REFLECTOR: What's the calculation?

[Laurence Coen]

Are you calculating the area of the master cylinder piston?  If so isn't it 
pi x r^2 not pi x d^2.  If the master cylinder is 5/8 diameter then the area 
is ~ 0.3^2".  Then it would take 138 # of plunger force to make 450 PSI.

Larry Coen
N136LC

P.S.: I have the original Matco brakes and master cylinders with no upgrades 
and have hade no problems stopping and no meltdowns.

----- Original Message ----- 
From: "Brian Michalk" <michalk at awpi.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Thursday, February 14, 2008 11:43 AM
Subject: Re: REFLECTOR: Leaking Brake Master cylinder


> Did not find 1/2" bore.
> http://www.desertkarts.com/item107915.ctlg
>
> Might not be too difficult to sleeve and get new rubber bits.
>
> Brian Michalk wrote:
>> Good question.
>> What's the moment arm used on these cylinders.
>>
>> Desert Karts has 1/2" diameter cylinders, I think.
>>
>> NMFlyer1 at aol.com wrote:
>>
>>> Brian,
>>>
>>> In my MATCO paperwork it says the calipers need 450 psi of force to
>>> make rated torque on the brakes (600 MAX before calipers start to
>>> bend). What I am curious about is if the factory master cylinders have
>>> enough PSI for the MATCO requirement. If they are low, then an exact
>>> replacement would be low also.
>>>
>>> They may work, but not be developing Max. Torque.. That would mean you
>>> have to brake longer... = hotter.. etc.
>>>
>>> Just curious.
>>>
>>> Kurt
>>>
>>>
>>> In a message dated 2/14/2008 9:23:37 A.M. Mountain Standard Time,
>>> michalk at awpi.com writes:
>>>
>>>     Are you talking about max operating pressure?
>>>
>>>     pi * (5/8)^2 = 1.227 ~ 1.25 in^2
>>>     needs 360lbs of plunger force.
>>>
>>>     Same diameter as the originals, so performance would be identical.
>>>
>>>
>>>
>>>
>>>
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