Individual System Solution For Measuring Brake Discs

Ettore Bugatti (1881–1947) is said to have reacted to the criticism of the bad brakes of his cars in the early 1920s with harsh words: "My cars are built to drive, not to brake." Mercedes-Benz is a car manufacturer for bad brakes not known. One of the reasons for this is that the Mercedes-Benz Technology Center (MTC) based in Sindelfingen near Stuttgart in Swabia is not only the nucleus for new technologies, but also ensures the safety of automobiles with a variety of test benches.

Tradition and modernity

The Mercedes-Benz Sindelfingen plant is the most traditional vehicle plant of Daimler AG and, in the global production network of Mercedes-Benz Cars, the center of excellence for luxury and high-end passenger cars. The E-Class (sedan and T-model), the CLS and the CLS Shooting Brake, the S-Class (sedan, coupé and convertible), the Mercedes-Maybach and the Mercedes-AMG GT are manufactured here. Around 200 vehicles are delivered to the local Mercedes-Benz customer center every day. In addition to the MTC, Sindelfingen is home to Daimler AG's corporate research as well as the development and design department for Mercedes-Benz vehicles.

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The brake discs are also among the components that are extensively tested in the Mercedes-Benz Technology Center. As part of the statistical inspection of the goods, the technicians must randomly determine the runout and thickness fluctuations of the brake discs. This is done on a specially designed test bench. "It is an individual facility that we have developed ourselves," said Michael Buck, test equipment officer at Daimler AG. "However, we asked Rodriguez, as one of our proven suppliers, to further develop the brake disc mount and then to manufacture the complete rotary unit." Daimler installed the measuring modules and the drive for the test bench on its own.

As free of play and plan as possible

The rotation unit enables the brake discs to be attached to a wheel replacement piece based on the rim and then measured without contact. The contact surface replicates exactly the wheel hub of a Mercedes-Benz vehicle. There was one main requirement for the mounting of the brake discs: It should be as free of play and flat as possible. The background: During the rotation, no fluctuations may occur - after all, they would be transferred directly to the brake disc and thus affect the measurement result. "The requirement for our unit was that the runout of the unit should be <7 µm", says Ulrich Schroth, Business Unit Manager Value Added Products at Rodriguez. "Daimler also wanted the rotation unit to be duplicated at any time and without great effort."

Rodriguez received sketches from his client on which the main dimensions were noted. From this, the Eschweiler drive specialists developed and designed a storage system including the necessary conversion parts. The rotation unit consists of a specially hardened mounting shaft, a double-row angular contact ball bearing as the main bearing, another bearing as a torque support and a clamping nut. The resulting component is screwed onto a base plate. The mounting flange of the rotation unit can be adapted for different brake discs. "Daimler is adding a drive to the unit that rotates the mounting shaft and thus the brake disc," says Ulrich Schroth. “This simulates normal driving. A measuring head checks the thickness and flatness of the brake disc.”

Content of the article:

• Page 1: Individual system solution for measuring brake discs
• Page 2: All process steps are taken over

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