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Air brakes on the trailer and glad hands on the HDT


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We have come across a trailer that we are thinking of buying or at least looking at it for some ideas but a couple of items we could use some assistance on. It is a long shot but hate to pass up a deal on bigger trailer if it will work for us.

 

The trailer has air brakes and air suspension on it. Any thing we should watch out for when inspecting it?

 

Trailer has 2 axles with single tires on each. They don't indicate in the info what size the axles are. I am hoping there is a tag on the trailer but if not any way to know what the axle capacity would be? Based on the length I think they would need to be 10k or larger. 8k would be pushing it.

 

The previous owner of our HDT had removed the Glad Hands and all we have there now is a air coupling for hooking up an air hose. Is there a lot required to add the glad hands back on and are there separate ones needed for brakes and suspension?

 

Do I need to add anything to the dash to control the air suspension on the trailer?

 

Dave

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Dave, just a quick answer on your trailer air suspension. There is a leveling valve on that suspension, just like your truck.

 

You may need to crawl under the trailer and look for a stamped weight rating on the axles.

 

Air brakes! That's interesting. Are you sure it's not Air over Hydraulic?

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Hero, thanks. I was actually hoping that trailer suspension was not controlled by a leveling valve as I thought I had seen where on some trailers you could add more air to raise it or remove air to lower it if needed.

 

As far as the air brakes go, I can only go by what the add says. Trailer is about 4 hours from us so we have not seen it in person yet. There is a good possibility it is air over hydraulic. Do we need a special trailer brake controller for that?

Dave

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There is a good possibility it is air over hydraulic. Do we need a special trailer brake controller for that?

 

No. Air over hydraulic (Blu-Dot or equivalent, if anyone else makes an air over hydraulic system) is, by its nature, proportional. The higher the pressure that the system sees on the service (blue gladhand) line, the more pressure will be applied to the master cylinder.

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Phil and Jack, Thanks.

 

From what we have been told is it is a 1998 trailer that was custom built in Indiana. What we like about it is it has a larger slide out than typical living quarters car haulers like our current non slide out trailer and still has 21' of cargo space.

What I don't like about it is it is a 53' trailer and depending on pin location may put us over 75' long which will present some parking challenges.

If the axles are smaller than 10k, I think that may be an issue as we are at 15k on 3 axles right now with a much smaller trailer. At (2) 8k axles that only allows an extra 1000# for increase in trailer weight.

Hopefully I can figure out a day in the next couple of weeks to go see it or hopefully they will send me some pictures of the trailer label with the axle ratings.

Dave

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Hero, thanks. I was actually hoping that trailer suspension was not controlled by a leveling valve as I thought I had seen where on some trailers you could add more air to raise it or remove air to lower it if needed.

 

As far as the air brakes go, I can only go by what the add says. Trailer is about 4 hours from us so we have not seen it in person yet. There is a good possibility it is air over hydraulic. Do we need a special trailer brake controller for that?

Dave

Why would you not want a leveling valve? If you develop an air leak behind a manual control valve, you'll be riding on the steel after a while. Let it remain on the leveling valve for now, and build in a manual control override if you decide you need it.

 

If the trailer's got air brakes, just remain in the air world from front to back, no controller needed.

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Since there is no drive line issues I would not think there would need to be a leveling valve except for various loads. I would not want to have leak with a leveling valve as it would then drain the truck tanks too.

 

We found out trailer has 8k axles so unless the trailer is lighter in weight (aluminium frame and structure maybe) then it most likely won't work. May try to look at it next weekend anyway.

Dave

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Jack could better answer this. But seems like a very unbalanced trailer or a lot of tongue weight with only two axles.

Have to agree to 8000 pound axles definitely seems light weight that things got to be over 21,000 pounds again Jack might be better to answer.

Who is the trailer manufacturer?

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Glads are easy, just buy a new set and use a good sealant on the threads. Inspect as much of the lines going forward as you can for any abrasion or rot if they have not been used for a long time.

 

A leveling valve on the trailer is always a good thing. No matter your desires to raise or lower, a leveling valve is a good thing. You can then add other valving to do as you wish, but leave the leveling setup in place and operational. You can then ad a control system in the cab, or on the trailer to either raise or lower the trailer, both to set it at that height or raise/lower momentarily for a terrain situation.

In the commercial world I do not know the legality of them, but my truck that I sold "Big Pete", had such controls for both the truck and the trailer in the cab. That setup consisted of a switch the activate the system, then a pressure regulator to raise or lower each unit. But the plumbing was a nightmare. For rv use, I would just run the standard issue leveling valve and set the unit at the height needed and let it do it;s thing.

IMO.

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Bronco, all we know at this time is it was custom built for a previous owner. Using the first 3 digits of the vin# shows a motorcycle manufacturer out of Canada, but maybe in 1998 that number was used by someone else.

 

Noteven, when I can get on our laptop, I will post a picture. I typically have trouble doing it from my phone.

 

Deezl, thanks we will use the leveling valve if it has one and may consider adding the overrides if we feel it needs it if we buy the trailer.

 

We are going to have to get the trailer weighed to verify it can handle approximately 7k of additional weight and have to verify the rear ramp door width as the dimensions they sent us looks like it is too narrow for us.

Dave

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Yes, we have high centered in the middle with our 44' trailer and dragged the rear end so many times, I have lost count. The last major time was when we parked in a truck stop near Madison WI and the parking lot was full of large holes that we could not see how bad they were (dark and rainy and full of water). The trailer went down in one while backing into the spot. The back rollers were almost hitting and if going back any further would have hit but the worst was the middle hit the ground and our skid bars that protect our drain pipes and steps were in the dirt and gravel a good inch. When we went to pull out I found out it had also raised up my air hitch to the full upward stops as that was going to be my backup plan to raise the trailer if I was stuck. Normal 2nd gear start did not work and had to use 1st gear for the first time to get us out of the hole. Having an air lift suspension that can be used to raise up would allow us to avoid some of the excessive dragging.

 

The original bottom rear skid bars on the trailer are long gone and the rear casters the previous owner put on got ruined but so far the new rear rollers we have put on are working good.

 

There have also been times that we have been on the rear rollers and all three axles and tires were off the ground. That cannot be good for the frame. Luckily it is only for a few seconds.

 

Dave

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We had air suspension on our Automate fiver and used it to jack the fiver up a few inches for ground clearance, went down a couple times to get under a low limb or bridge too. Working with our air hitch let us either keep the fiver level or really jack the back (axles full, hitch empty) to get past a problem spot.

 

Getting more under axle clearance can be done with larger diameter tires but you can only go so big before they rub together or rub on the fiver body when you hit a hard bump.

 

For getting more frame to ground clearance, we saw a couple designs where the owner didn't want to flip the axles because they thought that it was going to weaken the suspension. What they did was cut the spring hangers off the frame, add a rectangular tube under the frame and then weld the new brackets to it. I believe one was a 4" bump, similar to a spring flip and the other was a 6" bump. The 6" lift had some stiffeners and cross bracing added to the design to reduce chances of problems in high stress situations. Both sure looked stronger than flipping the springs and the cost wasn't all that much higher.

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You can always pop the cotter pin out of the leveling valve and set your height by moving it by hand if you don't have anything fancy installed.

Getting to the level valve would be a problem for most of us. Mine is between the 2nd and 3rd axle, close to the middle of the trailer.

Most would say my rig is set pretty high when aired up. I've had to replace that valve, but I was not the one to originally set the ride height. It is pretty high. In fact the top of my hitch plate on my Trailer Saver needs to be at 49.5 inches for level ride on the trailer.

But I occasionally still "activate" the full width roller on the tail of the trailer.

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I wish I'd kept the leveler info from my Automate fiver now, it had three switches, one for automatic / manual and two up / down (one for each side) that controlled the air bags. I can't recall the air valve arrangement which is frustrating.

 

In automatic the compressed air was connected to the leveling valve and things took care of themselves.

 

In manual the leveling valve was disconnected and compressed air was added as long as you held the up switch, bag air was dumped if you used the down switch.

 

I don't know if Bill will share the design but you might ask if you are interested: http://losbanosrvcenter.info/1673397.html

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