The disc brake uses the mechanism of transforming kinetic energy into heat energy through friction. There are two kinds of disc brakes, floating and fixed-caliper brakes.
The floating brake has one or two pistons, but both on the same side of the rotor disc. When hydraulic pressure is applied to the piston in the cylinder, the piston moves forward, pressing the brake pad against the disc. The brake pad on the other side of the disc is not powered by a piston, but is simply connected with the caliper in an overarching manner.
Braking with a single piston
When braking happens, the piston-powered brake pad presses against the rotor disk. But there is enough space for more hydraulic fluid to flow in and so the piston is pushed further even after the brake pads come into contact with the disc. What this does is, it pulls the brake pad on the other side towards the disc and adjusts the length of the overarching caliper. Thus, both the brake pads press hard against the rotor disc and the braking happens.
Disc brakes are manufactured according to the weight and power of a vehicle. For example, motorcycles require lighter brakes in order to prevent weighing down of the vehicle.
Floating calipers have to be serviced if they are slow in the pins on which they are mounted. This happens by dust getting accumulated in them. Due to this, the caliper won’t be able to slide freely and get stuck causing friction even when the brake pedal is not pushed. This is totally undesirable and it causes excessive wear warping on the rotor disc.
Self-centering and adjustment
Since the brake pads have the ability to move sideways and towards the center, they are always self-centered and irregular application across brake pads does not happen. It also has the benefit of not requiring an adjustment, automatic or manual. This is because; the piston does not recede completely into the cylinder due to the absence of a return spring. It also becomes a benefit because, since the pistons are big, once they recede in, a lot of pressure and hydraulic fluid displacement is needed to push them again. Thus, the brake pads stay close to the disc always.
Fixed brakes are firmly connected to the suspension and that is how they get the name. The brake pads are made to apply from both the sides. In the initial models, there was only a pair of pistons used from both sides, but nowadays, it may be up to four in number. Fixed caliper breaks cost more than disc brakes to manufacture, and so are expensive than floating brakes.