Wheel Slip And Hydraulic Control; Abs Operation And Motorcycle Control - Yamaha 2003 FJR1300 Service Manual

CHAS
ANTI-LOCK BRAKE SYSTEM (FJR1300A)
EAS00875

Wheel slip and hydraulic control

The ECU (ABS) calculates the wheel speed of
each wheel according to the rotation signal
Motorcycle speed
received from the front and rear wheel sen-
sors. In addition, the ECU (ABS) calculates the
motorcycle chassis speed and the rate of
speed reduction based on the wheel speed
Wheel speed
values.
The difference between the chassis speed and
Pressurized the wheel speed calculated in the slip ratio for-
mula is equal to the wheel slip. When the
Depressurized
wheel has a tendency to lock, the wheel speed
is suddenly reduced. When the wheel slip and
the wheel speed reduction rate exceed the
Brake force preset values, the ECU (ABS) determines that
the wheel has a tendency to lock.
If the slip is large and the wheel has a ten-
dency to lock (point A in the figure), the ECU
(ABS) reduces the brake fluid pressure in the
brake caliper and increases the pressure of
the brake fluid in the brake caliper when the
tendency to lock has diminished (point B in the
figure).
EAS00876

ABS operation and motorcycle control

If the ABS starts operating, there is a tendency
of the wheel to lock, and the motorcycle is
approaching the limit of control. To make the
rider aware of this condition, the ABS has been
designed to generate a reaction-force pulsat-
ing action in the brake lever or brake pedal.
NOTE:
_
When the ABS is activated, a pulsating action
may be felt at the brake lever or brake pedal,
but this does not indicate a malfunction.
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