Dynamic Driving Safety Systems
EBD
Electronic Brakeforce Distribution
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All current Mazdas with ABS have EBD (Electronic Brakeforce Distribution) which
eliminates the need for a proportioning valve. The B-Series is the only current Mazda
that still uses a proportioning valve (load sensing type) even though it is also equipped
with EBD.
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The EBD is a function, which is programmed in the ABS CM and needs only minor
modifications to the system. It allows the split in brake force to be adjusted much more
accurately according to the current driving conditions. The EBD detects the difference in
wheel slip between the front and rear wheels with the aid of the wheel speed sensors. If
wheel slip of the rear wheels compared to the front wheels exceeds a specified limit, it
reduces the brake fluid pressure applied to the rear wheels with the aid of the hydraulic
valves in the ABS HU/CM.
•
Handling response is continuously monitored and a larger proportion of the overall
braking force can be applied to the rear brakes when conditions allow. This results in
shorter brake distances and reduced wear due to less thermal stress on the front brakes.
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EBD operation stops when ABS operation starts.
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The graph shows when EBD operation begins, and when the CM changes to ABS
operation mode. Furthermore you will notice that the operation by the CM is always done
in advance, and that there is a difference in time between actuating the valves and the
resulting change in pressure/speed. This is because the electronic control is much faster
than hydraulics, and there is also an additional delay due to the momentum of the
vehicle and wheels.
Curriculum Training
02-27