Applying Handbreak - Press Release button or Not

Samsonite1

Zandoni wrote: »

Can't see how that would make any difference.

It makes a huge difference. If you press the button, you are applying force directly to the hand brake cable. The cable is what engages the brake - once stretched too much, the brake will no longer engage (imagine pulling a tooth by tying string to a door handle - if the string is too long and never gets taut, it will not do anything).

You can prove this to yourself if you do not believe it, if you have a standard ratchet hand brake. Go to your car and pull the hand brake as hard as you possibly can by pressing the button. When you release it, it will feel looser (provided you used a decent amount of force). If you repeat this a few times you will quite likely render your hand brake useless and the cable will need tightening. It may even go after one good pull (as happened with one of my old cars).

Zandoni wrote: »

I believe the reason lies in the poorer quality mechanisms that are used in modern cars.

On the contrary - the ratchet mechanisms are clearly better quality in modern cars, hence manufacturers instructing us to use them.

Joe_Horner

Samsonite1 wrote: »

It makes a huge difference. If you press the button, you are applying force directly to the hand brake cable.

No you're not. The ratchet is part of the lever and attached to the button by an entirely separate operating rod, while the cable is attached to the base of the lever and not connected to the button in any way.

Besides which, the average handbrake cable is around 2mm (or more) of multi-strand steel cable with a breaking load of 1/4 tonne or more. It wouldn't even notice the few grams of force you apply with your thumb even if it was applied to the cable, which it isn't

Zandoni

Samsonite1 wrote: »

It makes a huge difference. If you press the button, you are applying force directly to the hand brake cable. The cable is what engages the brake - once stretched too much, the brake will no longer engage (imagine pulling a tooth by tying string to a door handle - if the string is too long and never gets taut, it will not do anything).

You can prove this to yourself if you do not believe it, if you have a standard ratchet hand brake. Go to your car and pull the hand brake as hard as you possibly can by pressing the button. When you release it, it will feel looser (provided you used a decent amount of force). If you repeat this a few times you will quite likely render your hand brake useless and the cable will need tightening. It may even go after one good pull (as happened with one of my old cars).



On the contrary - the ratchet mechanisms are clearly better quality in modern cars, hence manufacturers instructing us to use them.

There's no difference, you can pull the lever just as hard button pushed or not.

almillar

As Joe Horner says, pushing the button in doesn't stretch the cable. Pushing the button in simply releases the ratchet and allows the handle to move freely. Pulling the handle up is what moves the cable, so pulling it up too far, or too hard, could stretch the cable. You're supposed to pull it enough to hold the car - not a certain number of clicks or anything, because this will change if you're on a hill for example.
I was taught to push the button in.
So do we have an answer to the question - why are manufacturers telling us not to use the button on the way up?!

Samsonite1

Joe_Horner wrote: »

No you're not. The ratchet is part of the lever and attached to the button by an entirely separate operating rod, while the cable is attached to the base of the lever and not connected to the button in any way.

Besides which, the average handbrake cable is around 2mm (or more) of multi-strand steel cable with a breaking load of 1/4 tonne or more. It wouldn't even notice the few grams of force you apply with your thumb even if it was applied to the cable, which it isn't

Ok, yes not directly to the cable but the button prevents the ratchet adding to the resistance. Pulling with or without the button is not the same at all, full stop. There is more resistance using the ratchet, so you are less likely to pull it as hard - it does not pull as quickly.

By stretching - I know what the cable looks like, I have fixed them myself. I mean (to take my string, tooth removal analogy) the length of slack. Because the mechanism has an adjustable nut for the cable, that is what pulling too hard affects. I have done this myself as have many people I know on many cars. Try it for yourself - feel free to argue all you like my friend.

Samsonite1

Zandoni wrote: »

There's no difference, you can pull the lever just as hard button pushed or not.

You think you can, that's why it's better to use the ratchet. There is a difference and you just don't know it. That's ok though.

Joe_Horner

almillar wrote: »

So do we have an answer to the question - why are manufacturers telling us not to use the button on the way up?!

My gut feeling would be that they're simply covering themselves against people who fail to make sure it's set properly. It's less likely to "hang up" on the tip of a tooth if you're "clicking" it and, if the ratchet does fail / seize, you're more likely to notice if you're in the habit of "hearing the click".

The cost of that idiot-proofing is an increase in wear on the ratchet that may, or may not, make a difference in the long term but categorically isn't their problem when the no-win-no-fee guys come calling.

If you don't keep up with maintenance then you're also more likely to notice that the travel is increasing as rear brakes wear and the (inevitably seized by now) auto adjusters fail to work if your 4-click handbrake is gradually taking 5, then 6, then 9 clicks to hold. But that's a maintenance issue, not a handbrake one

dannyrst

Some people press it, others don't. How has this spanned 3 pages?

Joe_Horner

Samsonite1 wrote: »

You think you can, that's why it's better to use the ratchet. There is a difference and you just don't know it. That's ok though.

No, you really can pull it as hard with the button pressed or not pressed. The force applied the cable is entirely down to how hard you pull "up" and the mechanical advantage provided by the lever itself.

Pushing on a button doesn't suddenly make you stronger, and the leverage is set by the geometry of the lever itself - its length, the radius of the segment the cable sits on, and the position of the pivot point. Pushing the button (or not) doesn't alter any of those factors, so the possible force applied to the cable remains the same.

Samsonite1

Joe_Horner wrote: »

No, you really can pull it as hard with the button pressed or not pressed. The force applied the cable is entirely down to how hard you pull "up" and the mechanical advantage provided by the lever itself.

Pushing on a button doesn't suddenly make you stronger, and the leverage is set by the geometry of the lever itself - its length, the radius of the segment the cable sits on, and the position of the pivot point. Pushing the button (or not) doesn't alter any of those factors, so the possible force applied to the cable remains the same.

I did not say you could not pull it as hard either way. I said that the ratchet adds resistance so it is not the same. Resistance means that more force is required to get to the same point. You cannot possibly deny that the ratchet does not increase resistance when pulling it.

Anyway, back to the question. This what my research from Web (a bit iffy) and talking to a mechanic have turned up:

Edit: Mechanic also said that the ratchet system is designed to outlast the life of a car in most cars these days and advice on not pressing the button has been around for at least 2 decades...

The ratchet provides sensory feedback to let you know how far you have pulled it. It also gives you feedback on any issues with slackness (well done JoeHorner).

Another aspect is safety. Once you press the button in on a steep hill, if something happens to you - your foot slips off the break pedal and your thumb slips off the hand brake, you could be in danger and endangering many people (maybe a heart attack, fainting, etc.).

A couple of "internet research" quotes (take what you will):

"You're actually supposed to let the pawl ride the teeth - if you press the button in and release, you can (rarely) accidentally leave the ratchet pawl holding on to the top of a tooth without you being aware. This can then slip off when you're not in the car. Letting the ratchet spring pull the finger back in prevents this.
There have been many instances of this happening, which is why most car manufacturers will tell you explicitly not to press the button when engaging the handbrake - the mechanism is designed for it over the life of the car!"


"My new Honda Civic was recalled for a handbrake fault (sadly after it rolled down my drive and parked itself in the middle of the road).

Honda wrote to all Civic owners affected stating in great detail exactly how to put the handbrake on properly. This included in bold that you should not press the button in when putting the handbrake on, which surprised me because when I learned to drive that was what we were taught to do. I guess cars have changed since then."

Hopefully all of this information is somewhat interesting to someone.