define torque

[1RACEBABE]

I was talking with my boyfriend Rob #940 last night.  I asked him to give me a definition of "torque" and he could not.  I got an explaination but not a true definition.  Can any of you give one, without the aid of Websters?

Hey Rob, I like your wet little....pug.  Yes, pug.  Give Mr. Fredricks #91 a shout and a big kiss for for me! ;D

[Super Dave]

You can feel torque.

HP you can't.

So, when you're buzzing in a car around the neighbor hood and you accelerate hard and it kind of gets going quicker....that's more of a torque feeling.  Car that has more of that feeling?  More torque...or it weighs less in comparison to a similar amount of torque generated by the engine.

That help?

[WebCrush]

Easiest way I explain it to g/f:

Torque is how hard you can twist

Hp is how fast you can twist it

and of course, the two are related in a mathematical and physics equation based upon rpm

(more definition view:  Torque is the amount of work you can perform, HP is the amount of work over a given time)

[GregR6]

a squid movie  ???


 :P

[Nate R]

Yep, torque is the immediate force applied. HP basically is how many times you can apply that force.

Taken from allpar.com/eek:

Both torque and power can be observed "directly". Think of slowing a free-spinning tire with your hand. Feel the tug on your palm and the tension in your arm? That's a measure of torque, the torque the tire experiences as a result of your palm slowing it down. Feel the heat build up from friction? That's a measure of power.

Lets say you have a motor that makes 50 ftlbs of torque at 4000 RPM, and another that makes 30 ftlbs of torque at 8000 RPM.

The one that makes the most power, and accelerates the fastest (Given the same chassis and motor weights, etc, the only variable being the power curve) will be the one that makes 30 ft lbs at 8000.

Torque is immediate, but power is really how often that torque can be used. That 30 ft lbs is used 8000 times/minute, compared to the 50 being used only 4000.

Motors with High RPM and no torque may make the same HP as a motor with the other extreme. (Think crappy dremel tool compared to rotissere (sp) motor) They might both make the same HP, but the motor with hardly any rpm, but TONS of torque (the rotisserie) could turn a bigger load. (Like a chicken) So, although they both make the same power, the dremel would never be able to start the chicken moving, whereas the rotissere motor would.


So, torque has importance.

Does this help the overall understanding at all?

[bweber]

Torque is defined as the product of a force by a moment arm:  T=F x L where T is Torque, F is force and L is the moment arm.
Torque and horsepower are related by the following equation:
(hp x 5250)/rpm = torque
when torque is measured in foot-pounds
That is why the hp and torque curves always cross at 5250 rpm on a dyno chart.

[Zac]

So, when you're buzzing in a car around the neighbor hood and you accelerate hard and it kind of gets going quicker....that's more of a torque feeling.  Car that has more of that feeling?  More torque...or it weighs less in comparison to a similar amount of torque generated by the engine.

Hmm, when I drove my dad-in-law's tractor (~45 HP, ~200 ft-lbs plus the torque amplification of crazy-low gear ratios) it didn't feel like my car buzzing around the neighborhood...

Torque is simply force times distance.  So if I turn my rear axle with a certain torque (not the same as the engine torque due to the mutiplication of the tranny) and multiply that by the radius of the wheel the will give the force one the ground and I can calculate the acceleration using F=ma (in a perfect world with no friction in a vacuum).

If I had a bike with only one gear, the engines torque curve and the weight of the bike and rider would determine the acceleration curve, while the horsepower and drag would determine top speed.  Include drag in the acceleration curve and it gets pretty complicated.

Give me a gearbox, and now I can turn a high HP low torque engine into large wheel torque with a low first gear.  Hence why a 600 in-line 4 can out accelerate a cruiser that has 4 times the torque, the 600 just has to shift a lot.

Then we can go itno the shape of the torque curve, the resulting HP curve, and the effect on ridability... ::)

-z.

[Zac]

So, although they both make the same power, the dremel would never be able to start the chicken moving, whereas the rotissere motor would.

Although I could hook the dremel tool up to a 5000:1 gearbox and turn the rotissere.  It might have some stall current issues getting the thing started though...might need a torque converter.

Which brings up the intresting point of electric motorcycles.  An electric motor makes maximum torque at stall (0 rpm) and the torque decreases as the rpm goes up.  Hence why if you turn on a drill it only goes so fast.  The free running speed is where the motor has only enough torque to cancel out the back EMF (the generator effect of the spinning motor)

 ;D

-z.

[dwilson]

A machinist I grew up around defined torque as "the ability to spin a rod".  If that clears anything up for you...

[MZGirl]

Then we can go itno the shape of the torque curve, the resulting HP curve, and the effect on ridability... ::)

-z.

I was wondering how long it would take the mechanical engineer to chime in on this... ::)

[MadXX]

there are a lot of detailed explinations on the web such as:

http://www.revsearch.com/dynamometer/torque_vs_horsepower.html

Dyno of an electric Ford Ranger:
http://www.mindbent.org/evranger/dyno/

its really interesting to see how the gasoline and electric compare on the graph.  The real world application of an electric motor charts out different than would be expected from a motor only charting.  The most interesting thing to me was the sustained peak horsepower on the electric motor in this application.

[motomadness]

All very interesting explanations.

On a race bike, torque and hp mean nothing without the proper transmission gear ratios and the chassis geometry to get the motive force to the ground.  And bear in mind that once you are going a constant speed you don't need the same amount of torque or hp to maintain that speed - think variable displacement engines.  Two stroke bike are good for this.  On my TZ I could go into a corner with the clutch all the way in (no motive force to the ground)and wouldn't lose much of my current velocity.

Basically, I just want to add the motor is part of a large system that cannot be separated without considering some important relationships.