Adding air brakes?

[ENafziger]

I've been trying to get some information together on what it would take to add air brakes to our trucks. Has anyone done this before, or is there a kit available to accomplish this?



I understand some 5. 9's came with an engine mounted air compressor in bigger truck applications, but that it mounts in the area where our power steering pump and cp3 are located. I also have been told that there are compressors available that run off the flywheel, and some that are PTO driven.



I've googled around, and searched here on TDR without much luck. Anybody? Thanks, Eric

 

[AKaiser]

Don't know about this class of vehicles, but would putting air brakes on it make it a requirement to have a CDL?

 

[ENafziger]

Well, I read my original post, and I think I was a little unclear. I'm not planning to alter the service brakes on the truck. I'm looking at getting a 40' gooseneck trailer, and would prefer air brakes on the trailer over electric or hydraulic.



I would like to add an air system to the truck that I could use to run air brakes on a trailer... and use for inflating a tire, maybe running an impact gun, etc.



I've got a Midland hand valve already, and I'm trying to see if I need to piece together a kit, or if something's already available. Thanks! --Eric

 

[Pawpaw]

Like this?



::Kilby Enterprises::



For what it's worth, Kilby is a TDR member too.





Bob

 

[ENafziger]

Yeah, I've seen several options for adding compressed air capability to our trucks, but am wondering more specifically about being able to tow a trailer equipped with air brakes.



As I understand it (which isn't all that well), there are several more components to an air brake system, other than just compressed air. It seems other components are needed, including a regulating assembly, dryer, manifold, the air brake connection lines, hand valve operated in the cab, etc.



I see gooseneck trailers for sale pretty often that are equipped with airbrakes, so I know that there must be trucks out there with airbrake capability. Anyone?

 

[NIsaacs]

Yes there are air brake equipped trucks out there, but not in the class three size. It would be possible to add a system to our trucks, however it would be complicated. If you are knowledgeable in the air systems it could be done. Most air brake equipped trailers are of a larger variety and usually require a larger truck. The hardest part of a trailer brake system would be an attatchment to activate it when you step on your hydraulic truck brakes.





"NICK"

 

[jelag]

A good friend had a mid range truck with hyd brakes and wanted to tow a large trailer with his sail boat... . the trailer had air brakes... . he installed a compressor on his truck... . and than ran a hand control into the cab to turn on the air brakes on the trailer... he couldn't find an interface to take hyd pressure and convert it to air pressure and make it work...

the hand brake would work for him when he was straight and steady down the highway... . on hills and curves he was really unhappy with the set up and was afraid of a panic stop..... or it getting away from him...

the boat was worth 100K so he traded trucks for a small truck with air brakes and is really happy.....

Just my thoughts...

 

[ENafziger]

the hand brake would work for him when he was straight and steady down the highway... . on hills and curves he was really unhappy with the set up and was afraid of a panic stop..... or it getting away from him...

That's interesting. I too have been unable to find a hydraulic to pneumatic interface, but have a hand valve that I was planning on using.



Could you tell me a little more about your friend's setup? Was he uncomfortable on hills and curves because of handling issues due to the weight he was pulling? Or did the air brake / hand valve setup somehow cause things to become unstable?



The hand valve I have (Midland), is a column mount, that "sticks" in position. In other words, when making a stop, you press down on the lever to achieve the desired braking, and then it stays there so you can downshift, etc.



I know this would require a little getting used to, but I figured the truck's service brakes along with the exhaust brake could provide very subtle speed changes and braking; anything requiring moderate to heavy slow downs and stops could be accomplished by first setting the air brake lever, and then supplementing with the truck's exhaust and service brakes.



Jelag, I appreciate your feedback... that is exactly what I'm looking for! --Eric

 

[DBoggs]

Eric, I found this schematic by googling "air over hydraulic brakes". I have no clue if something like this would be possible in our trucks with all the electronics or if would be cost be cost effective to even try.



Duane

 

[BarryG]

Not sure if this helps but the brakesmart brake controller says





The BrakeSmart controller is much more than a brake controller. Using a proprietary method, the BrakeSmart controller communicates with other Master Brake Systems, Inc. intelligent devices on the trailer.



Dr. Performance - BrakeSmart



Might be worth calling

 

[Rotty]

check this out





M&G Brake System

 

[ENafziger]

Hey, thanks for all the input so far. It looks like the M&G setup is close, but it is exaclty opposite of what I'm looking for. If you have an RV with air brakes, it allows the hydraulic brakes of the tow vehicle to be applied at the same time. I'll have to think on whether this could be adapted to fit the opposite application (using a vehicle with hydraulic brakes to control the air brakes of a trailer).



The diagram above is complicated! It certainly gives me some ideas though. I believe somewhere in the system, you would also have to add a drier, as well as a hand valve over-ride so brakes could be applied to the trailer manually as well.



I'll have to give BrakeSmart a call...



Thanks for all the help guys! --Eric

 

[jelag]

Understand that most air spring brakes... . the can located at the wheel that you see when you follow a truck... this spring brake has 2 chambers in it... . one is a large spring and it applies the brakes if there is NO AIR... . so what this means is that if the truck looses air the brakes apply and stop the truck... this has been an industry standard and law for as long as I've been in the business... . the second chamber is the braking chamber... .

So when you go to move the truck you flip a lever in the cab and apply air to the e-brake circuit..... this applies air and compresses the spring and releases the brakes... .

When you go to stop, the foot pedal, or in this case a valve will apply air to the second chamber and apply the brakes... most heavy trucks use a brake pedal that throttles the air... and most braking on large heavy trucks (class 8) is done between 15-25 lbs of pressure... but it takes 60 PSI to release the e-brake... so your hand lever needs to apply air in a throttled way... .

If the valve is just off and on, the air pressure will build and than the brakes will lock... . years ago, heavy haul trucks, logging trucks as an example would have a hand brake in the cab... . its design was to allow the driver to apply the hand brake lever which only applied the rear trailer brakes... this was to pull the load straight on wet slippery roads... . this hand lever I'm sure is the Midland brand lever valve you speaking of above... . NOTE HERE, is the valve your intending to use is only OFF/ON your in for problems... . this valve needs to work like an air pressure regulator, in that when you stop moving the valve the air pressure stops building up...

The only valve that I've seen on a truck is always spring loaded off... . except for the E-brake valve which is either off/on... . if you had a hand valve that you could turn loose and the brakes would stay on... you'd forget it with minor braking and burn them up... . I don't know of a driver that shifts with the brakes on... . one foot runs the clutch, the other foot runs the throttle and one hand on the wheel and the other shifts... these transmissions do not have synros... so the engine speed must be raised to mesh the gears when down shifting... read, you need to add throttle... .

Todays modern trucks have valves that crack at different pressures... . this means that when the driver places his foot on the pedal the last set of axles start to apply, than the next set, than the next set and last the front steer axle starts to apply... . this delayed braking keeps the trailers, and tractor straight down the road... . This valve is located at each axle... . if the mechanic mixes these valves up when doing repair work all hell breaks loose... the crack pressure or opening pressure is controlled to keep the trailers and tractor in line...

I hope this isn't too long or has confused you... . and it helps answer your questions... ... .

 

[bmoeller]

EN-

Call Jet Co. Jet Co. Manufactures Grain Trailers, Flatbed, Dropdeck and Tag Trailers

They use pickup trucks to deliver semi trailers to dealers. Seen them up at the plant, and on the road once in a while. Maybe someone there can help out.

They don't use dollies. Hitch plate is on the dually pickup itself.

 

[AKaiser]

If the valve is just off and on, the air pressure will build and than the brakes will lock... . years ago, heavy haul trucks, logging trucks as an example would have a hand brake in the cab... . its design was to allow the driver to apply the hand brake lever which only applied the rear trailer brakes... this was to pull the load straight on wet slippery roads... .

I always thought that valve was for loading grain on a downslope You just set the trailer brakes, and let off just long enough to let 'er roll a couple feet.

 

[WestTN]

Air brake systems can have their problems too. Why do you want them? Thousands of trailers have electric brake systems that work perfectly and fully automatically. You would almost certainly wind up with a strictly manual brake activation, as there cannot be very many, if any, interfaces that would give you automatic brake activation. In an emergency situation, you might have to keep both hands on the steering wheel and be unable to control the brakes at all. NOT a pretty situation.

 

[ENafziger]

Why do you want them?

Ah, just exploring the options. HD trucks use them rather then electric, so I'm sure there's reasons. One I can think of is if something fails, the trailer brakes are applied (no air pressure = brakes applied). I'm getting setup to pull a 40' gooseneck someday, and with a blown fuse, malfunctioning brake controller, etc. there is no way the service brakes of the truck could stop safely.

I'm still in the learning stages, but maybe a hydraulic/electric setup would be best. I have not been overly impressed with the electric setup on my current car-hauler. --Eric

 

[Ragain]

I've been doing some research on adding air brake controls for my float also. Get a product cataloge from Bendix.

What I've been considering is putting a treadle valve on the cowl area near the hydraulic assist unit that is connected to the brake pedal linkage inside the cab. Other things I have to consider are locations to mount several of the operating controls/valves. The system is fairly complex and I do not want a second rate installation that may compromise safety.

 

[MMichaels]

As mentioned, air brake systems are expensive and complex. A great idea if you need to stop 80,000 lbs, but way overkill for anything a pickup truck should be hauling...

 

[Cattletrkr]

The last time dad sold a GN trailer with air brakes I believe it added about $5300 to the cost of a $7500 trailer. That one was going behind a semi.

I have about 80K on my electric over hydraulic brakes. Not even close to needing any work done other than I have to change the oil in the axles. Usually that gets done with the brake work but I haven't done any brake work.

Elec. over hyd. brakes are far superior to plain old elec. except for the lag time.