The brake system on your Freightliner S2C includes drums and rotors. These parts are integral components for slowing down and stopping, as they are the surface which engages the disc pads or brake shoes. Working together, they are able to halt wheel movement. These are engaged whenever the brake pedal is pressed.
If you have been experiencing squealing noises or grinding whenever you engage the brake, it may be that the drums or rotors, which are specific to your Freightliner S2C, need replacing. Ignoring these signs or avoiding replacement can cause total brake failure and leave you susceptible to accidents and costly repairs.