Accelerated gearbox testing

I have designed accelerated life tests for a few things, but AC motors are difficult because of line voltages being the way they are. For example, one would have to use 240 VAC and a VARIAC to accelerate life tests for a 120 VAC motor (ya' just can't put 240 volts on a 120 volt motor -- it ain't fair). Bearings, on the other hand, can be overloaded and run at higher speeds than that for the application for which they would be used, and some companies, such as Timken have done that. DC motors can be run at higher speeds and higher currents than that for which they were designed, but I don't know of any 'standard.'

Gear boxes may be run at higher speeds and higher torques than that for which they were designed, but unless you can find ASTM (or otehr standard) specs for such, you will be shooting into the wind (so to speak), since no one would have established a criteria to determine how the accelerated life test relates to actual life.

Thanks for the reply. Do you have any rule-of-thumb advice on the effects of increasing either load or running speed on gearbox life? I've been told doubling the load halves the life, but that doubling the speed reduces life by 75%. Sounds over-simplistic to me!

Cormac

I would search the literature before jumping to conclusions. As I said earlier, if it has never been done before, then you will essentially be setting a standard for future testing of that sort. Rules of thumb? Sorry . . .