Is It Normal for Gears to Make Clunking and Loud Noises?

January 11, 2017

Gearing units incorporate multiple stages, therefore some noise is likely when an assumed load alters. This effect generally takes place over a predictable period of time, so the loading event is barely noticeable, but a sudden mechanical changeover will exaggerate the sound. Ratio altering mechanisms generate near imperceptible "clunks" sounds, for example, but only the very largest units would produce what could be described as a loud noise. As for smaller gearing packages, a loud clunking sound may indicate a problem.

Analysing Subjective Listening Habits

A client calls for help when a gearing product is too noisy during its normal operations, so a repair engineer is dispatched to troubleshoot the problem. An impartial check measures vibrations with special instruments and follows the cycling unit through its normal mechanical activity, but no excess sounds cause concern. The issue here is a subjective one, a case where a concerned client perceived a problem. An inspection was mandated, but an objective check found nothing of concern.

Quality Mutes Noise

The inspection was obviously necessary, but it's likely that the gearing unit in question was simply built from substandard parts. Tooth geometry in such a product is satisfactorily transmitting power, but losses are occurring due to small parts flaws. The noise represents one avenue taken by the losses. The other path would be via friction. Benzler-made gearing units avoid this problem by adhering to a high-quality engineering model, so all tooth geometries and ratio switching assemblies remain effectively noise free, even when a heavy load is creating friction.

Large-scale Applications

Massive aircraft undercarriage assemblies generate a loud rumble and metallic locking sound as gears engage and secure the wheels in place. Powerful motors and turbines encounter hysteresis effects as motor cores and poles create an electrical buzz, but the majority of industries' finest power transmission units do not make clunking tones, nor do they ever produce loud noises. Superior engineering practices recognise this event as a loss, a vibrational component, so advanced noise canceling systems are incorporated as a supplementary system element. Additionally, the bulk of this acoustic effect is generally dissipated by the lubricating oil.

Misalignment errors, such as a backlash problem, propagate when clearance and meshing margins are incorrect. A "thunk" as a gearing changeover occurs indicates the misalignment. A loss is taking place, but troubleshooting routines are quick to eliminate such incidents. In balancing quality-assurance matters against the results of this troubleshooting program, loud noises are not considered a normal part of a gearing package's operational running, not when they're considered an unaffordable loss factor.

Kelmar Engineering

95 Wayo St, Goulburn, NSW 2580

Phone: (02) 4823 9931


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