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Torque ratings of diesel tractor motors
The brochures always talk about the horse power of the models, what are the torque numbers? More specifically, how many foot pounds of torque does my 20hp Cub Cadet 7205 have at max rpm?


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Torque ratings of diesel tractor motors
I have wondered the same thing. Why don't manufactures post torque ratings for thier engines? I have some friends that when I told them I bought a 19 HP diesel, they thought I bought a small tractor....they said they had a 22hp Sears....uh....yeah...right. Definately 2 different animals!! Dealers are always trying new ways to sell their product, I'm sure if it was benificial they'd do it.
Jeff


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Torque ratings of diesel tractor motors
I think HP to torque takes a simple conversion formula. Something like: torque equals HP/RPM times some constant. Maybe somebody has the formula in mind. If not, I'll see if I can figure it out.


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Torque ratings of diesel tractor motors
HP = Torque*2*PI*RPM/33,000 or Torque = HP*33,000/(2*PI*RPM) (PI = 3.14) So knowing the HP at a particular RPM, you can calculate the Torque at that RPM. If the engine has a relatively flat Torque curve, than the Torque you calculate will probably be close to the max torque of the engine. However, if you have a peaky engine, the Torque produced at max HP will be lower than the max Torque at a lower RPM. I knew this Engineering degree was good for something :>


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Torque ratings of diesel tractor motors
Actually if you're going to go to all the trouble of doing the math, use the long version of Pi, 3.1415926535897932384626433832795, otherwise the rounding off will affect the outcome. Actually I use my Engineering degree all the time, the glass over the certificate makes a perfect mirror to see what is going on in the front office, .


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Torque ratings of diesel tractor motors
For a calculating formula, I'd use something like (HP*5251.9337)/RPM. I suppose that a text book formula uses PI explicitly to illustrate a principal. Something like RPM goes around in circles. Don't know what principal the 33000 illustrates. Should have been an engineer then I'd know principals, but guess applied math degrees find an occasional use too. However, it's more likely that it just illustrates the ways I spend my time first thing in the morning during these few weeks around here when most stinging insects known to man are out working.


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Torque ratings of diesel tractor motors
So three of you have found the formulas, which one of you wants to do the math? Remember, my question is: 20 hp. at 2500 rpm equals how many foot pounds of torque? thanks, Greg


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Torque ratings of diesel tractor motors
Looks like about 42ftlbs@2500rpm


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Torque ratings of diesel tractor motors
Gee, actually applying formulas usually was my role. Guess I'm not too sorry to be a little late. It gives me opportunity to say that the relation between torque and HP shouldn't be too surprising since HP is defined as 1 hp = 550 ft. lbs. per second. Torque is a static, and HP is a dynamic measure of about the same thing. Both measures have their limitation. In HP, for example, one big bang per second, or a bunch of little bangs equals the same HP, but the torque would be very different, and that can make a lot of difference to how an engine operates.


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Torque ratings of diesel tractor motors
I'd like to get down to the fundamentals. I know the equations but still don't understand why a 20 hp gas engine has less torque than a 20 hp diesel. I know how they each work, but I don't really understand the diffence in their operational characteristics. Can someone please explain? thanks.


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