| Message |
copied from elsewhere:
"Torque is a twisting force and is commonly measured in foot pounds. In the 18th century, James Watt made some observations. He concluded that the average horse of the time could lift a 550 pound weight one foot in one second, thereby performing work at the rate of 550 foot pounds per second, or 33,000 foot pounds per minute, for an eight hour shift, more or less. He then published those observations, and stated that 33,000 foot pounds per minute of work was equivalent to the power of one horse, or, one horsepower. This has been the accepted standard since then.
What we really need to know is how many revolutions must the crankshaft turn in order to cover 33,000 feet of distance within one minute. In order to do this, we must calculate the amount of distance covered 1 foot from the fulcrum (the center of the crank) when it makes one revolution. Then, it becomes simple to find how many revolutions must be made within one minute in order to have covered 33,000 feet. You just simply divide the amount of distance for one revolution into 33,000. The amount of distance covered in 1 revolution
(the circumference of a circle with a 1 foot radius) is 2 times radius times pie (2 * 1 * 3.14159 = 6.2832 feet). 33,000 divided by 6.2832 equals 5252.11. Thus, the equation for calculating horsepower with a given amount of foot pounds is borne. The equation is: (Torque times RPM)/5252.101 where torque is in foot pounds. Make sure you understand horsepower is calculated, not measured. On the dynometer, foot pounds of torque is measured. Using the equation, the amount of horsepower is calculated."
 |
 |
