Is the emergency brake (hand operated) also "anti-lock"?

Curious. Was practicing a little defensive driving early this a.m. on a empty wide section of road in a rural valley (read: It really was 6+ lanes, no median, no traffic, clear/safe and I'm getting new tires Friday - so don't give me any driving safety lectures please). Couldn't seem to get the rear wheels on my 1993 Legacy to lock. Do they? Can I? How? Thanks. Brian

Reply to
Brian & Cate
Loading thread data ...

Hand brakes do not use hydrolic pressure, but rather a cable (like on a bicycle). Thus, they bypass any "anti-lock" or power brake technology.

They are also quite weak, I would not be suprised if the AWD type vehicles prevent the classic "hand break to lock and spin" type manouver from being possible because they simply apply more power to the rear to overpower the brake.

[Think about it, if they were strong enough, you wouldnt be able to drive away with them on... which you can do too.]
Reply to
FUD_wad

"Brian & Cate" wrote

The brake cable probably just needs tightening.

Contrary to the other answer to you question, you should be able to lock the rears with the parking brake. I have never had a vehicle where I could drive with the parking brake on. That includes by Outback Sport and my 245hp Dodge truck.

Reply to
Brian

"Brian & Cate" a écrit dans le message de news:wkRTa.95$ snipped-for-privacy@monger.newsread.com...

Reply to
Philippe Javaux

The parking brake on the 90-94 Legacys is a drum style brake built inside of the rear rotors. Good design, hard to find the drum linings though, so I would recommend using them only for emergencies or parking. I don't think you could lock them up on a manual tranny car, maybe on an auto where the torque split is different.

Eric.

Reply to
Eric Davis

Reply to
someone

On Thu, 24 Jul 2003 18:45:26 GMT, "someone" wrote in news:aPVTa.69597$ snipped-for-privacy@nwrddc02.gnilink.net:

It certainly is an emergency brake. Since (at least in the cars I've owned) it uses a completely different mechanism from the main brake lines, it will function (maybe not very well) when the the main system has malfunctioned. I used it once in my Acura when the moron mechanic didn't bleed the system. First red light (100m from the dealer) and the pedal went to the floor. Thankfully the parking/emergency brake was there. I'm sure their lawyers were thankful as well.

Reply to
Dave Null Sr.

No, it certainly IS NOT an emergency brake, even if you've used it for such purpose. Read your owner's or any other manual, and I highly doubt you'll find anything suggesting that you use it as such. You will, however, find that they instruct you to use it when PARKING the vehicle.

Reply to
someone

They used to call it an emergency brake, and people didn't use it for parking and "parked" cars rolled around a lot.

They started calling it a parking brake, which kept the cars from rolling around on their own but left a whole generation of drivers clueless about how to stop when their brakes failed.

It's a HAND BRAKE and can be used to stop the vehicle if the brakes fail (IE, an emergency) or to keep the vehicle from rolling around when parked.

IE, it's both a furniture polish AND a dessert topping.

-DanD

Reply to
Dan Duncan

Regardless of what it's called, I know I'm going to give it a pull if the service brakes don't work.

It's also where my hand rests when I'm riding shotgun with my student driver daughter.

Reply to
Jim Stewart

They certainly test it in this state as an alternate way to bring the moving car to a halt. I have slid the rear wheels on my '03 OBW by cranking up on the hand brake. it's a 4EAT FWIW

Carl

1 Lucky Texan

Dave Null Sr. wrote:

Reply to
Carl 1 Lucky Texan

Good information. It's good that they went to a system like that - I now drive a Chrylser with that same setup. The old way of having a sloppy cable pull the service brakes to effect parking brake caused too much interaction with proper parking brake adjustment and proper service brake operation. I'm glad the industry finally wised up in that area.

And you're very correct: The fact that the dedicated parking brake shoes are designed only for that purpose now means that those shoes do not have much safety factor in them for stopping a moving vehicle (i.e., each incident of abuse will eat up a good portion of their design life). With the way the mfgrs. trim everything to bare bones for weight and cost these days, if the engineers determine that 3mm friction material thickness will get the car thru worst-case normal vehicle life, they might design them for 3.5mm to hopefully give a decent bell curve.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Reply to
Bill Putney

If you pull up slightly on the hand brake while coasting, you will hear the center diff uncouple on AT equipped cars. My H6 makes a definite "clunk" sound when it uncouples.

Reply to
Skweezieweezie

It is not a good idea to use the handbrake to lock the rear brakes on 4wd cars with viscous center (or other limited) center diffs.

When you try, the center diff actually fights against you and puts more torque on the rear wheels to try and keep them turning. This maybe what you are sensing, certainly could in my EVO. They don't recommend towing a car with this type of center diff with one set of wheels off the ground as it will try to turn the suspended set of wheels and if you lock them, overheat and damage the diff. Not sure if occasionally trying to lock the rears would actually cause damage though. The rally cars have a center diff that automatically disengages when the handbrake is pulled.

Reply to
Richard Gary Clark

Are you sure that was the design goal rather than the effect of moving from drum to disk brakes? One of the two shoes in a standard drum brake system will naturally "jam" against the drum when the "free" end is pressed against the inside of a rotating drum. Disk brakes have not such mechanical feedback system, which is why power brakes are almost always used with disk brake systems. An emergency or parking brake based on disk brakes will therefore naturally have far less stopping power than an emergency or parking brake system based on drum brakes.

-- Vic Roberts

Reply to
Victor Roberts

With mechanical leverages you could perfectly achieve the forces that would allow the wheels to lock. The problem is that the rear end of the car would come loose and could sway from the travel direction when driving on paved roads with a slant, same thing that happens when using the hand brake on dirt or slippery roads with a slant.

If I am not mistaken, the hand/emergency brake on the 93 Legacy is a drum brake system.

The requirements for parking/emergency brakes in passenger cars, are that they should be able to keep the car still when the car is fully loaded on a 16% incline. (Source: Bosch Automotive Technology Handbook)

I still remember the times when hand brakes were tested by making sure that you would leave tire marks when applying them while the vehicle was in motion and hand brakes that were applied to the rear axle propeller shaft, which on inclines on loose roads, they would allow one wheel to roll down hill while the other one would roll backwards (due to the differential), with the end result that the vehicle would roll down hill.

In cargo vehicles, the emergency brake system is different from the parking brake system. Emergency brake systems have to allow the gradual application of the braking force, while parking brakes do not need to meet this requirement.

In passenger cars, the parking brake allows for both functions.

Victor Roberts wrote:

Reply to
TM

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.