Main Concern

Jacobs Vehicle Systems™ has received inquiries regarding engine brake use and noise. The posting of engine brake signs (like the one shown to the right) along the roads and highways of North America has created much controversy with both residents and drivers alike. This page has been established to inform interested parties about engine exhaust noise, and provide the data and information necessary to understand the issue. We hope you find the information on this page useful, and we welcome any feedback. Click here to use our feedback form.

Questions and Answers

I've seen signs posted that say "No Jake Brakes", what does this mean?

Jake Brake® is a registered trademark of Jacobs Vehicle SystemsTM. The term "Jake Brake" is sometimes incorrectly used to refer to compression release type engine brakes in general. The term correctly refers to all of Jacobs Vehicle Systems retarding products. When an engine brake is used on a vehicle with a poorly muffled or un-muffled engine exhaust (using straight pipes for example), the sound can be offensive, which is what prompted the sign you saw. The sign you saw might have unfairly used our trademark, making it brand specific.

I'm bothered by the noise of big trucks using their Engine Brakes, what can I do?

The federal government has required all vehicles manufactured since 1978 to meet noise requirements when delivered to the customer, so trucks have been required to meet the requirements when they leave the dealership as new vehicles for quite some time. The real problem here is modified or defective exhaust systems. The use of the engine brake is not the problem. Citizens and truck drivers can both do their part to keep the noise down. Citizens, encourage your local police to stop noisy vehicles and check them for muffler integrity. Truckers, if you know someone who is operating a vehicle with an excessively loud exhaust system, encourage him or her to fix it.

More information on Engine Exhaust Noise

• Jacobs Engine Exhaust Noise Presentation

  To better understand engine exhaust noise and Jacobs’ standpoint view our updated presentation.
  
  Download Presentation (PDF)

• WHITE PAPER: Vehicle Noise and Compression Release Engine Braking

  For a more in-depth look at commercial vehicle noise laws and their relationship with compression release engine brakes, read Jacobs’ white paper that also provides appropriate solutions to the noise issue.
  
  Read Online | Download (Adobe Acrobat PDF)

• Sign Notice Sample Letter

  This is the letter that is sent when we are made aware of a sign specifically prohibiting Jake Brake®.
  
  Download Sign Notice

• Ordinance Help

  If you are made aware of an upcoming legislative ordinance, or it is your understanding that your community is considering an ordinance, that prohibits Jake Brake® or engine brake use, please let us know by using our feedback form.
  
  Complete Our Feedback Form

• Montana Legislation

  Montana’s 2003 House Bill No. 237 correctly recognizes engine exhaust noise issue by requiring motor vehicles equipped with an engine compression brake device to have a muffler in good working condition.
  
  Download Montana Law
  Go to Montana Legislature Web Site

• Multi-State Highway Transportation Agreement (MHTA) Update.

  Model legislation based on the recent law in Colorado requiring commercial vehicles with engine brakes to have proper exhaust mufflers on any truck operating in the state. The MHTA has adopted Colorado's law (with some modification) and it has been brought back to the member states of Arizona, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.
  
  Download MHTA Agreement

• American Association of Motor Vehicle Administrator (AAMVA)

  This web site contains information on the muffler identity and inspection procedures that can be adopted in your state. With these criteria, a commercial vehicle can be inspected for the presence and integrity of an appropriate muffler system.
  
  Download Muffler Inspection Instructions

• Donaldson Silent Partner^TM Muffler

  You may have heard about the Silent Partner^TM Muffler from Donaldson Company. This product was developed and tested in conjunction with Jacobs Vehicle Systems. The silent partner is an exhaust silencer designed to further decrease noise produced during both acceleration and engine braking to bring the engine exhaust levels below what they would be with premium mufflers. For those who want the ultimate exhaust noise reduction technology.
  
  Download Donaldson’s Silent Partner™ Brochure