Electronic parking brake explained: What is an electric handbrake?

Manual gear sticks and chunky automatic gear selectors aren’t the only controls to have been replaced in a lot of modern cars by tiny switches – the humble handbrake made that transition quite some time ago. Today, only a few new cars still offer you a big, physical lever between the seats to apply the handbrake.

Known as the electronic parking brake or electric handbrake, the technology first appeared in the early 2000s, in cars such as the Lancia Thesis, E65 generation BMW 7 Series, and Renault Vel Satis - all arriving in 2001. It was quickly adopted by other luxury vehicles, and like most automotive technology, began to filter down to even the cheapest cars.

Many drivers will be familiar with the electric handbrake technology then, but if you’re not, then we’ve put together a guide on the electronic parking brake, covering its function, how it works, and some of the advantages and disadvantages of the tech.

What is an electronic parking brake?

An electronic parking brake, sometimes called an electronic handbrake (EPB), is the replacement for the old manual handbrake and a common feature in modern cars. Where once you had to pull a lever between the seats to hold the car when you parked (or if you wanted to pull a cheeky late-night 180-degree turn in the McDonald’s car park), today that function is performed by a little switch – and sometimes, entirely automatically.

How does an electronic parking brake work?

Manual handbrakes were very simple in design, and for good reason, because while they’ve always been used for securing a parked car, they also served a backup purpose as an emergency brake should the main braking circuit fail. The handbrake system was always completely separate, so it wouldn’t be affected by a failure of the conventional brakes.

Essentially, it used a ratcheted lever which pulled on a cable and clamped either pads or brake shoes onto the existing brake disc or drum. This usually happened at the rear axle, but in some older cars, it operated on the front wheels.

Electronic parking brakes take that process and replace the manual action with an electronic one. In some systems they still use a cable setup, but the action of pulling the cable is actuated by an electronic servo. In others, the servo is built into a unit at each brake disc, mounted to the caliper (or sometimes using a separate caliper), using a screw-type system to slowly push a pad onto the disc.

What features does an electric handbrake allow?

While an electronic parking brake system still isn’t particularly complicated, it does allow for a few more features than a good old yank of a handbrake lever.

The first is that the process of using the parking brake can be automated. While you’ll usually still have a switch, most EPB systems are designed to automatically release when you pull away from rest, whether you’re in an automatic or whether you’re disengaging the clutch on a manual. Some automatic cars will also automatically apply the EPB when you shift into Park.

Another feature is that the technology can be self-adjusting. Old handbrake cables could stretch over time - if you’ve been driving for a lot of years, you’ll be familiar with having to pull your handbrake on harder and higher to secure your car on a slope, and going back to the garage to get the cable adjusted or replaced. The servo in cable systems can take up slack itself, while EPBs that don’t use cables don’t have the problem to start with, and can clamp the brakes as hard as necessary each time it applies force.

The old emergency function hasn’t disappeared either. Electric parking brakes can still be used to rapidly bring your car to a halt if the conventional braking circuit fails. While we’d not recommend trying this in a place with other traffic around, a pull or press of the switch while your car is in motion will quickly actuate the electronic brake to stop the car.

With a tiny switch rather than a large lever, EPBs have also allowed car designers to move that function more or less anywhere within the car’s interior, within reason. Common places for the EPB switch include the centre console between the seats, in the same bank of switches as a car’s transmission selector, or sometimes, lower on the dash beside the driver’s door – where some cars used to have the release lever for a foot-operated parking brake.

What are the advantages?

Ease of use is one of the advantages of an electronic parking brake. Not that pulling on a lever was ever particularly difficult, though there’s no ambiguity with an EPB - it’s either on or off, and for drivers who struggle with hill starts in particular, it’s a godsend. 

An EPB won’t let you roll backwards if you get the timing wrong – it simply won’t disengage until you’re good to go, though regular hill hold functions using the normal braking system have also made things easier in this area. Automatic actuation, both on and off, means you barely need to think about pulling away on a hill in modern cars.

As the switch doesn’t take up much room, modern cars also tend to make use of the old handbrake space for greater storage, which is always useful. And as we’ve already mentioned, they don’t need periodically adjusting, a minor but frequent frustration with old fashioned handbrake levers.

What are the disadvantages?

Aside from taking away the temptation and childish pleasure of a quick ‘Juha Kankkunen’ in an empty snow-covered car park, EPBs still aren’t perfect, useful though they are.

For one, manufacturers haven’t settled on the ideal location for their parking brake buttons yet, nor even a consistent shape, so if you spend any time switching between cars as a family, or use a rental car, or buy a new model, you’ll probably spend the first few drives forgetting where the switch is when you need it.

Perhaps more frustratingly, there’s not a consistent standard for how they operate either – some require a press to engage, others a pull. Some can also be quite picky about how they release – if you’ve not met whatever criteria it needs for you to pull away from a stop, the systems can be prone to just staying on, making the car squat embarrassingly on its haunches as you try and pull away with the brakes still stuck on.

And while the systems aren’t prone to failure, it’s not quite the cheap and simple fix to replace when they do. While a regular handbrake might cost £100 to replace, figures of £500, and in some cases upwards of £800, aren’t unusual when replacing actuators and pads for electric parking brakes.

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