Adding air to pickup for air trailer brakes.

[timberben]

i Would like to be able to tow trailers that have air brakes With my 12 GMC 3500. A tilt deck equip and a short log trailer. I know that I need to add a compressor tank gauge lines glad hands, that part is simple enough. I already have built a similar compressor setup on my 03 Chevy to control my air bags on the fly. My question is how or what controller do I need to correctly supply the air to the trailer brake? I tow both trailers with my water truck mostly so I’m not converting the trailers to electric brakes. I know this can be done and it is simple. Google is no help as it doesn’t understand the question. If anyone has this system or knows how to accomplish what I want to do please point me in a direction. How do I send the right amount of air pressure to the trailer? Will I be able to use my factory brake controller to control a valve that supply’s the air to the trailer? thanks

 

[2004LB7]

I'm not sure there is anything that does this. At least nothing I could find. I did see a thread on another site where someone wanted to do as you and ended up having to make one.

Incase you didn't know, air brakes take a lot of air and electric air compressors will not normally be able to keep up. More common to use an engine mounted compressor for the high output CFM

 

[timberben]

Yes I do know that. I know this can be done and I have seen the setup before although it was 20 years ago. I have already built a system that will supply enough air. Two large viair compressors and a 7 gallon tank gauges on the a pillar pressure switch on tank 200psi off 180psi on relay safety valve paddle switch’s on dash(left and right to inflate and deflate air bags) and a few fittings and couplers. The system works great for filling tires small 1/4 air ratchet air nozzle. The system has saved the day many times with flat tires. I have the air supply figured out just need a way to control the air to the trailer. I don’t plan on towing the trailers fully loaded as I will overload the pickups capabilities. I am a logging contractor and work in very remote areas. I need a way to get the trailers to and from the job sites. A pickup is more economical than my water truck. The log trailer I light enough that I think I can move it without the use of brakes but I still need air to release the brakes. I don’t want to cage the pots every time I move them. I think I can rig something up to supply enough air to release the pots. I have talked to a few truck shops and apparently there in nothing that will do what I want.

 

[2004LB7]

Are you wanting to modulate the air pressure to work with your truck brakes or just an on off setup to release them to be able to move the trailer?

If the latter then I don't see why you couldn't just add the appropriate air fitting at the back of the truck to supply the pressure with nothing else needed.

 

[Fingers]

Look for either Electric actuated or Hydraulic actuated relay valves. There are some ABS valves that can be used (with some tinkering) to provide proportional signal air using the electric brake controller.

You will, of course, have to mimic essentially all of the normal air brake system. But you already know that.

 

[2004LB7]

Look for either Electric actuated or Hydraulic actuated relay valves. There are some ABS valves that can be used (with some tinkering) to provide proportional signal air using the electric brake controller.

You will, of course, have to mimic essentially all of the normal air brake system. But you already know that.

I've been looking at some of those. Seems they all take several seconds to go from fully closed to fully open if they are the modulating type. The ABS method might be a way to go if he can find one that will understand a simple variable voltage

 

[jlawles2]

I've seen a few setups from hot shot drivers that have air brakes on there trailers. None seem to have automatic breaking but in stead use the column mounted air valve and just manually apply.

 

[Fingers]

I've been looking at some of those. Seems they all take several seconds to go from fully closed to fully open if they are the modulating type. The ABS method might be a way to go if he can find one that will understand a simple variable voltage

Relay valves are instantaneous. Normally used on trailers to translate low volume signal air pressure to the brakes using the trailer's air tank. there are a few aimed at the hydraulic to air conversion.

mico-inc-hydraulicoverair-relay-valves

 

[2004LB7]

Relay valves are instantaneous. Normally used on trailers to translate low volume signal air pressure to the brakes using the trailer's air tank. there are a few aimed at the hydraulic to air conversion.

mico-inc-hydraulicoverair-relay-valves

I thought you were talking about a modulating valve. Yeah solenoid valves are quick but if he uses one on the brake application side then it will lock up the brakes even with the littlest pedal application. Solenoid could be used to hold the trailer when it is stationary and release it when he wants to drive. And as jlawles2 said, he can always mount a hand operated valve to manually apply the trailer brakes

 

[2004LB7]

Relay valves are instantaneous. Normally used on trailers to translate low volume signal air pressure to the brakes using the trailer's air tank. there are a few aimed at the hydraulic to air conversion.

mico-inc-hydraulicoverair-relay-valves

Something like this may work too

Automann 171.19516711 Electric Over Air Relay Valve

This axle valve includes two industry-proven brake-style relay valves integrated into one single unit for compactness and ease of installation. The module provides excellent flow capabilities for rapid axle actuation. This heavy duty valve is more robust than commonly used spool valves that can...

mpparts.com

 

[jlawles2]

The issue in the hydraulic over air might be input pressure. It states 2,000psi. IIRC hydraulic brake pressure can be much more than that.

 

[Fingers]

Hydraulic line pressure is less than 2000 PSI.

 

[jlawles2]

I'd have to pull out the scanner and read the pressure from the ABS system.

 

[2004LB7]

I thought I remember it being something like 1400 psi

 

[Fingers]

My trailer brake controller senses off the hydraulic brakes. Max indicated I have ever seen was less than 1400 PSI

 

[Bdsankey]

My trailer brake controller senses off the hydraulic brakes. Max indicated I have ever seen was less than 1400 PSI

I wish they still made them like that for older vehicles

 

[bssifter]

The Mico valve will not work with brake fluid. The Mfg. said it is meant for tractors with hydraulic oil used for braking. I am waiting to hear back if the Automann valve will work. Has anyone done this?

 

[bssifter]

The valve used by 5thwheelers austrailia is not available currently.

 

[malibu795]

I'll have to dig in.. one of my threads there a link to hydraulically controlled air valve that is not on/off or open/closed but can be throttled via hydraulic pressure..
Unfortunately air controlled HYD valves are substantially more common..
Including air over HYD brake setups

 

[bssifter]

I'll have to dig in.. one of my threads there a link to hydraulically controlled air valve that is not on/off or open/closed but can be throttled via hydraulic pressure..
Unfortunately air controlled HYD valves are substantially more common..
Including air over HYD brake setups

I hope I can make this work somehow. If I wasn't in Ca. my 07' freightliner with 58k original miles would be legal and I wouldn't be having to downsize. Worst case I will have to use a hand operated lever.