The essentials of your car’s brakes haven’t changed much in five or six decades, but it can still be confusing. At New England Tire Car Care Centers in Attleboro, Mansfield, Seekonk, Northborough, Ma. and Warwick, RI, we’d like to clear things up and hopefully answer a few questions.
The first thing to remember is that the whole system relies on hydraulic pressure to operate. Think about taking a tablespoon of water in the palm of your hand and trying to throw it. Now, imagine that same tablespoon of water in a squirt gun or a syringe. Since the syringe or squirt gun can confine the water and put pressure behind it, it’s naturally going to deliver the water farther. That’s the principle behind hydraulics, and any problems with the hydraulics of your brakes will result in a brake repair job.
Let’s start off with your brake pedal. The strut that your brake pedal is mounted on is connected to a rod, which in turn leads to the master cylinder, which is mounted just in front of the passenger compartment on the firewall. The master cylinder is a reservoir for brake fluid and has connections to the front and rear brake lines. When you step on the pedal, the rod actuates pistons inside the master cylinder, which compress hydraulic fluid in the brake lines. That hydraulic pressure goes to the wheels, each of which have their own piston-and-cylinder assembly to activate the brake pads. The master cylinder is aided by a power brake vacuum booster, which scavenges vacuum from the engine to multiply the force applied by the brake pedal, making braking easier.
To understand disc brakes, it’s useful to think of how the hand brakes on a bicycle work. Two pads grab a spinning wheel and reduce its speed via friction, and that’s close to how automotive disc brakes work. Your car’s wheels are bolted to a glassy-smooth, machined steel rotor (or “disc”) with a caliper mounted to the rotor. On each caliper is two pads of semi-metallic or ceramic friction material, backed by a piston. When the brakes are applied, hydraulic pressure activates the piston in the caliper and the pads squeeze and drag on the rotor, slowing the vehicle down.
Disc brakes were an improvement on the old drum braking system, but there are many vehicles still on the road that use drum brakes in the rear. Drum brakes consist of a cast-iron dish-shaped drum mounted behind the wheel. Inside the drum is a piston and two rods that are linked to curved brake shoes. When you apply the brakes, the piston actuates and expand the shoes toward the drum’s lining, which drag and slow the vehicle down.
Since the 90s, almost all cars have been designed with antilock braking systems (ABS). In an ABS system, sensors monitor the speed of each wheel and sends that information to a processor. If a wheel is spinning much more slowly and could be on the verge of locking up and going into a skid, the processor meters braking effort via a system of valves and pumps to all four wheels, ensuring an even, safe stop. ABS systems were developed for aircraft in the 50s and actually made their debut with the ’71 Chrysler imperial. Newer cars incorporate ABS into their entire vehicle stability control system.
Without going too far in to technical detail, this is the essence of how a brake system works. At New England Tire Car Care Centers, we’re happy to help if you’re experiencing any brake repair
problems with your vehicle. Make an appointment with us today!