Torque Calculation - Not a basic application

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SUMMARY

This discussion focuses on calculating torque in a hydraulic machine used for tightening bolts and nuts. The machine employs a hydraulic ram with a 4-inch diameter piston, generating approximately 1,300 lbf of force at 100 PSI. Key factors affecting torque include the angle of engagement between the ram and cog, the distance from the center of the cog to the ram (variable r), and the maximum stroke length of 6 inches. Accurate torque calculations require understanding the relationship between these variables and applying the formula τ = rFsin(β).

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Mechanical engineers, hydraulic system technicians, and anyone involved in torque applications in machinery will benefit from this discussion.

  • #31
TeeBeeCee said:
Have no idea why the last pressure entry only increased by 15 when all the others were 25.
I'd guess the maximum operating pressure for the equipment is 315 bar, so the final value in the table is 315 bar rather than 325 bar.
 
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  • #32
TeeBeeCee said:
If so, the point I made was that I have no idea if the data is correct and wanted to verify.
Thats fine, but you are going to need precise/accurate measurements of the variables before you can do that. We have to be critical of the model that comes from pure mathematics over what was experimentally measured by the company which designs and manufactures it. There may be "hidden variables" that are difficult to pin down theoretically that would show up experimentally. It's not so easy. Do you suspect a miscalibration, why?
 
  • #33
erobz said:
Thats fine, but you are going to need precise/accurate measurements of the variables before you can do that. We have to be critical of the model that comes from pure mathematics over what was experimentally measured by the company which designs and manufactures it. There may be "hidden variables" that are difficult to pin down theoretically that would show up experimentally. It's not so easy. Do you suspect a miscalibration, why?
I don’t suspect a mis-calibration. It’s just that torque specs are important. A loose bolt or nut can cause severe equipment damage. Just trying to make sure I limit my liability.
 
  • #34
Steve4Physics said:
I'd guess the maximum operating pressure for the equipment is 315 bar, so the final value in the table is 315 bar rather than 325 bar.
Good guess. I just checked and the maximum pressure of the hydraulic pump is 300 bar.
 
  • #35
Regarding that table entry for 300 Bar.
It appears to be a transcription error by whoever supplied the table. The rest of the table is completly linear.

As for the 300 Bar entry, if the "9" is changed to "0", then all the digits match as 3 times the 100 Bar value and 6 times the 50 Bar value.

Except for the last digit, it also matchs as 12 times the 25 Bar value which is likely a round-off error in the 25 Bar value.
 
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  • #36
Tom.G said:
Regarding that table entry for 300 Bar.
It appears to be a transcription error by whoever supplied the table. The rest of the table is completly linear.
The torque at 300 bar is given as 59530.41 Nm. It appears that the '9' should be a '0', i.e. the value should be 50530.41 Nm.

This puts the 300 bar point exactly on the straight line formed by the other points.

Incidentally (I don't think anyone has said it yet) giving the torque values to 7 significant figures leaves something to be desired!.
 
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  • #37
Does anyone else suspect the table not to be actual measured data. It's too perfect (other than the expected typo)?
 
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  • #38
erobz said:
Does anyone else suspect the table not to be actual measured data. It's too perfect (other than the expected typo)?
Yes. Almost certainly.

Maybe the values are calculated from the accurately known dimensions (which was what the OP originally wanted to do).

Or maybe the values are based on actual measurements and the best-fit straight line was found. Then the table could be constructed using the gradient of the best-fit line.
 
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