Document g2zwLM0JgGRYO1XEb0mNNqQ6G

BULLETIN PLAINTIFF'SEXHIBIT FEBRUARY 9. 1976 \0. 083 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNlZf"HAYWARD 0^OAKVILLE0f SPRING BRAKE VALVE (All with MVSS121 Brake Systems) PURPOSE To recommend that operation of subject valve be checked periodically. RECOMMENDATION Check performance of the spring brake valve regularly, following the procedure and schedule given in bulletin. INFORMATION The spring brake (SR-1) valve supplies a specific, limited hold-off pressure to the spring brakes and. in the event air is lost in the primary brake system, it modulates the spring brakes through the treadle valve. In normal operation, internal parts of the valve undergo little or no movement and as a result could corrode and become inoperative over a period of time. To insure that the SF-1 valve will function in an emergency, it's operation should be checked every 24. 000 miles or at 3 months maximum. In addition to verifying correct valve operation, the checking procedure "exercises" the valve and helps to maintain it in good operating condition. The SR-1 valve (20QE3110R) is located as follows: F and MB - under cab on right hand frame rail. R, RD. PM, DM. DMM and U - on crossmember just behind cab. RL and RS - front of cowl, ahead of air vent WL and WS - under left hand splash shield, back of head light. CIRCULATION Service Manager Shop Foreman toight Foreman Night Foreman Inspector Leadman Inspector Leadman inspector Leadman Unit Over haul Room (Continued Over) Service Operations. Allentown. Pa. U.S.A. Shop Office Mack Procedure: 1. Make a standard brake application and note if all brakes are operating. 2. Chock wheels. 3. Release spring brakes. 4. Drain primary reservoir. 5. Have helper observe rear brakes for proper application while making four partial and four full applications of treadle valve. 6. If the rear brakes do not apply, remove the SR-1 valve, check it for serviceability and replace if necessary. MAIN SUPPLY SYSTEM PRIMARY SUPPLY SYSTEM PRIMARY SIGNAL SYSTEM SECONDARY SUPPLY SYSTEM SECONDARY SIGNAL SYSTEM ITEM A B C 0 E f M i K L M N o R NO. ) 1 1 1 1' |' / 1 13 COMPONENTS DESCRIPTION ONE BAY CHECK VALVE DOUBLE CHECK VALVE TREADLE VALVE MITI-WMCEL LOCK OOULTO V*lVf RELAY VALVE SPRINO BRAKE CONTROL VALVE RATIO VALVE barking CONTROL VALVE i -AAILER supply VALVE TRACTOR PARK CONTROL VALVE -BAILER CONTROL VALVE TRACTOR PROTECTION VALVE BRAKE CHAMBER-SERVICE CAM TYPE BRAKE ChAMBER SER. SPRING-CAM TYPE PRESSURE RESERVOIR OUAL AIR PRESSURE GAGE T a AC TOR PARKING SUPPLY SYSTEM Tac TOR PARKING SIGNAC SYSTEM mgm TRAILER SUPPLY SYSTEM t 1 " --n trailer signal system NORMAL AiR BRAKE SYSTEM air hydraulic iNTCNSIPiER TO PROMT BRAKES PROMT AXLE PNEUMATIC MVORAULIC PROMT BRAKE SYSTEM HYDRAULIC RESERVOIR TO SECONDARY RESERVOIR ANTI-RHCEU LOCK MODULATOR TO RATIO VALVE