Investing in transmissions

Tough economic times are not preventing transmission manufacturers from continuing to launch new products.

Voith for example has introduced a new automatic transmission to the UK aimed at the midibus sector; the first time it has competed in this area of the market. Now being installed in ADL’s Enviro200 and in Wrightbus’s new StreetLite, one of the DIWA 823.3e’s key virtues is its reliability contends John Domigan, Voith’s UK sales and marketing manager.

“It’s remarkably robust,” he states. “If anything it’s over-engineered for midibus applications.”

Tipping the scales at 270kg, it’s a three-speed transmission. A single gear replaces the first two gears that might otherwise be fitted, with an eye to reducing the number of low-speed changes and enhancing passenger comfort.

Four speeds are offered as an option and DIWA 823.3e comes with an integral retarder plus Auto Neutral Shift. It disconnects the input coupling when the vehicle is at a standstill to cut fuel usage.

When used in conjunction with SensoTop software, which identifies changes in terrain and optimises the shift pattern accordingly in line with load factors, DIWA 823.3e is helping operators in hilly territory cut fuel consumption by up to 7 per cent, he states. “Even on flat routes they’re seeing improvements of around 1 per cent to 2 per cent,” he contends.

SensoTop data can be downloaded and analysed by the operator and Voith to see if, for example, driver behaviour is causing fuel usage to increase unnecessarily.

That may mean that there is a need for retraining. Alternatively it may indicate that there’s a need for a change in vehicle specifications.  

Fifty-eight Enviro200s have been equipped with the new transmission to date, including eight in service with Arriva Southern Counties in Maidstone.

Not to be outdone, Allison has added the T390 and T390R automatics – the latter has an output retarder – to its Torqmatic line-up. They’re designed for use with engines with a power output of up to 380hp and generating torque of up to 1,650Nm.

Both the transmissions incorporate Shift Energy Management (SEM), a system that manages torque dynamically through the transmission and modulates it before the shift is engaged. The aims are to increase durability and allow higher ratings to be offered without increasing the transmission’s size.

SEM allows the best use to be made of LBSS – Load Based Shift Scheduling – along with Super Economy Shift Scheduling (SESS) and Vehicle Acceleration Control (VAC).

SESS allows the bus to stay in the highest-possible gear for as long as possible without compromising tractive effort. VAC ensures that acceleration is smooth and fuel-efficient.

The first manufacturer to install the T390R will be an unfamiliar name to the vast majority of UK operators. China’s Jiangxi Kama Business Bus Company – usually referred to as Bonluck Bus – is fitting it in its JXK6126 12.6m 47-seater coach.

Founded just three years ago, Bonluck uses Allison products extensively and is enjoying success in a number of export markets – Australia in particular – as well as domestically. It’s installing Allison’s T450R transmission in its new 500hp/2,100Nm JXK6145 upmarket touring coach.

Elsewhere, ZF’s EcoLife six-speed automatic is being steadily adopted by OE customers says the company. “It’s become more popular than we expected,” says UK marketing manager, Geoff Buck.

“We started with Volvo, it was subsequently taken up by ADL and it’s now being made available by MAN and Mercedes-Benz,” he continues. “One major player that isn’t offering it at present is Scania – it’s sticking with Ecomat for the moment – but we believe it will probably start installing it in conjunction with the move to Euro 6.”

Nor is its popularity confined purely to bus operations.

Coach firms whose vehicles spend a high percentage of their working lives on heavily-congested roads – if they’re on commuter work for instance – are contemplating specifying it too says Buck. “The automated manual transmissions often fitted to coaches use a dry plate clutch that can suffer in heavy traffic although to be fair it will probably last two or three times longer on city roads than a clutch working with a manual box,” he says.

EcoLife doesn’t suffer in traffic in that way – nor for that matter does Ecomat – but may not always be the right solution. “Although it’s got a higher torque capacity than Ecomat, there are still some coaches that offer more power and torque than it can cope with,” he says.

“Automated manual transmissions such as our AS Tronic can handle more torque than torque converter boxes and offer better fuel returns too,” he adds. “Furthermore, the current version of AS Tronic is less vulnerable to driver abuse than the last one.”

So what’s the future for Ecomat?

“It will gradually die away, although the final date of production has yet to be decided,” he replies. “EcoLife’s fuel figures, shift quality and general performance are without doubt superior.”

ZF is gradually developing a parallel diesel-electric hybrid version of EcoLife which should reach the market in 2013.

“It replaces the torque converter with a hybrid motor-generator,” Buck explains. “The system can absorb the energy generated during braking and put it back into the driveline ready for when the driver needs to accelerate, thus saving fuel.

“It’s being designed to allow the vehicle to travel quite some distance on electric power only,” he continues. “In our view it’s the only way to make parallel hybrids cost-effective.”

The aim is to ensure that it is as easy to install in vehicles as a conventional transmission – “it’s very compact, about the same size as a standard EcoLife” – and for a payback to be achieved in from three to five years, says Buck. “Unless you can get payback within that sort of timescale hybrids will not make a major impact on the market unless they are supported by big government subsidies,” he contends.

Such subsidies are likely to be increasingly thin on the ground given the present state of financial woe in Whitehall. That said, the Department for Transport has just announced a £15million second round of the Green Bus Fund, intended to help operators and local authorities in England buy low carbon buses.

The closing date for bids for funding is 5 October.

Is there anything holding back the ZF hybrid’s development?

“We’ve been constrained a little by the availability of high-capacity batteries but that situation is changing with the introduction of new technology and rapidly-rising production volumes,” Buck replies. “We certainly feel that lithium ion batteries are likely to be more effective in this sort of application than, for example, super capacitors.”

He is unconcerned that the new transmission’s introduction is still three years away even though it means that ZF could miss out on a significant amount of business.

Rival Voith has already tested a parallel hybrid in the USA and is putting a parallel system on trial in Germany in a Solaris Urbino 18 articulated bus in conjunction with the Ministry of Transport.

The ministry aims to put up to 50 Urbino 18 DIWAhybrid buses into service during the first half of 2011.

DIWAhybrid uses a system of super capacitors weighing 410kg to store energy recuperated during braking. The entire hybrid package increases the weight of the bus by just 600kg.

Buck however points to the considerable success that ZF has achieved with AS Tronic, despite the fact that it was late into the market with it.

“Other companies had automated manual transmissions available earlier than we did, but they were not always successful and we were able to analyse their strengths and weaknesses before introducing ours,” he observes. “We benefited accordingly.”

The higher cost of hybrid transmissions does of course have to be balanced against significantly reduced diesel usage and thus CO2 output; not to mention a cut in harmful exhaust emissions such as particulates.

Iveco says that the series diesel-electric hybrid transmission it has developed for urban buses can cut diesel fuel consumption by more than 30 per cent, with the best results obtained if the transmission is optimised in line with the regular route the bus is on.

“We’ve been active in this area since the mid-1990s and we’ve got a number of these transmissions in service in 6m-, 7.4m- and 12m-long buses operating in French, Italian and Spanish cities,” says a company spokesman.

Diesel savings of up to 30 per cent are a possibility from a parallel diesel-electric hybrid system under development for Iveco’s Daily.

It keeps the standard 2.3-litre 116hp diesel engine but is also fitted with a three-phase 32kW electric motor/generator. An AGile semi-automatic gearbox acts as an interface between the two.

When you’re stationary in traffic or waiting at the lights then it’s the ECODaily Hybrid’s electric motor that’s in charge, with the diesel cutting in quickly as you accelerate; and there’s certainly no lack of performance either.

Regenerative braking is fitted to help keep the traction batteries topped up.

It may be some time before the Daily hybrid arrives in the UK. The batteries-only electric Daily is available to special order however; but bearing a hefty price-tag of around £65,500.

No matter how sophisticated they are, all transmissions ultimately end up in the hands of specialist repairers and remanufacturers who in turn often rely on specialist parts wholesalers to supply them with the components they need.

Some repairers and remanufacturers enjoy close ties with transmission makers and act as their agents. Others are resolutely independent and work at one remove from them, which means they can at times face difficulties obtaining the technical data they require.

Over the years however firms such as HL Smith, Hindle Group, Mitchell Powersystems – which acts as a UK-wide service agent for Allison – and JP Automatic have all proved remarkably adept at adapting to constant changes in technology and providing customers with the necessary support.

Some of them are extensive businesses in their own right. Based on a four-acre site in Albrighton near Wolverhampton, HL Smith for example employs 100 engineers and lists the Ministry of Defence as one of its clients.

Diesel-electric hybrids aren’t the only ones around.

There is another approach to creating a hybrid transmission as Torotrak – some 10 per cent owned by Allison, which itself has over 3,000 parallel hybrid systems in operation worldwide – will doubtless testify.

Both companies are involved along with Ricardo and Optare in the £1million Flybus programme which is partly funded by the government-backed Technology Strategy Board.

Torotrak heads the programme, which employs its continuously variable transmission technology plus a high-speed composite flywheel for energy storage which Ricardo has developed. In effect it is a mechanical hybrid system, and one that can deliver fuel savings of up to 20 per cent according to its supporters.

Other claims in its favour are that it is twice as efficient as a typical battery-based electric hybrid system, half the size and half the weight.

Perhaps most importantly in the present climate however, it’s one quarter of the cost.


www.allisontransmission.com

www.baesystems.com/hybridrive

www.hindle.co.uk

www.hlsmith.co.uk

www.hindle.co.uk

www.jpat.co.uk

www.mitchells.co.uk

www.queensbridgeltd.co.uk

www.torotrak.com

www.zf-group.co.uk