Help me understand HP vs Torque
Posted: Wed Feb 20, 2013 12:40 pm
I suck at mechanics....
I am working on a project using small DC motors, and I'm trying to understand how all this Torque/HP stuff works so I can work on a diagram that indicates if I have X Torque at X RPM and it weighs X, it will move at roughly X speed.
My understanding with torque is that it's a rotation energy, if you will. 1 ft/lb of Torque means that if you have a circle with a 1ft radius, 1lb of force is being applied on the outside edge.
Horsepower is lifting 33,000lbs 1ft per minute.
To me, these just seem like interchangeable units of measurements, much like inches and feet. But I know a sports car has high HP/low torque, and a tow truck has low(er)HP/high torque, in a very generalized sense. I don't understand why that is the case. Wouldn't more HP equal more Torque, and vice versa?
More specifically, I have motor that has 8.84 oz-in torque @ 17,000RPM's. Using this formula, I have Horsepower = 0.0460416666372 (lb ft) * 17000 / 5252, or around 3/20HP.
That would imply my motor (assuming perfect efficiency and traction) could move around 4950lbs 1ft per minute. Obviously my motor isn't powerful enough to do that, so I assume it's implying when geared correctly (since at 17,000RPM's it would move much faster than 1ft/minute). Does this mean that theoretically I could move 10lbs at 6.625 MPH ( (4950/10) * (60/5280) ), 5280 being how many feet there are in a mile?
A little direction would be super....
I am working on a project using small DC motors, and I'm trying to understand how all this Torque/HP stuff works so I can work on a diagram that indicates if I have X Torque at X RPM and it weighs X, it will move at roughly X speed.
My understanding with torque is that it's a rotation energy, if you will. 1 ft/lb of Torque means that if you have a circle with a 1ft radius, 1lb of force is being applied on the outside edge.
Horsepower is lifting 33,000lbs 1ft per minute.
To me, these just seem like interchangeable units of measurements, much like inches and feet. But I know a sports car has high HP/low torque, and a tow truck has low(er)HP/high torque, in a very generalized sense. I don't understand why that is the case. Wouldn't more HP equal more Torque, and vice versa?
More specifically, I have motor that has 8.84 oz-in torque @ 17,000RPM's. Using this formula, I have Horsepower = 0.0460416666372 (lb ft) * 17000 / 5252, or around 3/20HP.
That would imply my motor (assuming perfect efficiency and traction) could move around 4950lbs 1ft per minute. Obviously my motor isn't powerful enough to do that, so I assume it's implying when geared correctly (since at 17,000RPM's it would move much faster than 1ft/minute). Does this mean that theoretically I could move 10lbs at 6.625 MPH ( (4950/10) * (60/5280) ), 5280 being how many feet there are in a mile?
A little direction would be super....