PDA

View Full Version : How Much Pressure

R W
02-17-2008, 02:27 AM
I recently constructed a heavy puller to remove the rear hubs from an old
Massey Harris tractor. A 1.5", 8 threads per inch bolt & nut are used as the
power source. Would like to know what the pressure at the puller would be
in relation to the amount of leverage applied to the bolt.

Ian B
02-17-2008, 04:57 AM
I found this:

http://www.coxhardware.com/usefulinfo/charts/7_btorque.htm

I guess what they refer to as 'clamping force' would be what's available as useful pulling power.

hth,

Ian

R W
02-18-2008, 03:49 AM
depending on how much pressure I was applying to the 5ft of pipe I was
tightening it with.

Fasttrack
02-18-2008, 12:40 PM
Hold up, i would think that the chart provided at that site is the maximum clamping pressure or the max torque before failure.

I would guess you could get a ball-park estimate (minus resistance, for instance) of the pulling power by figuring that it takes eight reveloutions to move a linear distance of 1" (approximately ... given the 8 tpi)

And since work equalls force times distance, you can solve for the force applied in the linear direction. Also note that the force applied to your cheater bar is always perpindicular so the work done is equal to the weight with which you are pushing on the end of the pipe times the length of the pipe times a radial displacement of 2Pi.

So we have the work done by moving the pipe as L*W*2Pi (i.e. Work = Torque times angular displacement of 2Pi since we are assuming one reveloution.) This work is equall to the work done in pulling the hub (assuming a frictionless screw which is definitely not true!! This is only an approximation!!).

So the torque times 2Pi equalls (1/8)(F) where F is the pulling force and 1/8 is the linear distance travelled in one reveloution. Note that the length of the pipe must be put into inches for this to work!

(Of course this approximation becomes worse as more force is exerted on the threads since more and more friction will be developed)

R W
02-26-2008, 01:26 AM

IOWOLF
02-26-2008, 06:30 AM
For stuck hubs on axles on running tractors...

Loosen the bolts, Spray with your Fav.Rust busting concoction, and drive it around for a bit, this will do it.

comerrm
02-26-2008, 12:25 PM
Whever I have a stuck hub on one of my tractors i get use some of my favorite tools.....puller, impact gun, big ass hammer and sometimes a little torch action....kroil makes a nice grease fire :)