tomcat404 Posted August 12, 2014 Share Posted August 12, 2014 Morning.... WHat is the current view of CTIS ( CEntral tyre inflation system) I have the portal boxes and the machined bolts and swivel adapters etc.. Am i making the car even more complicated or does it hold a real edge for challenge events/ rock crawling? I am still unsure how to control the air supply? Thoughts please? Quote Link to comment Share on other sites More sharing options...
Daan Posted August 12, 2014 Share Posted August 12, 2014 They use it in russia quite a bit. I suppose if you go rock crawling only, you just set the tyre pressure and run. But if you do rockcrawling or swampdriving one moment, than flat out the next, its perfect. It is quite complicated though, and the seals can fail (like an ARB air feed seal). I do remember a famous picture from ladoga of a car arriving at the finish with 4 flat tyres, due to a failure of the CTIS. I think they remove the valve internals to make pumping up and down go quicker, but then if there is a failure...oh dear. I would love CTIS, but I would have a good think about the failure modes, and the contingency plan. Quote Link to comment Share on other sites More sharing options...
Soren Frimodt Posted August 12, 2014 Share Posted August 12, 2014 Having messed around with Mog and Volvos I've too given this quite some thought. But as Daan states there is just so many things that can go wrong, and a flat tyre just is a game stopper.. But I suppose if you keep the stock tyre valve, and let the CTIS enter through a manual valve that you can close. Then in worst case you can just shut off this valve and fill the tyres the regular way. AND also you'd probably be best advised to do 4 separate systems, so that one failure will not cause any more wheels to go flat. But I've honestly come to the conclusion that if you were to fit either a very large tank, or one with very high pressure, and find a clever way to fit an air hose tucked away in each wheel well, and utilize a system like the ARB tyre deflater thing, where you can remove the valve, then for the copilot (or yourself) running out and connecting them and then filling up quickly wouldn't be that much of a time waster. But of course no match to CTIS which can be used on the go. Just my thoughts on the matter Quote Link to comment Share on other sites More sharing options...
elbekko Posted August 13, 2014 Share Posted August 13, 2014 In swampy/sandy conditions where you have to air down, CTIS should be a huge timesaver. Sure, it's a possible reliability issue, but then again so are portal boxes (added components). You just need to weigh the pros and cons, and I'd say CTIS definitely has enough pros to warrant it. Put a shut-off valve on each air line, carry spare cores, and have a regular tyre gauge on a long enough line that you can reach each wheel when needed. Quote Link to comment Share on other sites More sharing options...
Daan Posted August 13, 2014 Share Posted August 13, 2014 I dont think it needs the shut off valve; you can just disconnect the tyre valve from your line if need be. You are going to have to be able to disconnect it anyway, if you swap a wheel. so in case the system is down, disconnect all wheels, put valve bodys in the valves. you would probably have to have a seperate pump (ARB pump) to then pump them all up, because if your main pump has failed.... Daan Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 13, 2014 Share Posted August 13, 2014 I've only noticed it on specific vehicles; those at Ladoga where they can go from swamp to flat out to rock crawling, and on Dakar trucks where they can also go from flat out over rocky terrain to requiring maximum floatation on soft sand. Even then, it's a bit of a luxury and as Daan says it adds a fair bit of complexity and a load of new ways things can go wrong. Quote Link to comment Share on other sites More sharing options...
elbekko Posted August 13, 2014 Share Posted August 13, 2014 I dont think it needs the shut off valve; you can just disconnect the tyre valve from your line if need be. You are going to have to be able to disconnect it anyway, if you swap a wheel. so in case the system is down, disconnect all wheels, put valve bodys in the valves. you would probably have to have a seperate pump (ARB pump) to then pump them all up, because if your main pump has failed.... Daan That depends on how you set up your system. If you have a common regulator, you'll want to be able to just shut off one line to a wheel, so the rest can still function normally. No need to disable the whole system and add a whole lot of extra work if just one line is leaking... Quote Link to comment Share on other sites More sharing options...
tomcat404 Posted August 13, 2014 Author Share Posted August 13, 2014 Thanks for all your thoughts, I have the machined portal boxes and the machined mog bolts and the swivel unions at the moment... but i would need to have spares and design a system? What compressor is evrybody using ? i would need a suitable cylinder too i suppose? Quote Link to comment Share on other sites More sharing options...
zim Posted August 13, 2014 Share Posted August 13, 2014 Nathan, it's a really smart system...but is it really necessary ? I'd like to see one in use, but we all survive here without if you know what i mean. For compressor, i think you're pissing in the wind with something like an ARB item.... What about using an aircon compressor, it's how we run our vehicles now and touch wood haven't had any problems. I do however have a 12v compressor plumbed in as backup incase of air con pump failure. Or maybe find some sort of dedicated engine driven compressor ?? Gordon Quote Link to comment Share on other sites More sharing options...
elbekko Posted August 14, 2014 Share Posted August 14, 2014 Definitely a big compressor, that delivers enough oomph to air up all 4 tyres relatively quickly. Quote Link to comment Share on other sites More sharing options...
Soren Frimodt Posted August 14, 2014 Share Posted August 14, 2014 ofcourse a large compressor is needed but you'll never find one that is,capable of delivering enough air to fill all four,tyres at any acceptable speed. Therefore a lot of tank capacity is what is needed. With as high a pressure as possible to get the most out that capacity Quote Link to comment Share on other sites More sharing options...
simonr Posted August 14, 2014 Share Posted August 14, 2014 Strangely enough, I've given this a bit of thought - and a bit of machining too. I can't find my drawings though. I too was worried about the potential failure of the system - and my thought was to make a special valve. A spool valve with the spool held centrally by two springs. The air supply connects to one end of the spool and the tyre to the other with a pair of bypasses, one end of each is normally blocked by the spool. The springs are set such that for the normal range of tyre pressures (say 10 to 30 psi), the bypasses stay blocked. If you connect a high pressure to the inlet, it forces the spool towards the tyre side, allowing air to flow in to the tyre. If you connect low pressure (vacuum), the spool moves the other way, letting air out the tyre. With atmospheric pressure, the spool sits in the middle. This would be used with just a compressor (Air Con pump) without a reservoir and use a valve to connect the four valves to either the inlet or outlet of the compressor. A simpler option is simply to have a solenoid valve on each wheel - so the only failure points are your rotational coupling and pipe connecting to tyre valve. If any one of them fails, the solenoid valve prevents the others from deflating. With this setup, you just use an adjustable (3 port, venting) regulator in the cab, supplying each solenoid valve through a manifold. You dial up the pressure you want, open the valves via a switch and wait. Once they are at the required pressure you close the valves again. I used this on one of my air suspension setups - and it worked pretty well, though it was fairly slow to change pressure. If it works on air bags, it will work on tyres! Si Quote Link to comment Share on other sites More sharing options...
tomcat404 Posted August 14, 2014 Author Share Posted August 14, 2014 Strangely enough, I've given this a bit of thought - and a bit of machining too. I can't find my drawings though. I too was worried about the potential failure of the system - and my thought was to make a special valve. A spool valve with the spool held centrally by two springs. The air supply connects to one end of the spool and the tyre to the other with a pair of bypasses, one end of each is normally blocked by the spool. The springs are set such that for the normal range of tyre pressures (say 10 to 30 psi), the bypasses stay blocked. If you connect a high pressure to the inlet, it forces the spool towards the tyre side, allowing air to flow in to the tyre. If you connect low pressure (vacuum), the spool moves the other way, letting air out the tyre. With atmospheric pressure, the spool sits in the middle. This would be used with just a compressor (Air Con pump) without a reservoir and use a valve to connect the four valves to either the inlet or outlet of the compressor. A simpler option is simply to have a solenoid valve on each wheel - so the only failure points are your rotational coupling and pipe connecting to tyre valve. If any one of them fails, the solenoid valve prevents the others from deflating. With this setup, you just use an adjustable (3 port, venting) regulator in the cab, supplying each solenoid valve through a manifold. You dial up the pressure you want, open the valves via a switch and wait. Once they are at the required pressure you close the valves again. I used this on one of my air suspension setups - and it worked pretty well, though it was fairly slow to change pressure. If it works on air bags, it will work on tyres! Si wow ... where do i start? you make that sound very very simple... yet very very complicated ! would you be able to share some more info if i send you a PM please Si? thanks nathan Quote Link to comment Share on other sites More sharing options...
HoSS Posted August 14, 2014 Share Posted August 14, 2014 CTIS is fitted to the US army Humvees, and the Mil CTIS controllers do come up occasionally on eblag. For CTIS in portals have a look at http://www.terrangbil.net/forum/index.php?/topic/10323-bj%C3%B6rns-garage-b%C3%B6rjar-med-axelmodifikation/ and here http://www.terrangbil.net/forum/index.php?/topic/4615-nytt-projekt-ctis/?hl=ctis#entry53510 (Swedish translation required, but nice pictures to look at) If it fails, you just put the valve cores back in and re-inflate, yes some faf but not terminal. Or, i've seen a simpler system that has a hose with 4 tyre valves made up, and when you want to change pressure you jump out, hook it up to 4 tyres, operate and then disconnect. Quote Link to comment Share on other sites More sharing options...
sean f Posted August 15, 2014 Share Posted August 15, 2014 wow ... where do i start? you make that sound very very simple... yet very very complicated ! would you be able to share some more info if i send you a PM please Si? thanks nathan How you get the air into the actual tyre via the hub I have no idea but as to a controller. If you look at air suspension controllers for custom cars (US low rider stuff mostly), you can buy controllers off the shelf, basically a valve block with an "in" line for the air bag / tyre, then exhaust on one side and pressure on the other, open the exhaust valve to deflate, open the pressure valve to inflate, usually there is a line for a pressure gauge as well, one pair of valves per wheel. If you wire the valves back to rocker switches then you can set it up to rock up to inflate, down to deflate and have a pressure gauge above. More advanced controllers will let you go between sets of preset pressures at one push of a button, really advanced ones let you make the car dance up and down. There are several different valve configuration available this is the simple off the shelf one, I have one on my 90 for air suspension and it has been reliable for over 10 years now, with only one pipe bursting and one pressure gauge line failing, both replaced with better quality stuff. The only weak link which could leave you with a flat tyre should be the link from the controller valve body to the tyre, you can buy the bodies as a single pair which could then be placed as near the tyre as possible if you wanted. Quote Link to comment Share on other sites More sharing options...
tomcat404 Posted August 15, 2014 Author Share Posted August 15, 2014 Thanks sean,, from starting this thread i have bedn reading up on the air ride system. I would spec a larger comprssor and pump to account for the tyres @44" Quote Link to comment Share on other sites More sharing options...
sean f Posted August 16, 2014 Share Posted August 16, 2014 Thanks sean,, from starting this thread i have bedn reading up on the air ride system. I would spec a larger comprssor and pump to account for the tyres @44" If you can an engine driven compressor will deliver a lot more air, depends on your engine and room under the bonnet as to what will fit, otherwise fit the largest reservoir you can fit in or several smaller ones, again what ever fits in your build, range rover air tanks from p38s are quite small and come with mounting points pre attached, also quite cheap!. Might be possible to fit them inside the chassis rails or similar places so the are out the way and not likely to get knocked off or damaged. Once installed you can run any other air stuff off the same system although you might need a regulator depending on pressure, I fitted a cut off switch for this so if anything else failed my suspension still worked, I guess something similar would be a good plan for you as well. Running the pressure side at higher pressures gives more air volume to work with but increases the chance of leaks or blow outs, also check the routing of pipes for wear or heat, the one leak ihad was a pipe next to the compressor which melted after inflating someone tyres for them got the compressor very hot. Quote Link to comment Share on other sites More sharing options...
elbekko Posted August 16, 2014 Share Posted August 16, 2014 How you get the air into the actual tyre via the hub I have no idea but as to a controller. If you look at air suspension controllers for custom cars (US low rider stuff mostly), you can buy controllers off the shelf, basically a valve block with an "in" line for the air bag / tyre, then exhaust on one side and pressure on the other, open the exhaust valve to deflate, open the pressure valve to inflate, usually there is a line for a pressure gauge as well, one pair of valves per wheel. If you wire the valves back to rocker switches then you can set it up to rock up to inflate, down to deflate and have a pressure gauge above. More advanced controllers will let you go between sets of preset pressures at one push of a button, really advanced ones let you make the car dance up and down. There are several different valve configuration available this is the simple off the shelf one, I have one on my 90 for air suspension and it has been reliable for over 10 years now, with only one pipe bursting and one pressure gauge line failing, both replaced with better quality stuff. The only weak link which could leave you with a flat tyre should be the link from the controller valve body to the tyre, you can buy the bodies as a single pair which could then be placed as near the tyre as possible if you wanted. I've now got half an idea in my head that you could use a Range Rover EAS system, connect the tyres to the spring outputs, fit hand levers to the height sensors, and be able to control every tyre's pressure separately Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 18, 2014 Share Posted August 18, 2014 EAS compressors are at least rated for continuous running and made by adults, plus you get air dryer, valve block, pressure reg, etc. built in. You've just got to fathom the wiring! Mind you, it boils down to 12v to run the motor and a load of 12v actuated solenoids, so not complicated, just a bit of a jigsaw puzzle. Quote Link to comment Share on other sites More sharing options...
Jamie_grieve Posted August 18, 2014 Share Posted August 18, 2014 Regarding the reliability of CTIS I can comment first hand on various fleets of Kamaz over the last 8 years and have never once had a CTIS failure. I have quite a few friends in the UK and Ireland with Zils, Urals and Gaz and same too, I haven't heard of any failures while driving and not attributable to dismantling something or age related.. The Russian systems all use a manual valve on the wheels which can be opened before the CTIS might be required or to balance the air pressures in the tyres. The control is simply a 3 way valve which either inflates via a gauge, deflates or holds the pressure. I just got a Gaz 66 myself and had to play with the CTIS on the way home as the tyres were too soft and getting hot. I was reluctant to do this before leaving as I was expecting all kinds of dramas after it being unused and sat in a field for years but it all worked perfectly. Every Russian military vehicle over three tons had it such was the importance seen in CTIS to help combat nasty imperialist capitalist forces from the West wanting to steal the huge supplies of communist caviar.I'm not sure how relevant it would be on a dedicated off roader where it would never see a hard road surface? The CTIS on Russian vehicles is a little slow to operate compared to say that 6x6 G wagon with the portals. The tyre valves would need to be those bigger ones like you get on tractors to work quickly at low pressures I'd guess. Quote Link to comment Share on other sites More sharing options...
tomcat404 Posted August 18, 2014 Author Share Posted August 18, 2014 Thanks Jamie, When you have 5 mins would you mind sharing some pictures of the system, just so i can understand what the dimensions etc? also did you ever get a chance to measure that centre propshaft bearing you send through ages ago? thanks nathan 1 Quote Link to comment Share on other sites More sharing options...
Jamie_grieve Posted August 18, 2014 Share Posted August 18, 2014 I will do, I'll grab a photo of the valves and whatever's in the manuals I've got.oops, dimensions of the centre bearing fell off the radar. I had it and a universal joint sitting on a filing cabinet for ages in the shed. I'll get on it and report back!! Quote Link to comment Share on other sites More sharing options...
tomcat404 Posted August 18, 2014 Author Share Posted August 18, 2014 thanks buddy... just shows the progress on my truck ?? Quote Link to comment Share on other sites More sharing options...
JBs4wd Posted August 31, 2014 Share Posted August 31, 2014 Have a look here http://www.aircti.com Cheers John Quote Link to comment Share on other sites More sharing options...
-88- Posted September 5, 2014 Share Posted September 5, 2014 http://forums.offipalsta.com/showthread.php?t=58648&page=2 Pics in post #35 My design for my friends Suzuki. Quote Link to comment Share on other sites More sharing options...
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