Re: Tractor loading fan - HP curve
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Posted by john d. on September 16, 1998 at 14:17:04:
In Reply to: Tractor loading fan - HP curve posted by Tom S. on September 16, 1998 at 10:39:41:
: A friend of mine takes his homemade fan to tractor shows and lets tractor buffs hookup their belts to this fan. The faster they can turn it the more HP they can putout. The question for any engineers out there is, can the horsepower be plotted against the speed of such an animal. I will get the exact demensions if this can be done within some reasonable accurracy.
: Thanks If you had enough data on the fan, you could probably plot speed-vs-horsepower. Without true speed-vs-hp data, this is simply a comparison of one tractor against another. One of the problems with a test of this type is that it attempts to demonstrate power output by means of a load which in fact will vary as speed changes, but not necessarily at the same RATE the speed changes. Because of pulley ratios, this device also may not allow a tractor to run at whatever speed it will produce maximum power. A pto-type dynamometer is a better indicator. Maximum load may be applied at a fixed engine speed, or the engine may be loaded to maximum at varying speeds. Within reason, most engines will produce maximum hp at rpm levels well above the speed recommended by the manufacturer. The torque rating, or "twisting effort" of an engine will max out at a speed somewhat below the maximum hp achieved. Power (or horsepower) is the amount of work done in a given amount of time, so fan speed in this case is an indicator, but more of a RELATIVE indicator than a TRUE indicator of tractor horsepower. If you want some interesting (and perhaps unexpected) results with this apparatus, put a variable speed pulley in the equation and see what the maximum fan speeds are. This will allow the tractor to run at torque peak and pull the fan as fast as possible.
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