noise control of mobile construction machinery ken meitl caterpillar inc
TRANSCRIPT
NOISE CONTROL OF MOBILE CONSTRUCTION MACHINERY
Ken Meitl
Caterpillar Inc.
Introduction• Machine Noise - Past
– Little consideration given– One of machine outputs– Means of evaluating power or performance
• Machine Noise - Forces Driving Change– Regulations
• OSHA/MSHA & Environmental (site specific)
– Commercial & Competitive• Comfort
Current Status - Operator Noise• Test Standards:
SAE J1166 (work cycle)SAE J919 (static & moving)ISO 6394 (static at rated)ISO 6396 (dynamic - moving)
– Used for comparisons & development only
• Caterpillar models - Some data available for most• Most new enclosed cabs are below 85 dB(A) per SAE
J1166 tests, many in mid 70’s dB(A)– Varies by machine type
Key Factors - Operator Noise
• Cab doors & windows closed– If open, exposed to other background noise– Use of radios & music systems
• Cab condition - maintenance– Absorptive & Barrier materials – Sealing– Isolation mounts
Current Status - Environmental Noise(Exterior/Bystander)
• Test Standards: SAE J88 (sound pressure @ 15m (static & moving))ISO 6393 (sound power - static)ISO 6395 (sound power - dynamic)
– Above tests allow machine comparisons, not job site levels with machine doing actual work.
• Varies by work site (reflective surfaces, distance from machine, task performed, machine type, etc.)
• Many newer machines are quieter and have optional sound suppression packages available– Reductions of 2 - 6 dB(A)
Key Factors - Environmental Noise• Machine condition - maintenance
– Sound materials, isolationmounts, & enclosures
• Note:– Reduction of noise by sealing an engine enclosure is
not as simple as sealing a cab• Machine cooling, performance, and efficiencies have to be
considered
– How operated and application could be more of a factor than base machine levels
Comments - Environmental Noise
• Machine specific noise reduction is not always the most efficient solution – Change site layout– Site barriers– Modify work schedule– Machine cost
• Challenge - Engine exhaust emissions – Impacting machine noise sources
Summary
• Operator Noise– Noise levels are generally low for enclosed cabs– If using enclosed cab to control noise, operate
with them closed, and maintain them
• Environmental Noise– Lower noise machines are often available– Various site solutions often exist, user will need
to determine the best solution