Horsepower, Torque

1. Horsepower, Torque WORK, Force and Distance

2. Understanding Horsepower

3. What is Horsepower • Horsepower is a unit of power for measuring the rate at which a device can perform mechanical work. Its abbreviation is hp or bhp (for brake horse power). One horsepower was defined as the amount of power needed to lift 33,000 pounds one foot in one minute.

4. Horsepower was defined by James Watt (1736-1819), the inventor of the steam engine, who determined after careful measurements that a horse is typically capable of a power rate of 550 foot-pounds per second. • Today the SI(International System of Units) unit of power is named for Watt, and one horsepower is equal to approximately 745.6999 watts.

5. Work = force x distance • Work: the result of applying force • Force: is a measurement in pounds • Distance: is measured in feet • Work is defined as a force acting through a distance. Work is done only when a force moves an object.

8. WORK = FORCE x DISTANCE • No work is done by a force unless the force moves through a distance. • force = 20 pounds • Distance = 50 feet • Work = 1000 ft lbs

10. Calculating Horsepower

11. Magic Formula for calculating Horsepower • Horsepower = Torque x RPM Divided by 5,252 • 5,252 is called a constant • Horsepower: direction of motion is in a straight line • Torque: is related to rotation • RPM: revolutions per minute

12. Horsepower explained • OK. Remember Watt? He said that 33,000 foot pounds of work per minute was equivalent to one horsepower. If we divide the 6.2832 foot pounds of work we've done per revolution of that weight into 33,000 foot pounds, we come up with the fact that one foot pound of torque at 5252 rpm is equal to 33,000 foot pounds per minute of work, and is the equivalent of one horsepower. If we only move that weight at the rate of 2626 rpm, it's the equivalent of 1/2 horsepower (16,500 foot pounds per minute), and so on. Therefore, the following formula applies for calculating horsepower from a torque measurement: Torque * RPM • Horsepower = ------------ 5,252 This is not a debatable item. It's the way it's done.

13. What is Torque • Torque is one way to measure work. • Torque is defined as twisting force • The work that the engine produces is measured as torque at the flywheel

14. Do Torque and Horsepower have anything common? • Torque is the only thing that a driver feels not horsepower. • 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. • Therefore, horsepower isn't particularly meaningful from a driver's perspective. • at 5,252 rpm, the horsepower and torque always come out the same.

15. Torque formula Torque = Horsepower * 5252 ----------------- RPM • If horsepower = 350 • And rpm = 6500 • Torque = 282.8 ft lbs

16. Putting things in perspective • If we bolted an LT1corvette engine to a water wheel and assuming we needed 12 rpm for an input to the mill, we could run the LT1 at 5000 rpm (where it's making 315 foot pounds of torque), and gear it down to a 12 rpm output. Result? We'd have over *131,000* foot pounds of torque to play with. We could probably twist the whole flour mill around the input shaft, if we needed to :-).

17. More Horsepower is not always the answer but it helps • Torque • RPM • Gearing • Remember , there is no replacement for displacement