Transcript Heavy Mobile Equipment Noise - MSHA Part 62

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, isolation
mounts, & 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
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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