Hushpak mufflers and fan package achieves excellent results

leibherr 996 hushpak muffler

As part of environmental compliance requirements, mine sites have noise specifications for mobile machinery, including in service (existing machines) and delivered (new machines) specifications. The noise specifications for this mine site were 125 dB (linear) for existing machines and 123 dB (linear) for new machines.  The Liebherr 996 was an old machine with over 60 thousand hours. It had been previously fitted with a complete sound kit, and had accessibility and cooling issues.

Traditional “one-type-fits-all” attenuation solutions on excavators can include replacement or modifications to the mufflers, radiator attenuators, oil cooler attenuators and louvre panels. The additional equipment often causes visual obstructions, accessibility issues and maintenance problems and can cost in excess of $500K. The increase in engine back pressure further impacts performance as the vehicle has a high potential to overheat.


Working together with a large mine service provider, Hushpak set out to

  1. achieve the in service noise specification of 125 dB at a fraction of the cost of traditional attenuation kits
  2. use minimal equipment to improve accessibility issues and reduce the likelihood of overheating

Having noise tested hundreds of mobile machines, Hushpak has proven knowledge of acoustics and predominant noise sources.  Our specifically engineered solutions are developed using sophisticated analytics and design tools to achieve exceptional results with minimal equipment installation and less capital outlay.

The customer removed the traditional sound kit and associated equipment that had been previously installed on the excavator.  Hushpak then installed their custom designed mufflers and fan package.


Achieved in service noise specification at  low cost

Noise test results for Hushpak’s custom designed mufflers and fan package were 123 dB and 118 dB(A) – 2 dB below the in service noise spec. The 996 also passed the noise test for a new machine as well as an existing machine and cost one quarter of the price of some traditional sound kits.

Improved accessibility and cooling issues

Using minimal custom designed equipment, Hushpak was able to restored the machine to original OEM appearance – improving machine accessibility and eliminating cooling restrictions to reducing overheating.

More info

For more information on this case study, or to enquire about a similar project please contact:

Michael Neville | General Manager – Hushpak Engineering
+61 2 4964 4000