Torque: Ft. Lbs. Or lbs. Ft?

[RHestand]

Which is correct?

All my years as a gear-head, it was always ft. lbs. Untill a few years ago.

Now I see it both ways. About half one way, and half the other.

When I first started seeing it, I thought it was a typo. Now I see it all the time.

Who changed it, and why was it changed?

Is it more accurate one way than the other?

I've never seen this question addressed before.

My thinking is, "If anyone knows, one or more of the TDR guys will. "

TIA, Ray

 

[fox]

It is all the same!!!

Ft. Lbs for me.

Some engineer types like it backwards.

 

[ScottLewis]

Technically speaking, it's "pounds per foot" and refers to the torque force exerted in pounds, on a lever 1 foot in length. In reality, as long as you know how to apply it why does it matter?



Dan

 

[MChrist]

I've always heard it as "foot pounds of torque". Now I'm hearing "pound feet" of torque also. Since 10 "foot pounds" is the equivalent to the twisting force of a 10 pound weight on the end of a 12 inch bar, "pound feet" actually makes more sense, even though it does sound very European!!

 

[HBarlow]

Recently I've seen writers use TQ as in 350 hp, "650 TQ" which is obviously not based on engineering principles but it simple to write, read, or understand.

Few of us have an engineering education or background and truly understand the details of actual torque and horsepower measurements anyway. TQ is good enough for my limited understanding.

 

[fox]

Torque does the work.

Hp is the rate of the work.

Cummins knows!!!

 

[testraub]

Crud Does this mean if it say Lbs-Ft I'll need a new TQ wrench that reads that way? #@$%! :-laf

 

[Batphreak]

Technically speaking, it's "pounds per foot" and refers to the torque force exerted in pounds, on a lever 1 foot in length. In reality, as long as you know how to apply it why does it matter?

Dan

Since we're getting all technical in this thread and since I'm an engineer. Your explanation of torque there is correct, however the "pounds per foot" is incorrect. "Pounds per foot" indicates a division operation i. e. lb/ft, Torque is actually a multiplication operation lb(force being exerted)*ft(length of arm where force is applied). This is what leads to ft-lb or lb-ft. Since orer of operations tells us that it doesn't matter what order a multiplication operation is done either ft-lb or lb-ft is completely correct.

$0. 02

 

[THorn]

Batphreak... ... You just made my day for being an engineer! I had flash backs of machine desigg II and Dynamics class!

 

[SNiebaum]

Batphreak... ... You just made my day for being an engineer! I had flash backs of machine desigg II and Dynamics class!

Do I also make your day because I'm an Engineer?? Oo.



and it's definitely lb-ft... or in my world, K-ft... .

 

[Adventure Bob]

Ok, we are regular group of certified intelligent folks. As pointed torque is a multiplicative function so actaul order is irrelevent. The trend, and it s a trend towards standardization to the SI measurement lb-ft is to stay in line with other measuring systems torque measurement. In Metric it's Newton-Meters. It has never been meter-newtons even though stating it as such isnt necesarily incorrect, it's not what the governing bodies have decided to standardize to. Since the definition of torque is the tendency of a force (lbs) applied to an object to make it rotate about an axis, it is appropriate to state the force (lbs, newtons, dynes) the force required then the unit over which the force was moved (ft, inches, meters, microns)

 

[Pavemen]

or in my world, K-ft... .

what no N-m?

 

[SNiebaum]

what no N-m?

not anymore...

 

[Pavemen]

not anymore...

Must be nice to have consistent units... I'm an EQ engineer and there are so many different units for all the components of what I do, it's hard to kepe track of how they all relate to one another.

as for the original topic, its ft-lb when I am talking cars but lb-ft when speaking "engineer"

 

[TBartlett1]

I worked in the developement of the Transmission in the US Armys Bradley Fighting Vehicle which was powered by a 600hp 903 cummins. 1200 lbft @ 2600rpm

Torque gets the load moving

HP determines how fast you can go

 

[Jefff929]

and it's definitely lb-ft... or in my world, K-ft... .

What does black feet have to do with being an engineer?

 

[SMorneau]

Ok, we are regular group of certified intelligent folks. As pointed torque is a multiplicative function so actaul order is irrelevent. The trend, and it s a trend towards standardization to the SI measurement lb-ft is to stay in line with other measuring systems torque measurement. In Metric it's Newton-Meters. It has never been meter-newtons even though stating it as such isnt necesarily incorrect, it's not what the governing bodies have decided to standardize to. Since the definition of torque is the tendency of a force (lbs) applied to an object to make it rotate about an axis, it is appropriate to state the force (lbs, newtons, dynes) the force required then the unit over which the force was moved (ft, inches, meters, microns)

I don't have much faith in governing bodies anymore! But standards do make it easier to do engineering calculations. I was schooled and worked as an Engineer until about 2 years ago when i got laid off and went to work for a buddy repairing machines. Much more fun than a desk job and its way easier to make one boss happy than a bunch of overly educated people who have never used a torque wrench. College educated people are a dime a dozen. People who can fix stuff are a vanishing breed in some industries.

 

[RKerner]

I don't have much faith in governing bodies anymore! But standards do make it easier to do engineering calculations. I was schooled and worked as an Engineer until about 2 years ago when i got laid off and went to work for a buddy repairing machines. Much more fun than a desk job and its way easier to make one boss happy than a bunch of overly educated people who have never used a torque wrench. College educated people are a dime a dozen. People who can fix stuff are a vanishing breed in some industries.

Oooh, Oooh, how about a former ASE Master Mechanic turned college edumacated engineer type? I figure I'm worth at least a hundred bucks. To keep on topic, I use lbf-ft as torque or work units 'cause in BE units, you can have pound mass or pound force (nice). Kilogram and meter make way more sense and simpler calcs for sure.

 

[SNiebaum]

Must be nice to have consistent units... I'm an EQ engineer and there are so many different units for all the components of what I do, it's hard to keep track of how they all relate to one another.

We used to do work in both system of units thanks to the government… it was a royal pain. Do you soft convert or exact convert… is 8 ft 2440 mm or 2438. 4 mm…

To keep on topic, I use lbf-ft as torque or work units 'cause in BE units, you can have pound mass or pound force (nice). Kilogram and meter make way more sense and simpler calcs for sure.

I was going to say something similar but restrained myself… it is oh so true.

 

[Pavemen]

We used to do work in both system of units thanks to the government… it was a royal pain. Do you soft convert or exact convert… is 8 ft 2440 mm or 2438. 4 mm…



I was going to say something similar but restrained myself… it is oh so true.

most stuff is exact convert, then rounded after final calcs at times.