Re: Hydraulic force question

Nick Müller wrote:
> 
> Anthony <tonytn36sp@xxxxxxxxxxx> wrote:
> 
> > Force = Pressure x Area
> 
> ACK
> 
> > So, If you have 1 1.5" piston, and a supply pressure of 500 PSI, the
> > force is 500x1.7671 = 883.55, now divide that by 2, since half the
> > pressure will go to the other side, and you have 441.775 lbs of clamping
> > force on each pad, minus any friction losses in the caliper slider.
> > Now, say you have 2 opposed 1.5" pistons, and the same 500 PSI supply
> > pressure, the force is still 883.55 lbs per piston, but you do not divide
> > by 2, since the cylinders are opposed, thus your clamping force is now
> > 883.55 lbs per pad and you do not subtract anything for caliper slider
> > friction. So, yes, the host is correct.
> 
> NAK
> 
> To put an end to this funny discussion (I have put oil into the fire):
> With one piston, you have a reacting force on the other side of the
> bracket of exactly the same force coming from the piston (actio =
> reactio; or summ of vectorial addition of forces must be zero). Now if
> you introduce a piston on the other side, that piston can only have the
> same force as the first piston (same pressure, same diameter) and thus
> just will compensate the actio. One piston actio, the other reactio.
> 
> Vector addition! Force has direction!
> 
> Think of having a C-clamp with two opposed spindles. Close one spindle
> with all the force you can bear with your hands. Now close the other
> spindle with all the force. Will there be a difference? Will you be able
> to turn the other spindle? No.
> 
> So it makes no difference regarding the forces wether there is one
> piston or two opposed pistons (same diameter).
> 
> Nick
> 
LOl. What you're saying then, is that 1 x one ton jack will lift
as much as 2 x 1 ton jacks? Interesting hydraulic philosophy, I
wonder what Bramah would say.

Why is it then, that comparable capacity single piston brake
calipers have a far greater piston diameter than the equivalent
2 piston calipers?
Brake calipers work on one simple formula:

total piston area x working pressure ÷ pad area = pad pressure psi.

Tom
.

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