Caught up in the cogs

They keep out of the spotlight and not much is known about their work. Even so, they are an essential part of the car development and production process. This episode of our Škoda Storyboard series showcases the work of a gearing specialist.

9. 7. 2024 Škoda World

He needs to be familiar with all the technologies used to make cogs, as they affect their load-bearing capacity and strength. Precise measurement of the gearing also plays an important role and, of course, the construction itself remains an integral part. Gearing is an extremely important part of gearboxes. Gearing development engineer Jaroslav Prokop and his colleagues are not only responsible for gearing for cars with the winged arrow in their emblem, but they also develop gearing for internal combustion engine transmission systems found in dozens of models of seven VW Group brands.

Technology is literally in his blood. His father and grandfather both worked at Škoda, and his wife also studied machine engineering. And even her grandfather worked at the Czech car company in the era of models like the Spartak (made from 1955 to 1959). Fate then steered Jaroslav Prokop’s career in the same direction. As he recalls, “After leaving the Secondary Industrial School in Mladá Boleslav, followed by a course in economics and computer studies, I joined the mechanical tools workshop at the main plant, where I worked machines making transmission parts. At the turn of the millennium I started working in the gearing measuring centre, where I first encountered what I still do today.”

Gearing development engineer Jaroslav Prokop

The fascinating, complex and intricate world of gearing fascinated him. In 2004 he moved into development where, from a design perspective, he also worked on gearbox assembly, machining gearbox components and casting gearbox housings. Gradually, though, he began to focus on gearing. To this end, he studied at the Technical University in Liberec and later obtained a doctorate from the Technical University in Ostrava.

Gearing work

Years ago, the main technology used for gearing production was shaving, which was performed as the last chipping operation before the cog was hardened. For this purpose, a grinding wheel was used, which is a precision gear with a large number of teeth with cross-cutting cutting edges on each tooth and has approximately four times more teeth than the gear being machined. This technology, where the larger wheel machines the smaller one, finishes the sides of the gears more finely than milling. The problem is that after subsequent hardening, the teeth that have thus been precisely machined get deformed. This method of production is therefore not as precise for the final gearing as is needed in the most powerful units.

The gearing manufacturing technology used today is grinding, which provides greater precision.

This is why the automotive industry started to adopt the technology of grinding gears, which is done on the hardened cog. This eliminates deformations after heat treatment and inaccuracies resulting from machining prior to heat treatment. This results in a better surface quality and a more precise tooth shape than with hobbing or milling. Gear grinding technology is mainly used for precision hardened gears that can withstand heavier loads.

“Power honing began to be used in around 2004,” Jaroslav Prokop says. “This finishing technology ensures the same high surface quality and tooth shape accuracy as grinding. It also allows the machining of gears that could not use ground gearing due to the complex shape of the component,” Prokop explains. “The switch from shaving to honing was made because of the need to make transmission gearing stronger. This was brought about by higher demands from engines – they were getting smaller in volume but their torque was increasing, while the gearbox remained the same.”

Jaroslav Prokop has been a gearing specialist for two decades.

After twenty years of working in gearing, Jaroslav Prokop now works with a large team of experts. It is not a traditional or fixed team, though – the people in the teams he works with often never meet. There are experts working on various projects, gearbox design and technology, and Jaroslav Prokop contributes his gearing know-how to the process. They are currently working together to develop gearing with much lower tooth surface roughness that can be produced with existing tools and technology – they’re trying to achieve a reduction in mechanical losses in the gearbox from friction while increasing the gearing’s load capacity.

Gearboxes for India and Vietnam

Another area he and his colleagues are currently working hard on is gearboxes for one type of series of internal combustion engine. That’s because the Czech carmaker supplies transmissions for three-cylinder and four-cylinder petrol units with a capacity of 1.0 to 1.6 litres and has also taken charge of their development for the entire VW Group.

The work of Jaroslav Prokop’s team is applied both in Škoda models and throughout Volkswagen Group.

The way they are used varies from country to country and market to market. “Drivers in India, for example, have a very specific way of using the gearbox – it’s a lot more intensive than in Europe. We’re also starting to address the Vietnamese market, where we expect another specific form of gearbox use. We will be responsible for this directly in Mladá Boleslav, and this includes the gearing of the gearboxes. That is why we’re constantly expanding our know-how in this area and improving the tools and simulations we use. In this area our techniques are state-of-the-art, allowing us to respond quickly and flexibly to the specific needs of the market in question, even by developing new gearing as necessary,” Jaroslav Prokop concludes.