Gearing and power output.

Author	Message
Davo99 Guru Joined: 03/06/2019 Location: Australia Posts: 1581	Posted: 10:27am 18 Mar 2024       One for the mechanical engineers..... I have tried googling this question but no matter how I phrase it , I always get irrelevant answer's to what I think should be straightforward for those in the know. I found a Diesel engine today up the back I forgot I even had. It's 10 HP continuous @ 2400 RPM. I have an 8 KW gen head which is 1500 RPM. My belief is it takes double the engine HP to drive an alternator / Generator for every KW the alternator is. Going by this rule of thumb, the engine does not have the power to drive the gen head to full load. My question is if I reduce the driven speed of the engine output with the appropriate size pulleys and have the engine doing 2400 rpm and the alternator geared down to 1500 rpm, will the effective power the alternator sees be increased say to 12 or whatever HP it works out to be? As I understand, power is function of torque Vs. Speed but I do not know how this applies in this case. I would think that at the given speed, the alternator needs increased torque as the speed needs to be fixed so the answer should be Yes, the engine will have more effective power or if that is not the right term, Gearing the faster engine to the slower alternator will in fact increase it's ability to drive a higher load on the alternator at a fixed RPM. Can anyone confirm that gearing the engine down will effectivel increase its HP at the lower RPM the alt would see? Thanks in advance.