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C40106B - Pacbrake PRXB Exhaust Brake Caterpillar 3126B / 3126E / C7 4" Full Marmon

C40106B - Pacbrake PRXB Exhaust Brake Caterpillar 3126B / 3126E / C7 4" Full Marmon


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Part # C40106B PRXB Exhaust Brake Caterpillar 3126B / 3126E / C7 4" Full Marmon


Pacbrake’s flagship product, the PRXB (pressure regulated exhaust brake), is the unquestioned leader in the supplemental brake industry. The patented PRXB design delivers the strongest braking horsepower, greatest speed reductions and shortest stopping distances possible without the use of service brakes. It maintains optimum retarding performance by maximizing the exhaust backpressure throughout the entire RPM range. Unlike a typical exhaust brake, which requires high RPMs to work properly, the PRXB delivers constant exhaust pressure (braking) as early as 1200 RPM through to the maximum allowable RPM. 

Controlled by a master ON/OFF switch, Pacbrake’s exhaust brakes provide whisper quiet supplemental braking that allows service brakes to be used much less, ultimately saving you money. They have the ability to be left on all the time, making it ideal for in-city driving or for steep, downhill grades. This product pays for itself as less wear on the brake pads means fewer brake jobs.

In order to have consistent and effective braking over the entire RPM range, it is important (and necessary) to maintain constant backpressure. To achieve this, Pacbrake’s patented design has incorporated an additional waste gate on the butterfly valve to regulate the amount of exhaust flow that is being passed through. The flow is controlled by a spring-loaded arm, whose pressure rating and location are key factors in the functionality of the PRXB. Located outside of the housing and away from the heat, the spring is able to maintain its strength and durability for years of proper and precise braking performance.

Backpressure is created by exhaust flow entering the housing, hitting the closed butterfly valve and being forced back out in the direction it came. It is maintained by the pressure-controlled spring that is located on the outside of the exhaust brake housing.

As the engine’s RPM increase, the spring compresses and the arm moves away from the butterfly valve, therefore releasing more exhaust flow through the orifice. As the RPMs decrease, the spring releases and the arm applies pressure back onto the plate, covering the hole, and ultimately releasing a smaller amount of exhaust flow.

There is less than a 10% change in backpressure over the entire RPM range on the PRXB

Features & Benefits: 

  • PRXB Delivers Strongest Braking Horsepower
  • Less Wear & Tear On Service Brakes 
  • Ideal For In-City Driving Or Steep, Downhill Grades 
Will this fit my 2002 f650? Does it come with everything to install for this price ? ( Doug, 12/19/2019 )

The C40106B is just the brake itself. If you do not currently have a brake that you are replacing, you will need a mounting group and control group. Assuming you have on-board air, the part #'s that you will need in addition to the C40106B are C11558 and C10319.

( Support )
I have a 2005 Chevy C8500 with a Cat C7 with Eaton 8LL trans. current exhaust brake is off down pipe of turbo and an original air line powered actuated unit. the ball and socket design to hold rod on has failed, will this unit work in place and how would this be actuated? Same air line as i have currently? ( Randy Black, 11/05/2019 )
Yes, the PRXB uses air pressure to actuate. We always recommend contacting PacBrake to verify the correct part # to use and if any additional parts would be required. You can call them direct at 800-663-0096. ( Support )

I have a 2006 GMC C7500 with and C-7 cat and Allison 3000 transmission. My exhaust brake is an Jacobs and is hanging terrible. The brake is a inline style not on the turbo and the truck has on board air. will this product work?

( dan, 07/13/2015 )


Because your current exhaust brake is the inline style you will want to stick with that, so the part # you will need is C40113

You will also need a mounting group, so measure your exhaust pipe diameter. Most likely it will be 4" which would be part # C11400

( Support )

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