But if you notice, it is the second definer that gets pluralized in speech. Unfortunate that it is backwards from the mathematical reality. In torque, the force is usually expressed first as that is what we are interested in and will vary.
To separate high torques from low torques in fasteners, we change the moment of the loading from foot to inch. The pressure of say 30 pounds acted on a piston with a 4 square-inch area will produce pounds force lbf. Your prediction was correct. What a magnificent web find! Ask me about hanks or rroods. Now I know how finger ring sizes work. My maintenance manual English uses the abbreviations lbf ft and lbf in — also supplied as Nm and kgf c m.
When did all of this come about? So the manuals are wrong? A physicist such as myself , would not distinguish ft-lb from lb-ft they both have units of feet times pounds. In this case the forward slash is not a division sign but a virgule.
A lb-ft is not the same quality as a ft-lb, just as a Newton meter is not the same quality as a joule. Indeed…though there is a similar issue in that the joule and the Newton meter are the same quantity algebraically but represent two different properties. Nice deflection away from the argument against the use of a division sign by highlighting that it is indeed a virgule. However, a virgule itself is not appropriate since it is either i a short oblique stroke between two words indicating that whichever is appropriate, e.
In this case the virgule is being used as in a fraction, i. It is interesting to note that the unit definitions for Work and Torque are as such. But if you consider their mathematical definitions, you would think the units would be reversed. I will use LaTeX notations for this, but it should still be follow-able. By dimension analysis, the units should follow the order of the formulas, i. Again the order of the terms makes it seem the units should follow the same pattern, m.
N or ft. But from the property of cross product you may also get. I myself use the dimension analysis as a way to remember corresponding units. I am a retired mechanical engineer, and I distinctly remember that approximately fifty years ago the Society of Mechanical Engineers decided to make static torque pound-feet, and dynamic torque foot-pounds.
For the engineers and physicists.. A lowly mechanic asks: is two pounds of force upon a one foot lever the same torque as one pound of force on a two foot lever?
If the formula is force times arm length then I see it would have to be so. Good article. It is expressed in terms of applied load and the length of the moment arm applying it, usally in pound-inches, pounf-feet, or Newton-meters lb-in, lb-ft, N-m. No worries at all. Simply use the spec listed in the manual or other technical literature.
The numerical value is not affected. In some cases the folks making comments used the wrong nomenclature which actually disproves their own point. I have built many racing cars and tested many engines on dynos.
I even worked for the famous Smokey Yunick for a while on the dual turbo Chevy Indy car project. A person might say they have two feet but keep one foot in their mouth. We all understand exactly what they meant and I especially know because I practice this behavior often. Maybe the car companies have found a new way of stretching the truth about their product and a clever way to hide the true power of their product and plead ignorance when caught.
As a few pointed out in their comments the abbreviation is what may confuse folks who do not know how torque is measured. First it correctly stated that it is measured with a one foot lever but then the writer incorrectly calls out the torque value claiming the lever used for the test is longer.
How much longer? Feet is the plural form of foot. Torque is measured one foot from the center of the load absorbing device that must be one foot long not one feet long. I enjoyed and admired all those who took the time to write their opinions. I was ready to scour the internet and look for a quote or two, until I read your reply.
This is what happens when a young fella with a pocket protector gets involved. Your only embarrassing yourself. To me it is a clear difference although one must say Joules and Newton meter are in bed together. Think of X-amount of pounds resting on a lever of 1 foot length, perfect, makes sense. So Lbs. As for work, fts.
You now travel over a distance x with 1 lb in you lap WITH the addition of a time frame assuming it is a second. Example fts. How realistic does that even sound? Is it just me or does that seem less ridiculous? People hate the Metric system, but it makes more sense at times than Imperial.
Convert between the pound-force foot or pound-force inch and other major units of torque. Convert between the foot pound-force and other major units of energy. The foot pound and pound foot are a fertile source of confusion: confusing mass with force, and confusing torque with energy, because both have the dimensions energy and length. In everyday speech in the United States, the foot pound is a unit of torque used, for example, in expressing how strongly to tighten a nut or bolt.
Essentially, a manufacturer who specifies that a certain nut be tightened to 1 foot pound of torque is calling for turning the nut by applying a force of 1 pound to the wrench, at a right angle to the wrench, at 1 foot from the axis of the bolt.
The inch pound and inch ounce are similarly conceived. In the rest of the world, this unit of torque is usually called a pound foot. In SI the unit of torque is the newton meter , with the name of the unit of force first and of distance second. The pound foot follows that pattern. More correctly, since we are really not dealing in pounds, a unit of mass, but in pound-force 's, engineers call the auto mechanics' foot pound a pound-force foot.
Suppose instead of being applied at right angles to a lever arm, the pound-force is applied in a straight line over a distance of one foot. Metrologists call this a foot pound-force , and it is a unit of energy, not torque.
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