Removing frozen bolts?

Question

I work in utility construction. Many times we have to remove bolts and/or nuts that are rusted - "frozen tight!" - even after we spray them with various penetrating oils to "loosen them up."

How does this work? I put a wrench on the nut/bolt, pull as hard as I can. Nothing happens. Then I put a 5 ft. long pipe on the end of the wrench, pull on the end of the pipe (opposite side from wrench), and my "pulling" is 1/2 as hard, and the bolt/nut unscrews!!??

Sure, I understand this is called "leverage," but that does not make me understand WHY, with the pipe, I pull 1/2 as hard! I mean, the bolt/nut will STILL require more 'pull' than my arm can give, to 'break free,' but with the pipe, I see to "get-more-pull", with 1/2 the required strength.

This does not make sense. I guess I am saying, if you use a air wrench to tighten up the nut with 100 pounds of pressure, to remove it again -should require 100 pounds of pressure. My arm is pulling 50 pounds of pressure, so nothng happens!

Answer 1

The other guy was almost right. You aren't really concerned with torque. It's the moment that you are trying to figure out.



Moment = force * distance force is from center of rotation

It is slightly different than torque.



100lb force on a 4 inch wrench would be equal to a 50 lb force on a 8 inch wrench. Both would equal 400 lb-in.



Torque is similar except it acts parallel to the axis of rotation. Moments work perpendicular to the axis of rotation.

Answer 2

It's all about torque.



If you use a torque wrench to tighten a bolt to 90 foot pounds, that is equivalent to you pulling on the end of a 1 foot long wrench with a force of 90 pounds.



To remove that bolt, if you use the same 1 foot long wrench and the bolt does not come loose when you apply 90 pounds to the end of the wrench it is probably frozen on the bolt, so if you add a 5 foot long pipe to the end of the wrench you now have a 6 foot long lever to crank on.

If you now pull on the end of the 6 foot long lever with a 90 pound force you are actually applying a torque of 90 x 6 = 540 foot pounds instead of just the 90 foot pounds that you generate with just the wrench and the same force, which is why the bolt will usually come loose even before you pull with the full 90 pounds.

With a 6 foot long lever it only takes a 15 pound pull to generate 90 foot pounds of torque.

Answer 3

This is a question of physics. The equation is:



T = R * F



That means Torque = Radius (length) X Force.



So, if you have a 1 foot long wrench and are able to apply 50 lbs. of pressure by hand, you are generating 50 ft. lbs. of torque.



Add the pipe and now let's say you have 3 feet to work with. You therefore have increased your torque to 150 ft. lbs. (T = 3 X 50).



So, if you pulled half as hard, you still generated 75 ft. lbs. of torque, or 25 more than without the pipe.



Everything is based on how long the wrench was and how long you extended it.



If you had a 9 foot long pipe, you would generate 500 ft. lbs. of torque. Wrench + pipe = 10 feet. T = 10 X 50. T = 500.



This works for screw drivers too, but the equation is different. Ever notice it's easier to remove a screw with a long screw driver?



Ahhhh...physics!



***

Not trying to be "that guy" here, but I'm not wrong. I did oversimplified though.



The physics behind why a long shafted screwdriver delivers more force than a short shafted one is called torsion. The formula is much more complicated and has many variable, so not worth trying to outline them all here.



Yes, a bigger grip would allow the user to generate more torque along the shaft, but ultimately the length of the shaft will increase that torque through the laws of torsion.



So the bottom line is longer shafts are better. (Yes...I know that sounds hilarious).

Answer 4

Simple as I can make it::

You understand that it's called "leverage".

What it is about is 'force multiplication.

Work, what you apply to the nut), is expressed

as force x distance.

With the wrench only, to turn the nut say 5 degrees,

you would have to move the handle of the wrench,

, (the pull you feel), say 4 inches or so.

You find that you can't produce the required force.

With the, (breaker bar), in place, you move the end

of the pipe through a couple of feet for the same five

degrees so the force required is more "spread out",

and you can produce it.

The same total work, force x distance is being done,

but by going more distance, less force is required.

Answer 5

Ten Years Gone was right, up until the part about the screw driver.



The length of the screwdriver does not affect the torque. A big fat handle will allow more torque than a skinny handled screwdriver.



The equation for torque doesn't change just because it's a different tool.

Answer 6

I as quickly as had a frozen bolt in my automobile, i attempted each thing! What finally did artwork, replaced into the WD-40, in spite of the undeniable fact that it took an afternoon or so,I stored putting greater on, and then tapping the bolt and lots muscle straining, yet finally it broke unfastened. do you already know why that's reported as WD-40? as a results of fact the guy who invented it stored experimenting. the main suitable success replaced into batch #40.

Answer 7

First of all, leverage requires less "pull" to obtain the same force.

Nuts and bolts subjected to weather develop rust, which by itself will basically "weld" them together....Therefore your assumption that to loosen them should only require the same force used to tighten them, is not valid....

Often, if you use a spray such as WD-40 or similar product, then heat the bolt, it will release much easier than doing none of this....

Answer 8

I swear by PB Blaster. It always amazes me . Lowes and home depot carry it.