Disc Brake Guide

To stop a car or truck, a disc brake system uses calipers to squeeze a pair of brake pads against a disc. Disc brakes generally have better stopping performance than drum brakes. That’s because discs cool off more quickly. Here are the main parts of a disc brake system:

Here are the main parts (clockwise from the upper left):

Pad Clip or Brake Clip

These hold the brake pads in place

Support Bracket

Also known as a caliper mounting bracket, it connects the caliper to the rotor

Pad or Brake Pad

The piece that squeezes again the brake disc to stop the vehicle

Piston

A round plug, closed at one end, that transfers force to the brake pad

Square Cut Piston Seal (or just Piston Seal)

A fluid seal on a disc brake caliper piston

Caliper Body

Straddles the rotating disc and presses the pads against the disc

Bleeder Screw

A hollow screw used to open a bleeder valve to allow fluid and air bubbles from a system like the brake system during a bleeding process

Lock Bolt

Also called slider bolts or pins, these are high-strength bolts used to fasten together the halves of a split brake caliper

Guide Pin or Caliper Pin

A caliper mounting bolt used for fastening a floating caliper to its mounting plate

Pin Bushing or Bushing

Sometimes a rubber bushing, this is a bearing for a piston pin of one piece construction which may be removed from the part

Pin Boot

A rubber diaphragm-like seal that fits over the end of a hydraulic component and around a pushrod or end of a piston, not used for sealing fluid in but keeping dust out

Piston Boot

Often called a dust boot, this is a flexible rubber cover that keeps out debris

Boot Ring (or Pin Retainer)

A pin which locates the brake pad in a disc brake

Spreader Spring

A part designed to keep the pad away from the rotor, preventing drag

Drum Brake Guide

The drum brake system is used in older vehicles. It’s used in most heavy-duty trucks. And it’s also used in some hybrid cars. Drum brakes create friction by pressing shoes or pads outward against  a rotating part called a drum.

Here are the main drum brake system parts (clockwise from the upper left):

Backing Plate

The part of a drum brake to which the wheel cylinder(s) and the brake shoes are attached

Anchor Pin

A steel stud or pin upon which one end of the brake shoes is either attached to or rests against

Brake Shoe (Web)

The components of a drum brake assembly that are surfaced with brake lining and pressed against the brake drum

Wheel Cylinder

A small cylinder located at each wheel brake that uses brake fluid to exert hydraulic pressure

Wheel Cylinder Link

The rod that transmits the movement and force of the wheel cylinder piston to the brake shoe

Brake Strut Bar

A push bar between the shoes in a drum brake

Return Springs

Springs attached to the brake shoes to pull them away from the drum

Link

Connects the return rings to the hold down cup

Drum

The rotating part against which the brake press

Adjuster Lever

Assures adjustments occur at the right time

Hold Down Cup

Connects a brake shoe to the backing plate. The hold down pin passes through the backing plate and brake shoe. The hold down spring and retainer are fastened to the pin

Adjuster Assembly

An assembly of non-rotating parts of the brake system

Parking Brake Lever

A lever inside the drum brake which spreads the brake shoes outward

Brake Shoe (Lining)

A heat-resistant friction material pressed against the drum to stop the vehicle