Brake Systems: Understanding Your Car’s Calipers and Wheel Cylinders
Your brakes have a tough job to do. Every time you step down on the brake pedal, various mechanisms grip onto your brake rotors or drums hard enough to generate the friction needed to slow you down. These mechanisms are called brake calipers or wheel cylinders and they’re some of the most important parts on your car. You expect them to work day in, day out under any weather conditions without fail.
Types of Systems
There are two types of brake systems found on modern vehicles. Front disc brake/ rear drums or four wheel disc brakes. Disc brakes use calipers that house the brake pads which are used to clamp down on your car’s brake rotors. Calipers contain pistons that hydraulically activate this clamping force when you depress the brake pedal.
Drum brakes use wheel cylinders, instead of calipers. The wheel cylinder also use hydraulically applied pistons that push a pair of brake shoes against the inside of a drum in order to create the friction needed to stop.
Once upon a time, four wheel drums with wheel cylinders were more common than calipers but technology has largely pushed drums to the rear axles on entry-level automobiles.
Which Is Better?
When it comes to evaluating brake systems, calipers have several advantages. The first is that the surface of a rotor is much better at dissipating heat than the inside of a drum, which means the pads don’t see their stopping power fade nearly as quickly as the shoes in a drum design. The second is simplicity: drum brakes are relatively complex using a number of springs and other components that need to stay properly adjusted (usually an automated process). Calipers are straight-forward, free-standing housings for one to six pistons, typically needing no adjustments.
Which Brake Systems Are on My Car?
To figure out what type of brake is used on your own personal vehicle, take a look through the spokes on your rim: if you see a flat shiny disc staring back at you, with a somewhat curved housing (caliper) straddling it near the top, then you have disc brakes. If instead you’re looking at what seems to be a solid hat-shaped cover over the center of the hub immediately behind the wheel, then you have drum brakes. As stated earlier, it’s not uncommon to see some types of vehicles mix and match the two — particularly pickup trucks, which until recently all had drum brakes at the rear. Most vehicles today have 4 wheel disc brakes—unless your car hails from the ’60s, then you’ll find drums on front and rear!
For more information on brake systems, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Photo courtesy of Morguefile.