Keeping high-speed trains on track

José Luis López Gómez, inventor of a high-speed train guidance system

Winner of the Popular Prize

José Luis López Gómez, inventor of a high-speed train guidance system

It is tempting to fall asleep on a gently rocking high-speed train - in defiance of breakneck speeds of more than 300 kilometres per hour. While they zip along as fast as Formula 1 racing cars or airplanes during take-off, sophisticated technology helps stabilise these trains during high-speed turns and provides passengers with a comfortable and safe journey.

One of the pioneers of this guidance and stabilisation technology is José Luis López Gómez, former technical director at Spanish railroad company Patentes Talgo. His invention, patented at the EPO in 2007, ensures a train's wheels stay safely on track and keep their optimal position on the rails at all times.

López Gómez has spent more than four decades perfecting Talgo's train technology and has built up a large patent portfolio of innovative designs that are instrumental to the success of Talgo trains' unique design. His ‘method for optimising the guidance of railway vehicles' is among his proudest achievements.

Climbing every mountain

Mountainous regions with frequently curving tracks are very challenging for high-speed trains. In Spain - a country with plenty of mountains - this drawback was turned into an advantage by Talgo. Their trains sport a rather unconventional, but very successful, design: Instead of being joined by an axle, the wheels of Talgo trains are mounted individually.

Not only does this make them lighter, this unique construction also lowers their centre of gravity, making it easier for Talgo trains to take curves safely at high speeds.

To further enhance this unique design, López Gómez came up with a series of innovations that allow both the carriage and wheels of Talgo trains to automatically adjust to the slope of curves and prevent passengers from ever noticing the strong forces pulling on the train while it speeds through a turn.

López Gómez' system uses centrifugal force to push the carriage towards the outside of a curve. It detects where and when the track curves and realigns the train's position accordingly. This makes the journey more pleasant for passengers and allows Talgo trains to travel 33% faster through curving stretches.

Making contact with the track

Building upon the success of his tilting system, López Gómez then focused his attention to how Talgo trains' wheels adapt to the track. Railway technicians have long known that the ‘wheel/rail connection' - the contact point between the wheel and the rail - is not only responsible for significant wear-and-tear on both wheels and rails but also essential to a train's stability.

When contacting the rail, train wheels make a small elliptical footprint, which significantly reduces friction. Unlike a car tire that makes a flat imprint on the road across the entire width of its tread, a train wheel has a smaller diameter at the outside than on the inside. This slightly conical shape both minimises the surface area that comes in contact with the train track and allows the wheels to take a turn without sliding or grinding.

As a train travels around a curve, the outer wheels have a slightly longer distance to travel than the inner wheels. Thanks to their conical shape and smaller diameter of their outer edge, the outer wheels travel this extra distance, ideally spinning at the same speed as the inner wheels.

A new way of guiding train wheels

López Gómez' innovation, patented at the EPO in 2007, optimises this movement by detecting the precise speed at which the wheel is rotating and then calculating exactly which portion of the wheel is contacting the rail. Using this information, the train's tilting suspension system can ensure that the optimal contact point is maintained.

The technology is particularly useful when a train is entering or exiting a curve, where current technologies have not been able to improve contact between the wheel and the rail in a way that makes train rides safer and more comfortable.

Although this system has not yet been fully implemented, it is already operating in a number of test trains - with encouraging results. The tests show that the optimal area of both the wheels and the rail are coming into contact with each other. The system prevents squeaking noises, limits wear-and-tear and significantly improves the comfort of the ride.

Talgo - fit for the global market

The first Talgo train was built in Spain in 1942 and set numerous speed records. Since then, the company has manufactured many subsequent generations of trains deployed both in Spain and worldwide. An automatic rail gauge-switching system enables Talgo trains to switch from the Spanish track gauge of 1668 millimetres to other gauges (the European norm is 1435 mm) in four seconds or less per axle.

This capability, which López Gómez also helped develop, contributed markedly to the company's success abroad. Talgo trains are also in operation in France, Switzerland, Italy, Portugal, Kazakhstan, Canada, and in the USA.

A life devoted to trains

Born in 1941, José Luis López Gómez studied technical engineering at the Catholic Institute of Arts and Industries (ICAI) in Madrid. After starting out in other companies as a fitter and milling machine operator, he joined Patentes Talgo in 1967 as a manufacturing technician. He later held various management positions before becoming the company's Technical Director in 1990.

In 1996, López Gómez was appointed General Director of Technology, a position he held until his retirement in 2004. Since then, he has served as an advisor to the company's president.

His methods for optimising guidance of railway vehicles have played a key role in many of Talgo's technology advances. They have made high-speed train travel more stable and comfortable and helped turn Talgo trains into serious competition for the airline industry.


How it works

José Luis López Gómez' patented method for optimising the guidance of railway vehicles is applied to free-wheel train vehicles, whose wheels rotate independently from each other, such as Talgo high-speed trains.

The invention utilises an electronic system that detects when wheels deviate from their central and optimal position on the rails. It also includes an automatic mechanical apparatus for moving the wheels back into this optimal position.

When rounding a turn, centrifugal force causes a train's wheels to move sideways on the rails - often moving them away from the optimal turning position.

Because of their conical shape (slightly larger on the inside and smaller on the outside), the wheels on the outside will contact the rail with a larger circumference than the inside wheels. The increased circumference travelled by the outer wheels allows them to cover the extra distance of the turn. Ideally, they spin at the same speed as the inner wheels, which use their smaller outer edge to compensate for the reduced distance on the inside of the curve.

Should the wheels move too far sideways, a 28-millimetre-high ridge on the inside edge of the wheel (called a flange) will catch on the rail and act as a failsafe to stop the train from derailing. Contact between the flange and the rail results in significantly increased friction, often producing screeching sounds and causing the wagon to shudder.

López Gómez' system uses precise computer technology to detect the rotational speed at which a train wheel is travelling and then calculate where it is contacting the rail. When the wheel deviates from its optimal position, an automatic mechanical system moves it back to the best contact point.

High-speed train market growing at top speed

López Gómez' innovations have significantly shaped the company's success and helped place Talgo in a top spot among an exclusive club of high-speed train manufacturers.

From 2008 to 2011, Talgo's worldwide operational fleet grew from 1,737 high-speed trains to 2,517. Between 2009 and 2011, the amount of track for Talgo trains skyrocketed from 10,700 to almost 17,000 kilometres.

And this market is not expected to slow down anytime soon. By 2014, Talgo's global fleet is anticipated to total more than 3,700 units racing along a substantially extended network of tracks (seen reaching 43,000 km worldwide). Over the next two years, some 24 countries will be operating high-speed trains.

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