Yamaha 2007 FZ6-NA Service Manual page 20

f. Controlling zone
g. Slippery road surface
Wheel slip and hydraulic control
The ABS ECU calculates the wheel speed of each wheel according to the rotation signal received
from the front and rear wheel sensors. In addition, the ABS ECU calculates the vehicle chassis
speed and the rate of speed reduction based on the wheel speed values.
The difference between the chassis speed and the wheel speed calculated in the slip ratio formula is
equal to the wheel slip. When the wheel speed is suddenly reduced, the wheel has a tendency to
lock. When the wheel slip and the wheel speed reduction rate exceed the preset values, the ABS
ECU determines that the wheel has a tendency to lock.
If the slip is large and the wheel has a tendency to lock (point A in the following figure), the ABS
ECU reduces the brake fluid pressure in the brake caliper. The ABS ECU increases the pressure of
the brake fluid in the brake caliper when the tendency to lock has diminished (point B in the following
figure).
a. Vehicle speed
b. Wheel speed
c. Pressurized
ABS operation and vehicle control
If the ABS starts operating, there is a tendency of the wheel to lock, and the vehicle is approaching
the limit of control. To make the rider aware of this condition, the ABS has been designed to gener-
ate a reaction-force pulsating action in the brake lever and brake pedal independently.
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.
The higher the side force on a tire, the less traction there is available for braking. This is true
whether the vehicle is equipped with ABS or not. Therefore, sudden braking while cornering is not
recommended. Excessive side force, which ABS cannot prevent, could cause the tire to slip side-
ways.
d. Depressurized
e. Brake force
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FEATURES