TRUCK NOISE XI EVALUATION AND REDUCTION OF HEAVY-DUTY TRUCK NOISE

摘要

This report describes the work performed to examine the noise sources on two common truck configurations manufactured by this company, and to evaluate the noise reduction effectiveness of retrofit hardware. The two trucks selected were Cab-Over-Engine (COE) models with engines most often ordered with these models. One was a Kenworth K-123 with a Cummins NTC-350 engine, the other a Peterbilt 352A with a Detroit Diesel 8V-71T engine. The major noise source on both trucks was the cooling fan which led to modifications involving fan changes and fan speed decreases which resulted in decreased overall noise levels. The Kenworth's interior and exterior levels were reduced from 92 dB(A) to 89 dB(A) and from 91 dB(A) to 86.5 dB(A), respectively. The Peterbilt interior noise level was reduced from 95 dB(A) to 88.5 dB(A) and from 89 dB(A) to 84.5 dB(A) for the exterior. Further reduction of noise levels from these trucks would require additional cooling fan changes and some form of engine treatment, the engine being the second major noise source.