Technological Principles - corporate

From the very first conceptual design drawing, made more than seven decades ago, and up to date, and from the moment of the design approval to vehicle painting, thousands of rail cars produced in Talgo facilities share one basic characteristic: technological uniqueness.

Talgo´s main goal is to provide railway operators worldwide with efficient products that perfectly fit their needs, and to offer competitive prices, as compared to other rolling stock manufacturers.

Therefore, Talgo has developed a technological paradigm based on six fundamental principles.

Independently rotating and self-guiding wheels

Talgo is the only manufacturer to use a system in which each of the wheels on an axle, both left and right, can rotate at different speeds. This not only improves passenger comfort within the coaches, but it also minimises the wear to infrastructure caused by our trains.

For the last 200 years virtually all rolling stock manufacturers have used axles in which both wheels are fixed on a single axle and rotate at the same speed on a straight track. But rarely are train tracks straight: when the train passes through a curve, the wheel on the inner track will cover a shorter distance than that running on the outer curve track. This means the train never carries out a perfect turn as the flanges come into contact with the rails.

To avoid this malfunction in curves, from the 19th century manufacturers have used wheels with a slightly conical shape. However, this only mitigates the problem caused by excessive abrasion, and has an undesirable side-effect on straight tracks when each axle alternately moves up and down on the upper surface of the tracks. This so-called hunting oscillation translates into what passengers perceive as an uncomfortable side-to-side movement.

Talgo's running gear eliminates both these problems by separating the rotation on each wheel. Its system does not require axles but rodals or Talgo trucks, and utilises a self-guiding system which ensures that the wheel flanges are always parallel to the tracks. Consequently, the turn on a curve is smoother and uses less friction, and the uncomfortable - and sometimes, dangerous - hunting oscillation is eliminated when moving in a straight line.

Natural tilting

When renovating existing infrastructure is too costly, railway companies that want to increase the speed of their commercial trains only have one option: operating trains faster on existing tracks. Talgo's tilting technology can increase speeds by up to 25% through curves without having to carry out additional investments.

To avoid the transmission of wheel vibrations to the coach, and from the coach to the passengers, most trains deploy a suspension system. The problems lies in that, when entering a curve, these same suspension systems are responsible for the train tilting towards the outer side, which can cause discomfort to passengers. The tilting of the bodyshell is added to the centrifugal movement that pushes passengers to the side and outwards. This causes the balance system in the inner ear to send repeated alarm warnings that cause the feeling of motion sickness while allowing objects like mobile phones and drinks to move abruptly.

Ever since the railway was invented, many systems have been proposed to mitigate this problem. A possible solution could be to bank every curve, but this has significant technical limitations and would require intervention on existing infrastructure. Allowing the train suspension to sway and tilt inwards in curves is another potential solution, but it requires adding more weight and complexity to the vehicle.

Talgo's system emulates the cant effect but without having to force the swaying motion. By lowering the centre of gravity and having the passenger car body sway on top of the centre and towards the inner curve, the lateral force is compensated in turns. This system is called tilting, and it is automatic: the faster the train runs, the more it tilts, and the more the lateral forces are compensated. For the passenger this equates to a much more pleasant ride, and for the operator it means an increased train speed, since Talgo trains can pass through curves at a 25% higher speed than equivalent vehicles from other manufacturers.

Lighter and wider cars

One of the fundamental premises of our designs is to make the lightest trains on the market. The use of aluminium alloys and the reduced length of each car not only allows us to keep up our constant efforts to offer operators minimum energy consumption rates, but it also means we can maximise capacity by manufacturing wider cars.

The structure of a passenger train has not changed too much since railways were invented: they consist of heavy cars, the width and length of which is determined by a requirement and a limitation. The requirement is to reduce the number of wheels to the maximum possible extent while the limitation refers to the structural gauge - the maximumm size of the vehicle to pass through tunnels or other trains.

For almost all manufacturers this means building less vehicles and making them longer, up to 25m each. This reduces the number of axles, but results in heavier cars because of the need to use steel for their construction. Another repercussion of this design is that in order not to exceed side structure gauge in particularly sharp turns - where the sides exceed the outer curve of the track, and the intermediate part crosses the inner curve - cars must be narrower.

Talgo's in-house system tackles this problem by inverting the approach. Since the running gear is considerably lighter, our cars are likewise around 25% lighter than our competitor's equivalent vehicle due to the ability to use an aluminium alloy for fabrication. Energy consumption is also significantly reduced, and critically we can virtually halve the number of wheels used on our trains compared with our competitors, eliminating the need to make the individual vehicles longer.

The result is much less aggressive operation due to the train's ability to react to the demands of each curve, which reduces train and track maintenance costs, and shorter and wider trains, which increases internal capacity without sacrificing comfort.

Low floor at same height

The need for stable running gear forces most passenger train designers to create suspension systems that, out of necessity, elevates the car bodyshell over a metre above the top of the rail. This softens movements while the train is running, but, in turn, the car floor is higher than most train station platforms.

What does this mean for passengers? Generally they have to use a step to get on and off the train, which creates an accessibility barrier and makes it almost impossible for people with reduced mobility to board the train unaided.

Talgo is the only train manufacturer in the world whose trains allow any person - even those with mobility difficulties - to board the train and move around it in total freedom. Another consequence that stems from this boarding ease, is that the boarding and disembarking of passengers occurs much faster and with increased fluidity, meaning that trains can spend up to 20% less time at the station. This can help operators to improve performance on more saturated lines and increase the number of active services.

Our main aim is to allow railway companies to carry the highest number of passengers possible in the least amount of time. Our low-floor trains, which are the same height as the platform, reduce passenger loading and unloading times by 20% during operations, and also provide enhanced autonomy for people with reduced mobility.

Variable gauge

In the 19th century, when railway tracks were first being constructed, one of the first parameters that had to be defined was the distance between both tracks so that rolling stock could transit from one line to another without encountering obstacles. In most regions of the western world, the British standard measurement of 1435mm was accepted. However, its use wasn't universal and two centuries later these compatibility differences remain a barrier to some railways operating services in different territories.

This problem arises at international borders and in countries with non-standardised railway networks, such as Spain. There are two clear ways to overcome this obstacle: either the entire infrastructure is adapted to a universal standard, or the trains must be able to switch gauge automatically.

Talgo is not only the first manufacturer in the world to develop such a system, but its technology has been used by hundreds of trains on a daily basis for many years. The system enables a train to adapt it's wheel gauge while running at approximately 15km/h and without having to stop. The system is not only simple and sturdy, but also reversible and automatic: when passing through an installation, in whichever direction, the changer unloads the train onto some pads that carry its weight while allowing it to slide. It then unlocks each wheel and places it into its new position, re-locking it so that the train can once again hold its own load and continue rolling.

Variable-gauge running gear is a technology for which Talgo is renowned and is a distinctive feature of its offerings. Variable gauge technology, which has been used in thousands of operations since it was first launched several decades ago, gives our trains the edge in that they are able to adapt to any railway network and cross all borders seamlessly.

Entirely articulated trains

For operators, rolling stock maintenance and operation costs are two key factors considered during procurement. The best way to minimise both is to opt for Talgo's entirely articulated trains. The dynamic behaviour of these trains increases reliability and the time between maintenance interventions, thus maximising the use and performance of each train. It also reduces energy consumption and increases safety.

Most trains comprise independent vehicles which are coupled together and are pulled or pushed by one or several power cars. Each of these vehicles is independently supported by a set of axles encased within a bogie which rests on the track. This design is certainly the most common in rail transport today, and definitely the most appropriate for freight transport. However, it is not the most efficient for passenger transport, particularly for operators that wish to transport passengers cost-effectively. This is why Talgo only manufactures articulated trains.

Identifying the difference between these types of train is easy: one only has to look under at the coupling of the cars we construct to realise that all of them share running gear with the adjacent car. The train is no longer merely the sum of its various components, but works as a single, fully integrated vehicle.

There are many advantages to articulation and they are linked to a good many of our other technological principles. First of all, the number of axles decreases, which means less mass and a reduction in the friction between the train and the tracks, energy consumption and noise. On top of that, the cost of maintaining the running gear, which is potentially one of the most expensive and time-consuming maintenance activities, is minimised. The train now displays semi-rigid behaviour, since the cars depend on each other, limiting hunting oscillation and increasing passive safety. Finally, articulation means that we can make the most of the loading gauge by getting rid of the useless space that conventional cars take up in the outer curve side due to the excess length existing between the points on which they rest and their respective ends. Articulation is also the reason why our cars are shorter and wider, and can seat more passengers in the same space.