You've just set science back at least four hundred years. "Seek the
piston"? Is phlogiston involved here somewhere?
-----Original Message-----
From: Joe Curry [mailto:spitlist@gte.net]
Sent: Wednesday, June 20, 2001 2:47 PM
To: Mark J. Bradakis
Cc: fot@autox.team.net
Subject: Re: GT-6/Spitfire brakes
Once again,
In a stationary system, with a constant source of pressure, this is the
case.
But the system does not have a constant pressure and the slave cylinder
moves, so it is not a stationary system.
The fluid will travel along the path of least resistance and seek the
piston when pressure is applied. Pressure on the input end (master
cylinder)
shows up on the other end as movement of the slave cylinder system. The
amount of energy put into the system is going to be equal to the energy
that
is gotten out of the system (see the law of conservation of matter and
energy). If the slave cylinder is smaller than the master cylinder, it
stands
to reason that that amount of energy will be concentrated on a smaller
area and therefore will be expressed by a smaller piston as a greater
force
applied to the brakes or clutch.
Now, that makes sense to me (May not be correct, but it certainly makes
sense)!!! :)
Joe (C)
"Mark J. Bradakis" wrote:
>
> If you take the same setup and apply the 10 psi to a 0.5 square inch
> piston you are now getting 10 lbs per 1/2 square inch which is 20 psi
and
> you get 20 lbs. of force out of the system.
>
> No, you don't. This is nonsense. If you have a pressure of 10 psi
(that's
> pounds per square inch), you have a pressure of 10 pounds per square
inch,
> over every single bit of area in the entire system. The insides of the
brake
> or clutch line, the bore of the fittings, against the base of the bleed
screw,
> *any* area inside the system will have that same force.
>
> If that pressure is applied to 1 square inch, you get 10 pounds of
force.
> If that pressure is applied to 2 square inches, you get 20 pounds of
force.
> If that pressure is applied to 1/2 square inch, you get 5 pounds of
force.
>
> The force in pounds is the product of the area times the pressure,
simple,
> basic high school math. Write out the equation, and see how the units
cancel:
>
> pounds pounds inch * inch
> Force ------- = Pressure ----------- x Area ------------
> 1 inch * inch 1
>
> This is classic Newtonian physics. The work that goes in is the same as
> the work that comes out. That is, negating the effects of mechanical
friction
> and things like the force used to distort the clevis, the pins, etc. on
every
> pedal application. Here I use work in the classic physics definition, a
force
> applied over a distance.
>
> People are confusing volume, pressure, area and distance in the
situation.
> They are all related by basic mathematical equations.
>
> mjb.
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