Operating Principle - Ducati MULTISTRADA 1200S ABS 2015 Workshop Manual

Operating principle

The Anti-Lock Braking System (ABS) has been developed to enable riders to use the motorcycle braking force to
the fullest possible amount in emergency braking or under poor pavement or adverse weather conditions. ABS is
an electro-hydraulic device that controls the pressure in the brake circuit when the control unit, by processing
information from wheel sensors, determines that one or both wheels are about to lock up. In this case, pressure
decrease in the brake circuit allows the wheel to carry on turning, thereby preserving grip. After that, the control
unit restores the pressure in the brake circuit, to resume the braking action. This cycle is repeated many times
until the problem is completely eliminated. The system can modulate pressure at the calliper through a set of
solenoid valves which first prevent any further increase of hydraulic pressure (EV valve closing), and then make
the pressure decrease (AV valve opening). When the wheel begins to turn again in response to the diminished
braking force applied and its speed reaches the reference value, the AV release valve will be closed.
Simultaneously, the EV inlet valve is reopened, restoring normal operation of the brake system.
Normally, the rider will perceive ABS operation as a harder feel or a pulsation of the brake lever and pedal. The
front and rear brakes use separate control systems.
The Ducati ABS functionality is disabled at vehicle speeds lower than 5 km/h.
The Multistrada 1200 is provided with further functions compared to the standard ABS as outlined below:
- "ABS cornering" function that widens ABS functionality to the conditions where the motorcycle is leaning over,
thus controlling the front and rear brake systems depending on the vehicle lean angle with the purpose of
preventing wheel lockup and slipping as much as possible, within the physical limits allowed by the vehicle and by
the road conditions. The ABS system limits the braking gradient and pressure at the calliper upon the first braking
besides the standard ABS mode with pressure reduction and increase at the calliper to prevent the wheel from
blocking.
- braking force distribution only from the front to the rear wheel allowing to restore the bike track alignment
during the braking. By means of the ABS valve activation, the pressure on the front calliper is released and thanks
to the dedicated valves called USV and HSV and the ABS pump the pressure is increased at the rear calliper.
- anti lift-up function that improves the feeling during strong braking especially on the front wheel.
These functions are divided into 3 different levels, each associated with a Riding Mode.
According to the selected level, some of the just described functions will be disabled. Refer to the owner's manual
of the Multistrada 1200 for further details.
If desired, the ABS system can be deactivated from the instrument panel, setting the level to OFF within the Riding
Mode for which you wish to disable it.
The hydraulic component of the ABS system consists of a primary circuit (from the cylinder to the control unit and
from the control unit to the calliper) and a secondary circuit (completely within the control unit). Please find below
the ABS system hydraulic diagram.
Key to ABS hydraulic system colours:
Green: oil delivery
Light blue: oil return
Key to ABS hydraulic system
A Rear brake master cylinder
B Front brake master cylinder
1A Rear brake calliper inlet valve
1B Front brake calliper inlet valve
2A Rear brake calliper exhaust valve
2B Front brake calliper exhaust valve
3 Master cylinder
4 Little tanks