Car Hand Brake - Its Working Principle, When To Use It And When Not To

Hand brakes, also called parking brakes, e-brakes or emergency brakes as the case may be were you are from. is the lever to a completely mechanical braking system, which will bypass the primary hydraulic system if it fails.  in this article we shall discuss

• the basic mode of operation of the hand brake

• when to use the handbrake

• when not to use the handbrake

When the handbrake is applied, the brake cable passes through an intermediate lever, to increase the force of your pull; this force is then split evenly between your brakes by an equalizer.Well, handbrakes are cable-actuated for a start so the amount of power they have is wholly dependent on the amount of tug you have in your arm. So with handbrake, there's no hydraulic system to help you out.

Whilst they're good for doing handbrake turns, they're not especially effective at actually slowing you down. They will - don't get me wrong - but you won't be seeing any spectacular performance out of them. Although it is reassuring to have a secondary braking system for emergencies, the primary use of the handbrake tends to be when parking as they remain engaged until a release button is pressed; stopping your car potentially rolling away. This is good practice, as it keeps your brake cable from seizing up, ready for when you really need it.

So why the term 'emergency brake? It is because it stands in when the hydraulics fail. However don't expect the spectacular.

Hand brake only work on the rear wheels, so you're not getting four-wheel braking. On drum-brakes, the handbrake is connected to a small lever that pivots against the end of one of the brake actuating pistons. When you pull the handbrake, the lever gets pulled and the brake shoes are pressed out against the inside of the drum.

On disc brakes, the handbrake normally works a second set of brake pads in the rear caliper. They're little spots, about the size of a grown man's thumbprint and they're clamped mechanically against the brake rotor. These pads never need changing because they're normally only used at standstill so generally don't wear much. Their small size is the other reason you shouldn't expect spectacular stopping performance if you yank on the handbrake. In fact, using your handbrake to stop a moving car can actually damage the brake system, so it is best to save this for real emergencies!

 That being said, there are derivatives of disc-based handbrakes that use a mechanical arm to press the main brake pads against the rotor although these are less common as far as I know. It's worth spending a moment here to talk about handbrakes.

When to use handbrakes

Typically you ought to use your handbrake whenever you're stopped somewhere, be it parked, on a hill or waiting at traffic lights. The reason is simple : if you're parked or stopped, you generally don't want the car to run off without you. At traffic lights, it's an accident minimization function as much as anything. If you're sitting there with your foot on the brake and someone drives into the back of you, the impact will cause you to take your foot off the brake and you'll go sailing into the car in front, causing more accidents. If you have the handbrake on in the same scenario, your car will largely stay put (apart from the initial shove across the ground as the energy from the impact is dissapated through your tyres). 

Of course there are personal habits and mechanical complications to contend with here. For example in a car with an automatic gearbox, it's force of habit to just use the footbrake. Even so, you should still use the handbrake when you're parked, especially on an incline. The 'park' setting on automatic gearboxes isn't sufficient to hold a car on a hill, and apart from that, it puts incredible strain on the transmission and clutch system if you let the whole weight of the car transfer into the transmission to try to keep it from moving.

In some American cars, the handbrake isn't a handbrake at all, it's a second footbrake on the far left side of the footwell, which is basically totally useless because it's a pain to put on and even more of a pain to get off because it's a one-way ratchet system (you have to force the pedal all the way down to get it to release). Then there's the ignorance factor. When I went to my new owners orientation evening after buying a Subaru in America, one lady asked what the parking brake was for. (Apparently the name wasn't obvious enough). The dealer representative told her it was a relic of days gone by, not to be used, and he didn't understand why manufacturers even put them in cars any more!

When not to use handbrakes

The first and most obvious answer to this is : when you're going at any speed. If you yank on the handbrake at any speed much over 30km/h, the back end of your car will start to slide. Great for stunts and tricks, not so great if you're trying to stop in 5 lanes of crowded motorway traffic.

The other time you should not use your handbrake is in post-snow, freezing conditions. With the salt and grit that gets put down on the roads, you'll be driving through a salty, snowy slush and it will be spraying all over the underside of your car. If you park and put the handbrake on, you risk it binding on by freezing. 

Why? Well handbrake cables are almost always exposed to the elements at some point under your car. If you put the handbrake on and the cable is covered in slush, as it freezes again it will lock the handbrake on. There's no solution to this other than waiting for the weather to warm up. Well, not unless you fancy a crack at the Darwin Awards, because some people have tried using blowtorches to thaw the ice, not understanding that they were working right underneath the petrol tank. So here's a tip : don't.
If you need to park in those types of conditions, try to find level ground and leave your automatic gearbox in "p" or your manual gearbox either in first or reverse gears.

Regional variations

One last thing to know about handbrakes : for some reason, from-the-factory settings on handbrakes vary largely with region. In Europe for example, the handbrake is easily capable of exerting enough friction to prevent the engine from being able to move the car from standstill. In America, it's not uncommon to see handbrakes adjusted to lightly that even when fully on, you can just drive off. The only way you'll notice is the handbrake light on the dash, the lack of performance, or the smell of burning as your rear brakes burn off. 

Read more about hand brakes from Carbible.com