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# calculating drivetrain effeciencies2

## calculating drivetrain effeciencies

2
(OP)
what is the easiest way to measure the moment of inertia of an entire drivetrain, gear, pulley and or chain drive? what about the effeciency of the entire setup? I'd like to bench test a variety of small drivetrains that will end up behind a 10hp gas motor before attempting installation in an existing chassis. ideally the final design would be tested and ready for installation without alot of fuss making inefficient parts fit in a small space only to not use them. I can only calculate the theoretical moments on parts i manufacture, but some assemblies are purchased and would be brutal to reverse engineer and then do the math.
thanks

### RE: calculating drivetrain effeciencies

Maybe you could measure the maximum torque it takes to get the system moving from a dead stop, under no load?  You could use a good torque wrench if the required torque is in the proper range, or hang weights at the end of an arm clamped horizontally onto the input shaft.  For more accurate measurements you would need a torque sensor.  The maximum torque measured should be, I think, a combination of the maximum inertial load and the torque required to overcome friction in the system.  This assumes that the system has the same or greater efficiency at full speed.

Good luck!

Mike

PS:  You could compare different assemblies by starting them up with an AC motor and measuring the current draw on startup, then comparing the max draw for each arrangement.  The one with the least draw is the most desirable for you it sounds like.  This is all a bit out of my baliwick, anyone else have input for this?

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