

            When Storsand filed his patent for his flywheel system for vehicles, his main objective was for it to be used in short range industrial vehicles like mining locomotives. But of any possible use he proposed, it was the gyrobus that would receive by far the most attention.

            The prototype gyrobus was built using the chassis from a 1932 bus. The flywheel was located inside the chassis between the two axels. Yes, that means that it was taking up space that would otherwise be used for passengers in a traditional bus, but being able to see the flywheel that operated the bus would certainly be an interesting novelty, at least at the bus’s inception.

If you’re worried that a giant metal wheel weighing 3,000 pounds (1,360 kg) and spinning at 3,000 rpm might be dangerous for passengers, then fear not! The flywheel was encased in an airtight chamber. This was done primarily for the functionality of the device as the chamber in which it was enclosed was filled with hydrogen gas at reduced pressure to limit air resistance from impacting the wheel, but it had the happy side effect of protecting the device from the hands of stupid children who, if left unsupervised for even a second, would undoubtedly try to touch the dangerously spinning metal disc out of curiosity.

With the prototype now complete, it was time to release this bad boy into the wild. The prototype gyrobus made its first appearance in 1950 were it performed test runs around Zurich. It provided airport service and received a great deal of media attention, then it was tested in other nearby towns. Zurich’s Public Transport (VBZ) showed a lot of interest in the gyrobus, but they didn’t actually order any. The VBZ already had trolleybuses, trams, and motor buses, so adding a fourth type of vehicle to their arsenal seemed like overkill.

https://commons.wikimedia.org/wiki/File:Gyrobus_aan_het_opladen.jpg

Commercial Service Begins

            Commercial use of the gyrobus wouldn’t begin until three years later in 1953. It was October of that year that a private company, the Societé aonyme Gyrobus Yverdon – Grandson (GYG), would inaugurate a bus service between the towns of Yverdon and Grandson. The GYG purchased two gyrobuses to service this route. Unlike the prototype, the chassis of these buses were designed specifically for the gyrobus which allowed them to cut down on weight.

            So how did the service go? Well it was technically successful, in that the buses did their job. The route between Yverdon and Grandson was 4.5 kilometers long, and the gyrobus could travel at 50-60 km/h for as much as 6 km without needing to recharge. While they could theoretically make that trip every time without needing to charge, road and traffic conditions can be unpredictable so there were four recharging points between the beginning and end of the route.

            The recharging points were located at normal bus stops, which allow for minimal delays for charging. The buses were charged utilizing three booms attached to the roof of the bus that would come into contact with an overhead pole to provide three-phase charging, a means of ensuring maximum charging efficiency. To recharge the bus took from 30 seconds to 3 minutes depending on how much charge was needed.

            Despite everything working according to plan, demand for this route was not high enough for the venture to be commercially viable. Still, in October of 1960, seven years after the experiment began, the gyrobus service was shut down. This was the first of three locations to attempt use of the gyrobus, and the final one to end its service.

            The second order of gyrobuses came from the Belgian Congo. The city of Leopoldville ordered 12 buses to service four separate routes covering a total of 20 km. This was the largest area covered by a gyrobus service, and the buses built for Leopoldville were the longest gyrobuses at 10.4 m (24 ft). These buses had constant problems. Some were mechanical, such as gyro ball bearings breaking or others mechanic issues stemming from high humidity. One of the biggest problems, however, was the drivers. The drivers liked to take shortcuts which took them off the city streets and onto dirt roads. After rainfall, the soggy dirt paths were no match for the buses weighing nearly 11 metric tons. Ultimately those problems were manageable, and what killed this operation was the price. The high energy consumption was deemed too expensive and the gyrobuses were swapped out for diesel fueled motor buses in the summer of 1959.

            The final location to try out these gyrobuses was Ghent, Belgium. Ghent ordered three gyrobuses in 1956 that would service a route between Ghent and Merelbeke. This was meant to be part of a larger network of gyrobuses, but after three years the buses were taken out of commission. Once again, the gyrobuses were faced were problems. The operator of the Belgian railways felt that these buses were unreliable, and was quoted as saying the buses were “spending more time off the road than on.” The extreme weight of the vehicles also proved to be an issue in Ghent where the buses reportedly caused damage to the road’s surface. Once again, cost was also a major factor. The gyrobuses were intended to replace a tram line, but each bus consumed 20-50% more electricity than a tram and held a much lower capacity of passengers.

https://commons.wikimedia.org/wiki/File:Gyrobus_G3-interior2.jpg

Why It All Went Wrong

            On the surface, the gyrobus seems like a fantastic idea. It was a fully electric means of mass transportation that did not require rails, allowing it to take any number of routes with only minimal infrastructure needed to construct the recharging stations at bus stops. It was a smooth, quiet ride that was extremely environmentally friendly, as the buses themselves produced no pollution.

            One major issue was the weight. The gyrobuses were extremely heavy, especially compared to the number of passengers they carried. However, the quality of roads has greatly increased since the 1950s, especially in Europe, and roads are subjected to far heavier vehicles without it causing any undue wear and tear on the road itself.

            Another issue comes from the flywheel itself. We mentioned earlier that, in addition to storing energy, one of the uses of a flywheel is directional stability. Not only was this not the intended effect of the flywheel on the gyrobus, it was an unwanted effect. Handling these gyrobuses was particularly challenging for the drivers, as the gyroscopic motion meant that the bus didn’t like to change directions, so the drivers had to adapt different driving techniques to maneuver the bus.

            But at the end of the day, it really all came down to cost. Most of the issues with the early operations of the gyrobus were external factors, not issues with the bus themselves. The quality of roads has improved and drivers should know better than to take a passenger bus off-roading through the mud. Even the issue of maneuverability can be easily solved by having two contra-rotating flywheels attached to the same axis to counteract the gyroscopic effects on driving.

            With those other issues being solvable, and with the original Swiss buses traveling from Yverdon to Grandson for seven years with no issues other than a lack of profitability, cost was the big factor. A small issue is that the gyrobus was a new and experimental project. Had it taken a larger foothold in the transportation industry, economies of scale would have driven the price of the buses themselves down, leaving the only cost as the electricity to power them. This was the real problem, as electricity was expensive, at least relatively speaking.

            In the United States, one kilowatt-hour of energy in 1953 cost 32 cents, and the best case scenario for the gyrobus was that it would take 3 kWh to travel 1 km. Gasoline, on the other hand, cost 27 cents per gallon, and the average bus gets approximate 10 miles (16 km) per gallon. At those prices, it was roughly 56 times more expensive to power the buses using electricity rather than gas. Since then, gas has dramatically increased in price while electricity has come down. While both gasoline and electricity prices vary by country, the cost in electricity to run the original gyrobuses is approximately 1.5-2 times the cost in gas, depending on the country. One could argue that’s a small price to pay for a much more environmentally friendly option to citywide mass transit, much less than the 56 times modifier from the 1950s, but it’s important to note that technology has come a long way in the past 62 years since the gyrobuses stopped running, and it’s possible newer designs could bring the operational cost of these electric vehicles to be lower than the cost of motor buses.

https://commons.wikimedia.org/wiki/File:Gyrobus_G3-3.jpg

The Future of the Flywheel

            Many attempts have been made to recreate something like a gyrobus, but thus far nothing has been successful. One of the major concerns is weight, as a flywheel suitable for powering an entire vehicle weighs literal tons. However, flywheels are again being implemented in vehicles in an auxiliary role. Flywheels are implemented in Kinetic Energy Recovery Systems, or KERS. In this role, they store some of the energy that is wasted when breaking for future use by the vehicle. This is being used in a variety of vehicles from trams in Dresden, Germany to Formula 1 racecars. Perhaps someday a suitable solution will be found such that flywheels can power buses or cars more effectively, and the research is still ongoing.

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