Posted by MarkB_MI on December 25, 2020 at 11:05:20 from (174.230.13.56):
In Reply to: Re: H.p. at lower rpm posted by Ronnie Budd on December 25, 2020 at 09:21:46:
> Now , go back and read the rest of the history on how James Watt came up with the "formula" that we have been using for a hundred years. The measurements he did resulted in odd numbers that wouldn't easily convert. So, they rounded them off to come up with the constant of 5252 that is used as the divisor in our modern horsepower formula. So yes, it is "theoretical".
The formula for power has not changed since Watt's time. It is P = fv, where P is power, f is force and v is velocity. When dealing with rotational rather than linear work, the formula becomes P = 2πTn, where T is torque and n is the rotational speed. That "constant" of 5252 is not really a constant but rather a conversion factor. Working in the metric system, there is no need for a conversion factor. But using English units, one horsepower equals 33,000 ft-lb/min. 33,000 divided by 2π is 5252.
Power is not a "theoretical" value. It is a derived value, meaning it is calculated from other values (torque and speed) as it cannot be directly measured. To say power is theoretical would be like saying electrical resistance is theoretical, just because it has to be calculated from voltage and current.
Upload one or more videos to your post. Photo and video filesizes should be less than 5MB. Formats allowed are gif, jpg, png, ogg, mp4, mov, and avi. Be sure to use filenames without spaces or special characters, and filetypes of 3 digits lower case.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - A 1937 John Deere Unstuck - by Gary Hickman. Here is my story of how I got the pistons out of a 1937 JD B that the engine had been stuck for about 14 years: About 12 years ago my Dad gave me one of the tractors I ran as I was growing up on our farm in central Nebraska. The engine on this tractor, a 1937 John Deere "B", had been stuck for 2 years before he gave it to me. This last spring (1999) I hauled the tractor to our 2 acre lot in St. Libory Nebraska where it joined my antique machinery collection, at that time a 1929 Caterpillar T
... [Read Article]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
