Volkswagen Transporter 2004 Self-Study Programme page 51

Pneumatic brake assist system
The brake assist system is installed exclusively in conjunction with ESP.
The role of the brake assist system is to support the driver in emergency braking situations. In addition to
normal functioning of the brake servo, the version with brake assist system features a coil, a release
switch and a travel sensor.
Function
The travel sensor serves as a means of detecting
the speed at which the brake pedal has been
pressed. This sensor signal is picked up and eva-
luated in the ESP control unit. If the actuating
speed is > 120 mm/s, the control unit applies
voltage to the coil and the brake servo can pro-
vide maximum support. This means that the force
applied through the brake pedal is reduced. In
this way, greater pressure is built up in the brake
system.
The brake assist system is deactivated when the
control unit, via the release switch, detects that
the force at the brake pedal is reduced.
You can find more detailed information about the brake assist system in self-study pro-
gramme 264 "The brake assist system".
Duration
Normal braking
Emergency braking, without brake assist system
Emergency braking, with brake assist system
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