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Anti-lock Brake Systems ABS. ABS. designed to prevent wheel lock-up to minimize stopping distance & help maintain steering control by preventing wheel lock-up, tires will maintain traction with road surface is also used on motorcycles and even trucks & buses with air brakes. ABS System.
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ABS • designed to prevent wheel lock-up to minimize stopping distance & help maintain steering control • by preventing wheel lock-up, tires will maintain traction with road surface • is also used on motorcycles and even trucks & buses with air brakes
How Many Channels? • a channel describes a hydraulic brake line that is capable of being controlled by the ABS module
Wheel Speed Sensor • wheel speed sensor is a magnetic impulse sensor • works like a crankshaft position sensor • creates an AC voltage signal as the tone ring rotates with the wheel • the AC voltage signal frequency changes as the wheel speed changes
AC voltage ripple frequency will change with wheel speed changes
Modulating Brake Fluid Pressure • Electronic Brake Control Modulator EBCM • EBCM-activated solenoids modulate brake fluid pressure • the solenoid valves can (while driver is stepping on pedal) either… • hold (maintain) pressure • dump (release) pressure • increase pressure • these solenoids can cycle the brakes 15 times/second Hold Pressure Dump Pressure Increase Pressure proportioning valve is no longer needed!
Electronic Brake Control Module (EBCM) • interaction between inputs, EBCM & outputs
ABS Modulator • may be attached to the master cylinder • integral ABS • may be mounted separate from the master cylinder • non-integral ABS