User manual BENDIX MC-12 MODULATOR CONTROLLER ASSY

[. . . ] ® Bendix® MC-12TM Modulator Controller Assembly DIAGNOSTIC DISPLAY DIAGNOSTIC DISPLAY EC-12TM CONTROLLER M-12TM MODULATOR DELIVERY PORTS (4 VERTICAL) 14 PIN CONNECTOR CONTROL PORT DELIVERY PORTS (2 VERTICAL 2 HORIZONTAL) FIGURE 1 - MC-12TM MODULATOR CONTROLLER ASSY. DESCRIPTION The Bendix® MC-12TM modulator trailer antilock system is designed to improve vehicle stability by reducing wheel lock up during aggressive braking. Like Bendix's tractor antilock, the trailer system can provide single or tandem axle control. The main component is nipple mounted to a reservoir, so the system requires no special trailer modifications. The trailer antilock system consists of the following: MC-12TM modulator/controller, WS-20 TM wheel speed sensors, electrical connectors and wiring. [. . . ] Make several trailer brake applications and check for prompt application and release at each wheel. With the trailer service brakes released, coat the exhaust port and the area around the retaining ring with a soap solution. A 1" bubble in 3 seconds is permitted. With the trailer service brakes fully applied, coat the exhaust port with a soap solution. A 1" bubble in 3 seconds is permitted. Coat the outside of the modulator body to check for seal ring leakage. If leakage is excessive around the supply and exhaust solenoids, replace the M-12TM modulator. If excessive leakage is detected where the solenoid assembly and M-12 TM modulator body meet, replace the M-12 TM modulator. If excessive leakage is detected at the exhaust port, before replacing the M-12TM modulator perform the following test: Place the vehicle in park by exhausting the air pressure from the emergency side of the spring brake. Perform the leakage check around the exhaust. If the air continues to leak out the exhaust replace the M-12TM modulator. If a leak exists between the emergency and service sides of the spring brake, the leakage at the exhaust will cease when air pressure is exhausted from the emergency side of the spring brake. The air pressure will pass from the emergency side to the service side of the chamber, out the service inlet and out the M-12TM modulator exhaust. ASSEMBLY--REFER TO FIG. 291126) lightly coat all o-rings and the bores of the valve body. Install spring seat (9) onto the inlet/exhaust valve (8) so that it covers the rubber seat of the inlet/exhaust valve. Place the inlet/exhaust valve, large diameter first, into the M-12TM modulator's bottom bore. Install spring (10) over the barrel of the inlet/exhaust valve (8) so that one end of the spring rests on the spring seat (9). Install the o-rings (11 8 12) into the respective grooves of the O. D. Place the large diameter of the exhaust assembly against the spring (10) and compress the spring until the exhaust assembly enters the bore of the body and the o-ring (11) seals against the wall of the bore. Depress the exhaust assembly into the bore until it exposes the groove for the snap ring (14). Install o-ring (5) into its groove in the piston (6). Install piston (6) into the M-12TM modulator body. [. . . ] INSPECT CONNECTOR, THEN CHECK RESISTANCE BETWEEN PINS ON SENSOR. IF RESISTANCE IS NOT CORRECT (BETWEEN 1500-2500 OHMS FOR THE BENDIX® WS-20TM SPEED SENSOR), REPLACE SENSOR, OTHERWISE PROCEED TO STEP B. CHECK "GAP" BETWEEN SPEED SENSOR AND EXCITER OR TONE RING. (GAP FOR BENDIX® WS-20TM SPEED SENSOR, SPEED SENDER IS BETWEEN 0 - . 015 INCHES) IF SENSOR GAP MUST BE ADJUSTED, CHECK FOR LOOSE OR WORN WHEEL BEARINGS BEFORE RE-GAPPING SENSOR. [. . . ]