How it works: Electronic parking brakes

Electronic park brakes started to appear in vehicles from the early 2000s. They've arrived with little fanfare, but there are solid reasons for the global automotive industry adopting the new technology.

With this electronic system there is no need for a cumbersome lever fitted in the vehicle cabin, and nor is there any need for a cable mechanism to the rear wheel brake callipers.

The tiny switch in the centre console frees up space in the cabin for important conveniences such as more cup holders or an ashtray or an audio-system volume-control knob. This switch can theoretically be fitted anywhere in the cabin but located in the centre console, near the gear shift lever, it remains within easy reach of the driver. Companies like Porsche and Mercedes-Benz swim against the tide, placing the switch in the dashboard, to the right of the steering column. There, it's still easily operated by the driver, but allows even more free space for comfort and convenience features in the centre console.

This system uses either a separate Electronic Park Brake Control Module or it runs as a function of the Stability Control Module (depending on manufacturer). To accommodate the electronic parking brake, the rear brake callipers operate by means of a hydraulic/electric system rather than hydraulic/mechanical.

To actuate the system the driver simply pulls the park brake switch (or presses it down in some cars). This sends a signal to the park brake control unit, which in turn sends a signal to activate the electric motors on the rear brake callipers. These then apply the brake. To release the Park Brake the driver pushes (or pulls) the Park Brake switch and the electric motors are activated to release the rear brake callipers.

As mentioned previously this system frees up some space in the vehicle, however it has some other advantages too. Being electronically controlled means some functions can be automated, such as auto release. In most cases if the driver's door is closed, the driver's seat belt is on and the gear select lever is in Drive, the driver can simply touch the accelerator pedal and the park brake will automatically release.

On the other hand if the driver forgets to apply the park brake it may be programmed to operate automatically, if the gear select lever is in Park or Neutral and the seat belt is released as the door is opened. Not all manufacturers offer this sort of facility.

The electronic Park brake can also be used for other functions, such as Hill Start Assist. This system applies the rear brakes when a vehicle is stopped on an incline, holding the vehicle for the short time it takes the driver to move his or her foot from the brake to the accelerator, thus preventing vehicle roll back.

Depending on the individual vehicle set up the EPB can be used as an emergency brake. By simply lifting/pressing or pulling/pushing the EPB switch and holding it up the park brake will be applied, bringing the car to an emergency stop.

There are some precautions the service technician must observe when working on a car's EPB. If any work is to take place the car must first be placed in service mode. As you can imagine, your technician won't want the park brake applied while he or she has one or more fingers in the way. Also if the park brake is applied while the calliper is removed from the brake disc it may pop the calliper piston out, damaging the calliper.

All in all this is a simple but clever system that also boasts the advantage of needing no adjustment, since there is no cable to stretch over time. And that means you'll never again have to yank hard on an archaic lever to hold a car locked in place on the side of a hill.