# What are torque parameters?

1. Jun 3, 2014

### CraigH

Torque is just the turning force on an object, i.e the force multiplied by the perpendicular distance from the force to the pivot.

But when torque parameters are mentioned in mechanical engineering papers, what are they referring to? It's the plural "parameters" thats confusing me.

Is it the collection of properties such as maximum torque, starting torque, etc?

If so, can somebody please provide me with a list of the all, or some of the "torque parameters", along with what each means?

Finally, if looking at the torque parameters of a crankshaft, what would the important ones to pay attention to, and what are some typical values?

Thanks!

Last edited: Jun 3, 2014
2. Jun 4, 2014

### tygerdawg

To make a rotating system turn, torque must be applied to overcome various resistances to rotation. For example, stiction & friction.

Torque must also be applied to accelerate rotational inertias and translational inertias driven by the applied torque through gearing. Load masses, shafts, gearing, couplings, etc.

After acceleration to desired speed is accomplished, then the speed must be maintained by a lesser torque.

Then it is necessary to slow it all down to a stop (deceleration). Torque is required for this, too.

Maintaining a position of a rotational system may require torque.

And so on, and so forth. All of these components add up. A motor used to apply a torque (with or without gearing) is sized to overcome the "maximum torque" which is the appropriate sum of those component torques.

Motor systems (electrical or fuel) usually provide an amount of torque as a function of RPM...called a torque curve and is usually non-linear. Systems are sized for optimum torque at RPM (usually).

I've only touched on the subject, but this should help a bit.