Testing the heavyweights

| Environmental Testing

Double decker bus under test at Millbrook's CSA Leyland test facility

Jonathan Newell visits Millbrook’s Leyland technical centre to find out what the future holds for sustainable heavy transport.

Once one of the two great manufacturing powerhouses for buses and heavy goods vehicles in the UK, the town of Leyland in northwest England suffered a spectacular decline in the 1970s as the world moved on and British Leyland didn’t.

Revival attempts following the Ryder report largely failed except for the shrewd decision to establish a test and development centre for the Leyland Truck and Bus division, a concentration of industry expertise that would live on through privatisation and a management buyout a decade later.

Automotive industry expertise is something that the UK is certainly not short of and in the 21st century, the country is renowned for its niche market manufacturing skills, its volume production centres and its test and development know-how, including such giants in the international market as Millbrook.

Keen to continue to expand in a climate of rapid change in the automotive industry, Millbrook is constantly making investments, the latest being the purchase of the CSA Leyland Technical Centre, giving the Leyland legacy a bright future.

To find out more about that future and the direction heavy transport is taking in an environment of rapid change, I went to Leyland and spoke with its Managing Director, Dr Paul Wilkinson.

Collaborative Partnership

With its strong background in commercial vehicles, the Leyland site has never seen itself in direct competition with Millbrook and has spent considerable time as its collaborative partner. According to Wilkinson, although some of the activities have converged in recent years, they are still complementary, an example being engine testing, where their combined capacity can meet the demand expectations of the industry.

The company is set up for testing primarily design specifications rather than for homologation. In this way, the Leyland site helps manufacturers to get good products to market through the use of test capabilities that might not physically exist elsewhere or may address a gap in the OEM’s capability. This could be at a system level, on powertrains or increasingly interior systems.

Leyland performs tests from component level through to full vehicles and includes structural and vibration testing on double decker buses, articulated vehicle tractor units and off-highway vehicles such as construction equipment.

A particular focus in the commercial vehicle industry at the moment is the drive to implement carbon reduction initiatives. Millbrook Leyland is equipped with a suitable chassis dynamometer designed to fulfil such testing requirements.

Powertrain development

According to Wilkinson, engine testing has changed considerably from the simple testing that was performed in the past to much more complex routines that include emission control system verification. Engines are now invariably electronically controlled and there is more reliance on robust test planning, which typically use standards supplied by the major manufacturers. However, Millbrook Leyland also helps to identify test requirements for the OEM’s R&D activities. “This definition work can take a lot of time, sometimes up to 12 months, as was recently the case with an electric drive train for an off-highway vehicle,” Wilkinson said.

“This requires collating the knowledge base and experience we have with small motors, large motors and other aspects of the power train. Such experience is important to use lessons already learnt so you’re not looking for the “unicorn” of testing,” he continued.

Central to powertrain development is the company’s impressive dynamometer, which Wilkinson demonstrated to me. The impressive facility is located in a <30dBA semi-anechoic hangar-like structure to enable large commercial vehicles to be housed. The 500kW dynamometer is embedded beneath the floor and can handle large, 3-axle vehicles with 2 drive axles.

“Having such a facility enables us to be innovative in the tests we perform and there are lots of things we can do here, including fuel consumption testing with reproducible profiles and driving cycles, emission testing and monitoring the effect of additives on fuel economy,” explains Wilkinson.

However, the real innovation comes to light in such tests as examining the effect of different driving cycles on hybrid power train development, such as the difference between local delivery operations and long distance haulage. The dyno has also been used for measuring the effect of heating and air conditioning in buses on fuel consumption and even noise transmission profiles.

“Having a semi-anechoic facility enables us to place acoustic and vibration sensors in the vehicle interior to measure reverberation and sound levels for drivers and passengers,” Wilkinson said.

Structural Testing

Vibration testing doesn’t just happen in the dynamometer chamber. The company also has a large structural testing laboratory, the floor of which consists of a suspended 1200 ton concrete seismic isolation slab fitted out with a modular array of anchoring slots.

Here, vibration testing is mainly performed as part of powertrain developments and includes a complex fixturing capability to ensure the actuators deliver the vibration input to the correct points of the structure whilst avoiding resonances that could influence the results.

Exhaust mufflers have a surprisingly high prominence in the structural testing performed in the lab, since their durability in operating conditions has high importance for commercial vehicle operators.

“To test mofflers, we mount the truck with the muffler attached onto 7 vibration actuators with a test track profile programmed in. During the test, gas is made to flow through the exhaust at 600 degrees to replicate real conditions,” Wilkinson explains.

The test is designed to test the muffler’s durability to ensure its structural integrity is maintained because this is important for emission control. If it loses structural integrity, gas leaks and the truck will fail its periodic testing requirements at significant cost to the operator.

Beyond 2040

With the Government’s recent electrification plan announcement, I asked Wilkinson for his views on how this would affect the commercial vehicle industry.

“It’s important now to establish a vision for the industry such as low carbon drivelines and lightweight structures and work to that vision. It’s a big challenge for the industry and one which Millbrook is willing to invest in,” he said.

He explained that there are still question marks over such details as whether batteries or fuel cells will predominate as well as other factors such as distributed charging infrastructure but it’s clear that for the commercial vehicle industry, long term developments will take two paths.

“For heavy vehicles, the direction will be either hydrogen fuel cells or LNG (Liquified Natural Gas). If bio-LNG is used, then all the better. This is good for reducing poisonous emissions but the fuel still produces CO2,” he explained.

To clarify, he explained that long distance, heavy vehicles have a different engine cycle profile with heavy fuel burn going up hills and for overcoming wind resistance. Long distances and high demands on power delivery make the use of hybrid or all-electric drivetrains unlikely.

LNG powertrains have come to the fore since CO2 reduction initiatives have to some degree been displaced by a drive to reduce poisonous emissions. There is still some uncertainty about what will continue to prevail.

“Hybrids are great for last mile delivery vehicles because the technology matches the driving cycle with short distances, frequent stops and the ability to make use of regenerative braking for greater efficiency”, he said.

Jonathan Newell
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