Electronic parking brake?

[JTK]

For what ever reason, the 2010+ Subaru Legacys have this. It's your typical rear rotor, drum-in-hat with parking brake shoes and the system is mechanically cable actuated just like normal.

Unfortunately, that's where the similarities end. Instead of a hand-lever or foot pedal to yank the cable, a motorized, electrical actuator under the vehicle pulls/releases the p-brake cable for you!

I'm struggling to see the cost savings of doing this?

Do you think this is done to keep tighter control on when/where/how the p-brake can be used? Maybe stopping your boy racers from yanking up the brake to do power-slides?

Or is it to tidy up the interior?

I'm grasping to understand this one.

Joel

 

[The_Jeff]

There's a federal (DOT/NHTSA) requirement that the e-brake alone must be able to stop the car from 60, eventually.

I don't like the sounds of this either. I don't even like the solenoids that release them automatically when you put it in drive.

It could help fix what would have been a circuituitous route for the cable around 4wd stuff, which would lead to friction, rusting, and snapping.

 

[JTK]

Originally Posted By: eljefino
There's a federal (DOT/NHTSA) requirement that the e-brake alone must be able to stop the car from 60, eventually.


I didn't know that one!

What's crazy about the electronic system is, if you loose 12VDC and the system is locked, you have to crawl under the car to manually release it. There's a means and a tool to do so (screwdriver). It takes something ridiculous like 200+ revolutions of the screwdriver to release.

Joel

 

[MrHorspwer]

It's a cost saving for vehicles that are offered in both RHD and LHD. A single system can service both vehicles instead of having to design and produce two hardware assemblies, levers, center consoles, etc.

It also allows more freedom when doing interior design, since you only have to package a switch instead of a large moveable lever.

 

[musicmanbass]

My LS has an electronic e-brake and I have no complaints. Over 8 yrs old and 130,000 miles with no problems. It's pretty nifty, and I'll never drive around with the e-brake engaged.

 

[fdcg27]

This seems like an overly complicated, Rube Goldberg setup.
What was Subaru thinking?

 

[Kestas]

Can the mechanism fail in a way the you can't apply the e-brake? This would be a horrible disservice to the driver. After all, the e-brake is a Plan B for when the service brakes fail. It must be as fool-proof as possible.

Originally Posted By: eljefino
There's a federal (DOT/NHTSA) requirement that the e-brake alone must be able to stop the car from 60, eventually.

I believe it has to also stop within a certain distance as well. All cars stop from 60 eventually.

 

[bdcardinal]

Seen this on Lincoln LS going back to I think 2000MY when they first appeared. Don't have much if any problems with that part of the vehicle.

 

[JTK]

Originally Posted By: Kestas
Can the mechanism fail in a way the you can't apply the e-brake? This would be a horrible disservice to the driver. After all, the e-brake is a Plan B for when the service brakes fail. It must be as fool-proof as possible.


As far as I know, no. The system will stay in the state it was in before 12VDC power loss.

Then again, I always thought parking brakes were only intended for parking!

Joel

 

[MrHorspwer]

FMVSS standard 135 outlines NHTSA's requirements for light vehicle braking systems. Specifically, S7.12 outlines the performance requirements of the parking brake.

Per the FMVSS standards, a parking brake must hold the vehicle loaded to it's maximum GVWR for 5 minutes on a 20% grade with the transmission in neutral. That's it. There are no parking brake performance or design requirements for slowing a vehicle from speed. NHTSA always specifically calls it a "parking" or "service" brake, never an "emergency" brake. Stopping the vehicle is not the parking brake's purpose.

Here's the standard:
http://www.access.gpo.gov/nara/cfr/waisidx_00/49cfr571_00.html

 

[The_Jeff]

Interesting!

FMCSA has specified distances for commercial vehicles, including (presumably) passenger cars that are used for commercial purposes, eg livery cabs. It could be this, that I was thinking of:

http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?reg=393.52

 

[JTK]

That makes sense MrH. Thanks for clearing that up!

Joel

 

[JustinH]

I rented a new buick regal and was surprised to see the electric parking brake in it also. Something I would have never thought even existed. Press a button to engage the parking brake.

 

[JTK]

Yes, it's a little counter-intuitive. You push to set and pull to release. As you can see, it's a multi-function switch for the Legacy.

Note the "hill-holding" feature? I guess it will hold you on an incline until there's forward motion. Why you'd need this with AT is a mystery to me?

Joel

 

[kevco]

I wonder if it the new thing since many new cars come with remote start. So that when you start the car by remote the brake can engage its self.

 

[mechtech2]

More crud to complicate things.
Enough is enough!

 

[Win]

Our Xj8 has an electric parking brake; it's been problem free and works great.

I was somewhat surprised the '08-09 GM cars didn't have this feature. It would seem to be cheaper to manufacture than the conventional setup.

 

[dishdude]

My Buick Regal has this feature, and I rarely use it since I don't park on inclines. I do like the fact that it tidys up the center console, but I was fine with the foot operated pedal.

I really am not into the hand operated brakes, they take up too much real estate in the center console area.

 

[rjundi]

Originally Posted By: JTK
Yes, it's a little counter-intuitive. You push to set and pull to release. As you can see, it's a multi-function switch for the Legacy.

Note the "hill-holding" feature? I guess it will hold you on an incline until there's forward motion. Why you'd need this with AT is a mystery to me?

Joel


You know Subaru (thankfully) offers the Legacy with 6 speed manual transmission? The hill holder has been in Subaru's on-off since the 1980's with manual transmissions. Possibly this the manual transmission part.

 

[rpn453]

Originally Posted By: Kestas
Can the mechanism fail in a way the you can't apply the e-brake? This would be a horrible disservice to the driver. After all, the e-brake is a Plan B for when the service brakes fail. It must be as fool-proof as possible.


I guess they figure that a simultaneous failure of the electrical system and the hydraulic system is unlikely enough to be considered virtually impossible, or at least as unlikely as a mechanical cable snapping following hydraulic failure. Sounds reasonable.

My buddy's S4 has this sort of park brake. I prefer the feel and instant response of a mechanical lever. I don't like having to hold the brake to use it, and I don't like waiting for it to engage or disengage after the button is pushed. I prefer systems that are incapable of denying or delaying my requests. I've actually been wanting to see how well it works in actually slowing the car down. Has anyone tried using one of these to slow the car down at all?