Best current practice on air hose from chassis to axle.

bevans6 · September 15, 2011, 06:53:58 AM

No one bit on my question on how to install an air hose with non-swivel pipe thread fittings on both ends, so I will ask what I probably should have asked in the first place - what is the best current practice for the flex air hose that goes to the service chamber from the chassis? Mine is currently the aforementioned rubber line with compression fittings and pipe thread. I see a lot of DOT nylon with push-on fittings. I am using fabric covered lines with a steel braid layer for all the lines that don't flex, but are tied down. I read in one manufacturers page that the nylon lines and fittings they had were not for the connection between the chassis and the axle, but no where else was that even addressed.

So - guys with current experience - what is the best possible way to do this? The lines in question are to the check valve and inversion valve that is mounted on the differential, and from the R8 valve to the service ports on the DD-3's. the lines are all in good shape and were new in 2002 when the valves were changed.

Thanks, Brian

bobofthenorth · September 15, 2011, 07:30:55 AM

I'm not sure about "best" practice Brian but I buy mine at the NAPA truck store - my buddy Al has them hanging on a rack in various lengths. They're rubber hose with what I believe must be a fabric braid - they seem too flexible to be steel braid. Compression fittings with a swivel on one end. I'm never sure what size they measure for hose sizing but I think they would be 3/8 hose. That's what my trucker shop owner told me to use. Personally I would not use the DOT plastic hose in this application but you are right, I see it fairly often.

Oonrahnjay · September 15, 2011, 07:42:10 AM

Quote from: bevans6 on September 15, 2011, 06:53:58 AM
No one bit on my question on how to install an air hose with non-swivel pipe thread fittings on both ends, so I will ask what I probably should have asked in the first place - what is the best current practice for the flex air hose that goes to the service chamber from the chassis? Mine is currently the aforementioned rubber line with compression fittings and pipe thread. I see a lot of DOT nylon with push-on fittings. I am using fabric covered lines with a steel braid layer for all the lines that don't flex, but are tied down. I read in one manufacturers page that the nylon lines and fittings they had were not for the connection between the chassis and the axle, but no where else was that even addressed.

So - guys with current experience - what is the best possible way to do this? The lines in question are to the check valve and inversion valve that is mounted on the differential, and from the R8 valve to the service ports on the DD-3's. the lines are all in good shape and were new in 2002 when the valves were changed.

Thanks, Brian

Yeah, the "rubber" hoses (which are of course really composite of high-pressure fabric, reinforcement layer, liner and rubber out-coating) with the copper end fittings for all the flexible couplings from the chassis to the components that are mounted on the moving suspension. I got lucky in that my bus was built with brackets on the frame at the end of the frame-mounted lines; where the frame-mounted lines end, they're secured to those brackets, the "rubber" hoses go from those secure locations to the cans. (On my bus, there were also brackets in the perfect place on the frame for the R-12 and R-8 valves. So those items are mounted to the frame and both the parking and service hoses to my rear cans are "rubber". Bendix said that that was good. But it makes it easy when all the lines to those valves are "hard lines" on the frame and the only lines that need to be flexible are the hoses to the cans.)

The hoses that I bought (not NAPA but a really good truck/bus supply place in Charlotte NC) also had the swivel that Bob was talking about. Really easy to install. I also agree with Bob about no nylon pipe between the frame and moving parts -- can't imagine how that would work for long; it's really good stuff when it's in a "secured" location but it's pretty easily abraded if it rubs on anything and I'd expect that it would fatigue and crack before too long in a flexible use location.

belfert · September 15, 2011, 07:54:55 AM

On my bus on the front at least the rubber line goes from the chamber to a bulkhead fitting that goes through the C channel frame member. The other side is standard DOT nylon line. When the shop replaced my front brake chamber they also replaced the hose for some reason.

bevans6 · September 15, 2011, 07:57:47 AM

Thanks, guys, appreciate it. That's the hose type I have, just my current hoses don't have a swivel at one end. If that's the right stuff, that's what I will use! Just didn't want to miss a trick. I have heard that the nylon stuff is used because it's cheaper and easier to repair, not because it's necessarily better.

Brian - just saw your post. Did the shop install the nylon line to the chamber, or the rubber line to the chamber that they installed?

Brian

Oonrahnjay · September 15, 2011, 08:10:48 AM

Quote from: bevans6 on September 15, 2011, 07:57:47 AMThanks, guys, appreciate it. That's the hose type I have, just my current hoses don't have a swivel at one end. (snip)

Brian, I'm not sure that you'd really call it a swivel. It's a flexible adaptor on one threaded end; you secure the non-flexible end to a component (I put that end on the frame side but I'm not sure it matters), route the hose to lie where you want it, and then when you tighten the other end with the flexible fitting (to the can or valve) it doesn't "wind up" the hose as you tighten it. Like Bob said, most places have a rack of them in various lengths (or good places can make them up if you need a special length) -- you can just have a look at one and you'll see how it works.

luvrbus · September 15, 2011, 09:07:35 AM

Brian, we do it different but I use the fitting you posted from Fastenal the hose just screws into the fitting like a Air Quip fitting there forever they don't come loose and if you blow a hose unscrew and replace the section fwiw I buy mine from Eastern Marine comes in all different flavors

good luck

belfert · September 15, 2011, 09:18:10 AM

Quote from: bevans6 on September 15, 2011, 07:57:47 AM
Brian - just saw your post. Did the shop install the nylon line to the chamber, or the rubber line to the chamber that they installed?

Rubber hose from the chamber to a bulkhead type fitting. Nylon hose on the other side of the bulkhead fitting over to the QR-1 valve.

bevans6 · September 15, 2011, 09:54:29 AM

Well I went with my hose to the truck store (Traction) and they had a big rack of DOT hoses all made up. They have crimped ends, one is a swivel, and the are a shiny material but I don't think the same material as the nylon hose. Very inexpensive $9 each for around a 2 foot long hose. The look good to me...made specifically to go from the chassis to the chamber.

Brian