car emergency brakes

I know very little about cars, other than how to drive one (and not even much about that). Somebody please explain to me the point of the emergency brake, and how I can manage to not only drive, but drive for 50 miles on a highway going 60+ mph with the brake still on???

First off it’ll depend on what type of brakes you have, how hard the brake was set and what condition your rear brakes are in. Most cars (up until recently, but still alot) have drums in the back. The E-brake just sets those brakes. Drum brakes arn’t all that great, at least compared to the discs you have in the front. Also, if it wasn’t pulled that far you probably wouldn’t notice it at all. I have to assume that if you managed to drive that far, either the brake wasn’t set that hard, or your rear brakes are shot now and should probably be looked at. Even if they didn’t wear all the way down, you probably over heated them enough to warp the drums. The point of an e-brake is at least three fold First, it keeps the car from rolling in the even that the pin in the transmission brakes while your in park, when you put your car in park, it’s actually neutral but the transmission is locked by a pin. Second, when you park in a hill, you want to (first angle the wheels appropriatly) keep your foot on the brake, pull the e-brake, then put the car in park, the idea is that this will keep the car from rolling those few inches and putting stress on that pin (torque lock) making it difficult to get the car back out of park, all though I’ve never actually seen that happen myself. Third, in the even that you lose all of your breaks (it would take quite an even to lose all four, but that’s another thread) this allows you to slow down by using the e-brake, since that is actuated by a cable and is compleatly independent of the hydraulic system the rest of the brakes use. (also in this even shut the car off and probably leave it in drive as the resistence of the transmission and engine will help to slow you down).

The emergency brake was provided originally as a back-up in case the foot brake failed. For safety purposes you don’t need redundant systems for making the car go. However, one the car is in motion is is a real good idea to have more than one way to make it stop.

When hydraulic brakes came along the emergency brake was doubly necessary because a leak in the hydraulic brake system would leave you with no brakes whatever.

Brakes are now dual systems with separate hydraulic brakes systems for front and rear brakes and the probability of complete failure is less likely than with a single system.

It is useful for parking on hills, etc.

Rule #1 about emergency brakes. When you set the damned thing set it so that there is no doubt that the brake is on. Don’t be namby-pamby about it. That way you only will be able to drive with it on if you stay in low gear at full throttle, and maybe not even then.

While the emergency brake is certainly better than nothing as a back-up for the service brakes, it doesn’t stop a moving car very effectively. It’s often – I would say usually – called a parking brake, as it’s much more useful for that purpose.

Some parking brakes work so well that the car won’t take off when they’re applied. Others will slow it down noticeably, but not prevent it from moving, and others have no noticeable effect. This is largely a matter of the parking brake mechanism being in good repair and proper adjustment, though the particular design can also be a factor.

So to sum up the answers to your specific questions, the point is mainly to have a parking brake (especially useful with a manual transmission, but still a good idea to have and use with an automatic), and you were able to drive with it on because yours either doesn’t work as well as it should or wasn’t fully applied.

By the way, if the parking brake doesn’t hold, it doesn’t hold. How far you go with it on may make a difference in how much extra wear its components get, but if it will drive at all with the parking brake applied, it will drive indefinitely with the parking brake applied. So there’s nothing significant about your going 50 miles with it on – it could have been ten feet or 5,000 miles, same difference.

The answers so far assume an automatic transmission.

With a manual transmission, only friction and compression in the engine prevent the car from rolling. Even an engine in good condition may allow the car to slowly roll (creep) on a steep grade, so it is important to make a habit of setting the parking brake. Actually getting in this habit isn’t a bad idea, because the habit of disengaging the parking brake before starting will also be engrained.

On a standard, the brake serves an additional function: Uphill starts can be done with no back-roll, and generally easier on the clutch if the brake is used to hold the car in position untill the clutch is providing enough thrust to prevent back rolling. This is most easilly done with a hand operated brake, and that is one reason hand operated e-brakes are more common on manual transmission cars.
A foot operated brake is still usable in this case, but you get no second chance if you misjudge and release the brake early…thus it is easier to do a smooth start with a hand operated brake.

I would consider that to be a safe bet based on the OP.


Even someone who doesn’t know much about cars, as the OP stated, would most likely know that the e-brake (or parking brake) keeps the car from moving when it’s not in use and probably wouldn’t ask what the point of it is.

Yes, I am aware that the emergency brake is an extra precaution for when I am parked. The GQ that I am really trying to ask is that if this is an extra precaution, then WHY can I even start moving at all with it applied? It only gives me the impression that the brake isn’t even doing its job!

How far was the brake pulled? How old is the car? How old are the brakes?

The brake pedal (the one next to the gas pedal, that you normally use for stopping) is a hydraulic system. Basically, that means that a small force applied to the pedal by your foot is translated into a large force applied by the brake. So, it doesn’t take all that much foot pressure to apply the brakes sufficiently to stop your car.

The emergency/parking brake, on the other hand, has a cable that connects the lever inside the car directly to the brakes. So the amount of force that you apply to that lever is essentially the same force that gets applied to the brakes. (Not to even mention that the brake pedal operates both the front and rear brakes, whereas the parking brake lever operates just the rear brakes). So it’s a lot harder to apply the parking brake with enough force to keep the car from rolling than it is to apply the foot brake with enough force.

So, if you are like most people and you just casually pull up on the parking brake lever, it’s not going to be putting all that much pressure on the brakes. The brakes are not going to be set very tightly, and so it will be similar to you just pressing lightly on the brake pedal. The brakes are just not being applied with enough force to keep the car from moving when you step on the gas.

Here’s something to try: Drive into an empty parking lot, stop, and pull up the parking brake lever the way you normally do. Put the car in Drive and take your foot off the brake pedal. If the car actually rolls forward, it means that your parking brake isn’t doing squat. So stop, and now try pulling up really hard on the parking brake lever. If you can’t get it to even stop the car from rolling, then you should have it looked at by a mechanic, because something is likely wrong.

If it at least stops the car from rolling, now try giving your car some gas. If it doesn’t take much gas to get moving, then again, stop and try pulling up harder on the lever. If you can get to the point where you really have to gun the car in order to get it to move, then your parking brake is working ok, and you’ve learned how hard you need to pull up on it in order to make it effective at its job.

Boy, here is a rare occurence, I am going to have to disagree with Gary T!
On some cars with rear disc brakes, the parking brake / E brake applies pressure to the rear brake pads to hold the car when parked. If the brake is not fully applied, the brake rotor will turn while the pads are pressed (lightly) against it. This causes accelerated wear of the rear brake pads, and can cause them to get worn out in just a few thousand miles. Just like would happen if you drove around with your left foot pressing on the brake pedal all the time. :smack:
I also know of one case where a customer had their car towed in to the dealer for two complaints:

  1. Car did not seem to have much power
  2. Both rear tires were flat
    You guessed it, they had applied the parking brake full on, and then proceeded to drag the rear wheels until they both went flat. I did not believe the technician when he told me, so I tried it with my training car. I could drag the rear wheels! :eek: The car was very slow.
    Getting back to the OP.

There should be a big RED light on the dash whenever the parking brake is applied, and the engine is running. If you see a red light you should stop and discover what it is. The next one might be a low oil pressure light, and a blown engine could be the result. Those red light are there for a reason, learn what those little hyroglyphics mean, they are important!

What are you disagreeing with?

In my post I said “How far you go with it on may make a difference in how much extra wear its components get…” which seems to be what you’re referring to here.

The OP mentioned going 50 miles as if he thought that was worse than if it had only gone 5 miles. My point was that if it will go 5 feet, it could just as well go 5 miles or 5000 miles – the parking brake isn’t holding, and it’s not going to magically start doing so after travelling any given distance.

It’s a good idea to look and see if that light is functional. In the 15 or so cars I’ve owned, only a few of them had a working parking brake indicator.

The only car that didn’t have one was my '65 Mustang which had no warning lights but “Oil” and “Generator”.

The new cars I’ve owned seemed to be the worst for not having a working indicator. Specifically, a '98 Mustang, a '01 Mustang, a '97 Dodge Avenger and a '91 GMC Truck. None of these ever had a working brake indicator. My '85 LeBaron which my dad had bought brand new had one for the first year or so and then it quit working along with all of the other warning lights (except for the low wiper fluid, which stayed on permanently until I disconnected it at the fluid tank).

That’s essentially right, as answered and explained in posts # 2, 3, & 4.

Do you have a cite for any of this? IMO it’s entirely wrong, at least in terms of cars on the road today.

I think the answer that the OP is looking for is that the parking brake is designed to prevent the car from rolling when parked, and that’s all. It’s purpose is not to turn the car into an immovable object, or to serve as a backup if the road brakes fail. (Yes, in an emergency you can give it a try, but AFAIK, it is not designed with that function in mind.)

The force the parking brake is intended to counteract is quite small, i.e. the force of gravity acting on a stationary car parked on a shallow incline. (In places where steep streets are common, like San Francisco, people are routinely advised to turn their wheels into the curb, to reduce the chance of an accident if the parking brake fails.)

On the other hand, in most modern cars, the force that the engine can apply to the wheels is much, much greater than the force that the parking brake is designed to overcome. Thus it is possible to drive off with the parking brake set. Especially if it is old and worn or wasn’t set very firmly in the first place.

A properly functioning and set parking brake should make the car noticeably more sluggish, but that depends on the driver paying a little attention, which, in my experience, many drivers do not do. (This is a general comment, and not intended as a poke at the OP.) If you didn’t notice anything, it was probably worn out or not set firmly.

Now, obviously, you should have it repaired, if you haven’t already done so.

Well, let me state that I have been a consultant to Bosch and Delphi in the past so can state a few things. . . First of all, if you look at your owners manuals, it is NEVER referred to as an emergency brake. This is because that implies that it was designed to be used in an emergency situatuion. Not so, it’s a parking brake. Only designed to withstand the loads applied in a parking situation.

That said, it’s fun to go out on a snow covered road and yank the damn thing and do some cool donuts! :cool: But really, they only design them to handle parking on hill type stuff. Use it for other things and you are on your own.

Will it stop you from carining down Pike’s Pike at 80mph. Maybe. But it’s not designed to do so. YMMV. :wink: It could very well over heat and break off, it’s normally just a racheted pawl device, the pawl (catch) is usally just a catch in an 1/8" piece of sheetmetal. Not something that you would want to place your life, or your family’s life in.

They are working on emergency brakes for vehicles like school buses and UPS trucks. But don’t expect to see them on commercially available passenger vehicles anytime soon. Just to expensive for everyday use.

That’s not necessarily true. If you drive for a while with the parking barke set firmly, the brake pads/discs can melt. Then if you stop for a moment, they can freeze and fuse together, locking up the wheels. I don’t know how often it happens, but I have heard of it happening.

Perhaps this summation will more clearly address the OP’s questions:

The point of the parking brake is to keep a stationary vehicle from rolling without the driver having to stay in the car with his foot on the service brake pedal. While the parking brake can and sometimes does act as an emergency brake, it has nowhere near the stopping power of the service brakes.

Whereas service brakes use a hydraulic system that operates on all four wheels, the parking brake uses a mechanical system that operates on only two of them. With its inherent lesser braking ability, its tendency to suffer mechanical wear and get out of adjustment, and the fact that it can be partially applied without the driver necessarily realizing it, it’s not uncommon for it to fail to restrain the vehicle from the driving force of the engine.

Ageed, and even service brakes are never referred to as emergency brakes. The OEM’s have lot’s of lawyers that demand that they are never referred to as such and are still working on “mechanical” service brakes. Brakes that keep a vehicle from physically being impossisble to move without any applied (ie hydralic, or something else) force. Just thught I’d add that. IANAL, YMMV. :slight_smile:

another note.

if you park you car on the street and fail to turn the tires or set the parking brake and your parked car gets hit, rolls into ANYTHING (i.e. person, car, dog, bus stop full of 6 year olds) you are responsible.

park wont do squat to stop a car from rolling with any significant impact, hell on a hill a light tap can send it rolling.

I suggest you have the cable looked at (or if you are at all mechanicaly inclined have a look yourself) most have an adjuster set up you can use to pick up some slack.

Gary What I am disagreeing with is when the parking brake is applied just enough to drag the pads on the rear rotors, but not enough to keep the wheels locked. Just enough that the wheels will rotate with enough torque applied. If you drive under these conditions, you will wear the brake pads. If you do this on a regular basis, you will wear the pads out very early. IMHO opinion draging the rear pads for 50 miles is worse than draging them for 5 feet. Besides the wear on the pads, there will be a fair amount of heat generated, the gas mileage will suck, and the trans may not be too happy about the amount of extra work it is doing.