In Need of a Lift?

Ever since BILSTEIN first fitted gas pressure shock absorbers into the winning vehicle at the Monte Carlo Rally 50 years ago, the company has been recognized as an innovative systems partner for the automotive industry. When it came to designing a hydraulic system for a sports car manufacturer, Trelleborg was on hand to support BILSTEIN with an equally high-performance sealing solution.

-By Nigel Luhman

IT IS NOT MERELY A QUESTION OF LOOKS. Sports cars have a minimum ground clearance to lower their center of gravity, resulting in better handling at high speeds as well as minimizing air flow beneath the car. However, at the end of the day, the car has to return to the garage and this can be a problem. To ensure low-slung sports cars can drive over ramps and curbstones, BILSTEIN was commissioned with developing a so-called lift system to hydraulically raise the chassis in such circumstances.

Strong partner for a prestigious project

The partnership between Trelleborg Sealing Solutions and BILSTEIN extends back over several decades and numerous shock absorbers of many different types have been fitted with Trelleborg seals. Originally working out of the Trelleborg Sealing Solutions head office in Stuttgart, Germany, Thorsten Nitze is currently based at the the company’s North American Automotive Hub in Michigan, US. In his role as Sales Engineer European Automotive Hub, he was responsible for BILSTEIN at the end of 2016. It was at this time that a design engineer from BILSTEIN asked for his help in developing the seals for the new lift system, as Nitze had already successfully managed a series of projects for the customer.

“BILSTEIN has an impressive list of performance-orientated car marques among its clients, and I believe they wanted a strong partner to support them on this prestigious project,” he recalls. Work began swiftly and during the design phase the main challenge was to develop a system for mass production with only limited space available inside the strut. By working closely with BILSTEIN on site and using customer-specific components, Thorsten Nitze was able to overcome the challenge and meet all the requirements. This proved to be relatively easy, in fact, as all of the prototypes tested by BILSTEIN worked flawlessly and within six months, by May 2017, Trelleborg had won the contract.

Successful novel concept

In total, Trelleborg Sealing Solutions supplies six different components, three made of rubber and the rest of polytetrafluoroethylene (PTFE), to seal the entire unit. There are two QUAD-Rings and one O-Ring using hydrogenated nitrile butadiene rubber (HNBR) plus two PTFE back-up rings and a PTFE Slydring. The PTFE-based parts are produced by Trelleborg Sealing Solutions at its Helsingör site in Denmark, and Thorsten Nitze specified Turcon® M12 for its good allround characteristics and cost-effectiveness. The elastomer used in the rubber is HC66S, as it is similar to a tried-andtested material that has proved to be suitable in similar projects but offers even better processing properties

The BILSTEIN lift system is already integrated in some sports cars currently on the road, built into the front axle to provide extra ground clearance at the touch of a button. While the company has developed countless specialized absorbers for a wide range of applications and vehicles in the past, incorporating a hydraulic lift system in the strut was a completely new concept. BILSTEIN is more than satisfied with the products Trelleborg Sealing Solutions supplied for the hydraulic unit and further projects are continuing between the two companies. For Thorsten Nitze this success comes as no surprise. “The prototypes all performed so well that my contact at BILSTEIN said the whole system stood up to the tests extremely well.”