AEveryone is talking about the car and the turnaround in transport policy, the declared goal is to move away from fossil fuels and towards clean electricity. But there are a number of other construction sites, for example on large equipment such as trains, railways and ships, in the middle area there are construction machines as well as trucks and those for agriculture and forestry. The smallest combustion engines can be found in portable tools, for example where electrical operation is not yet an option for various reasons. For example, this has so far been the case for chainsaws in the forest, because the energy density of gasoline is far from being achieved by even the best batteries.
How could the conversion to climate-neutral operation look like? “The internal combustion engine is far from over,” says Anke Kleinschmit, Stihl’s Chief Development Officer. The Swabian company is one of the leading manufacturers of motor-driven equipment for forestry and agriculture and, in addition to products for professionals, also offers lines for private individuals. The company has been producing in Germany in a climate-neutral manner since the beginning of this year, with plants abroad to follow in 2022. Kleinschmit has held the office for almost three years; she was previously head of the Powertrain technology factory at Daimler AG.
Stihl is further developing the light two-stroke engines, as they are mainly used in the saws, with a view to low-emission operation, because the regulations are becoming stricter and stricter. An unregulated catalytic converter was introduced at the end of the 1980s, but the same and better results can be achieved today with the patented flushing device, whereby an air cushion is placed in front of the exhaust slot through separate channels, which largely prevents unburned mixture from escaping into the exhaust. In addition to lower emissions, the result is lower consumption and a better torque curve. The first chainsaw with electronic fuel injection instead of the previously common carburetor came onto the market three years ago, which also improves emissions. The development continues in other directions, recently the first saw with magnesium pistons was presented, the weight saving on the moving masses mainly benefits the turning ability.
With a view to further tightened regulations in the future, it would be conceivable to combine the options for reducing emissions, says Kleinschmit, but that is also a question of cost. For motorized hand and garden tools, particularly clean and at the same time significantly more expensive alkylate gasoline is used anyway, because the user has to spend a long time in the exhaust gas flow. Stihl is the only manufacturer of devices to offer something like this under its own brand as MotoMix, a fully synthetic two-stroke oil is added to the oil supply of the 2-stroke (and the in-house 4-stroke with mixed lubrication), which naturally burns. For the operation of four-stroke engines with separate lubrication, the counterpart without the addition of oil, called Stihl MotoPlus, is used, says Kleinschmit.
Show teeth to wood: Anke Kleinschmit
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Image: Stihl
Even the cleanest conventional gasoline cannot burn CO2-neutrally, of course. That is why efforts are being made to produce the fuel synthetically. Kleinschmit sees this as the future of motorized devices in the medium term, but also says that large amounts of hydrogen are required for climate-neutral fuel, which is obtained from green electricity in an environmentally friendly way by means of electrolysis. Where it comes from is the most important challenge.
The alternative is foreseeable. Still ridiculed a few years ago, battery-operated handheld devices have become more and more powerful and their market share is increasing. The youngest child of the further development and available from the coming spring is the MSA 300, which, according to the company, is the most powerful cordless saw in the world. It reaches a chain speed of 30 meters per second, the motor has an output of 3 kilowatts. With these data, the cordless saw comes close to the performance of medium-sized chainsaws with about the same weight, but significantly less noise and without emissions. This is made possible by the rapid progress in battery technology, the latest generation of Stihl’s professional line, the AP 500 S, delivers considerably more power than previous generations and at the same time has a higher energy content of 337 watt hours. “We have to develop charging technology further,” says Kleinschmit, adding that fast charging and mobile charging are issues.
Stihl works with manufacturers of battery cells and is proud of its compact 36-volt batteries. “We have the most powerful cells in the world,” says the head of development, referring to the relationship between energy content, power and weight. If the trend continues, the cordless saws will probably not only be of interest to gardeners and private users, as before, in tree care, but also for professional use in the forest. Just as battery technology is currently becoming more and more popular in municipalities for leaf blowers and brushcutters.
The different formats of the manufacturers, which are not compatible with each other, are still a stumbling block for further dissemination. Some large companies in the industry such as Metabo and Bosch have made their interfaces available to smaller niche providers, who can then all use the same batteries. This is an interesting concept, says Kleinschmit, but the manufacturers who dock onto the system then have the difficulty that their old devices cannot be operated with the new batteries.
Whether motor or battery, the future belongs to connectivity. A component on the device records the operating hours and other data, they are transferred to the smartphone via Bluetooth and from there to the cloud. This makes it possible to manage and plan the equipment fleet much better than before, says Kleinschmit. The app then offers everything you need to know.
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