Odd Brake booster question

[Andyg]

I have a potential application for the airpac booster on a civilian truck. Hopefully you folks can tell me if my idea will work. I have a 1.5 ton truck with fluid brakes. I want to pull a trailer equipped with air brakes. Can I use the airpac to power the airbrakes on my trailer. I do not plan to use the airpac booster on the truck's brakes though.

 

[Barrman]

Interesting idea. You are just wanting to use it as an air valve, correct?

I would suggest you plug all the outlet fittings and then just plumb in the air. Does your truck have OBA of some sort? Use a T to bring fluid to the airpack. Probably be best to have it down stream of the ABS or proportioning valve for the rear brakes. That way it won't mess up the performance of the trucks brakes any.

I am sure there are purpose built units out there for this however. Neat idea though.

 

[Andyg]

I'm not sure what an OBA is so I can't answer that question. I am working with a 1999 Ford F53 motor home chassis.... now truck. The chassis has 4 wheel antilock disk brakes. It is equipped with hydroboost power brakes. Hydroboost uses pressure from the pwr steering pump to boost brake pressure. I am converting the chassis to a light duty tractor to pull a trailer with air brakes. I did find a commerical unit that will take a signal from the hyd system and uses it to apply air pressure to the trailer brakes. The unit is very expensive compared to an airpac unit which might perfrom the same job. When I asked about interfering with the antilock brakes I was advised to tap the hyd brake line BEFORE it enters the antilock unit on the chassis.

 

[supermechanic]

Spend the money, buy the unit engineered for the job.
Not likely you could get a cobbled together homemade brake valve through a D.O.T. inspection.
Brakes are a place where it pays to have known good parts and engineering.
In today's litigatious society, it is imperitive that you cover your a##.

 

[DDoyle]

Where are you gonna get the compressed air from?

 

[BFR]

do you meant to just plumb it backwards? (thinking the airpac will translate hydraulic pressure into pneumatic pressure) I imagine it is theoretically feasible, but highly unlikely you will get the pressure/flow you need. Kind of like it is possible for me to win the lottery but I am not holding my breath....

 

[gimpyrobb]

OBA= on board air, as in air compressor. You will need oba to work air brakes.

 

[Andyg]

I have a compressor (OBA) to put on the truck. I have a pretty good understanding about how air brake systems work. The trouble is converting the hyd pressure signal produced by the master cylinder to an air pressure signal to activate the trailer brakes. I asked the ATHS list awhile ago about this issue and that is where I got the idea about using the airpac for a military truck. No, I don't want to plumb the booster "backwards". I noticed that the booster has a connection comming out of it to operate trailer air brakes. I thought that I could basically use half of the booster to operate the air brakes on my trailer.

 

[Barrman]

I still think it is a cool idea. Chris already wrote it, but OBA is On Board Air. You will need a constant running compressor and tanks to store air in.

A line from the tanks will go to the airpack. Everything else on the air pack except the vent and the output air to the trailer should be blocked off. Another line from the tanks will go to be the trailer emergency air.

 

[gimpyrobb]

Tim, you kind of missed an important bit of your experiance. Make sure the first 2-4ft from the compressor's pressurized output is copper! And put check valves on the reserve tanks. Don't want to loose what powers your brakes.

 

[WillWagner]

Tim, you kind of missed an important bit of your experiance. Make sure the first 2-4ft from the compressor's pressurized output is copper! And put check valves on the reserve tanks. Don't want to loose what powers your brakes.

Braided stainless is the norm now. Navistar still uses copper though.

 

[Barrman]

You are correct Chris. I did learn that the hard way. Put something besides plastic air lines at least the first 3-5 feet from a compressor.