Just read in the archives a statement that I find hard to believe. The author states that using an extension does Not affect the torque values because it doesn't extend the lever arm. I have always heard that when using an extension, remember to make allowances for the extension. My question--how much do you increase your torque setting to allow for various lenghts of extensions? Are there multipliers for 1/4-1/2 and 3/4 inch diameter extensions? Also, for the various lenghts of each? Thanks.
- Thread starter Dr. Bert
- Start date
dave guest
Well-known Member
Only thing I know is if you are using an air wrench to remove lug nuts and they don't come off using an extension, try deep socket and no extension, usually will come loose.
As long as you are not using an impact wrench and are using a mechanical torque wrench, extension length will have no effect on torque wrench settings.
Of course, if you have a "crow foot" or other offset socket or wrench at the business end of the extension, that is another matter.
Of course, if you have a "crow foot" or other offset socket or wrench at the business end of the extension, that is another matter.
Whether it's an extension of any length between the socket and the torque wrench or one that extends the "lever arm" of a mechanical torque wrench, there is NO effect on the accuracy of the torque values. As was stated correctly, however, if something is used between the torque wrench socket (i.e. like a crows foot or any device that changes the wrench mechanical advantage) then there is going to be an error in the torque wrench setting/value.
John G. Hasler
Member
> Only thing I know is if you are using an air
> wrench to remove lug nuts and they don"t come
> off using an extension, try deep socket and no
> extension, usually will come loose.
Because the springyness of the extension soaks up some of the impact. Doesn"t happen with a manual torque wrench as there is no impact.
> wrench to remove lug nuts and they don"t come
> off using an extension, try deep socket and no
> extension, usually will come loose.
Because the springyness of the extension soaks up some of the impact. Doesn"t happen with a manual torque wrench as there is no impact.
rustyfarmall
Well-known Member
Bert, in theory, you are correct. If that extension did not have some "flex" or twist desingned into it, the extension would most likely just snap when you applied torque to it, so yes, the use of an extension will effect torque values, and in some applications it might actually be critical, but in the real world of torqueing down the head bolts or manifold bolts on an old farm tractor, the use of an extension is nothing to be overly concerned about.
Here is my thinking.
If you are putting 100 ft lbs to the drive end of the extension, the other end of the extension is putting out 100 ft lbs also.
If it starts flexing at 90 foot lbs it is still putting out 100 if that is what you are putting to it.
It is not geared up or down so the energy put into it has to come out the same.
Look at it this way you put a tire between two chains to pull a 10,000 tractor.
If you set the pulling tractor to pull extactly 10,000 lbs it will pull the tractor.
10,000 lbs into the tire and 10,000 lbs out if the tractor moves.
The tire will stretch but still pulls 10,000 pounds.
Gary
If you are putting 100 ft lbs to the drive end of the extension, the other end of the extension is putting out 100 ft lbs also.
If it starts flexing at 90 foot lbs it is still putting out 100 if that is what you are putting to it.
It is not geared up or down so the energy put into it has to come out the same.
Look at it this way you put a tire between two chains to pull a 10,000 tractor.
If you set the pulling tractor to pull extactly 10,000 lbs it will pull the tractor.
10,000 lbs into the tire and 10,000 lbs out if the tractor moves.
The tire will stretch but still pulls 10,000 pounds.
Gary
Bob M
Well-known Member
"Just read in the archives a statement that I find hard to believe. The author states that using an extension does Not affect the torque values because it doesn"t extend the lever arm."
Dr Bert - That statement is 100% correct!
What DOES have an effect are the use of fixtures between the extension and the socket that result in an offset between the centerline of the extension and the fastener - eg a crow’s foot wrench. Also angling between the wrench and socket by using of a universal joint with an extension will result in distorted torque values (the greater the angle the greater the error).
Dr Bert - That statement is 100% correct!
What DOES have an effect are the use of fixtures between the extension and the socket that result in an offset between the centerline of the extension and the fastener - eg a crow’s foot wrench. Also angling between the wrench and socket by using of a universal joint with an extension will result in distorted torque values (the greater the angle the greater the error).
Doc, While it may be hard for you to believe in the PRACTICAL SENSE in the THEORETICAL SENSE its indeed true...... In theory it dont matter how long an extension (were NOT talking about any horizontal lever arm here, the vertical extension) might be, the rotational torque force around the pivot point REMAINS THE SAME PROVIDED theres no flexing away from or off center (which could affect the lever arm length)
Nowwwwww the reason your impact wrench dont have as much force out on a long extension is the flexing and unflexing and torqueing extra movements and vibration is robbing and absorbing some of the energy which would otherwise go into staight rotational torque on that nut each time that impact hammers.
John T
Nowwwwww the reason your impact wrench dont have as much force out on a long extension is the flexing and unflexing and torqueing extra movements and vibration is robbing and absorbing some of the energy which would otherwise go into staight rotational torque on that nut each time that impact hammers.
John T
ScottyHOMeY
Well-known Member
Amen. To what you said along with John T above and observing Bob M's cautions. (Days like this might make me actually believe I'm hangin' out with good company!!) ;8^)
An extension on the handle of a torque wrench (it'd have to be a big one on a tight nut for there to be any need of that) won't have any effect on the reading (or the "pop" point) of a torque wrench.
And for anything that can be tightened by hand, an extension running perpindicularly (ain't that some kinda word!) off the drive of the torque wrench won't appreciably distort the reading, as long as one makes the effort to keep the sweep of the wrench handle perpindicular to the axis of the thread being torqued. Your arm will give before the steel in the extension twists.
The caution is to do with things like crowfoots, which are sometimes necessary to get to the bolt/nut to be torqued. For that you need to do add the length from the center of the drive on the torque wrench to the center of the fastener to the working length of the torque wrench, divide by the newer length and adjust to a lower torque accordingly. Torque is foot-pounds. Add feet, reduce pounds to get the same result.
And a little fudging is allowed. These are tractors that (with the possible exception of the ETD) will never be exposed to the the conditions to be met in outer space, where torque tolerances can be a matter of life and death.
An extension on the handle of a torque wrench (it'd have to be a big one on a tight nut for there to be any need of that) won't have any effect on the reading (or the "pop" point) of a torque wrench.
And for anything that can be tightened by hand, an extension running perpindicularly (ain't that some kinda word!) off the drive of the torque wrench won't appreciably distort the reading, as long as one makes the effort to keep the sweep of the wrench handle perpindicular to the axis of the thread being torqued. Your arm will give before the steel in the extension twists.
The caution is to do with things like crowfoots, which are sometimes necessary to get to the bolt/nut to be torqued. For that you need to do add the length from the center of the drive on the torque wrench to the center of the fastener to the working length of the torque wrench, divide by the newer length and adjust to a lower torque accordingly. Torque is foot-pounds. Add feet, reduce pounds to get the same result.
And a little fudging is allowed. These are tractors that (with the possible exception of the ETD) will never be exposed to the the conditions to be met in outer space, where torque tolerances can be a matter of life and death.
Janicholson
Well-known Member
Holding the torque wrench at the head with one hand to counter the offset leverage of the force applied (holding the head stationary over the axis of the fastener) will remove even more error. Just do not deflect the pointer with your hand if it is the beam type wrench. I love discussions like this. JimN
Jim, I figured as much from you, hows about we suck down a few barley sodas n get into all that Einstein stuff about how we shrink in size but get heavier as we approach relativistic speeds but we dont age as fast !!!!!! I guess if you put a watch on the space shuttle when you return back to earth its a tad slow correct??? HMMMMMMMM now theres some deep stuff
John T (Once a Nerd always a Nerd)
John T (Once a Nerd always a Nerd)
ScottyHOMeY
Well-known Member
John, closer to earth and at spees we can all expect to achieve, have ya given any thought to how you weigh less when you inhale? The mass within the confines of your carcass actually increases when you inhale by the mass of the inhaled air, but your weight decreases, as the volume of the air inhaled is less dense than the body mass it displaces, increasing your buoyancy in the ambient atmosphere and thereby decreasing your weight.
Whew! Have ya got an extra beer?
Whew! Have ya got an extra beer?
Shhheeeeeeeeshhhhhhhh, I never thought of that one lol. Reminds me when my kids were young they asked if a vehicle full of flies weighs less if the flies are sitting around or flying??? I told em when flying their wings are exerting a sufficient downward force (albeit air pressure) to lift their weight so the weight of the vehicle stays the same, now Im not sure thats right or not lol
Likewise, whats that Bernoulli or some other dudes thing about buoyancy ?? is it when you put a boat in the water the buoyant force is equal to the weight of the water it displaces???
Although I majored in Electrical Engineering (wayyyyy back in the sixties) I still remember some of that mechanical stuff n physics etc
John T
Likewise, whats that Bernoulli or some other dudes thing about buoyancy ?? is it when you put a boat in the water the buoyant force is equal to the weight of the water it displaces???
Although I majored in Electrical Engineering (wayyyyy back in the sixties) I still remember some of that mechanical stuff n physics etc
John T
Hoss In ME
Member
Can someone tell me why the yolk of an egg is on top when you crack an egg open no matter how the egg is held?? Inquisitively----Hoss
screwstick
Member
I realize finding the proper torque with a crowsfoot (or other linear extension) wasn't the original question, it was brought up a couple times and though some may find this link useful. Torque Wrench Extension Calculator:
http://www.norbar.com/Calculators/TorqueWrenchExtensionCalculator/tabid/70/Default.aspx
http://www.norbar.com/Calculators/TorqueWrenchExtensionCalculator/tabid/70/Default.aspx
Janicholson
Well-known Member
For a balloon to float (in air) the balloon must be filled with something lighter than air. Helium, hydrogen, are two common gasses that will work.
The pressure in the balloon is just modestly above atmospheric (to stretch the rubber). A balloon filled with air falls to the ground. A tank of compressed air indeed weighs more than a air tank with a open fitting balancing internal and external pressure.
0.076lb per Cubic foot for 60 degree air at sea
level.
0.456lb per cubic foot for 60 degree air at 75psi
(Rock Excavation Handbook)
JimN
The pressure in the balloon is just modestly above atmospheric (to stretch the rubber). A balloon filled with air falls to the ground. A tank of compressed air indeed weighs more than a air tank with a open fitting balancing internal and external pressure.
0.076lb per Cubic foot for 60 degree air at sea
level.
0.456lb per cubic foot for 60 degree air at 75psi
(Rock Excavation Handbook)
JimN
dave guest
Well-known Member
Good explanation. Thanks
Anonymous-0
Well-known Member
Because the yolk is lighter and floats on the whites
The weight of air can be seen vividly in any dive shop. Empty SCUBA tanks (@14.7 lbs./sq. in. internal pressure) float. They are filled in water in a tank of water in order to reduce the temperature rise with compression. The empty tank starts to sink during the filling process and ends up solidly on the bottom when full to 2200 lbs. per sq.in.
Bernoulli theory is as speed increases, pressure decreases. Thats how venturies run vacuum gauges.
Basic aircraft wings are rounded on top, air moves faster over the rounded top than over the flatter bottom but reaches the trailing edge of the wing at the same moment, therefore the air on the top of the wing is moving faster decreasing the pressure, the aircraft moves up into that lower pressure ie. flying.
Basic aircraft wings are rounded on top, air moves faster over the rounded top than over the flatter bottom but reaches the trailing edge of the wing at the same moment, therefore the air on the top of the wing is moving faster decreasing the pressure, the aircraft moves up into that lower pressure ie. flying.
I meant to say " air moves further (instead of faster)over the rounded top"
Top air movers a further distance than the bottom air in the same time, therefore it is moving faster.
Pick up a piece of typing paper by the bottom two edges then bring it straight up in front of your face letting the top part roll over your hands draping away from you (huh?) Now blow hard above and across the part that is rolled over your hands and it will rise up - straight out if you blow hard enough. That"s how an aircraft rises into the lower pressure air. (And you thought it was magic!)
Top air movers a further distance than the bottom air in the same time, therefore it is moving faster.
Pick up a piece of typing paper by the bottom two edges then bring it straight up in front of your face letting the top part roll over your hands draping away from you (huh?) Now blow hard above and across the part that is rolled over your hands and it will rise up - straight out if you blow hard enough. That"s how an aircraft rises into the lower pressure air. (And you thought it was magic!)
Rumplestiltskin
Member
Hi, Scotty.
I disagree. Let me suggest this to see if it makes sense:
First, let's assume that gravity does not change for the purposes of this discussion -- i.e., that the gravitational "constant" is indeed constant.
Now...
When you inhale, you capture molecules of air. This increases the overall mass of the "confines of your carcass" and, by definition, increases your weight (barring weird stuff like a negative gravitational constant or the inhalation of anti-matter). So you weigh more after you inhale, period.
Your buoyancy in the ambient atmosphere increases because your overall DENSITY (mass PER UNIT OF VOLUME) has decreased. The confines of your carcass are now larger; they were made larger by expanding your chest to inhale a substance less dense than your body's density before inhaling.
So, although you encompass extra molecules and therefore MUST weigh more after you inhale, your density (kg/m^3 or whichever units you prefer) has decreased. If the density of the ambient environment (a swimming pool full of water, for example) hasn't changed, you'll find it easer to float in it -- because, although heavier, you're less dense.
Hey! It just occurred to me that maybe the advice to "take a deep breath" if we're ready to do something dumb has some scientific basis -- it makes us less dense!
Mark W. in MI
I disagree. Let me suggest this to see if it makes sense:
First, let's assume that gravity does not change for the purposes of this discussion -- i.e., that the gravitational "constant" is indeed constant.
Now...
When you inhale, you capture molecules of air. This increases the overall mass of the "confines of your carcass" and, by definition, increases your weight (barring weird stuff like a negative gravitational constant or the inhalation of anti-matter). So you weigh more after you inhale, period.
Your buoyancy in the ambient atmosphere increases because your overall DENSITY (mass PER UNIT OF VOLUME) has decreased. The confines of your carcass are now larger; they were made larger by expanding your chest to inhale a substance less dense than your body's density before inhaling.
So, although you encompass extra molecules and therefore MUST weigh more after you inhale, your density (kg/m^3 or whichever units you prefer) has decreased. If the density of the ambient environment (a swimming pool full of water, for example) hasn't changed, you'll find it easer to float in it -- because, although heavier, you're less dense.
Hey! It just occurred to me that maybe the advice to "take a deep breath" if we're ready to do something dumb has some scientific basis -- it makes us less dense!
Mark W. in MI
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