Looking for feedback on this presentation designed to illustrate the topics in a DESIGN WORLD article about how to design quiet gearbox and electric motor assemblies. “How to design quiet gearmotors: Gear engagement, housing geometry, and more,” explored all the ways gearmotors are designed and manufactured to reduce noise. Read the article here, https://www.motioncontroltips.com/design-quiet-gearmotors/. Thanks for the feedback.

1. Page 1
Motors Gearboxes Inverter Partner
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Your Customer- and Industry-specific Systems Supplier
Top Ten Gearbox &
Electric Motor Noise
Questions

2. | GEARBOXES
Page 2
Top Ten Gearbox & Electric Motor Noise Questions
10
Why is my gearbox
& electric motor
squeaky?

3. | GEARBOXES
Page 3
Top Ten Gearbox & Electric Motor Noise Questions
10 ½ Why is my gearbox & electric motor squeaky?
Frankly we have never heard of one of our types of gearbox & electric motor
described as squeaky! It would mean that there is a serious problem with a part
of the system rubbing against one another.

4. | GEARBOXES
Page 4
Top Ten Gearbox & Electric Motor Noise Questions
9
What causes gearbox
whine?

5. | GEARBOXES
Page 5
Top Ten Gearbox & Electric Motor Noise Questions
9 ½ What causes gearbox whine?
Gear whine is created by the gears as
they mesh and is amplified by
resonances in the housing’s ribs, beams,
and sides.

6. | GEARBOXES
Page 6
Top Ten Gearbox & Electric Motor Noise Questions
8
How does the gearbox
housing amplify noise?

7. | GEARBOXES
Page 7
Top Ten Gearbox & Electric Motor Noise Questions
8 ½ How does the gearbox housing amplify noise?
Vibration is generated at the gear mesh
because of time-varying mesh
stiffness, manufacturing errors and
assembling errors.
This vibration is transmitted to the
housing through shafts and bearings.
The radiated noise is induced from the
vibration of the housing.

8. | GEARBOXES
Page 8
Top Ten Gearbox & Electric Motor Noise Questions
7
Why does my gearbox
rattle?

9. | GEARBOXES
Page 9
Top Ten Gearbox & Electric Motor Noise Questions
7 ½ Why does my gearbox rattle?
Gearbox rattle is a sound that is
excited by the driving source such as
the electric motor.

10. | GEARBOXES
Page 10
Top Ten Gearbox & Electric Motor Noise Questions
6
What causes gearbox
noise?

11. | GEARBOXES
Page 11
Top Ten Gearbox & Electric Motor Noise Questions
6 ½ What causes gearbox noise?
Gearbox noise isn’t just a gear problem
- it’s a system problem. Physical
interactions between gears can excite
system dynamics, so most gear noise
doesn’t originate from the gears.

12. | GEARBOXES
Page 12
Top Ten Gearbox & Electric Motor Noise Questions
5
How do bearings
cause gearbox noise?

13. | GEARBOXES
Page 13
Top Ten Gearbox & Electric Motor Noise Questions
5 ½ How do bearings cause gearbox noise?
The asymmetric gear noise spectrum arises from
amplitude and frequency modulation of gear-mesh
excitation produced by low-frequency manufacturing and
assembly errors. Gearbox and electric motor sounds
from gear mesh, bearing rotation, lubricant movement,
motor vibrations and interaction of the housing all
contribute to the overall sound generated.

14. | GEARBOXES
Page 14
Top Ten Gearbox & Electric Motor Noise Questions
4
Can you prevent
gearbox noise?

15. | GEARBOXES
Page 15
Top Ten Gearbox & Electric Motor Noise Questions
4 ½ Can you prevent gearbox noise?
It’s impossible to eliminate all gearbox noise,
because it’s impossible to cut perfect gears.
Even if one could, it’s impossible to limit the effect
of system dynamics. One can only minimize and
control gearbox noise to the extent that it won’t be
considered problematic or audible.

16. | GEARBOXES
Page 16
Top Ten Gearbox & Electric Motor Noise Questions
3
How do you reduce
gearbox & electric
motor noise?

17. | GEARBOXES
Page 17
Top Ten Gearbox & Electric Motor Noise Questions
3 ½ How do you reduce gearbox & electric motor noise?
To solve gearbox & electric motor noise
problems, the first step is to determine
the type of noise that is objectionable.
What’s considered gear noise depends
on the speed of operation. Use
qualitative and quantitative terms to
describe how design factors and
manufacturing mistakes play into the
noise equation. Then discuss with the
design team (and potential suppliers)
the problems of gear noise, dynamics,
measurement, and modeling.

18. | GEARBOXES
Page 18
Top Ten Gearbox & Electric Motor Noise Questions
2
What is gearbox
noise?

19. | GEARBOXES
Page 19
Top Ten Gearbox & Electric Motor Noise Questions
2 ½ What is gearbox noise?
Gear noise is generated by tooth-to-tooth load transfer
that causes pressure-pulse trains radiating through the
gearset and motor housing. The noise’s frequency is
the product of gear rotational speed and the number of
gear teeth. Most types of gear noise occur at tooth
mesh frequency or harmonics in the audible range.
Gearbox noise can be very annoying — even when it
isn’t the most significant noise source. That’s because
it occurs as pure tones that the human ear can detect
even at 10 dB lower than the overall noise level.

20. | GEARBOXES
Page 20
Top Ten Gearbox & Electric Motor Noise Questions
1
How do you diagnose
a noisy gearbox &
electric motor?

21. | GEARBOXES
Page 21
Top Ten Gearbox & Electric Motor Noise Questions
1 ½ How do you diagnose a noisy gearbox & electric motor?
To minimize noise, all gearbox & electric motor components
should be optimally tuned to each other. Three types of
gear tooth transmission errors are spacing errors, random
errors, and elastic deformations, which combine with mean
profile deviations. Gear resonance can be reduced by
identifying excitation mechanisms; using finite element
analysis to determine the natural frequencies of individual
gears; eliminating torsional modes from operating range;
detuning and damping helical and bevel gears; and
identifying remaining resonant problems with other
elements of the gearmotor such as the housing and electric
motor.

22. Page 22
Strong, Flexible, Innovative
Our Motivation – Your Drive – Engineered in Germany
Gabriel Venzin, President of ABM DRIVES INC.
ABM Greiffenberger U.S. Subsidiary
394 Wards Corner Road · Suite 110
Loveland, OH 45140 · USA
Phone: +1 513 576-1300
gabriel.venzin@abm-drives.com
Thank you for your kind attention!