Design
Last year, the pedal box took up more than 350 mm in the front of the car. This was primarily due to a horizontal mounted master cylinder and a combination proportioning valve. For this year, it was desired to have a much more compact design. For master cylinders, it was chosen to use AP racing’s CP7855 master cylinder, since they allow for an angled mounting. This meant that it was possible to make the new design a lot more compact than the old, with the new pedal boxes being reduced with approximately 200 mm lengthwise. This has a major benefit, as it allows us to reduce the front end of the chassis and thereby saving weight in unneeded steel tubes.
The proportional valve from last year’s design was not helping in trying to keep the design compact. That is why this year’s system consists of two CP7855 master cylinders and one CP5520 balance bar. The balance bar allows for easy adjustment of brake line pressure distribution between the two master cylinders. The balance bar from AP racing plays a major role in keeping the design compact, since it is not taking up a lot of space.
The acceleration pedal is using two mechanical springs with a combined force of 80N. If the springs should be too weak, the design allows for easy change to stiffer springs. The positive stop is made with a slot, so the range of motion of the pedal can be adjusted. The bottom plate bolts to an L-profile steel bracket, which is welded to the chassis allowing for easy adjustment of pedals to the different drivers. Overall this design is very simple, easy to manufacture, and yet functional.
Manufacturing
A very important aspect of the design was manufacturability. The pedal box is designed so it can be manufactured in-house at Skylab, DTU. The bottom plate was machined manually, and every hole was laid out with DRO to ensure precision. Most of the components in the brake system are made from aluminium to keep the weight down.
All custom made components have been produced in Skylab. A huge thanks to the workshop for guidance, machine time and material. The manufacturing of the pedal box is scheduled to be done by the end of March, hereby having time to adjust things if needed.
Stay tuned!
Thanks for reading.
Jacob
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