As a result of carefully focused and detailed work, Continental has succeeded in developing new brakes which weigh between 10 and 40 percent less than before, depending on the individual components. This development can make a significant contribution towards reducing CO2 emissions because lighter vehicles use less fuel. The particular challenge when developing brakes which weigh less is not to compromise safety. Consequently, not every technically feasible weight reduction becomes a reality.

Light-weight due to intelligent design

One means of saving weight when designing brake components is to replace the materials used so far, such cast iron or steel, with lighter materials, such as aluminum, other light alloys or even plastic. However, the use of alternative materials is currently restricted to aluminum since extremely high demands are made of these materials. During its life, a brake will be operated several million times, subjecting it to great pressure; the material is also exposed to moisture and road salt and so far only cast iron, steel and aluminum have shown that they are able to cope with such demanding conditions. Due to its high cost, aluminum is the material of choice for luxury-class vehicles, for example in a new aluminum fixed caliper brake which the Chassis & Safety Division has developed for a top-category premium vehicle.

The objective for Continental's development engineers is to develop lighter braking systems – using traditional materials but employing state-of-the-art development and manufacturing methods.

More efficient design techniques and intelligent light-weight construction can produce slimmed-down components without limiting their functionality. Specialized CAD software makes it possible to optimize component structures on the computer. Without the need for time-consuming trials using costly models, it is possible to achieve components of maximum strength but, at the same time, of the lightest possible construction. A good example is the 2FNR-Al aluminum brake caliper housing whose shape the development engineers have been able to improve using these state-of-the-art simulation and topology optimization methods. Despite bigger recesses and reduced wall thicknesses, meaning less material is required, the re-designed housing provides the same degree of stability as the tried and tested model, but still weighs 440 grams less than its initial weight of 4,185 grams.

Brake lining backplates can also be slimmed down to some extent without limiting their functionality. The standard metal thickness used so far is 6.5mm throughout. But this is only necessary over certain areas of the plate where the greatest stresses occur. In some places, the optimized backplates are only up to 4mm thick with reinforcement provided in areas particularly subject to stress, and this can lead to the weight being reduced from 424 to 300 grams. For a pair of brake pads this is a not inconsiderable weight saving of roughly 250 grams.

New materials and manufacturing processes

It does not always have to be aluminum or another light alloy in order to reduce weight. An outstanding example is offered by the brake pistons, currently going into series production, and manufactured using a new process. In this process, patented by Continental, the pistons installed in the brake caliper's hydraulic system are no longer cast or turned, but are press-formed from a 3.5mm thick circular metal blank. A total of 15 metal-forming steps convert the blank into a very thin and light, but equally very stable, brake piston which not only weighs almost 25 percent less than its cast predecessor but also delivers production cost advantages.

Tie-rod design brake boosters have already proved their worth. Compared with conventional brake boosters, tie-rod brake boosters - significantly more stable due to their integral steel tie-bolts - produce a 30 percent weight reduction. Transferring the principle behind the tie-rod design to aluminum - a development which has already taken place - produces a further weight reduction of 25 percent. But even with the present steel design, depending on the size and shape of the brake booster, the weight savings in absolute terms are between 150 and 1,150 grams – that's a lot of CO2 saved over a vehicle's life and an important milestone towards reducing global CO2 emissions from vehicle fleets in the years ahead.