Brakes - SMART Series 451 Service Manual

SN_Typ 451_us.book Seite 69 Freitag, 30. November 2007 1:56 13
Task
The task of the brake system is to brake the vehicle or
hold it at a standstill.
The system includes the service brake, which brakes
the vehicle while it is being driven, and the parking
brake, which secures the vehicle when it is at a stand-
still.
Components of the parking brake
• Hand brake lever with hand brake cables
• Parking brake mechanism integrated into rear
drum brake
Function of parking brake
When the handbrake lever is actuated, a relay lever is
actuated at the rear brake shoes of the left and right
drum brakes via the handbrake cables. This presses
the brake shoes of the drum brakes against the
insides of the brake drums to build up the required
brake force.
Components of the service brake
• Disk brakes with brake calipers on front axle
• Drum brakes with aluminum wheel brake cylinders
on rear axle
• Brake fluid reservoir
• Brake lines and brake hoses
• Brake pedal module
• ESP unit, consisting of ESP control unit and ESP
hydraulic unit
Function of service brake
The service brake is a hydraulic 2-circuit brake
system with TT (front/rear) split.
The force applied to the brake pedal is transferred to
the brake booster via a linkage. The brake booster
multiplies this forces and uses it to pressurize the
master brake cylinder. The brake pressure is built up
via the master brake cylinder.
The brake force is distributed to the disk brakes and
drum brakes by the ESP unit via the integrated
antilock brake system (ABS) and the electronic brake
force distribution (EBD) system.
Introduction of the smart fortwo, Model Series 451

Brakes

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