Torque specifications... help please
Mar 5, 2011, 12:16 PM
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Torque specifications... help please
I know this sounds dumb, but with no experience with torque specs I am kind of at odds with these numbers:
(181 ± 21 ft-lb)
Does this mean 181 ft-lbs of torque plus or minus 21? so anywhere in the 160-202 ft-lbs of torque would be sufficient? I am just trying to make sure I do everything correctly.
Thanks
On a further note, I have been trying to search about how to specifically set the 'torque'. Is there a special tool attached to a regular ratchet or is it a special ratchet or torque wrench with a built in torque 'specifier'? I don't know where I am trying to go with that.
(181 ± 21 ft-lb)
Does this mean 181 ft-lbs of torque plus or minus 21? so anywhere in the 160-202 ft-lbs of torque would be sufficient? I am just trying to make sure I do everything correctly.
Thanks
On a further note, I have been trying to search about how to specifically set the 'torque'. Is there a special tool attached to a regular ratchet or is it a special ratchet or torque wrench with a built in torque 'specifier'? I don't know where I am trying to go with that.
Mar 5, 2011, 01:32 PM
#2
I know this sounds dumb, but with no experience with torque specs I am kind of at odds with these numbers:
(181 ± 21 ft-lb)
Does this mean 181 ft-lbs of torque plus or minus 21? so anywhere in the 160-202 ft-lbs of torque would be sufficient? I am just trying to make sure I do everything correctly.
Thanks
On a further note, I have been trying to search about how to specifically set the 'torque'. Is there a special tool attached to a regular ratchet or is it a special ratchet or torque wrench with a built in torque 'specifier'? I don't know where I am trying to go with that.
(181 ± 21 ft-lb)
Does this mean 181 ft-lbs of torque plus or minus 21? so anywhere in the 160-202 ft-lbs of torque would be sufficient? I am just trying to make sure I do everything correctly.
Thanks
On a further note, I have been trying to search about how to specifically set the 'torque'. Is there a special tool attached to a regular ratchet or is it a special ratchet or torque wrench with a built in torque 'specifier'? I don't know where I am trying to go with that.
Mar 5, 2011, 05:51 PM
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What you need is a 'ratchet with a torque specifier', called a torque wrench. A torque wrench has a graduated scale on it's handle, which will allow you to specify a torque (in lb-ft or N-m), as long as it's within it's operating range. A typical torque wrench will be :
http://buy1.snapon.com/catalog/item....re&dir=catalog
Once you've set the torque on the wrench, start torqing the capscrew/bolt/nut with even smooth motions. You'll know you've hit the specified torque when the joint between the head and the shaft of the torque wrench 'gives', or 'clicks'. You can try to re-apply torque and confirm if it gives/clicks again, to be sure you've hit the torque.
On any professional torque specification, you'll encounter this kind of notation : 181 ± 21 ft-lb. This is read as "Nominal Torque" ± "Tolerance". A simplistic reading of this notation is that, your resultant torque should lie within 160 to 202. The specification calls for upper and lower limit of 11% from the mean value.
You need not worry about being in the tolerance region of the final torque limit , for 80-90% of the bolted joints / fasteners. Anyways, using a hand hend torque wrench, production capscrews, and already-used threads, the variation in final torque is typically 30%.
Bottom line, how you will use this information is by setting the wrench at 181 lb-ft.
http://buy1.snapon.com/catalog/item....re&dir=catalog
Once you've set the torque on the wrench, start torqing the capscrew/bolt/nut with even smooth motions. You'll know you've hit the specified torque when the joint between the head and the shaft of the torque wrench 'gives', or 'clicks'. You can try to re-apply torque and confirm if it gives/clicks again, to be sure you've hit the torque.
On any professional torque specification, you'll encounter this kind of notation : 181 ± 21 ft-lb. This is read as "Nominal Torque" ± "Tolerance". A simplistic reading of this notation is that, your resultant torque should lie within 160 to 202. The specification calls for upper and lower limit of 11% from the mean value.
You need not worry about being in the tolerance region of the final torque limit , for 80-90% of the bolted joints / fasteners. Anyways, using a hand hend torque wrench, production capscrews, and already-used threads, the variation in final torque is typically 30%.
Bottom line, how you will use this information is by setting the wrench at 181 lb-ft.
Last edited by RevMatcher; Mar 5, 2011 at 09:21 PM.
Mar 6, 2011, 07:09 AM
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For starters, yes you need a torque wrench to properly torque any nuts or bolts. Pick up a Craftsman at Sears. When you store it after use, make sure it is completely backed off and that it isn't locked. This will help it to stay calibrated longer. That being said, you are correct with the torque specs. That means 181 ft-lbs or torque with a variance of 21 ft-lbs.
What you need is a 'ratchet with a torque specifier', called a torque wrench. A torque wrench has a graduated scale on it's handle, which will allow you to specify a torque (in lb-ft or N-m), as long as it's within it's operating range. A typical torque wrench will be :
http://buy1.snapon.com/catalog/item....re&dir=catalog
Once you've set the torque on the wrench, start torqing the capscrew/bolt/nut with even smooth motions. You'll know you've hit the specified torque when the joint between the head and the shaft of the torque wrench 'gives', or 'clicks'. You can try to re-apply torque and confirm if it gives/clicks again, to be sure you've hit the torque.
On any professional torque specification, you'll encounter this kind of notation : 181 ± 21 ft-lb. This is read as "Nominal Torque" ± "Tolerance". A simplistic reading of this notation is that, your resultant torque should lie within 160 to 202. The specification calls for upper and lower limit of 11% from the mean value.
You need not worry about being in the tolerance region of the final torque limit , for 80-90% of the bolted joints / fasteners. Anyways, using a hand hend torque wrench, production capscrews, and already-used threads, the variation in final torque is typically 30%.
Bottom line, how you will use this information is by setting the wrench at 181 lb-ft.
http://buy1.snapon.com/catalog/item....re&dir=catalog
Once you've set the torque on the wrench, start torqing the capscrew/bolt/nut with even smooth motions. You'll know you've hit the specified torque when the joint between the head and the shaft of the torque wrench 'gives', or 'clicks'. You can try to re-apply torque and confirm if it gives/clicks again, to be sure you've hit the torque.
On any professional torque specification, you'll encounter this kind of notation : 181 ± 21 ft-lb. This is read as "Nominal Torque" ± "Tolerance". A simplistic reading of this notation is that, your resultant torque should lie within 160 to 202. The specification calls for upper and lower limit of 11% from the mean value.
You need not worry about being in the tolerance region of the final torque limit , for 80-90% of the bolted joints / fasteners. Anyways, using a hand hend torque wrench, production capscrews, and already-used threads, the variation in final torque is typically 30%.
Bottom line, how you will use this information is by setting the wrench at 181 lb-ft.
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