Vital Component in the Electric Drive Train

vital component in the electric drivetrain

Manufacturers are now examining all of the elements which will be needed to create the future electric truck and a vital component in the electric drivetrain is the motor itself and where to put it.

With the appearance of the electric drive train a number of engineering problems are going to raise their heads. One of the issues is where to put the relatively heavy electric motor which will drive the rear wheels of the truck. In some of the examples we have seen developed so far, the motor has been placed between the chassis rails about halfway between what used to be the engine compartment and the rear axle. This configuration is going to remain as one of the options used by truck makers.

However, weight distribution is going to become an important factor in truck design. One of the more obvious options, which is being considered, but may well become the norm, is for the electric motor to be placed at the rear axle. Many designs have the electric motor as an integrated part of the axle in the position normally occupied by the differential or in the hubs.

Earlier this year, PowerTorque spoke to the two executives from ZF who will most likely be involved in the introduction of electric axles for trucks when they arrive in the country as both of them already play an integral part when it comes to the introduction of electric buses. They explained that it is not as simple as replacing one axle with another, and it is going to take some time to fully integrate an axle into a modern truck.

“We are going through exciting times from a transport point of view, there’s a lot of unknowns and a lot of opinion,” says Gary Bain, ZF Head of OE/OES Oceania. “Governments don’t really know either, they are mandating electric buses, but where can you charge them? It takes a lot of electricity to charge up 100 buses.

“The development of the technology is a key factor, as it develops it will obviously improve. Then infrastructure is also an important factor. Reaching critical mass is going to be the tipping point, but I don’t see that happening in line haul trucks for many years.

“Our electric axle for a truck will commence production in the near future. The research and development, the development software and the new technology is in there. At the moment, there are other suppliers in the market who see a short term opportunity and haven’t really got a lot of research and development backing.

“From a technology point of view, ZF has a development process which it goes through, there is a lot of development testing before something actually gets to market which ensures quality controls. It is coming, ZF is involved in all market segments.”

ZF also has to deal with the different strategies of the truck manufacturers which they partner with, who are all taking different routes to the solution, using batteries, hybrids etc. Battery weight, battery range, software development and many other factors have to be taken into consideration when designing the entire system.

In its development process, ZF has to have a range of options available to tailor the solution they have on offer, to the needs of each of the different truck manufacturers, which use its components.

“For us, it is still too early to say how this will play out,” says Shane Trenbath, ZF Technical Services Business Manager. “We are finding our way, just as our customers are finding their way, with decisions like whether they sacrifice weight to improve range or not.

“The trucking industry is going to be interesting. The day deliveries around the city will be fine, but long haul, it’s a totally different ballgame. We run pretty heavy in this country, compared to Europe, and until such time when we can charge quickly or produce hydrogen with zero emissions, we don’t expect to see a rapid transition in heavy trucks.”

In Australia and New Zealand, ZF already have some examples of electric axles in buses on our roads. There has been a steep increase in demand for electric axles in the bus market, mainly driven by some state and local governments’ zero emission priorities.

Some of the issues which have cropped up in this early stage of development for the bus industry are likely to re-occur when this kind of technology is introduced into the trucking industry.

“The operational considerations, like how many kilometres do they run in a day, have come up for bus operators,” says Gary. “Is it a hilly terrain? That makes a difference, because then you can get regenerative charging on the downhill section. Battery weight has come into the equation, because they are heavy.”

“From the operator’s perspective, it is cheaper to run, but with a battery life of 8 to 10 years, when they have to be replaced and disposed of, it is all a bit of an unknown. So, there are savings in one respect but not the other, over the 20 year life of a bus.”

The reality is that substantial infrastructure will need to be in place before a large number of electric vehicles will be able to function on our roads. Vehicles will need to be able to access ‘opportunity charging’ in order to be able to function in the real world.

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vital component in the electric drivetrain