[Dan789]

I am having difficulty finding out how to build or buy one of these systems.

Let me explain. I have seen trucks with a centralised on board system that have them installed into their valve stems permanently. This lets them automatically fix tyre pressure issues. I am not after an automatic version, but am interested in building or purchasing a manual version.

Now I know what I want, just not smart enough to get it built. Has anyone seen this on a 4wd where I could copy or make something similar? What I want to do is deflate and inflate my tyres without ever leaving my seat. As far as I am concerned, this is the ultimate setup when going off road, as being able to deflate as you drive then re-inlfate whilst still driving just would make things that much quicker, especially when spending extended periods touring going from dirt to black top.

Hope sopmeone can help put me in the right direction here.

 

[andrew1964]

I suspect it would be very difficult to build and retro-fit something like this. The only systems I have seen like this have a specially designed hub that has the air line integral to the hub centre, and an airtight fitting that swivels 360 degrees allowing the wheel to turn without twisting the air line. You could possibly get hold of those swivels, but you’d have to find a way of getting the air supply line through the centre of each wheel hub. I haven’t looked at them closely enough to see exactly how the factory achieves it, but my guess is that it is built into the hub design, not fitted as an afterthought.


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[dkril]

Do you really want a hose in such an exposed position on a 4wd?

 

[AndrieK]

There are two types. One is used primarily on big trucks and has a hose running from the fender down to the centre of the hub. This is then connected to a unit with a rotating seal that has another hose running from the hub to the valve stem. The hub with the rotating seal is the most intricate part, but not too difficult to achieve. The problem with this system is the exposed hose like dkril pointed out.

The second type has the air running from inside the axle / hub. These systems are commonly used on military vehicles but they require axles, hubs and even wheels designed specifically for this purpose. (Inflation occurs through the mounting face where the wheel mounts up against the hub, not through the tyre valve.) The easiest way to get this done on a vehicle like a Patrol, would be to fit a set of portal hubs so that you can get into the back of the hub.

Something like this:

https://www.axletech.com/at-admin/resources/Literature/portal-wheel-end-flyer-web-1.pdf

I thought about this many times since working in the military vehicle industry, but I just cannot see how you're going to come up with a system that is robust, but won't cost you more than the car is worth. IMO the best cost effective option would be to run 4 airlines, one to each wheel arch from a large enough central compressor and have 4 short quick connect hoses that you connect up to each tyre so that you can inflate all 4 tyres at the same time. You'd have to connect the hoses manually and will only be able to it while stationary, but it'll be a helluva lot cheaper.

Google CENTRAL TYRE INFLATION SYSTEM

 

[Neardood1]

I though about this years ago myself, and came to a similar conclusion. If you modified the factory hubs/axles ect (drilled a hole through the centre) you make them weaker and probably unreliable. Transplanting an axle from a central inflated equipped vehicle is an option, however that comes with its own problems and considerable expense.

While having a fully automatic system would be mint, I'm happy enough to settle for the next best thing. Stauns to deflate, and a high flow compressor with wireless on/off

 

[turps]

I have always wanted a thru the hub style of system. Only issue is the smallest axle I have seen a commercial option on was a Dana60. Normally that’s a pretty robust axle.
Depending on how it is designed it should reduce strength.

Working backwards this is how I remember it working.
Almost fixed air line from valve to hub. Usually had a cover over it. To prevent damage.

Hub and part of CV (stub axle) is gun drilled so air can pass thru the middle. Then on the swivel hub there is a sealed air ring that feeds air into stub axle.
Then it’s just a simple air line that runs back to a controller.

So you would lose free wheeling hubs (which is no biggie, I forget to unlock mine all the time). And would need a hub flange. Superior already make hub flanges for patrols.

On a patrol. It would depend on how much room is in the swivel hub to put an air ring just behind the bell on the CV.

Or you could just fit hummer portals.


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