SCREW-ADJUSTMENT 7F9571 - Caterpillar

Federal law prohibits tampering with or a modification to the noise control system on medium and heavy duty trucks (gross vehicle weight rating in excess of 10,000 pounds) that have been distributed in the United States, and certified to meet Environmental Protection Agency (EPA) Vehicle Noise Emission Standards.
The Federal Register, Volume 41, Number 72, pages 15538 through 15558, dated April 13, 1976 gives complete details on Title 40, Code of Federal Regulations, Chapter I, Part 205 which gives noise level standards and regulations for vehicles manufactured on and after January 1, 1978. Vehicles which are manufactured after the following effective dates, shall be designed, built and equipped so they will not produce sound emissions in excess of the levels indicated.
The regulations state that the manufacturer of the vehicle is responsible for production verification and complying with the labeling requirements. The regulations also state that any person who performs subsequent manufacturing operations on the new vehicle must assure that his manufacturing operations do not cause the vehicle to exceed the EPA Vehicle Noise Emission Standards, or obscure, or remove the required labels.
The area of most concern to Caterpillar dealers and personnel is section 205.58-2 Tampering. This section requires the manufacturer to submit a list of acts to the Administrator, which in the manufacturers estimation, might be done to the vehicle on more than an occasional basis and result in an increase in noise emission above the standards prescribed. On the basis of this information, the Administrator will develop a list of acts which constitute the removal or rendering inoperative (other than for purpose of maintenance, repair, or replacement) of noise control devices or elements of design of the vehicle. The manufacturer will then include in the owners manual the following information: (1) The statement: Tampering with Noise Control System Prohibited
Federal law prohibits the following acts or the causing thereof:
(1) The removal or rendering inoperative by any person other than for purposes of maintenance, repair, or replacement, of any device or element of design incorporated into any new vehicle for the purpose of noise control prior to its sale or delivery to the ultimate purchaser or while it is in use, or (2) the use of the vehicle after such device or element of design has been removed or rendered inoperative by any person.(2) The statement: Among those acts presumed to constitute tampering are the acts listed below:
Immediately following this statement, the manufacturer shall include the list of acts developed by the Administrator. The following is a typical list developed for a truck manufacturer:
1. Removal of engine noise deadening panels.2. Removal of cab skirt noise deadening panels.3. Removal of transmission noise deadening panels.4. Removal or rendering engine speed governor inoperative so as to allow engine speed to exceed manufacturer specifications.5. Removal or rendering inoperative the fan clutch including bypassing the control or any thermostatic fan drive to cause it to operate continuously.6. Removal of fan shroud.7. Removal or rendering inoperative exhaust system components including exhaust pipe clamping.8. Removal of air