42 replies to this topic

[Gremlin]

Rethinking me design it can't! I want to know how people do these hydraulic handbrakes, basically you've got to have a path through for the normal foot brake and a way of isolating the front for the handbrakes, but it's proving difficult to do with simple plumbing

[tiger99]

It can not be done with one way valves. I have already explained how it can be done, and why I would not even consider doing it.

 

By the way, in an earlier part of my career, I was doing flight safety analysis on aircraft brake systems, and initial design of the hydraulic system for a couple of medium to large turboprop airliners, so I can tell you that in a powered hydraulic system it is difficult, but not as difficult as doing it in a hydrostatic system on a car.

[Gremlin]

It can not be done with one way valves.

I realise this now, I thought my initial idea was brilliant and it would nearly work it's just that the back brakes would stay on when you either pressed the foot brake or pulled the handbrake - not ideal, would be a bit annoying

[Carlos W]

 not ideal, would be a bit annoying

 

As you brake before the corner, take your foot off the brakes but the rears stay locked on, you lose control and spin the car and go backwards through a hedge!

 

Yup, a bit annoying!

[Gremlin]

 not ideal, would be a bit annoying

 
As you brake before the corner, take your foot off the brakes but the rears stay locked on, you lose control and spin the car and go backwards through a hedge!
 
Yup, a bit annoying!

Or spin completely and go through forwards? Dunno which I'd prefer?

[Dusky]

 

 

 not ideal, would be a bit annoying

 
As you brake before the corner, take your foot off the brakes but the rears stay locked on, you lose control and spin the car and go backwards through a hedge!
 
Yup, a bit annoying!

Or spin completely and go through forwards? Dunno which I'd prefer?

 

I'd prefer going backwards, so you don't slam your face in your steering wheel

[Carlos W]

 

 

 

 not ideal, would be a bit annoying

 
As you brake before the corner, take your foot off the brakes but the rears stay locked on, you lose control and spin the car and go backwards through a hedge!
 
Yup, a bit annoying!

Or spin completely and go through forwards? Dunno which I'd prefer?

 

I'd prefer going backwards, so you don't slam your face in your steering wheel

 

Safer going backwards if you've got headrests!

 

I wonder if you could do something with a front drum set up on the back? Use a pair of cylinders for the foot brake, and a set for the handbrake ????

 

Ultimately though, it wont be something I'll be doing, I'll just use the cable operated handbrake  

[tiger99]

You could install dual hydraulic actuation, with two wheel cylinders operating in parallel on the same set of shoes. It does give a lot of problems, how to squeeze them in, and the need to re-shape the shoe ends, for instance, but in theory it can work. Basically, two bores in the one cylinder casting would be the way to do it. Not so good, in fact rather poor, would be an internally divided cylinder, with one piston fed by the footbrake, presumably on the leading shoe, and the other the handbrake, on the trailing shoe. It would just need a specially machined cylinder body, and a larger hole in the backplate to admit two hydraulic feeds and two bleed nipples.

 

Or indeed, as suggested, TLS front brake backplates, bearing in mind that braking in reverse would be abysmally poor (my drum braked Minis were extremely poor in reverse) and the handbrake does have to hold the car in reverse on a 1 in 3 gradient. And how do you fit the mechanical handbrake? Possible, but messy.

 

Or, two-pot calipers and tiny discs, pointless for braking performance, but a neat way of getting two distinct systems per wheel. I don't know if you can get twin pots which also have a mechanical handbrake system, which will still be legally required, but it is an interesting possibility.

 

I assume that the hydraulic handbrake, or even fiddle brakes, would be reserved for off-road use only....

 

How about spring-applied, hydraulically released brakes?

[Gremlin]

Mounted :) Just got to plumb it in and try it out

 image.jpg   45.27K   33 downloads

[mad mk1]

Looks good, bit Is that not the wrong way around? As it's push not pull?

[Gremlin]

I figured that if you had to pull it it would take longer as you'd have to wrap your hand around it, and also you'd be pulling yourself away from the seat. Mainly because it's a bit different and it's never really gonna get used

[Goacher65]

How did this end up going for you?

 

Not sure what the relevance of how long it takes you to wrap your hand around it if it's as an aid for parking on a steep hill.... As mentioned earlier in this thread, I'm fairly sure you can get a hydraulic handbrake the the foot brake runs freely through when the handbrake is "off", but uses the feed from the main cylinder to brake the rear wheels when used.

 

If I'm parking on a hill. I'd leave it in gear as a matter of course. Even handbrake cables can snap...

 

Sorry to drag up an old thread, but I was searching with relation to fitting one for auto test/rally use.

[nicklouse]

we used to use Hillman Imp Brake Mcs and just plumb them inline on a single circuit brake system. I just needs to be after the pressure regulator.