Editing Disc brake (section)

===Pistons and cylinders===
{{Unreferenced section|date=January 2016}}
The most common caliper design uses a single hydraulically actuated piston within a cylinder, although high-performance brakes use as many as twelve. Modern cars use different [[hydraulic]] circuits to actuate the brakes on each set of wheels as a [[car safety|safety measure]]. The hydraulic design also helps multiply braking force. The number of pistons in a caliper is often referred to as the number of 'pots', so if a vehicle has 'six pot' calipers it means that each caliper houses six pistons.

Brake failure can result from the failure of the piston to retract, which is usually a consequence of not operating the vehicle during prolonged storage outdoors in adverse conditions. On high-mileage vehicles, the piston [[Seal (mechanical)|seal]]s may leak, which must be promptly corrected.