Posted at 22-Feb-2019

Getting the Best Efficiency from Geared Drives

Paul Skade
By Gareth Lenton
General Manager, Power Transmission

I joined WYKO in January of 2000, the dawn of a new millennium and a completely new start for me after spending 2 years backpacking through South East Asia and Au...

Read full bio

Motor efficiencies are well known, IE2 (high efficiency) and IE3 (premium efficiency. Depending on how much you are willing to invest, you pay your money and make your choice, but are you selecting your geared motors in the same manner? If not, then you should be!

geared drive


Choosing the most efficient geared motor unit takes a little more consideration as there is currently not industry standard, but you can rest assured that an educated choice can be the RIGHT choice.

Ranging from under 50% up to 95%, efficiencies are dependent on many factors – unit size, required ratio and the type of internal gearing utilised. So you may ask, where do I start? Well, check out this working example:-

A conveyor requires a right angle drive solution generating a torque of 1,300Nm with an operating speed of approximately 15rpm – this results in a calculated absorbed power of 2.04kW.

So here’s three solutions based on the above:

  • A typical single reduction worm gear unit could have an approximate efficiency of 65%. To produce 1,300Nm you need to fit a 4kW motor – this sees an annual operating cost of £1632.
  • A typical helical worm gear unit would have an efficiency of around 80%. To produce 1,300Nm you need a 3kW motor – this sees an annual operating cost of approximately £1224.
  • However, the jewel in the efficiency crown, is that the helical bevel unit has an efficiency of 95% - only needing a 2.2kW motor to generate the required 1,300Nm at an annual cost of £1032.


So now onto the payback period. The annual operating costs can vary by several hundreds between the worm units and helical bevels. The initial purchase price for the helical bevel would be higher, but a simple calculation would show a total cost of ownership (TCO) for both versions, indicating when payback is achieved and the full benefit of the efficiency savings start to be realised.

As an example, the purchase price of the more efficient unit could easily be £500 higher, but the operational savings would result in a quicker payback period, as well as a reduction of your carbon footprint and contribution towards your CSR commitments.

In short, just remember, IE2 and IE3 motor efficiencies can vary by just a few percent, but different types of gearboxes can vary in efficiency by over 40% - so it’s always a wise decision to consider this when making a selection.

Fenner produce a comprehensive range of geared drives and are able to provide all the relevant operational efficiency information when selecting drive packages for your specific applications.

Why not give us a call on 0121 508 6000 and speak with one of our highly trained engineers or alternatively visit our Fenner website for more information.

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