Anti-Lock Brake System - Lotus Evora 2011 Owner's Handbook Manual

Anti-lock Brake System

The Anti-lock Brake System (ABS) is used to optimise brake
performance in extreme conditions and reduce the potential
for any wheel to lock up. Under most conditions, the maximum
braking force is provided by a wheel which is rotating at about
90% of road speed. Apart from the likelihood of increasing the
stopping distance, a locked wheel provides little or no steering
force, such that with both front wheels locked, movement of the
steering wheel has no effect on car direction. With the anti-lock
system, even panic braking results in controlled deceleration and
the retention of steering response. ABS is especially advanta-
geous when braking on slippery road surfaces and in bad driving
conditions, but it is important to realise that the ABS cannot
increase the friction level at the road surface, but can only make
optimum use of the grip available.
WARNING
When driving in adverse weather, or on poor road surfaces,
always be alert to the possibility of slippery conditions and
make the necessary allowance for increased stopping distances.
Failure to do so may result in an accident in which you or others
may be killed or seriously injured.
Normal braking, controlled by the pressure applied to the
brake pedal, occurs when the road conditions allow for the
required deceleration to be achieved without danger of wheel
lock. The relative speeds of the four wheels are continuously
monitored by the ABS when the brakes are applied, and if one or
more wheels begin to lock, the brake pressure to that wheel(s) is
modulated by the ABS to help keep the wheel rotating and provide
the maximum controlled braking force. The wheels may appear
to lock momentarily as the wheel speed rapidly changes, and
some tire noise (intermittent screeching) may be heard which is
normal and will vary with road and tire conditions. Note that the
ABS does not function at speeds below 5 mph (7 km/h).
When the ABS is activated, the driver will feel a 'pulsing' sen-
sation at the brake pedal as the fluid pressure is modulated, and
may also hear clicking from the control solenoids. These signals
indicate to the driver that maximum braking is occurring, and that
driving style should be modified to suit the conditions.
The minimum stopping distance is achieved by applying the
brakes firmly and steadily, and allowing the ABS to modulate
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