I Torque without a torque wrench

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    Torque Wrench
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To achieve 250 ft lbs of torque without a torque wrench, one can use the formula Torque = Force x Distance, which allows a person to calculate the necessary distance to apply their weight on a breaker bar. A person weighing 142.3 lbs would need to stand 21 inches from the nut to exert the required torque. While the calculations are correct, practicing the technique is crucial to avoid accidents, and safety measures should be taken, such as using a platform under the wrench. Experts recommend investing in a proper torque wrench for frequent use, as it ensures safety and accuracy. Overall, while alternative methods exist, they carry risks that should be carefully considered.
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I need to tighten the nut for a trailer hitch ball to 250 ft lbs but I don't have a torque wrench that can do it.

I read on a different forum that an alternate old school method to get 450 ft lbs of torque is:
  • Torque = Force x Distance
  • So in that forum's example, have a 180 lb person stand on a 2.5 ft breaker bar. The calculation is 180 x 2.5 = 450.
Is that a correct way to get 450 ft lbs of torque?

If so, then since I weigh 142.3 lbs, 250 ft lbs / 142.3 lbs = 1.76 ft.
0.76 ft is about 9 inches. Therefore 12" + 9" = 21".
So I would have to stand on a breaker bar at 21" from the nut to exert 250 ft lbs of torque.
The breaker bar would of course have to be horizontal while I stand on it for the 250 ft lbs of torque.

Need confirmation from physics gurus whether this is correct or not.
Thanks!
 
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Your math is correct. I would practice my technique before standing on the breaker bar with the nut attached.
You don't want to bounce the bar or have your weight shifting +/- an inch along the bar.
Plan and Practice.
 
Yes, it's right. Plus what @.Scott said. And you get a +1 for actually properly tightening the hitch ball.

I once designed a threaded connection that needed 3000 ft-lbs of torque. So we bolted a 15 foot length of pipe to the part, attached a deer scale, tied a rope to the deer scale, and had two men pull on the rope until the scale read 200 lbs.

A deer scale is a spring scale used by deer hunters for weighing deer. Like this, but 300 lbs full scale:
Deer scale.jpg
 
We need to close this thread now, since there is liability involved in helping you do something dangerous to save a few bucks. Especially if you are going to be changing trailer balls very often, you should just invest in a new torque wrench. Also, you may want to invest in an extension for that wrench so you can get the nut back off again... :wink:

As a safety tip, since you will likely be turning the hitch 90 degrees in order to be able to use your weight vertically to turn the nut, also put a box or other platform under the part of the wrench where you will be applying your weight, so if you do slip off, you only slip a couple inches onto the box/platform.
 
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