Self Built Central Tyre Inflation System

Shovelhands

Member
Location
Sunny Essex
I’ve been thinking about this for a long time, but never done anything about it...
Project A may have to be my test platform for a home made system! :D

Some of the systems I’ve seen on terragators, have a 1/2 or 3/4 fitting welded in the rim, totally separate from the inflation valve. With a simple 1/4 turn lever ball valve on it. This gets the air in and out fast! This is then connected via a short hose to the rotary coupling. In the event of a hose getting ripped of, you would simply have have to shut the ball valve and inflate the tyre as normal through the original valve, with an airline, until a fix was made to the CTI hose. Also I’m sure these CTI hoses are disconnected when traveling on the road in between jobs, this saves things getting caught in hedges, and unnecessary wear and tear on the rotary coupling.

A large air tank, dedicated to the CTI system is what I have in mind, and simple control system , analogue gauges in the cab for each wheel to keep an eye on things.
I many have to start putting some real thought into this?.....
 
You just need to fit a biggger compressor to the unit! Something like this should be just big enough....:p

huge compressor.jpg
 

Henarar

Member
Livestock Farmer
Location
Somerset
Do you really need it Pete ?
how much load does the trailer put on the back axle ? should be 3 ton max
I would have thought it would be more for things like tankers that run on the road loaded but as your buggy is what 10 ton lighter on the road I am struggling to see to much advantage to outweigh the disadvantage of something like that stuck out wider than the wheel [and don't forget your overall width in this]
yes maybe some system where if you get a dodgy job you could let air out quick and pump back up quick one by one or something along the lines of what @Mursal was talking about
All I know is that back when I was spreading things like that stuck out the side of the wheel would have lasted about five minutes but having said that some of the places we had to drive we use to get dirt rammed between the tire and the rim on the duel wheels and knocked them off the rims a few times but your work may be different but all the same it looks very vulnerable
 
If they unclip or disconnect the pipes on the road (or off-road!) to avoid damage / prolong the life of the rotary unions - fair enough.

But then why fit all these fancy unions - 4 pipes and a couple of quick couplers and job done....if you don’t absolutely need inflate/deflate on the go.

 
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TurboCon

New Member
It seems most use an electric valve to open before the compressor starts inflating, so if the line gets whipped off the valve automatically closes leaving the tyre as it is, rather than flat. Also possibly a pressure sensor feedback. But does it not look delicate sitting out there.

View attachment 670234

thats a pneumatic line....the small line one opens the valve when pressurised (where the valve stem would have been) and the large on controls the tyre pressure.

A system like this could be rigged up very easily once you could source the swivel connector on the hub. Use a simple mechanical PICV to control the pressure from the cab.

The problem would be finding a 12v compressor that would have the output to pump up the pressure of 4 tyres fast enough if you were in and out of a field often. Otherwise you would have to use a pto or hydraulic compressor....
 

Steevo

Member
Location
Gloucestershire
thats a pneumatic line....the small line one opens the valve when pressurised (where the valve stem would have been) and the large on controls the tyre pressure.

A system like this could be rigged up very easily once you could source the swivel connector on the hub. Use a simple mechanical PICV to control the pressure from the cab.

The problem would be finding a 12v compressor that would have the output to pump up the pressure of 4 tyres fast enough if you were in and out of a field often. Otherwise you would have to use a pto or hydraulic compressor....

That explains the control hose in the earlier picture. Couldn’t understand why it needed a third hose other than Main and Monitor.

Non-electric compressor sounds like a good plan in this instance.
 

fermerboy

Member
Location
Banffshire
All of the hauliers pulling trees out of the forestry round here have inflation/deflation systems fitted to their trucks. It's definitely retrofit in a lot of cases. I know that they go through the trailer axles and the connections come out the centre of the hubs. Drive axles a bit more tricky but if they can keep if all working in the forestry job then you should be sound. That may be the setups you know about though.
 

mo!

Member
Mixed Farmer
Location
York
Look into earthmover valves as well, standard Schrader valves are very restrictive. I'd get it on a weighbridge as well, if you aren't running loaded on the road you may not need to drop pressure in the field, it depend how much load the low loader is putting on the rear tyres. Without decent data its all guesswork. I looked at a manual system years ago which used the tractor air system and a pair of preset valves, you ran the pipes to each wheel while it was stood and pumped up or let down as required. No electronics. It was about £500.

Have a look at tyre droppers as well, little valves that you set at the pressure you want and screw on. They release air until it is what you've set. 50 quid for a set.
 

Andrew

Never Forgotten
Honorary Member
Location
Huntingdon, UK
As said, get your outfit over a weighbridge when it’s ready for the road, and again when it’s loaded for the field, and again empty in field.

If my fag packet calculations are correct you’ll have just under 1100 ltrs of air per tyre at 14psi.
2400 ltrs of air at 30psi.

So to do all 4 tyres you’d need 5200ltrs of air.
Thats around a dozen 60 ltr trailer air tanks charged to 116psi (8bar).

If you only need to pump tyres up when you’ve finished a job I guess 10mins to load loadall up and chain down etc. At a guess, tractor will put out ~3000 ltrs of air in that 10 mins depending whats its revving at.

For my project I only need 3000ltrs, but I need it in 30s!
Tractair do a 4000ltr / min hydraulic drive screw compressor but it’s a lot of money - anyone know a cheaper source.

Of course this is early Sunday morning calcultions so I could be completely wrong.......
 

Pilgrimmick

Member
Location
Argyll
A standard 15 ltr diving bottle at 203 Bar will give over 3000 ltrs of air, fit two and have the pressure high enough to ensure rapid filling even when tyres are almost up to pressure. Fill the bottles when you get back to the yard if you have a compressor that can manage it, it would be cheaper to buy a diving compressor, (without the filters and cleaning system) than some of the other options mentioned so far!
 
As said, get your outfit over a weighbridge when it’s ready for the road, and again when it’s loaded for the field, and again empty in field.

If my fag packet calculations are correct you’ll have just under 1100 ltrs of air per tyre at 14psi.
2400 ltrs of air at 30psi.

So to do all 4 tyres you’d need 5200ltrs of air.
Thats around a dozen 60 ltr trailer air tanks charged to 116psi (8bar).

If you only need to pump tyres up when you’ve finished a job I guess 10mins to load loadall up and chain down etc. At a guess, tractor will put out ~3000 ltrs of air in that 10 mins depending whats its revving at.

For my project I only need 3000ltrs, but I need it in 30s!
Tractair do a 4000ltr / min hydraulic drive screw compressor but it’s a lot of money - anyone know a cheaper source.

Of course this is early Sunday morning calcultions so I could be completely wrong.......
That hydraulic drive compressor sounds like a bit of a beast. How much oil does it take to drive that?

I don’t know off the top of my head how much a standard Wabco type integrated piston compressor would produce but I’m sure it’s much, much, much less than that!
 

Andrew

Never Forgotten
Honorary Member
Location
Huntingdon, UK
That hydraulic drive compressor sounds like a bit of a beast. How much oil does it take to drive that?

I don’t know off the top of my head how much a standard Wabco type integrated piston compressor would produce but I’m sure it’s much, much, much less than that!

90lpm to run full speed!
I’m told the integrated one on my JCB 4220 is 250cc so 250ltr at 1000rpm?
 
A standard 15 ltr diving bottle at 203 Bar will give over 3000 ltrs of air, fit two and have the pressure high enough to ensure rapid filling even when tyres are almost up to pressure. Fill the bottles when you get back to the yard if you have a compressor that can manage it, it would be cheaper to buy a diving compressor, (without the filters and cleaning system) than some of the other options mentioned so far!
It’s a novel concept, but have you seen it done? There must be some reasons why this is not ordinarily done?

Perhaps some potential pitfalls / downsides...

- high-pressure to low pressure (7.5/10 bar) regulation, which most common air systems operate at. Would you have to have one for each bottle or one in common - run a high pressure manifold? Don’t know, this might be trivial or might not?

- where to safely mount several 200 bar bottles on the tractor/multidrive? To aid swapping/checking the bottles, might not be that simple?

- carriage of high pressure bottles on the road, not sure of any regs esp regarding such high pressure vessels. The H&S and road laws are such these days you’d need to make sure you were on the right side of the law, especially if there was a collision

- how many tyre inflate cycles could you get before needing to refill the cylinders? I haven’t done the fag pack Boyle’s Law (PxV) maths, but you’d want at least two or three fill cycles I would’ve thought

- cost as against simply an updated compressor, even the big separate screw-type unit mutha Andrew has mentioned?
 

Andrew

Never Forgotten
Honorary Member
Location
Huntingdon, UK
So about the output of an ordinary workshop compressor for the standard integrated tractor compressor (maybe around 10 cfm) vs 140 cfm odd for the oil driven screw type. No competition is it?

Priced to match I suppose.

Only thing I’ve found so far that will do what I want. Problem is the £8k price tag.....
 

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