Q&A with Mario Jurcevic

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What is your experience and background in the gear industry?

I’ve always been involved in the gear industry since I graduated from college. I started out as a quality engineer just because it was hard to find work straight out of college. This was where I was first exposed to the gear industry. I learned a lot about gears and how they are manufactured and how they are inspected. Later, I decided to get into the design aspect of gears and gearboxes. I’ve been doing it ever since, I design gears/gearboxes for customers in various markets (i.e., aerospace, industrial, mining, steel, sugar, and wind energy, to name a few).

I’ve had lots of great opportunities designing gears and gearboxes. I designed the powertrain system for various size rigid haulers and then had the opportunity to drive them on test tracks. How cool is that?

I’ve designed an entire product line of planetary gearboxes for sugar extraction for the sugar industry. I then had a blast traveling around the world selling and installing them. I designed actuators and gearboxes for various commercial and military aircraft and was able to see them installed on the aircraft and successfully tested.

In your experience, what do you find are the most challenging gears to design?

Every gear is challenging to design. There are a lot of factors that must be considered when designing a gear. To name a couple: operational requirements, environmental conditions, gear-type selection, material and heat treatment selection, lubrication, dimensional restrictions, manufacturing, and cost. These are all things that you learn through industry standards (AGMA, ISO, DIN, etc.) and years of experience.

How do you approach a client when they come to you with what could be a difficult project?

Being honest and upfront to the customer is key. I’ll ask a lot of questions pertaining to the project, and I make sure the expectations are mutual and within reason. Some customers have an idea of what a job entails; some don’t. Regardless, I’ll let them know upfront what it is going to take to do the job. I make sure the customer is up-to-date on the project status and “in the loop.” Like every contractor or consultant, having a happy, satisfied customer is extremely important.

How important are gear advances when it comes to the future of EVs?

Electric vehicles are here. Electric vehicles (EVs) are becoming more prevalent on the roads and almost all automotive companies are announcing plans where EVs will eventually dominate their product portfolio. As the shift from internal combustion to electric continues, the number of drivetrain components will dramatically lessen and the remaining components found in cars of all types will be more critical to the vehicle’s operation and longevity. Gear advances are necessary to convert the high-force torque from electric motors to the RPMs at the wheel. The biggest factors to gear advances are efficiency and gear noise. In order for people to invest in electric vehicles, automotive companies will need to reach similar mileage as found in internal combustion vehicles. How does one accomplish this? Lowering surface friction. Lowering surface finish or texture will increase the vehicle’s overall range. On the other hand, the sound from the internal combustion engine typically masked the noise from the drivetrain. Sound dampening in the passenger cabin was designed into the vehicle frame and the passenger compartment. In the electric vehicle, this could become an issue if the manufacturing methods and processes don’t improve as well. Design and manufacture of precision machines will be required, as well as metrology equipment, to be able to precisely inspect and evaluate the manufactured product.

You worked with a well-known OEM in designing its 1.5-MW and 3.0-MW wind turbines. What was your role in that project?

I was working as a design engineer for an engineering consulting company at that time. The company was asked to assist with designing a new 1.5- and 3.0-MW wind turbine. The senior gear engineer and I worked alongside with the OEM’s gear engineer to design the gearbox. Our goal was to determine the gearbox selection via calculations, analysis, design layout, etc., and assist with producing models and manufacturing drawings. We had designed various types of gearboxes, and we determined, based on the loads we were provided, to use a compound planetary design and modify it accordingly to make it work.

How has the use of software (i.e., KISSsoft) changed how gears are designed? Does it make it easier or just allow for more intricate designs?

Gear design software provides so many benefits over traditional “hand calculations” or Excel spreadsheets. I believe software today does make it easier to do designs and is leaps and bounds better than it used to be. It is continuously being improved and updated as well to the latest standards and technology. Software today allows you to size various machine elements (gears, bearings, shafts, etc.) based on required parameters. It allows you to make modifications and optimize the machine elements without doing extensive calculations. KissSoft does extensive calculations for you. For example, microgeometry modifications can be added to the tooth profile, and the software will calculate and provide values and charts and diagrams of the contact pattern, transmission error, stress distribution, etc. And if you’re not satisfied with the outcome, you can have KissSoft generate “x” number of suggestions, and you can pick the solution that works best for your application and analyze the results within seconds. 

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