Torque Wrench

[Chillimau]

An extension such as a deep well socket ( a very short extension) or any other length extension is not going to change the torque reading. The length of the lever, the torque wrench hasn't changed.

However, using something like a crows foot which changes the effective length of your torque wrench will need adjustments to the setting to get the proper torque applied to the fastener. With a crows foot or some other type of offset attachement you have a longer lever and will not need to apply the same amount of force to get the proper torque.

An engineer could give us a formula for this but I think the "moment" is force x length? This would allow you to correct for the added length and set the torque wrench to the proper setting .

 

[BillyP]

Seems to me like using a longer torque wrench would only change the force "you" supply to reach the same torque setting? In other words, it would be easier on you to use a 24" torque wrench to get 500 ft lbs than it would to use a 12".

 

[JohniusMaximus]

A 5 inch extension did it. I also bought a 10 inch extension just to have if we need it. I checked all wheel bolts. Took about 1 minute.

 

[txhawg]

Extensions that are in-line with the socket will not affect the torque applied. It is when you extend the effective length of the wrench with an extension such as a crows foot socket. In that case the formula to determine torque would be:

((L+E)/L)* (Torque setting)

L would be the length of the wrench (to the center of the square that goes into the actual socket), and E would be the length of the extension. For example, let's say I have a 12" torque wrench and set it for 10 lbs. I add a 3" crows foot extension to it. I now take 12" + 3" for a total length of 15", divide that by the original length of 12", and get 1.25. I take the setting of 10 lbs and multiply by 1.25 for a true torque reading of 12.5 lbs. In this example the result is not significant, but as you go up in torque and length the actual vs setting gap grows quickly and bolts begin snapping.

 

[trlong]

Glad to hear it went simply. You may want to check them occasionally, especially if using a backhoe. My dealer warned me on that and, sure enough, after extensive use of the backhoe the rear wheel bolts often need a slight tweek.

See what you've started though? We could get several entire threads on torque wrenches, extensions, moment arms, tensile strengths,....you name it. /forums/images/graemlins/smirk.gif

 

[Stef]

I use a 24" torque wrench and I have to say that using it without extension is far more easier than otherwise. With a 12" extension you have to force with both hands: one on the handle and the other on its head to keep it aligned with the bolt.

But, this is the only way to be sure that every bolts are tightened just enough and not too much. I think this is a must have for a tractor owner.

 

[Cheyenne]

Weight X Arm = Moment, or, in this case Force X Arm = Moment. So, 70 lbs force at the end of an 18-inch wrench equals 1,260 in.lbs or 105 ft.lbs.

 

[gbick]

Attatch the crows foot at a 90 degree angle to the arm of the torque wrench. This will not change the effective length of the wrench, and torque will remain true.

 

[rb4410]

ok,i see i have opened up a can of worms here,,,,,,,,,,,,,,,just for kicks and giggles, use a standard 1/2" drive ratchet wrench, a 3/4" socket and you will need a 3" extension and a 12" extension. tighten a wheel nut to proper torque without the use of an extension. now using you're ratchet wrench with the 3" extension,break the fastener loose and pay attention to how much force is needed, then re-torque again without the extension and then repeat the procedure again using the 12" extension.can you tell if there is any difference in the force required to remove the fastener??????????? it's actually simple physics. length + diameter determines necessary force.torque values are determined by the hardness of the fastener as well as length and diameter not to forget the required clamping force deemed necessary which would fall back on the size and the thread pitch of the fastener being used as well as the type of material being used.
i hope this clears things up a bit ,,,,,,,,,,,,,,,,,,,,,,,

 

[trlong]

<font color="blue"> </font><font color="blue" class="small">( Weight X Arm = Moment, or, in this case Force X Arm = Moment. So, 70 lbs force at the end of an 18-inch wrench equals 1,260 in.lbs or 105 ft.lbs. )</font> </font>

But, but...what about sin(theta)? Are we really "Nomal" to the plane of rotation? /forums/images/graemlins/grin.gif And, "lb. force"? isn't that redundant? /forums/images/graemlins/shocked.gif

Just couldn't resist being a PITA /forums/images/graemlins/smirk.gif