Line locker as a park brake ???

[cjsammut]

Has anybody had any experience with or considered using a line locker on the rear wheels for a park brake.
My park brake is useless on #1691 so I’m thinking of this as an option.
Thoughts welcomed.
Cheers

[joyridin']

I have had one for years. Works great as a PB and a theft deterrent as mine has a key to unlock it. I have the manual PB also like you, but it has a bit to be desired sometimes.

[Tom Wells]

cj,

Interesting question.

I guess the answer depends on your view of the device's main function.

Originally, and I think still today, the thing we think of sometimes as the parking brake was known as the emergency brake. It was there to provide braking of sorts when the main braking system had a failure.

It's also a convenience when parking, or for holding a stick shift car on a grade while the driver starts off from a stop going uphill.

So I guess one answer would be that if there is no main braking system failure, then a line lock might be a handy device. Be aware that the line lock is intended to work on both front wheels only through the car's hydraulic system, not as a separate mechanical device. Possibly the line lock could be adapted to work differently.

I have the emergency brake. I make sure it works!

You pays your money and you takes your choice ;-)

Tom

[Grubby]

I have never installed a line lock, but I have a pretty good idea how they work.

Wouldn't it run the battery down over a period of time? I think it is using battery power to keep a solenoid or something that holds hydraulic pressure actuated.

John

[eschaider]

Grubby is right about the Line Loc style devices. They are a normally open hydraulic valve that when activated close off to the hydraulic fluid flow back to the master cylinder creating the locking event.

Because they are normally open they require continuous activation to be used as a parking brake. The continuous activation will draw current from the battery because the car is off. As Grubby has already pointed out, given a long enough activation they could potentially draw a battery down significantly. The continuous activation also heats the energizing coil inside the device used to close off the hydraulic circuit.

The coil inside the Line Lock is designed for periodic, temporary operation. When left on for extended periods of time it can overheat and eventually fail. The overheating is an interesting problem because as it does, the resistance in the coil increases and it draws additional power creating additional heat and, well you can see the problem.

If you could find a valve that would latch and unlatch mechanically with an external coil activated toggle, that type of design should work very nicely. Remember if there is any way for the hydraulic fluid to escape from the closed system over time, after activation, it will and the brake will release.

Historically most auto manufacturers have relied on mechanical mechanisms for the 'parking brake' for just that reason. Some of the newer vehicles use an electrically operated mechanical valve that latches. That valve can be easily built into the anti-skid braking system. If you can find one that is not and is implemented as a stand alone it should work nicely.

The primary design consideration should be the ability to lock the brakes without requiring a continuous draw of power from the car's electrical system.


Ed

[olddog]

As stated a line lock is intended to be activated for a very short period of time. Aside from the solenoid coil getting cooked and draining the battery, hydraulics bleed off over time. Additionally hydraulic fluid changes volume with temperature. It will also boil if too hot, the reason why large trucks have air brakes.

So in short, this is a very bad idea. Just fix the parking brake. That is what it is made for.

[jwoodard]

If you are a member of SCOF, there is a very extensive Technical section with in depth explanations on how to adjust the parking brake. When I owned SPF 1938 I followed that guidance and was able to adjust mine so it would hold tight under any condition.
If you aren't a member of SCOF you are missing a lot of good information and interaction with other SPF owners, so get out there and join.
With the proper adjustments, the SPF parking brake works just fine.

[cjsammut]

Thank you for the points you have raised. Having never used a line lock, I had wondered whether it would operate without power.

[joyridin']

Originally Posted by cjsammut

Thank you for the points you have raised. Having never used a line lock, I had wondered whether it would operate without power.

You can get a line lock that doesn't need power. On the one I have, you push the pedal, turn the key, and the release the pedal. Rear brakes are locked. I had another version on a previous car. You push the pedal, push the knob, and it held the rear brake. When you wanted to release it, you just push the pedal again and it would release.

Been using them for 25 years now without a problem. I use them for a parking brake, not an Emergency brake.

[twobjshelbys]

When I see things like this the question I always ask is "it seems like an obvious solution, and if it was a good idea it would already be the solution". Since it isn't there's probably something that doesn't work well. Standard mechanical parking brake always works. Doesn't need battery.

[kyleb]

Originally Posted by twobjshelbys

When I see things like this the question I always ask is "it seems like an obvious solution, and if it was a good idea it would already be the solution". Since it isn't there's probably something that doesn't work well. Standard mechanical parking brake always works. Doesn't need battery.

I have a BMW X5M that has a button (electric) for the parking brake.
Too scared to push it to see if it works as an emergency brake as well.

[twobjshelbys]

Originally Posted by kyleb

I have a BMW X5M that has a button (electric) for the parking brake.
Too scared to push it to see if it works as an emergency brake as well.

The ECU probably prevents it from being activated if the vehicle is moving or maybe even if not in neutral.

[kyleb]

Originally Posted by twobjshelbys

The ECU probably prevents it from being activated if the vehicle is moving or maybe even if not in neutral.

I should probably get the owners manual out but where’s the fun in that?

[Gaz64]

I don't think the switch just applies the parkbrake in an emergency. Can you imagine an electric parkbrake locking up the rear wheels with no modulation possible?
Appling the parkbrake switch in many cars at speed above about 8 mph actually applies the hydraulic brakes on ALL wheels to slow the car quickly and safely to a stop.
Great aid for a medical emergency, especially for a passenger.

[spdbrake]

I wouldn't activate yours while at speed Kyleb. The X5 only pulls the normal emerg rear cables for you via a motor and gearbox VS a lever.

https://www.youcanic.com/vehicle/bmw...ke-malfunction

[LMH]

I don't know about other states but in AZ, a braking system operated by a different system than the hydraulic system is required for registration. In other words, besides the fluid system, a mechanical system is required.
Does anyone in authority ever check that, probably not but I want to have it work as intended.
Larry

[CompClassics]

I know there is a mechanical / hydraulic system available for Panteras.

[kyleb]

Originally Posted by spdbrake

I wouldn't activate yours while at speed Kyleb. The X5 only pulls the normal emerg rear cables for you via a motor and gearbox VS a lever.

https://www.youcanic.com/vehicle/bmw...ke-malfunction

No problem.. I’ll ask a mate to try it on his then.

[1795]

Originally Posted by Gaz64

I don't think the switch just applies the parkbrake in an emergency. Can you imagine an electric parkbrake locking up the rear wheels with no modulation possible?
Appling the parkbrake switch in many cars at speed above about 8 mph actually applies the hydraulic brakes on ALL wheels to slow the car quickly and safely to a stop.
Great aid for a medical emergency, especially for a passenger.

Gary,

Back when I was young and stupid, as opposed to old and stupid, we used to take our cars out in parking lots or on rarely used back roads and at about 50 mph would pull on the emergency brake (which was mechanical) and slide to a top. Left a lot of rubber on the road and you had to react quickly.

It seems like the emergency brake, which was meant to stop the vehicle by a progressive mechanical means if the hydraulic system failed, has transitioned to more of a paring brake meant to lower the risk that a car would roll when parked. With a properly set emergency brake you would have a difficult time moving the car under power. Most parking brakes today will not stop you from moving the car under power.

Jim

[Gaz64]

Jim,

Pre 2005 cars with a well adjusted hand brake should be able to stop the car albeit with less g force than all 4 wheels.

Many cars can slide to a stop if adjusted well. Some will hold well under power.

Some cars I know that have "electric park brake" are a switch operated electric servo operated cable operated mechanical handbrake within the rear brake rotors.

If the car is driven away from a stop, the electric park brake is released automatically, so impossible to drive with the park brake on.

When the switch is operated at some speed, the normal hydraulic braking system is operated, and they do stop VERY well from all 4 wheels braking.

I was a sceptic at first, until a GM trainer showed me on a drive.

If you get a chance, try it in a late model car with electric park brake.

I think that many cars that have this now would use similar architecture.