-
04-13-2009 04:52 PM
Understanding Power and Torque
- Difficulty
- Easy
- Estimated Time
- N/A
- Skills Required
- None
- Parts Required
- None
- Tools Required
- None
Hello.
This is a brief tutorial about torque, horspower. I will put up some exemples to clarifie things. Most people know what these terms are and what they meen. If you don't, it's pretty important.
Torque :
Torque is calculated in lb-ft or oz-in (not lb/ft or oz/in!). A simple example of applied torque is on a bicycle. When you push on the pedal, you exert a load (mass) on the pedal. Let's say you are pushing 15 pounds. If the pedal is a foot away from the center of rotation (where the gears meet the shaft of the pedals), you would be producing 15 lbs-ft of torque.
If, by some weird event, the shaft linking your pedal to the center of rotation (the gears) is 10 feet long, you would be producing (10 feet * 15 pounds = 150 lbs-ft.) 150 lbs-ft of torque. This is the basic comcept.
So, the formula is :
T = torque
F = Force
D = Distance.
T = F * D
Example :
So let's say you would want to know how much weight a servo rated at 200 oz.-in. could lift if it were 12.5 inches away from the center of rotation.
T = 200 oz.in.
F= ?
D = 12.5 inches.
T/D = F
F = 200 oz.in./12.5inches = 16 oz.
So the servo could theoretically pull 16 oz of weight.
HORSEPOWER :
Horsepower is calculated using the following formula :
HP = (RPM * TORQUE)/5252
The constant 5252 may seem like it comes from nowhere, but it doesn't! It's just a bunch of numbers simplified into one. But you don't really need to know where it comes from for now.
Example :
If you know your engine is turning at 2000 RPM (Revolutions Per Minute) and that the torque it's producing is 160 ft-lbs, how much power is it producing?
HP = (RPM * TORQUE (in ft-lbs) )/5252
RPM = 2000 rpm
TORQUE = 160 ft-lbs
HP = 2000 rpm * 160 ft-lbs/ 5252
So this is the basic for understanding and using torque and horsepower.
Sam