That would be the vacuum power booster for the brakes.
Behind the wheel holding the disc brake pads.
There should be two rotors if your truck is 2wd. They are located where the brake pads clamp to. Rotors are also called brake disc. It's the round disc between the brake pads.
Master cylinder or drum brake (hydraulic slave) wheel cylinder or disc brake caliper cylinder? drum brake shoes rear
disc brake components
The rotor is the disc in the disc brake system.
With rear drum brake:-The brake drum may be out of round or may have a rust spot in it. -The brake drum may be cracked.With rear disc brake:-The brake disc may have extreme lateral runout or be mounted improperly. -The brake disc may be cracked. This would be dangerous-Combination of soft brake pads and a directional finish on the disc surface. A directional finish may go away with use and take the noise with it.Regardless of brake type:A brake disc or drum mounted to a bent hub flange or bent axle shaft can cause this noise.
Bad fluid in master cylinder,flush system,bleed brakes
To change the disc brake pads on a 2003 F250 you will first need to remove the wheel and tire. There are 2 caliper bolts behind the caliper which need to be removed. Then use a special tool or C-Clamp to push in the caliper pistons and replace the disc brake pads.
A disc brake is a type of brake that uses the calipers to squeeze pairs of pads against a disc or a "rotor" to create friction. This action slows the rotation of a shaft, such as a vehicle axle, either to reduce its rotational speed or to hold it stationary. The energy of motion is converted into waste heat which must be dispersed. Hydraulically actuated disc brakes are the most commonly used form of brake for motor vehicles, but the principles of a disc brake are applicable to almost any rotating shaft. The components include the disc, master cylinder, caliper (which contains cylinder and two brake pads) on both sides of the disc. More
Could be a disc brake rotor, pulley.
Front rotors are round metal plates / disc. Hence the term, "Disk Brakes" They fit onto the axles behind the wheels and are part of the brake system. Specifically they are the part that the caliper/brake pad assembly applies pressure to, to create the braking action.
worn thin