Vol 5 issue 4

Tornado steam locomotive embraces microelectronics

1 March 2010
By Sharon Ann Holgate
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Tornado steam locomotive

Hidden away on the world's newest steam locomotive, Tornado, is a wealth of electronics. E&T discovers what's onboard.

Think of the technology involved in a steam locomotive, and you're not likely to count a mobile phone charger, radio communication system, LED lighting or electronic safety equipment among your first thoughts. But the recently completed Peppercorn class A1 Pacific locomotive Tornado contains all of these - and they're all directly steam-powered.

'Because we were starting from scratch, we decided to design a system that was fit for the 21st century,' says Rob Morland, director of electricals for the A1 Steam Locomotive Trust, which built Tornado.

Some of the electronic additions are essential. 'The engine as it stands is fine for operating on the mainline,' says Graeme Bunker, operations director for the A1Trust. 'But the main difference between now and the 1950s is that we have two electronic safety systems that must be carried. The first one is the Train Protection and Warning System (TPWS) that applies the brakes if the driver is going to pass a red signal. The second is the railway 'black box' On-Train Monitoring Recorder (OTMR).'

Morland adds: 'On a steam locomotive, OTMR records signals like boiler pressure, steam-chest pressure, speed, and applied brake-force pressure.'

Although most heritage steam engines use pre-charged batteries to power the OTMR and TPWS, the trust took a different approach.

'We wanted a proper on-board power supply for the electrical system, and have three different methods of charging our batteries,' Morland explains. 'We have a steam-powered turbo generator, which is similar to those carried by the original A1s for powering lighting, but with a higher power output. Then there is an axle-driven alternator on the tender. Thirdly, we can plug in a shore [offboard] power supply that runs off the mains when we're stationary.'

'We also have two completely separate power supplies, with two sets of batteries mounted in battery boxes underneath the cab, two battery chargers and two control panels. On the driver's side is the Essential Services Supply which powers headlamps, marker lamps, the OTMR and TPWS. Then on the fireman's side we have the Auxiliary Services supply for cab lighting, lighting under the frames, and other auxiliary equipment,' continues Morland. 'The batteries would enable us to run the locomotive for at least 12 hours even if we didn't have any method of charging them.'

Robust components

'Steam engines are extremely unpleasant places for electrical and electronic components, so we have designed the system to be as robust as possible,' says Morland. This includes being able to run the entire electrical system off either of the power supplies in the event of one failing.

'The idea is to make this at least as reliable as a modern traction locomotive, and I think we've achieved that. Looking at the operation for the first year, we've had a few small faults on individual circuits, but no failures of the system,' he recounts.

Despite using such high spec components, the actual parts for the electrical system came to £20,000 - less than 1 per cent of the overall cost of building the locomotive. This included the additional cost of meeting the latest flammability regulations by wiring with low-smoke zero halogen (LS0H) cable, as used on modern traction.

These costs did not include the design, construction and installation of the system, which was achieved by a combination of paid and voluntary work. According to operations director Graeme Bunker, it was easier fitting the electronics starting from fresh than retro-fitting on a heritage loco. 'Because we were doing it at the start of the process, we could tuck all the conduits away, so it's very difficult to see where any of it is,' he says. Installation was not, however, trouble-free.

'The biggest challenge was finding room for everything, because, although it appears to be a large engine, there's an awful lot on it and there was competition for space underneath and around the cab,' explains Morland. 'As our guy was installing the electrical system, there were all sorts of active discussions about where a particular conduit could go.'

Much to Morland's delight, his bench-tested system worked perfectly on board the locomotive. 'Effectively it's a prototype because it's all been designed from scratch, and we only had one chance to get it right. But just a few small modifications got it all working. I was really surprised and pleased,' he says proudly.

Error-free testing

During the series of test runs the A1 Trust carried out through the summer of 2008, firstly on the heritage Great Central Railway then on the mainline, there was more good news for Morland's team. No errors showed up, and the only alterations carried out were to meet crew requests for additional LED cab lighting.

The system is kept in good condition via detailed maintenance and checks. For Morland it is the six-monthly 'B exam' that is the most critical.

'It takes me about two days,' he says, 'and involves taking the covers off the main panels, vacuuming out coal dust, cleaning connectors, cleaning the lamp lenses and checking the lamps are within specification. I also need to take the tops off some of the conduit boxes which occasionally fill up with water, and generally make sure the engine will run for another six months as far as the electrical system is concerned.'

One thing that reduces the overall amount of maintenance is the use of state-of-the-art LED headlamps and tail lamps. 'LED lifetime is significantly greater than conventional bulbs, and these lamps will probably outlast the boiler.' says their designer Alan Green, from Cambridge-based technology management and product development company Sagentia.

Green, who specialises in LEDs, became involved with the Tornado project via his old colleague Morland. He designed not only the headlamps - which contain an array of seven latest-generation high-brightness LEDs - but the small marker lights that can show train headcodes and tail lamps.

There are four marker lights on both the front of the engine and rear of the tender, and two from each set are combined marker/tail units. The marker/tails each contain one red and one white LED, mounted in such a way that a beam splitter allows light from either to be emitted from the lamp. 'When the loco is going forwards, the marker/tail lamps on the front need to be showing white and the ones at the rear red, and vice versa when it is going in reverse,' explains Green. 'In the old days the driver would have got out and flipped a lever on the side which put a red filter in front of the lamp. Our LED lamps can be switched into marker or tail configuration from the cab.'

Unlike a car, the two headlamps on Tornado work separately. The left-hand lamp is used during daytime, and must be much brighter than the night-time headlamp so that track side workers can see the train in enough time to move out of harm's way. Conversely, after dark the right-hand headlamp is used instead to avoid dazzling oncoming drivers.

Steam locomotives usually have a derogation - a reduction of normal regulatory standards that allows them to use battery powered portable headlamps up to 75mph. But as the A1 Trust eventually wants to run at 90mph, they decided the headlamps should meet the latest Railway Group Standard for visibility of trains running above 60mph.

Headlamp specifications

'The most challenging part of the project was meeting the specifications for the headlamps. Not only did they have to be very bright, you couldn't buy a reflector that produced the narrow beam needed,' explains Green. However the reflectors in the operating theatre lights Sagentia recently designed for manufacturers Brandon Medical were ideal for Tornado. 'So we used these, and to meet the specifications for the beam spreading more horizontally than vertically, there is a cylindrical diverging lens on the front of the reflectors for three out of the seven headlamp LEDs,' says Green.

Although they had to meet today's standards, the A1 Trust still wanted the headlamps to look like the original 1950s oil lamps. So they turned to footplate equipment supplier John Beesley - who specialises in recreating authentic steam locomotive lamps - for bespoke lamp casings.

'The headlamps for an A1 are derived from the LNER [London and North Eastern Railway] standard pattern, which became a standard BR Eastern region lamp for steam locomotives,' says Beesley. Since each region had its own design, he copied an original Eastern region lamp as closely as possible to remain authentic. His only concessions were creating a lens mount 30mm larger in diameter than the originals in order to accommodate the electronics, and permanently clamping to the locomotive's lamp bracket to accurately point the lamp's narrow beam.

'Making a case indistinguishable in size from an original, but which allows the electronic circuit to drop in from the top, was very tricky to do. It made the project for me when I realised the lamp would look true to form, and their electronics would fit it,' says Beesley, who donated the first set of cases he made for Tornado.

The design of Tornado's electrical system has room for adaptation and modernisation. For example, various electronic safety systems used by other countries could be temporarily installed if the engine were ever to run there. They are also ready for meeting the latest European standards for safety equipment - including a new radio system.

At present, Tornado carries an National Radio Network (NRN) radio that the footplate crews use for various operational tasks including contacting signalmen. The analogue NRN radio is the most commonly used private mobile radio system for trains operating on the UK network, and will soon be superseded by GSM-R, a version of the Global System for Mobile (GSM) cellular communications system. It handles voice and data using frequencies allocated specifically for railway use. GSM-R forms part of the new European Railway Traffic Management System (ERTMS) gradually being phased in throughout the EC. This will replace the different train protection safety systems used in each country - in the UK's case, TPWS ' in the hope that a standardised technology will increase the competitiveness of the European rail industry.

'We can install ERTMS as soon as Network Rail asks us to do it,' says Morland. 'In fact we've just completed a study with an MSc student from Imperial College that concluded we can get everything into a space on the tender. And the power requirements are acceptable.'

Thanks to dedicated volunteers and helpful contractors, A1 Trust chairman Mark Allatt's claim that Tornado 'contains the most advanced electronics ever put inside a steam locomotive' is likely to hold true for a number of years to come.

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