can we install a button for ((P)) parking brakes

[yarismo]

i wish to have a button in my yaris for parking brakes, instead of that handle, because i intalled an armrest recently which makes releasing the handle a little difficult.. i know this will require some modifications and special equipements. anybody taught about it already !!

[CTScott]

That would be a little tricky to do. Besides needing a fairly powerful solenoid to yank the cable, you would lose the ability to apply them gently (as you would need to do if you were using them in an emergency situation where the hydraulic brakes failed).

[CrankyOldMan]

The big problem I see is that you would need something like the air brakes on a large truck. They are set up so that they are "on" when they are not pressurized, and "off" when they are pressurized. You would have to add an air compressor and a pneumatic cylinder that is strong enough to pull on the parking brake cable, in addition to the button and wiring. It could be done, but would be pretty expensive, and complicated.

The scary part of that is if it fails while you are driving, it will be the same as making an "e-brake" stop. If you have a manual transmission, just park with it in gear instead of using the handbrake. I don't use my handbrake at all because it can freeze stuck in the winter.

[CrankyOldMan]

Originally Posted by CTScott

That would be a little tricky to do. Besides needing a fairly powerful solenoid to yank the cable, you would lose the ability to apply them gently (as you would need to do if you were using them in an emergency situation where the hydraulic brakes failed).

I wouldn't use an electric solenoid, because it would have to be constant-duty. Too much current draw when driving to be practical.

yarismo: Here's a link to what I'm talking about: http://auto.howstuffworks.com/auto-p.../air-brake.htm

[CTScott]

Originally Posted by CrankyOldMan

I wouldn't use an electric solenoid, because it would have to be constant-duty. Too much current draw when driving to be practical.

yarismo: Here's a link to what I'm talking about: http://auto.howstuffworks.com/auto-p.../air-brake.htm

Our ebrakes don't work like truck ones, so the solenoid would only need to pull the cable to turn them on. Using a latching solenoid would allow them to stay pulled without power.

[CrankyOldMan]

Originally Posted by CTScott

Our ebrakes don't work like truck ones, so the solenoid would only need to pull the cable to turn them on. Using a latching solenoid would allow them to stay pulled without power.

Aah, I didn't realize there were such things as latching solenoids. I was thinking that the only way to make it work would be either a continuous duty solenoid (drawing power when the car was off) or converting to a truck-like system by adding a spring to force the hand brake to be on by default, and turning it off with a pneumatic actuator when operating.

I'm still pretty green with my engineering skill set, so it's good to hear an alternative solution from another engineer.