1. NOISE CONTROL OF MOBILE CONSTRUCTION MACHINERY Ken Meitl Caterpillar Inc.

2. 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

3. 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 70s dB(A) –Varies by machine type

4. 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

5. 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)

6. 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

7. 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

8. 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