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 Clockwise from below: the Leyland test facility can handle a wide range of large commercial and off-road construction vehicles; and complex, modular fixturing provides flexibility in performing a large number of vibration tests on exhausts, whole vehicles or interior systems; innovative test plans are carried out in the semi-Anechoic dynamometer chamber

tomarket, through the use of test facilities thatmight not exist elsewhere, ormay address a gap in the OEM’s capability. This could be at a systems level, on powertrains or increasingly interior systems. Leyland performs tests fromcomponent 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 on commercial vehicles 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 toWilkinson, engine testing has changed considerably fromthe simple testing that was performed in the past tomuchmore complex routines that include emission control system verification. Engines are now invariably electronically controlled and there ismore reliance on robust test planning, which typically use standards supplied by themajormanufacturers.However,Millbrook Leyland also helps to identify test requirements for theOEM’s R&Dactivities. “This definition work can take a lot of time, sometimes up to 12months, as was recently the case with an electric drive train for an off- highway vehicle,” saysWilkinson. “This requires collating the knowledge base and

experience we have with smallmotors, largemotors and other aspects of the powertrain. Such experience is important to use lessons already learnt so you’re not looking for the ‘unicorn’ of testing,” he adds. Central to powertrain development is the

company’s impressive dynamometer, which is located in a <30dBA semi-anechoic hangar-like structure to house large commercial vehicles. The 500kW dynamometer is embedded beneath the floor and can handle large, three-axle vehicles with two drive axles. “Having such a facility enables us to be innovative

in the tests we performand there are lots of things we can do here, including fuel consumption testing with reproducible profiles and driving cycles, emission testing andmonitoring the effect of additives on fuel economy,” explainsWilkinson. However, the real innovation comes to light in such

tests as examining the effect of different driving cycles on hybrid powertrains, such as the difference between local delivery operations and long distance haulage. The dyno has also been used formeasuring 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 tomeasure reverberation and sound levels for drivers and passengers,”Wilkinson says.

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 1,200 tonne concrete seismic isolation slab fitted out with amodular array of anchoring slots.

Here, vibration testing ismainly 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 while avoiding resonances that could influence the results. Exhaustmufflers 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 testmufflers, wemount the truck [with the

muffler attached] to seven vibration actuators with a test track profile programmed in.During the test, gas ismade to flow through the exhaust at 600 degrees to replicate real conditions,” explainsWilkinson. The test is designed to test themuffler’s durability

to ensure its structural integrity ismaintained 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 askedWilkinson 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 says. He explained that there are still questionmarks

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(LiquifiedNaturalGas). If bio-LNGis used, then all the better. This is good for reducing poisonous emissions but the fuel still

produces CO2,” he explains. To clarify, 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. LNGpowertrains 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 lastmile delivery vehicles

because the technologymatches the driving cycle with short distances, frequent stops and the ability tomake use of regenerative braking for greater efficiency”, says Wilkinson. EE

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October 2017 /// Environmental Engineering /// 47

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