Posted by David Sherman on Thursday, April 12, 2007 at 10:46:43 :
In Reply to: Re: Belt it up on the RPMs posted by Willy-N on Thursday, April 12, 2007 at 10:30:55 :
He should definitely not lug it down, that is, overload it at low rpms, but there are a lot of advantages to running it direct if possible. A belt drive requires maintenance, takes up space, costs 10-20% in efficiency (more fuel cost), and puts side loads on the shafts. The rate of wear of an engine is directly proportional to rpms, so running it slower, so long as you don't lug it down, will increase the life proportionately. The peak rpm of the old caterpillar bulldozer engines is about 900 rpm, which is partly why there are so many of them still running.
1750 rpm is a very reasonable speed for any larger diesel or gas engine. For a small engine like this, it may be on the slow side, but so long as he's not asking it to put out more than rated HP at that speed, it should not damage the engine. If I was building this setup, I would try hard to find an engine that will put out 15 hp at 1750 RPM before I'd go to a belt drive system. Of course it's possible the machine he's driving already has a belt drive, such as a fan or an air compressor, in which case it makes sense to run the engine at its point of peak efficiency (get that info from the manufacturer) and change the pulley(s) as needed to get the right speed on the machine.
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