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LMTV CTIS Question

Third From Texas

Third From Texas

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Maddog Driver said:
Any contact gouge for Plasa ?
Click to expand...
Here's his thread.

@Plasa will see this

CTIS and Arduino

Hello forum. I am thinking of creating a Arduino hack for the CTIS controller for M1078, first and maybe second generation. I gave a very fast look at the system and seems not really complicated. Does anyone have some information or a workflow diagram, some sensor value or something else that...
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S

Stellaevil

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You do not need the ECU to control the system. There is a switch box diagram on one of the other posts. The PCU has the deflation relief valve that controls the line pressure at 8psi allowing the wheel valves to dump. You also do not want to turn on "supply" without turning on the "control" solenoid first or air will blow out the PCU vent. You could separate the front and rear axle air lines but I would not try individual tires as that would be very dangerous. Also, using a switch box will allow you to over inflate the tires to 125 psi supply. They will not stay high after you shut off the air, but if the air lines are left pressurized for long periods of time, the hub air seals will not last long.

I am the applications engineer on this system. There is also a safety feature in the software that will automatically bump up the tire pressures if the vehicle speed is too high for the setting. You will not have this feature and could damage the tires if they are low while driving on the highway. All this being said, the use of of switch controller bypasses about 6 critical safety functions and is not recommended.
 
coachgeo

coachgeo

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Stellaevil said:
You do not need the ECU to control the system. There is a switch box diagram on one of the other posts. The PCU has the deflation relief valve that controls the line pressure at 8psi allowing the wheel valves to dump. You also do not want to turn on "supply" without turning on the "control" solenoid first or air will blow out the PCU vent. You could separate the front and rear axle air lines but I would not try individual tires as that would be very dangerous. Also, using a switch box will allow you to over inflate the tires to 125 psi supply. They will not stay high after you shut off the air, but if the air lines are left pressurized for long periods of time, the hub air seals will not last long.

I am the applications engineer on this system. There is also a safety feature in the software that will automatically bump up the tire pressures if the vehicle speed is too high for the setting. You will not have this feature and could damage the tires if they are low while driving on the highway. All this being said, the use of of switch controller bypasses about 6 critical safety functions and is not recommended.
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on the bump up pressure to match speed.... when did that feature get in there? As early as the A0.... or later in the A1's? How much did it bump things up?

Would you mind offering up the 6-ish safety functions it checked?

much appreciate in advance any info you can offer.
 
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Ronmar

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I think the pressure increase with overspeed is mentioned in the A0 op manual.

Yea fixed switches on a manual control is not a good idea. These vehicles ride on some very large air filled bombs. I have always reccomended and demonstrated momentary switches for controlling supply. You would have to hold a momentary switch a very long time to over-inflate... but as with anything manual, even filling with an air hose, operator attention is required...

It actually isnt that difficult to add some safety limitations to a manual electric over pneumatic system.
 
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ramdough

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Ronmar said:
I think the pressure increase with overspeed is mentioned in the A0 op manual.

Yea fixed switches on a manual control is not a good idea. These vehicles ride on some very large air filled bombs. I have always reccomended and demonstrated momentary switches for controlling supply. You would have to hold a momentary switch a very long time to over-inflate... but as with anything manual, even filling with an air hose, operator attention is required...

It actually isnt that difficult to add some safety limitations to a manual electric over pneumatic system.
Click to expand...
I guess a pressure switch could deactivate your manual switch at high pressure…..

That sounds pretty easy.


Sent from my iPhone using Tapatalk
 
R

Ronmar

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ramdough said:
I guess a pressure switch could deactivate your manual switch at high pressure…..

That sounds pretty easy.


Sent from my iPhone using Tapatalk
Click to expand...
Yes except you need to put a little bit of delay into the resonse. When you command a fill with full tanks, the PCU pressure momentarilly exceeds what I would call a max allowable tire pressure alarm point(spikes over 100PSI). The periods where the PCU exceeds where I would like my alarm set at, get longer and longer as the tires get fuller. You need to delay the alarm/safety switch response to filter out these peaks in order to respond to the average pressure.

I was actually working on automating the fill process back to a 85PSI highway pressure as you have to hold that button a long time. And for that I would definitely want a failsafe disable/alarm before 90PSI...

But considering how much I woukd actually use it, it might not be worth my time:)
 
coachgeo

coachgeo

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Ronmar said:
Yes except you need to put a little bit of delay into the resonse.....
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what about fixed switch AND momentary..... as in FIxed switches set to ALWAYS take tire to no more than ten lbs away from final pressure (psi pressure relay cuts if off) leaving one to have to manually take it from there to the final point desired point. That way if you are on Sand pressure and your going to highway... you can hit the fix switch and keep driving with both hands.... untill your at 75psi where the cut off for that is... then you have to manually take it to 80 or 85?
 
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Ronmar

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No real difference having it go to 85 vis 75. I don’t see a reason to sneak up on it, so why not have it go all the way? That bit is easy, using the wet tank switch to control the fill cycles, and measure the pressure switch between fill cycles during stable tire pressure.. The safety cutoffs would be entirely separate circuits and hardware to disable the system if it for some reason exceeded the commanded pressure.
 
coachgeo

coachgeo

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Ronmar said:
No real difference having it go to 85 vis 75. I don’t see a reason to sneak up on it, so why not have it go all the way? That bit is easy, using the wet tank switch to control the fill cycles, and measure the pressure switch between fill cycles during stable tire pressure.. The safety cutoffs would be entirely separate circuits and hardware to disable the system if it for some reason exceeded the commanded pressure.
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mentioned it thinking it might be tad easier to design since it was stated the complexity in dealing with the "delayed responce" times may make the task of building one not worth the effort ( https://www.steelsoldiers.com/threads/lmtv-ctis-question.162326/post-2494341 )
 
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Ronmar

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Stellaevil

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Ronmar said:
No the complexity isn’t really the issue, it is just that it is some work and another project for a feature I might only use a few times a year…
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The PCU will handle 140 PSI so it is not a problem. When using switched you have inflating is easy, just turn on "Control" then "Supply" and air will flow into the tires if the supply is higher than the tires. NOTE* If the supply is lower than the tires, the tires will deflate down to the supply.

Deflation is a little more complicated: First as always (Control) ON, then (Supply) On for 3+ seconds, then (Supply) Off, now flip (Deflate) On. To stop the deflation shut (All) Off and the valves will close. Putting a pressure switch on the 24V to the switch box or even a press regulator in the supply line set at 90psi would be a safety must.
 
R

Ronmar

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Stellaevil said:
The PCU will handle 140 PSI so it is not a problem. When using switched you have inflating is easy, just turn on "Control" then "Supply" and air will flow into the tires if the supply is higher than the tires. NOTE* If the supply is lower than the tires, the tires will deflate down to the supply.

Deflation is a little more complicated: First as always (Control) ON, then (Supply) On for 3+ seconds, then (Supply) Off, now flip (Deflate) On. To stop the deflation shut (All) Off and the valves will close. Putting a pressure switch on the 24V to the switch box or even a press regulator in the supply line set at 90psi would be a safety must.
Click to expand...
Yep, been doing this for years now.

The issue with a regulator can be flow. If you limit pressure differential you are going to significantly lengthen fill times. And as I mentioned a pressure switch needs a little delay to prevent triggering during normal fill cycles...

 
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Lostchain

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Ronmar said:
I was actually working on automating the fill process back to a 85PSI highway pressure as you have to hold that button a long time. And for that I would definitely want a failsafe disable/alarm before 90PSI...
Click to expand...
As soon as you are talking automation… Why wouldn’t you just run a factory CTIS computer?
 
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