Document Rp9gKKoVmdx7VEQ60beMEdDnn

LESSON ONE-MODULE 2 BRAKE SYSTEM SERVICE PARKING BRAKE SERVICE The parking brake system should be inspected and adjusted whenever the service brakes are repaired. Parking brake service primarily consists of testing the system operation, adjusting the cables and linkage, and replacing components when necessary. Checking the service brake pedal travel is the first step in diagnosing a potential parking brake problem. The next step is to inspect and test the parking brake control and the linkage, Finally, a performance test will verify that the parking brake can hold the vehicle stationary. Parking brake cables and conduits are exposed to water, snow, ice, mud, and other under vehicle corrosives. These conditions can cause corrosion concerns. Whenever a vehicle is having brake service, inspect the parking brake cable and conduit closely. If the cable is suspected of sticking or being seized, replace it Parking brake service will vary from vehicle to vehicle, depending on the type of parking brake used. Linkage Inspection and Test If parking brake adjustment is too loose, the brakes may not be applied well enough to hold the vehicle stationary. If parking brake adjustment is too tight, the brakes can drag, causing brake fade and premature lining wear. To check the adjustment, perform the following steps: Raise the vehicle on a hoist with the parking brake released. Rotate the rear wheels by hand and check for brake drag. Have an assistant operate the parking brake control while you check the movement of the cables and linkages. The pedal or lever should apply smoothly and return to it's released position. Inspect the cables for broken strands, corrosion, and kinks or bends. If the brakes drag or the linkage binds in any way, the parking brakes must be adjusted or repaired. See the vehicle Workshop Manual for complete parking brake adjustment and service procedures. If the vehicle has a transmission mounted parking brake it is serviced separately from the brake system. Rear Drum Brake Parking Brakes A parking brake lever or pedal connects to a steel cable. The cable runs through a device called an equalizer. The equalizer connects to two individual cables. These cables connect to a parking brake lever on the rear brake shoe. As the pedal is applied or the lever is pulled, force is transmitted through the cables to the lever, applying the rear brake shoes. Because the service brake shoes are the parking brakes for vehicles with rear drums, service brake adjustment directly affects parking brake operation. If lining to drum clearance is excessive, the parking brake linkage may not have enough travel to apply the parking brakes completely. Always check and adjust the rear lining-to-drum clearance before adjusting the parking brake cables and linkage. 56 September, 2005 Brake System Diagnosis and Repair