Design

Design

Parking brake switch




The parking brake switch has three positions of which two are counter sprung and the third is the neutral position.
The parking brake switch consists of a number of smaller switches. The switch has 6 terminal pins. When the switch is activated the smaller switches open and close inside the switch. This creates a pattern for the 6 terminal pins. The Park Brake Module (PBM) recognizes certain approved patterns for activating and deactivating the parking brake. If a faulty pattern occurs the Park Brake Module (PBM) indicates this by a diagnostic trouble code being set.
Background lighting/instrument lighting for the parking brake switches are supplied with voltage via the central electronic module (CEM).

Brake caliper right/left




The brake caliper which is used together with the Park Brake Module (PBM) is a special design. The brake caliper consists, in addition to the normal components of a brake caliper, an electric motor, a gearbox and a shaft/spindle which presses on the brake pad. The electrical motor is connected directly to the Park Brake Module (PBM). For vehicles equipped with Park Brake Module (PBM) there are two brake calipers of this type located on the rear wheels. These brake calipers replace the normal brake calipers. The brake caliper has a connection for the hydraulics and functions as a normal brake caliper when the parking brake is not used.

Parking brake activated




When the parking brake is activated the electric motor provides a torque which is transferred to pressure via a spindle. The spindle is located in the brake piston and presses on it so that the brake pads are applied. When the current to the electric motor is broken (the vehicle is parked) the self-locking thread on the shaft retains the brake pressure.

The Parking brake is released




When the parking brake is released the spindle is wound back and the piston releases the pressure. The shaft remains in position.

The spindle follows the wear on the brake pads




The spindle on the shaft is screwed out continuously with the piston in order to follow the wear in the brake pads. The spindle applies the pressure in the same way the entire time.