Penny + Giles Transducers Bridge the Gap at Brush Traction

Penny + Giles: Loughborough, UK-based Brush Traction, part of the Wabtec Rail Group, offers a complete design and installation service for repowering packages that help improve the efficiency of older diesel-electric locomotives and the environmental credentials of train operators and the rail network.

Key to both improvements are extremely reliable converted engine governors for the repower packages, which use Penny + Giles LVDT technology to bridge a gap between the old and the new control and power equipment whose designs were conceived a few decades apart.

The engine governors fitted to older diesel-electric locomotives are electro-hydraulic control devices. The various types, produced by different manufacturers, can be up to 40 years old and all have to be converted by Brush engineers with very little support from the OEMs who produced them, as most no longer exist.

Since 1998, Penny + Giles LVDTs have been used to re-engineer locomotives that are having old-style hydraulic sub-systems ‘changed-out’ and replaced with new electronic sub-systems. The new systems provide faster feedback signals, allowing the locomotive’s new electronic control system to respond to power changes much more quickly than the existing hydraulically controlled system.

Neil emphasises that a closed-loop system is absolutely reliant on receiving accurate feedback from the sensor, so the Penny + Giles SRH280DP Hall effect sensor is effectively the cornerstone of the system.

As Brush Traction senior design engineer David Moore explains: “Re-power contracts depend on us understanding the old technology and integrating it with our own new technology, and that’s where Penny + Giles’ LVDT technology has proved invaluable.

“In effect, we receive old locomotives that will easily last another ten or twenty years, and re-engineer them with brand new repower packages and new electronic control systems. Our twenty-first century sub-systems frequently have to integrate with elements of much older systems so we use custom Penny + Giles LVDT displacement transducers that are specially designed to bridge the gap between the old and the new. It is essential that old and new technologies communicate with each other, and the Penny + Giles displacement transducers are critical to making that happen and helping to give the re-engineered locomotives another twenty or so years of service.”

The Penny + Giles LVDTs are installed in engine governors – electro-hydraulic engine control devices found on all older diesel-electric locomotive engines. The governors control the power output of the diesel engine based on feedback from the LVDTs.

The Penny + Giles LVDTs and custom-designed transducer driver electronics provide the demand signal from the governor to control the traction alternator or generator, which in turn provides power to the traction motors. The rugged construction of the LVDTs makes them ideal for extremely hostile locomotive environments, where they are running in hot oil which, as David Moore explains, is another reason why they are specified.

Brush Traction has re-engineered numerous locomotives – sometimes fitting new engines, sometimes re-engineering old ones – but since 1998, always specifying Penny + Giles LVDTs. Well known locomotive types include the DRS Class 20 and 37, the Freightliner Class 57, Virgin Class 57 and the First Great Western Class 57.

More recently, starting in mid-2011, a project to re-engineer the DB Schenker Class 60 is not only using Penny + Giles LVDTs but also the custom-designed Penny + Giles LVDT driver electronics system. Brush Traction commissioned complete assemblies from Penny + Giles, which provided full support as well as building pre-production prototype units for Brush to use in trials on actual locomotives.

A re-engineered diesel-electric locomotive is a major investment for operators, so component longevity in traction-critical conditions is essential. Before Brush specified Penny + Giles LVDTs, sensors from a number of other manufacturers were failing due to the arduous conditions in the rail traction environment, primarily the high temperatures and extreme vibration experienced over thousands of hours of operation. Failure, which can leave locomotives without traction power on the track, exposes train operators to huge fines from other operators and the rail network.

Cheaper sensors are available but the quality, reliability and durability of Penny + Giles LVDT technology is excellent and engineers are confident that they will last the life of a re-engineered system. In fact, whilst the company has experienced 30% failure rates with other sensors that have been have fitted, since specifying Penny + Giles LVDTs in 1998 Brush hasn’t had a single sensor fail.

As he explains: “The performance and reliability of the Penny + Giles LVDTs represents real value-for-money and we are now so confident that if someone suspects a failure with a re-engineered governor’s LVDT, we suggest they look elsewhere for the problem. And so far, we’ve been right!”

Today, the relationship between the two companies is as strong as ever and David Moore says the introduction of the new LVDT Driver Electronics System is typical of the precious customer support Penny + Giles has provided Brush Traction over the years.

“Penny + Giles UK-centred service and support is second-to-none, the sales engineers know our business and communicate our specifications accurately to their designers. We’re confident that the LVDTs won’t fail and disrupt the network.” He says, adding: “Brush Traction is providing repower and reliability packages for 20-year-old locomotives that make them serviceable for another twenty years. We need to ensure that the old and new control systems are capable of communicating with each other for that length of time, and experience tells us that the Penny + Giles LVDTs will also last that long.”