# Simple Question?

#### Drifter

[SOLVED] Simple Question?

I need help in solving a friendly debate,
a simple spur gear reducer with a ratio of 4:1, pinion being 4" in circular Dia./it's Inertia is .098/ driven gear 10" in circular Dia. it's inertia is 3.86 /+ both gears are 2" in thickness/ H.P. input available is 100 H.P. @ 1000 RPM/ 0 torque requirement on output/ we'll use 1% as the friction coefficient. My question is if the gears were switched so the larger was used as input and smaller as output (1:4 speed increaser) again using 0 as the torque output, is the heat generated from friction between meshing gears going to be the same or is the speed increaser going to create more heat due to additional friction proportionately to it's ratio increase? If I'm missing required info please let me know. If you could also give me the formulas to caculate a simialar scenario, it would be greatly appreciated as I have no access to such info at the moment, or if I was given direction to a site containg such material would be greatly appreciated.

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#### krab

My question is if the gears were switched so the larger was used as input and smaller as output (1:4 speed increaser) again using 0 as the torque output, is the heat generated from friction between meshing gears going to be the same or is the speed increaser going to create more heat due to additional friction proportionately to it's ratio increase?
So you basically have 2 shafts, call them A and B. In one case, shaft A is going 1000rpm, and shaft B is 250rpm. In the second case, shaft B is at 1000rpm, and shaft A is at 4000rpm. This kind of frictional loss is usually close to linear, so with everything going 4 times as fast, the second case has 4 times as much loss as the first case.

#### phoenixthoth

Stick to the topic of the thread.
Integral

cheers,
phoenix

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