math forumla question?
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From: On A Ship, MI
math forumla question?
i was changing the ball joints(still am ) and i was wondering if there is a mathematical formula to figure out if how much force (psi) i am exerting on the ball joint that i am trying to force out. i am using a standard Ball joint/ U joint Press tool( giant aluminum C clamp) my torque on the ball joint press is 150lbs, the diameter of the screw head is roughly 3/4". so how much pressure am i exerting on this ball joint.
btw, i've had the press on this knuckle for 4 days @ 150 lbs of tq, and the ball joint hasn't moved yet.
btw, i've had the press on this knuckle for 4 days @ 150 lbs of tq, and the ball joint hasn't moved yet.
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From: Calgary, Canada
I'm purely guessing but I would think it's something like
3.14 * T * 12 * 150 Where T is the number of threads per inch on the clamp. Which, at 10 TPI comes to over 56,000 lbs.
Like I said I'm guessing and that don't really look right to me. And that is 'perfect world', without friction on the threads.
3.14 * T * 12 * 150 Where T is the number of threads per inch on the clamp. Which, at 10 TPI comes to over 56,000 lbs.
Like I said I'm guessing and that don't really look right to me. And that is 'perfect world', without friction on the threads.
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From: UT
It appears that there is: (from http://www.cs.cmu.edu/~rapidproto/mechanisms/chpt2.html see discussion of jack)
F*2*pi*R=W*P
F= force applied to lever arm
R=length of lever arm
W=Weight or output force
P=thread pitch for screw (how far the screw moves per rotation)
You're applying 150 ft lbs torque (F*R) to the wrench turning the screw. So F*R*2*pi=942.5 ft lbs.
I don't know you thread pitch, but if I assume 12 threads per inch (144 threads per foot) then P=.006944 ft
W=F*R*2*pi/P=~136,000 lbs
I think that's right, unless I misunderstood something.
F*2*pi*R=W*P
F= force applied to lever arm
R=length of lever arm
W=Weight or output force
P=thread pitch for screw (how far the screw moves per rotation)
You're applying 150 ft lbs torque (F*R) to the wrench turning the screw. So F*R*2*pi=942.5 ft lbs.
I don't know you thread pitch, but if I assume 12 threads per inch (144 threads per foot) then P=.006944 ft
W=F*R*2*pi/P=~136,000 lbs
I think that's right, unless I misunderstood something.
Last edited by mrshorty; Mar 3, 2008 at 05:28 PM. Reason: wrong unit
pedant
Joined: Jan 2008
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From: EXTREME southwest CT
Shorty's right, if it is 12 tpi.
Finer threads will = more force for a given torque.
But that's not psi, it's the force applied to the balljoint.
A 3/4" shank only has .4417865 square inches of area.
Finer threads will = more force for a given torque.
But that's not psi, it's the force applied to the balljoint.
A 3/4" shank only has .4417865 square inches of area.
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From: Calgary, Canada
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From: Princeton, MN
Originally Posted by rangersvt04
so how much pressure am i exerting on this ball joint.
sic
sic
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From: sunny fla sometimes windy
You need to get some propane persuasion involved!! A bit of heat on the outer and
some keyboard duster upside down to freeze the inner part will get it removed quickly.
Don't be afraid to use the temperature differential t force things apart!!
some keyboard duster upside down to freeze the inner part will get it removed quickly.
Don't be afraid to use the temperature differential t force things apart!!
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From: On A Ship, MI
wow that is alot of force.... yes i have used the biggest hammer i have, and have played
with the propane torch, although i used snow/ice but the duster sounds like a good idea. im thinking that may be i should move the knuckle from cold garage (outside temp 23F) to inside(65F ish) while pressing on the joint. if that doesn't do it im gonna go visit the school and barrow the acetylene torch.... or get access to a bigger press.
with the propane torch, although i used snow/ice but the duster sounds like a good idea. im thinking that may be i should move the knuckle from cold garage (outside temp 23F) to inside(65F ish) while pressing on the joint. if that doesn't do it im gonna go visit the school and barrow the acetylene torch.... or get access to a bigger press.
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From: St. Peter
When I did the ball joints on my F150, I used the ball joint press with a wrench on it, then on the end of a wrench I had a pipe, and on the end of the pipe I had an axe handle. I just kept turning until it wouldnt go any further, then finally, BANG (sounded like a shotgun) things went flying, and it came apart. I dont think 150 Ft-Lb is enough to do what you are trying to do. Dont be afraid to hammer on it a little.
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