En route to end-to-end development competence
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The Bertrandt Group took a major step forward in the creation of an end-to-end development process chain with its first ready to drive prototype - the Bertrandt Competence Car (BCC) - which was developed and built in just eleven months. We were able to achieve this by continuously extending the range of services we offer. For example, our majority holding in ZR - Zapadtka + Ritter GmbH & Co. KG. gives us access to comprehensive sheet-metal expertise for the manufacture of near-series prototype parts.
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Design development and construction
In August 1998, the decision was made to build our very own ready to drive prototype in the form of a pick-up. Taking aspects such as looks, costs and the tight schedule into account, it was decided to modify and redesign a vehicle which was already on the market. We opted for the Mercedes-Benz M-Class, as we had already been closely involved in the development of this car. In collaboration with DaimlerChrysler, it was decided during the design development stage to cut the M-Class behind the B pillar and to build up the new body from there.
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The new data was produced in Sindelfingen in just two and a half months. The data was tested for feasibility using state-of-the-art simulation (digital mock-up) and visualisation techniques (real-time renderings). In parallel, tests were carried out in the technical computing department and flow simulations were performed.
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The data control model shows detailed precision
The BCC was first milled as a 1:3 scale model and then assembled from 14 individual parts. The unusual way in which various alternatives were presented in just one model made the final decision-making much easier. One example of this is the Bertrandt pick-up with a continuous belt rail instead of one with broken lines.
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Tool and parts manufacturing
A detailed tool manufacturing plan was drawn up using the parts list and taking all the influencing factors into consideration. Several of Bertrandt's subsidiaries worked on the manufacturing - for example small metal parts were produced by hand whilst the interior trim parts necessary for the vehicle concept changes were being manufactured. At the same time, the data was validated from a design perspective, and any improvements were immediately taken into account in the physical production of the parts.
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The BCC takes shape: Vehicle modification and construction
In January 1999, we were ready to cut the body shell of the M-Class. The entire rear structure behind the B pillar was carefully separated at the cutting points defined by the design data. At the same time, Bertrandt removed the complete ladder-type frame including the drive train from an original vehicle and installed it in the future Bertrandt pick-up. These cutting points provided the basis for the subsequent construction – including for example the handmade rear panel, the side panels and the interior trim elements. Changes were also made under the outer skin. In order to regain stiffness, reinforcements were welded into the entire rear side panel and floor area.
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Newly designed interior
Based on the M-Class interior, all the trim parts from the B-pillar backwards were completely redesigned. The design of the trim elements had two aims: the harmonious continuation of striking surface lines and the creation of additional storage space. Two large “pompadour” bags were integrated into the rear wall trim, and two generous storage compartments were created in the space between the main floor and the loading platform. The negative tools required to produce the roof lining and rear wall trim were milled, smaller parts were manufactured as SLS components and the visible surfaces then reworked manually.
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Electrics
The modifications to the bodyshell called for relocation of the electrical system under the loading platform from the B-pillar rearwards. At the rear, the run of the cables was redefined and the resulting wiring harness changes were made to existing and additional components.
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Testing
During the early computing stage, we were able to use the available data to carry out simulations and crash and rigidity calculations. The tailgate was tested in a typical empirical “non-stop test”, which involved intermittently opening and closing the tailgate at predefined speeds. The conclusion was that the lifetime of the tailgate and its components will exceed that of the vehicle.
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Completion
By mid-May 1999, work had been completed to the extent that the bodyshell could be painted. During the next four weeks, the pick-up was assembled and the interior parts fitted. Thanks to the outstanding expertise of the Bertrandt subsidiaries that participated in the redesign and the excellent cooperation between them, by the end of July the Bertrandt Group was ready to present its first ready to drive prototype - the Bertrandt Competence Car.
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