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Braking system
Intakes and supplies
1. Supply to the rear brake calliper.
2. Intake from the rear brake pump.
3. Intake from the front brake pump.
4. Supply to the front brake calliper.
ABS OPERATION
General specifications:
The front circuit is similar to the rear circuit.
•
The ABS inlet valve (10 - 11) is normally open and it is closed only when the system inter-
venes to avoid wheel locking.
•
The exhaust valve (12 - 14) is normally closed and is only opened when the system inter-
venes to prevent locking.
•
With the system in stand-by mode, the ABS processor controls the wheel speed instant by
instant to assess any slippage of the wheels.
•
When in standby, the system does not intervene at all when the rider brakes; the braking
system is the same as the one without ABS.
Stages in ABS cycle (the following operations refer to the front circuit but are also applicable to
the rear one):
A - Brake activation: the rider starts braking as he would usually do.
B - Pressure reduction: coincides with the recognition of the dangerous situation (wheel slippage
exceeds the threshold): the system closes the inlet valve (10-11) and opens the outlet valve (12-13)
temporarily.
At this stage the rider cannot increase the pressure on the callipers (8-9) and the system reduces the
pressure on the callipers partially. Excess fluid temporarily fills the "reservoir" located inside the ABS
modulator until the ABS pump (16) automatically activates to direct the fluid to the brake master (2 -5).
C - Pressure maintained: the pressure in the callipers (8-9) remains low until total recovery of speed /
wheel grip.
The system restores the fluid taken from the calliper (8-9) in the section of the system between the
brake pump (2-5) and the ABS inlet valve (10-11).
D - Pressure restoration: by opening the inlet valve (10-11) momentarily, the pressure of the callipers
(8-9) is increased until maximum deceleration is reached. Then, the system gives the control over the
braking back to the rider.
BRAK SYS - 454
TUONO V4 R a-PRC ABS
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