Probably the most important system on your car. The brakes on many cars can last for 50,000 to 100,000 miles or more with regular inspection and routine servicing. The Hand Brake or Parking Brake forms a mechanical link. The modern braking system uses an hydraulic link to transfer power. The brake pedal is attached to a piston called the Master Cylinder. Depressing the Brake Pedal increases the pressure of the brake fluid within the hydraulic braking system. Since the fluid does not compress; the pressure is transferred along the brake pipes to the wheels and depresses a slave cylinder or piston controlling the movement of the the brake pads against a brake drum or brake disc The friction between the brake pads and brake drum or brake disc slows down and stops the vehicle.
Disc Brakes and Drum Brakes
Drum brakes are an older system using two half moon shaped "brake shoes" pressing outwards under pressure against the inside of a "brake drum". They are most often found on the rear wheels of vehicles. Pressure from the slave cylinder controls a brake caliper that applies even pressure to a pair of disc brake pads mounted on opposing sides of a flat brake disc.
A vaccuum or hydraulic system is used to magnify the power applied to the brake pedal during braking and assists with slowing or stopping the vehicle. Pressing the brake pedal activates a valve that starts the Power Assisted Breaking. An electronic sensor system monitors the breaking power to help ensure uniform breaking without the wheels locking and losing control. If the engine stops suddenly then power assisted breaking is lost. Providing the hydraulic seals remain intact then breaking can still be achieved by increasing the pressure on the foot-brake.