Exhaust Brake Idea. Feedback?

I won't delete your idea....I'll think on it some more. :D Robbing air from the turbo through a check valve is quit intriguing.

So, I guess I need to figure out how much pressure and what cylinder diameter it will take to hold at least 50 psi of backpressure on the exhaust.

It also helps to have a milling machine about 1/2 mile from the house that I can use anytime too.
 
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I am going to follow this closely....

The pop-off valve could be rerouted into the exhaust as well. I know we also see high drive pressures on some turbo setups, could it be possible to use this pressure to activate the brake? Wouldn't that eliminate the moisture issue with using the boost pressure? Although soot might be an issue. Hmmmm
 
I know a cheap alternative Jory. Buy an air compressor and get after it man. If you go with an inline brake you can go bigger diameter brake whereas with a stock vacuum brake, you are diameter limited. Just add better exhaust springs!
 
If PacBrake was right on the 12 valves, I would keep the pressure differential <60lb.
 
Ok, ok, ok, dammit, I'll do pressure vice vacuum. You all HAPPY?!?!?! :hehe:

I just didn't want to have to wire the compressor and install a tank and all that crap. I can make the tank. If I use pressure, I will only have to route one line to the device, insteal of a feed and a return and I will only have to switch one line open/closed instead of swapping both lines for the vacuum to work. Thing is, there is a vacuum line for the front axle right under the exhuast. I could splice into it and just use it. I won't be doing 85 and need the exhaust brake when I'm in 4x4 anyway.

I need an small air cylinder. :D
 
Been draftin' a tad today. Lots of good ideas, I just need refine the fine print so I can make everything work without having to machine junk to .xxx tolerances. I can start the holes in the flapper small and monitor pressures then widen them to "tune" the max back pressure.

EbrakeA.jpg
 
4x4dually said:
Been draftin' a tad today. Lots of good ideas, I just need refine the fine print so I can make everything work without having to machine junk to .xxx tolerances. I can start the holes in the flapper small and monitor pressures then widen them to "tune" the max back pressure.

EbrakeA.jpg
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You can also limit the initial travel of the butterfly, so it remains say half open and slowly allow more closing, until your at a level you feel comfortable with.
 
zstroken said:
You can also limit the initial travel of the butterfly, so it remains say half open and slowly allow more closing, until your at a level you feel comfortable with.
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You know....that's what a wise man would do....so one only has to assemble the junk once. :bang

Duh...thanks. I can design in an adjustable stop.
 
Gimme a shout on the cylinder, I work with them every single day, might have something in the obsolete bin that would work for you.
 
Billysgoat said:
Gimme a shout on the cylinder, I work with them every single day, might have something in the obsolete bin that would work for you.
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Thank you sir. I got one commin', but it might be a little big. I may have to steal the controls of it and replace with a smaller cylinder. We'll see when it gets here.

It sure would be nice if any size of standard sch 40 or 20 pipe would mate up with exhaust pipe. :D I'm still searching for that right size. I'd like to use a piece of sch 40 pipe of some variety to adapt my 4" dp to the 5" FTE and put the flapper in that adapter. Kill two birds with one stone.
 
If I weld a piece of sch 40 4.5" and a small ring of sch 40 4.0" and a 4" OD to 4" ID adapter together to make the middle section of this picture, it should slide on the downpipe and then the FTE resonator should slide right on the back of it. Two clamps and whalla!

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Now the fun part...designing the cylinder mount and adjustable stop. :D Once I get some hardware, I'll tackle that. I need more info to get started.
 
Ok, Dan, and other smart people. Here's the current plan.

If I used compressed air and a 5 port, 2 position valve which I think is going to come on this cylinder another Comp D member has so graciously given me, I can use a regulator and set the main pressure to say 40 psi to drive the cylinder to its retracted position normally. Once I engage the spool, it will extend the cylinder thus closing the butterfly. This will cause the backpressure in the down pipe to rise. My drive pressure guage will read what that value is already (bonus!). If I tie a line from a port in the downpipe to the exhaust port of the spool (where the air is coming out so the cylinder can move) I will be able to get some feedback. If I have 40 psi pushing the cylinder to 'extend' and the backpressure starts to exceed that, the differential will start moving the cylinder back to 'retract' until the pressures equalize and the backpressure drops. My only concern is that the butterfly will oscillate. What say you guys? Think it will work? I can basically 'set the limit' of the backpressure by controling the pressure regulator on the main line...factoring the resistance of the air against the butterfly or course. It will take some doodling I'm sure.

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If the feedback idea doesn't work, I can always just limit the cylinder travel and let it exhaust normally. I don't think soot in the line will be a problem. That port is closed normally and when the brake is engaged, it is always with foot off the pedal thus no smoke.
 
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Why not use a spring return open for the butterfly. That way if you have an air pressure issue, you just lose the function of the brake.
 
You are going to soot up the valve, these valves do not like contaminants in the spool worth a flip. If you want to feedback using backpressure, use a filter inline and just tie the retract port to the DP, maybe with a spring. The manual gauge I use to monitor will bounce like a fat kid chasing the ice cream truck when the brake is first applied, so with the pressure spikes I can see a cycle getting started.
 
I will use a spring as a secondary or back up in case of no pressure and the spool in the relaxed state needs to allow the cylinder to vent and be pulled back using the spring. The spool may come in with an AC coil, if so, I will have to swap it out anyway. If I do, it won't be a 5 port. Then I don't have to run the DP line through the spool.

How do the pneumatic cylinders handle contaminates? Will a tad of soot hurt it if I run it into the rod end of the cylinder to push back on the piston? I can control the initial spike by a needle valve restricting the flow when the spool slams to the extend position. The oscillation worries me. I will most likely tune it on the truck with my video camera tied up showing me the cylinder position when I first take a test drive. :D
 
This is what I thought up at 11:15 last night trying to go to sleep in bed.

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Edit: Crap....the clylinder would never retract. That was brilliant. Needs a vent. Maybe I do need the 5 port valve.
 
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It would have to be this to allow a vent.

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I think the addition of flow control would keep the oscillation to a minimum. I think it is built into this spool, but won't know 'til it gets here. It has been shipped.

This will slow the flap down and keep it from spiking the hell out of it when engauged.

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Anyone know of a belt driven compressor that can easily be added to these trucks? I bet these are cheap. LOL

::Kilby Enterprises::
 
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It is a shame the clutch pedal position switch is a single pole single throw. It would be nice if it had a pole for the normally closed side as well. Then, if the clutch was pushed the valve would be opened up so it don't choke off an idle motor and then come back on once the downshift is made and the clutch is let back out.

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I guess a relay would cure that but that equals MORE DAYUM WIRES! :D
 
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