Yamaha FZ8NA Service Manual page 18

ABS
The operation of the Yamaha ABS brakes is the same as conventional brakes on other vehicles, with
a front brake lever for operating the front brake and a rear brake pedal for operating the rear brake.
When wheel lock is detected during emergency braking, hydraulic control is performed by the
hydraulic system on the front and rear brakes independently.
Useful terms
• Wheel speed:
The rotation speed of the front and rear wheels.
• Chassis speed:
The speed of the chassis.
When the brakes are applied, wheel speed and chassis speed are reduced. However, the chassis
travels forward by its inertia even though the wheel speed is reduced.
• Brake force:
The force applied by braking to reduce the wheel speed.
• Wheel lock:
A condition that occurs when the rotation of one or both of the wheels has stopped, but the vehicle
continues to travel.
• Side force:
The force on the tires which supports the vehicle when cornering.
• Slip ratio:
When the brakes are applied, slipping occurs between the tires and the road surface. This causes
a difference between the wheel speed and the chassis speed.
Slip ratio is the value that shows the rate of wheel slippage and is defined by the following formula.
Chassis speed –
Wheel speed
Slip ratio =
Chassis speed
0%: There is no slipping between the wheel and the road surface. The chassis speed is equal to
the wheel speed.
100%: The wheel speed is "0", but the chassis is moving (i.e., wheel lock).
× 100 (%)
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FEATURES