Smart gears improving efficiency

Smart gears improving efficiency

Almost a year after acquiring three Van Hool TX coaches equipped with Allison T525 fully-automatic transmissions, Richmond's Coaches managing director, Andrew Richmond, remains delighted with his choice; and he is particularly impressed by the Allison gearbox.

"In fact we've just ordered three more coaches built to the same specifications," he says.

"OK, the fuel economy delivered by the Allison box is not quite as good as that provided by a ZF AS Tronic box but the difference isn't worth worrying about," he continues. "It's around a quarter of a mile to the gallon and Allison is working on doing something about that."

The slight fuel economy penalty is more than offset by the T525's smoothness says Richmond. "It's like silk," he remarks.

By contrast the automated manual AS Tronic transmission is not as seamless, he says - "it's a truck box in a coach after all," he observes - and in his view the best way to deliver the smooth journey that his passengers expect is to employ it in manual guise. 

The Allison boxes have been reliable so far,  he reports, and the Royston, Hertfordshire-based operator's drivers like them.

The first TXs with T525 transmissions to be delivered in the UK, the three coaches Richmond is so pleased with, consist of a pair of 53-seat TX16 Astrons and a 61-seat TX18 Altano. All powered by 510hp DAF MX-13 12.9-litre Euro 6 engines, they are employed on a wide variety of work.

"We use them on continental runs as well as in the UK and they are regularly in and out of London," he says. That means they have become only-too-well used to tackling congestion. 

One way of cutting emissions and fuel usage when vehicles are stuck in heavy traffic, at the lights or waiting for passengers to get on and off is to specify start/stop. It can drive down diesel consumption by up to 10 per cent, according to ZF.

Cummins is among those manufacturers with start/stop available on its engines - around 1,000 fitted with it are in service at present - but they have to be married to a transmission with the corresponding functionality. The three leading bus and coach transmission suppliers are at different stages in its provision, however, so far as the UK is concerned.

Voith Turbo is some distance ahead of its rivals. Its solution has been available on this side of the Channel since 2015 and is increasingly widely accepted.

National Express was an early adopter and saw fuel efficiency improve by 10 per cent when it specified Voith transmissions with start/stop on two Cummins-engined ADL Enviro200s it put into service in Birmingham. More recently it has ordered almost 100 ADL Enviro400s fitted with Voith DIWA.6 automatic gearboxes with start/stop functionality.

At the other end of the spectrum, Allison Transmission would appear to be some distance away from making start/stop widely available. 

Although there are exceptions, at a global level bus and coach manufacturers are not racing to embrace it according to Thomas Bonnicel, Allison marketing director for Europe, the Middle East and Africa. "They're proving surprisingly slow to show any interest," he observes.

"In the USA for example they're saying it's a cool feature but they're not enthusiastic about offering it," he says. The main concern appears to be that the price of the vehicle might have to go up.

"They're saying they want to wait until legislation obliges them to fit it," he adds.

ZF has a start/stop function available in its re-engineered EcoLife auto box but the facility has yet to appear on a bus in the UK. The six-speed box's torque converter and lock-up clutch have been strengthened to withstand the stresses and strains imposed by an engine re-starting umpteen times daily.

Start/stop functionality is not the only means by which transmissions can cut fuel costs and shrink carbon footprints. 

Allison points out that Optare's Euro 6 Metrocity has been added to the list of Low Emission Bus accredited vehicles thanks to the installation of its T3270 xFE gearbox and its FuelSense Max package. They have helped it achieve an 8 per cent fuel economy improvement, Allison says.

The xFE designation denotes optimised gear ratios from transmissions with significantly more lock-up operation that operate at lower engine speeds in higher ranges for better fuel efficiency. FuelSense Max features include Acceleration Rate Management and Neutral at Stop.

Allison has just unveiled a new version of FuelSense under the FuelSense 2.0 banner. It can deliver an additional fuel saving of up to 6 per cent over and above what can be achieved by the original FuelSense software, the transmission manufacturer claims. 

It uses something Allison describes as DynActive Shifting to provide what the company contends is an infinitely-variable combination of shift points thanks to a set of software enhancements. It relies on a learning algorithm to continuously find just the right balance of fuel economy and performance.

Like FuelSense, FuelSense 2.0 is available in three different packages with varying levels of sophistication. At the time of writing the technology was scheduled to be released within the next few weeks but its availability to end-users will depend on how quickly it is adopted by bus and coach manufacturers, says Allison.

The more efficient a transmission, the fewer harmful exhaust missions a vehicle will produce. Bus and coach operators have been busy getting to grips with Euro 6; but  how soon before they will have to face Euro 7? 

Nobody seems entirely sure, says Kevan Browne, UK communications director at Cummins.

"In fact it's not clear if Euro 7 will ever happen," he observes. "There has been no activity in that area by the European Union although there has been some media debate about what such a standard might look like.

"If a Euro 7 were to be proposed though then it could include fuel efficiency requirements," Browne suggests. "There is also some indication that a reduction in total NOx is being considered."

Emission cuts could involve a particular focus on NO2 - nitrogen dioxide. "It's now viewed as more problematic than was previously thought," he comments.

Any roll-out of fuel efficiency and CO2 standards will involve VECTO - Vehicle Energy Consumption Tool. It is a computer simulation which will give an indication of how economical different vehicles are so that prospective purchasers can compare them with one another. 

"The EU aims to have a proposal in place by early 2018," says Browne. 

Once a body of data is in existence then regulators may of course aim to make the achievement of certain levels mandatory.

Britain's bus operators benefit from a well-developed aftersales support network for the transmissions and engines they rely on. Businesses such as Ossett, Wakefield-based Queensbridge (PSV) have long been rebuilding ZF, Voith and Allison transmissions while firms such as Salford, Manchester-based E & E Potts have plenty of experience when it comes to rebuilding diesel engines.

The latter's services range from cylinder head and block re-surfacing to pressure testing.

In future they may increasingly find themselves working on gas-fuelled power plants.

Compressed natural gas has long been touted as a viable alternative to diesel and has been embraced by Reading Buses among others. 

The Berkshire operator has just put the first CNG-fuelled double-decks in the world into service. Complete with ADL Enviro400 MMC bodywork, the five Scania N280UDs join 37 CNG single-decks. 

Iveco alternative fuels director Martin Flach, has no doubts about CNG’s environmental credentials. It produces 95 per cent fewer particulates than diesel he points out, NOx output is down by 35 per cent while CO2 output is reduced  by 10 per cent.

"A 3dB reduction in noise levels compared with diesel means that engines that run on it are quieter too," he adds.

This August will see MAN deliver nine Lion's City CNG buses to Arriva for use on Merseyside, says Wayne Ulph, general manager, MAN Bus & Coach. "They surpass Euro 6 by a country mile so far as emissions are concerned," he contends.

CNG has its drawbacks. The onboard gas tanks that contain it are heavy and its lower energy density means that CNG engines are around 10 per cent less efficient than those powered by diesel. Furthermore, gas-powered vehicles are pricier than their diesel counterparts.

"Don't forget though that CNG costs 25 per cent less than diesel on average," says Flach. As for the price premium, a CNG minibus would cost approximately £5,000 more than the diesel equivalent; a premium that would soon be won back by lower running costs.

What about the capital cost of setting up refuelling facilities? There is a way of making that rather less painful than it might otherwise be, says Tony Griffiths, UK sales director at Gas Alliance Group.

"We lease part of your depot, install everything that is required and the cost is included in the cost of the gas," he explains. "It's what is known as a wet lease." 

GAG is then responsible for ensuring that the refuelling equipment always works. It can deliver the fuel it supplies through the UK's gas mains and arrange for the  biomethane it sells operators to be injected into the network. CNG’s close cousin, carbon-neutral biomethane can be produced from landfill sites; which means it has a particularly attractive environmental story to tell.

Nobody can argue against the environmental virtues of producing power from decomposing waste.