Every time engineers think they’ve come up with new and innovative responses to challenges posed by the world, physics comes roaring back with another challenge. Engineering progress can seem like a two-steps-forward, one-step-back kind of arrangement. Consider the example of the automobile. Here you have a brilliant answer the problem of the need for speedier transportation in growing economies. But the minute you come up with the combustion engine, one of the most paradigm-shifting inventions ever, you have to come up with new engineering developments to deal with all the challenges that spring up as a result of this new development.
Take brakes, for example. The combustion engine allowed for the use of horseless vehicles; these vehicles could achieve sustained speeds over longer distances than any vehicles in history. But now, engineers had to develop ways to control those speeds and to make their vehicles safe. Among the solutions that eventually emerged out of automotive engineering was the disc brake and disc brake pads. This is the system on which most automobiles’ braking systems rely these days.
The disc brake is quite a brilliant invention. It involves mounting a disc on the axle, which spins around as the axle and wheel spin. Sort of hovering above the brake is the caliper assembly, in which can be found the brake pads. When the operator of the vehicle needs to slow down or stop, operating the brakes causes the caliper assembly to direct the brake pads into contact with the brake disc. The friction caused by this contact causes the rotation of the disc to become slowed, which, because the disc is connected to the wheel, causes the vehicle’s speed to slow. Disc brakes and friction materials are examples of the engineering world’s persistent innovation in the face of the challenges of physics.