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Handbrake Pressure...
scootz - 3/6/12 at 10:54 AM

I've tried googling, but to no avail!

Can anyone hazard an (educated) guess at how many KG's of force would be required to actuate a typical handbrake calliper (say Sierra for the sake of argument)?

Slimy38 - 3/6/12 at 11:57 AM

I might be wrong, but isn't there something in the IVA/SVA regs about the minimum clamping force required for a handbrake caliper? Or possibly in the type approval regs for production cars?

JAG - 3/6/12 at 12:41 PM

No idea on the actual cable force to actuate a pkb caliper - BUT it can be done by hand on every one I've ever handled. So I'd guess it's probably less than 10kg force.

britishtrident - 3/6/12 at 02:27 PM

if you mean the the tensile force exerted by the cable. more like 1kn to 2kn

Based on the the assumptions of a approx old money force of 30 lbf exerted on the lever (133 Newtons) and roughly 10:1 leverage on the handbrake lever .

scootz - 3/6/12 at 02:49 PM

quote:
Originally posted by britishtrident
if you mean the the tensile force exerted by the cable. more like 1kn to 2kn

Based on the the assumptions of a approx old money force of 30 lbf exerted on the lever (133 Newtons) and roughly 10:1 leverage on the handbrake lever .


I did mean the cable...

1-2kn = 100-200kg force. I would never have thought it that much.

JAG - 4/6/12 at 09:09 AM

Jeez - 1kn is 1000N and is WAY too much.

I've been involved in the design of these things and I've visited several factories where they are made and it's do-able by hand - easily on new ones.

I'd say about 10kg or 100N of cable force is plenty

blakep82 - 4/6/12 at 09:21 AM

quote:
Originally posted by JAG
Jeez - 1kn is 1000N and is WAY too much.

I've been involved in the design of these things and I've visited several factories where they are made and it's do-able by hand - easily on new ones.

I'd say about 10kg or 100N of cable force is plenty


it takes about 10kg to pull on the lever hard enough, and with a lever with a 10:1 ratio built in, i'd imagine 1000N is right tbh.

[Edited on 4/6/12 by blakep82]

JAG - 4/6/12 at 12:58 PM

Hmmm ok - I did say I designed these things for a living so I had a dig through my calculations from previous projects.

ECE Regulation 13H and FMVSS 135 regulate 'light vehicle brake system' design in Europe and America.

Both say there should be a maximum of 400N at the Cab lever (the lever inside the car) for a hill hold on a 30% incline.

From my own personal calculations I can tell you that the 2000MY Toyota Corolla needed 294N (30kgf) at the Cab lever which gave a cable load of 758N (per caliper) to hold the car on a 30% incline.

The cable load had to overcome the calipers internal spring and I allowed 120N per caliper.

Therefore the answer is 120N at the lever on the back of the caliper or 12.25kgf

Don't forget this is just enough force to make the lever (on the back of the caliper) lift off the stop - not hold the car on a hill.

[Edited on 4/6/12 by JAG]