Air Brake Test and Slack Adjusters

Air Governor Test

Start Engine and build air until compressor cuts out. Depress service (Foot) brake until the air compressor cuts in (should be about 85 psi.). Let air build until it cuts out (should not exceed 130psi). Wait for compressor to cut in between brake applications.

Static Brake Test

Start in a level location, or block a wheel to keep from rolling. Place the transmission in neutral. Turn engine off and release parking brake. Keep foot off service brake. Air loss should not exceed 2psi in one minute.

Applied Brake Test

MAKE FULL (Foot) BRAKE APPLICATION (BE SURE you have released your park brake before you do this or you will damage the system.) Hold the pedal all the way to the bottom for one minute. Watch your air gages as they should not move (Allowable loss in this mode for 60 seconds is 3 psi. Listen for audible leaks as you wait for the 60 seconds to expire. After 60 seconds release the pedal. (YOUR AUTO SLACK ADJUSTERS WILL SET UP AUTOMATICALLY DURING THIS PROCEDURE.)

Low Air Warning Device

Turn ignition switch to on. DO NOT START ENGINE. Observe the air pressure gauge and pump service bake until you can see the warning light come on and/or hear the warning buzzer. The low warning must come on around 60 psi.

Emergency Brake System Test

Turn off the ignition and then reduce the air pressure by pumping the brake pedal until emergency (parking) brake handle pops up (should be below 45 psi). Start the engine put transmission in gear and try to move the coach slowly against the emergency brake with low air pressure. Caution should be used so as not to apply too much pressure against the brakes and drive train.

Compressor Check

Place the transmission in neutral. Run engine at 1000rpm using your cruise setting. Time 3 minuets. In this time your air pressure should be up to between 50 and 90psi. This will tell you your compressor is functioning properly.

Emergency Brake Test

Allow air pressure to build up until it cuts out. Put coach in gear. Release the parking brake. Move the coach slowly and apply the emergency (parking) brake. This test checks your emergency brake.

Check Service Brakes

Release Parking Brake. Set coach on motion and apply service (foot) brake firmly to see if the steering wheel pulls to the left or right.

(Auto slack adjusters are used to maintain proper brake chamber stroke and lining to drum clearance during normal operation. The entire slack adjuster operates as a unit rotating with the brake camshaft as brakes are applied or released. THE MOST EFFICIENT BRAKING OCCURS WHEN PUSH ROD TRAVEL IS HELD TO A MINIMUM.

Auto Slack Adjusters adjust themselves automatically during full brake applications to accommodate brake lining and drum wear. The key words here are FULL BRAKE APPLICATIONS.)