TM-9-2320-283-13-P
ANTI-LOCK BRAKE SYSTEM (ABS) M915A1
TECHNICAL MANUAL; OPERATOR AND FIELD MAINTENANCE MANUAL INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST (RPSTL)
AUGUST 2012
TM-9-2320-283-13-P - Page 28 of 400
TM 9-2320-283-13&P
0002
0002-2
LOCATION AND DESCRIPTION OF MAJOR COMPONENTS – CONTINUED
TONE RING – There are four tone rings each located on inner bearing and seal end of hub at the front and
rear-rear axles. The tone ring rotates with hub and wheel assembly and passes in front of wheel sensor. The
tone ring is a round steel disc with equally spaced open slots near its outer circumference.
TONE RING
MODULATOR
Figure 2. Tone Ring.
MODULATOR – There are four identical modulators each located inside frame rails near front and rear-rear
axles. The modulator is controlled by the ABS ECU and rapidly applies and releases air pressure to control
braking force at the wheel. The modulator is an electrically operated valve connected to ECU via modulator
harness, and has inlet and outlet ports connecting it from the air supply to the brake chamber.
Figure 3. Modulator.
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