Calculating Power Drawn by a Gear Box

Can you disconnect them individually and measure the resistance, either of the individal gbox, or the line as a whole? If you could disengage them one at a time and see the drop in torque required you might deduce something about the drag of that particular drive. Not sure how the torque would vary with speed though.

Or measure the current consumption of the motor if you manage to drop-out individual drives.

On second thoughts you might have a nasty noise if the timing of these drives is inter-related. Ooops, stupid idea!

Thank you.Good suggestion .I can try this method and find out the drop in KW using power analyser.Any more ideas ?

Cor, have I been of use? Thought I was just an annoying passenger!

Be Carefull (Wrenched hit the nail on the head) most paper and printing machines are run from a single motor because of the need to sychronize all sections of the machine. Out of sync machines can make an awfull mess.

Measuring the torques before and after the gear box one can calculate the power absorbed by the gears. The gear manufacturers should have a decent idea of what percentage of power consumption is to be expected for various levels of power and speeds. The torque measurement is not difficult, it is done commonly in industry, one can find several companies willing to do this.

Be carefull. Yopu can end up with a pile of broke. Eliminating the drive shaft will lead to difficult control problems. You will have to control tension and draw at many points, rather than just between sections. This can dramatically drive up the cost of the project.

I would first go to the manufacture. They should be able to give you the information. If you know the configuration you can calculate the efficiency. If this box is on a paper or web machine it may be a differential and the efficiency calulation can be a pain.

If you have a test stand you can measure the efficiency, but be sure to measure it at the rated load.

Hope this helps.

<driven by a common line shaft with single motor?>

You have a neat arrangement already:

• Read the Current to the line shaft drivemotor with all loads drawing power.All you need is a Clamp-on Ac Ammeter+ AC Volt Meter=I₁
• Take the gearbox -you want to know is loading what KW- out from line-shaft.
• Now read the Motor Current I₂
• Hence that Gear Box took 3Ep.( I₁-I₂)
• So on.

Thank You Mr Mukul.I hope you are from Paper Mill.Wrenched was right at the first time itself and you have confirmed that no mess will be created by following his idea.Thanks others also for cautioning.I will let you know the outcome shortly.