CTIS Theory questions.

[jesusgatos]

I don't have any firsthand experience with the CTIS system on A3's, but it doesn't have a great reputation. Would be curious to know whether this is due to any mechanical shortcomings, or if it's just by virtue of how the system operates. If the mechanical parts are even halfway reliable, what about stripping out the control system and redesigning to suit our needs? Would be pretty darn interested in retrofitting CTIS to my A2 in that case.

 

[emr]

From the guys at the maintenance shop here , and its a big one, all i know is they have said in many conversations over the years , the set up is poor and the plumbing is all over the place, and a major pain to fix, and then after they fix em they still do not work well if at all, I have no personal experience, but its hands down on base here, they are terrible, and almost never work, just an fyi from the guys here, not from me, thats all I have ever heard of e, except for a very few guys here who are attempting to make em work, all the best and good luck,

 

[motomacguyver]

From the guys at the maintenance shop here , and its a big one, all i know is they have said in many conversations over the years , the set up is poor and the plumbing is all over the place, and a major pain to fix, and then after they fix em they still do not work well if at all, I have no personal experience, but its hands down on base here, they are terrible, and almost never work, just an fyi from the guys here, not from me, thats all I have ever heard of e, except for a very few guys here who are attempting to make em work, all the best and good luck,

Any chance you could talk to them about my questions please?

 

[glcaines]

I've been doing some research on how the CTIS system from CM Automotive works. I decided to look for patents on the system. A man by the name of Chander Mittal started CM Automotive and he has several patents. Patent number 5,629,873 appears to cover the M35A3 CTIS system and is a very interesting read. You can view this patent at http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=23&f=G&l=50&co1=AND&d=PTXT&s1=5,629,873&OS=5,629,873&RS=5,629,873 . I warn you it is somewhat confusing when you first start reading. From what I read in the patent and elsewhere, the system works as follows. Please note that this is my interpretation of how the system works.

When the pressure from the manifold to a wheel valve reaches atmospheric pressure, the wheel valve closes and is isolated from the rest of the system, thereby maintaining tire pressure. The line from the manifold is then purged in this situation, eliminating pressure on the axel seals and extending the life of the seal. When the manifold cycles to check the pressure in a particular tire, the controller sends an electrical signal to the manifold to pressurize the line to that particular axle at the setpoint pressure. When the pressure from the manifold to a wheel valve exceeds atmospheric pressure, the wheel valve opens. If the tire pressure is lower than what is in the line, a burst of air enters the tire through the wheel valve. The line is then vacated and the process is started again. Once the tire pressure equals the pressure in the line, the manifold dumps the air from the line, thereby closing the wheel valve. if the tire pressure is higher than the set point, air in the tire evacuates back through the wheel valve and vents out through the manifold since the tire pressure is higher than the pressure in the line. The system is designed to dump air very fast in this situation.

The system inflates tires through a series of bursts of air, which causes the familiar air pulses you can hear when the CTIS is inflating a tire.

 

[Rustygears]

Mr. Chittal is the CEO of CM. He was the one that responded to my request for information on the system and any documentation/parts lists for component rebuild as well as any additional troubleshooting information. He said bring the truck to their facility. When I explained that I an a skilled mechanic and engineer, plus travel extensively for a living and therefore could not consider travelling a few hours to their facility during business hours and could they please assist with my original request - no reply. What terds!

SS website has more insight & help.

 

[jesusgatos]

But he invited you to bring the truck to his shop? Hardly seems like anything to badmouth the guy and his company over. 3dAngus explained why they might be reluctant to give you more direct support and/or technical info, and it sounds like renovate7 got some helpful information out of them.

 

[AceHigh]

A much better response than you would get from AM General. They have a somewhat informative web site too.

http://www.cmautomotive.com/Brief Description.htm

 

[mktopside]

But he invited you to bring the truck to his shop? Hardly seems like anything to badmouth the guy and his company over. 3dAngus explained why they might be reluctant to give you more direct support and/or technical info, and it sounds like renovate7 got some helpful information out of them.

Yea really! If I didn't live on the other side of the country from them, I would take a day off without hesitation to take the truck there and shoot the ****. Times in the past when I have been invited to a manufacturers facility in relation to a problem I was having, or to help with R&D on a product; it has always worked out in my favor by a great margin.

I don't think the owner of the company and the patent holder of the product would invite you to his shop to waste your time and give you ****. I mean seriously dude, at very least you'd leave with a T-shirt that none of your friends have.

 

[3dAngus]

In the corporate world, they would/might call it propreitary data, meaning, it is protected. If any document held by a govt. engineer for evaluation is marked "Propreitary Data" from the company that forwarded it, even the government engineers are required to protect it, and in some cases, like classified. So it cannot be reproduced nor distributed. This forces the government to buy it, and the company to hold it. The one way they can protect it is to invite you in and control what goes out. They will NOT give you any drawings or data to cart off if you go in, but sounds like they would help you out, and probably for free labor, just for the good relations aspect of it. You might have to sign a non-disclosure agreement if you go in and they show you any data. That would mean you could not share with the rest of us anything you learn from within, or be as risk of liability.

 

[Rustygears]

Uhh, I do this sort of activity for a living - my day job - and that's not how proprietary data is managed, thanks. My employer's attorneys would have us for dinner.

I don't need a t shirt or a fun day hanging out with CM dudes. I am looking for a method to provide self help and assistance to the community. I've already started reverse engineering the system to document it and publish. BTW, it's a pretty sad design, as was stated by others in this forum.

The system is in the public domain, so anything the public can discern is not controlled. I'm really starting to hate the thing as an example of a good idea done poorly.

 

[mktopside]

Uhh, I do this sort of activity for a living - my day job - and that's not how proprietary data is managed, thanks. My employer's attorneys would have us for dinner.

I don't need a t shirt or a fun day hanging out with CM dudes. I am looking for a method to provide self help and assistance to the community. I've already started reverse engineering the system to document it and publish. BTW, it's a pretty sad design, as was stated by others in this forum.

The system is in the public domain, so anything the public can discern is not controlled. I'm really starting to hate the thing as an example of a good idea done poorly.

LOL..... Keep on keepin' on then broseph

Serious hobby truck is serious!

 

[3dAngus]

Uhh, I do this sort of activity for a living - my day job - and that's not how proprietary data is managed, thanks. My employer's attorneys would have us for dinner.

I don't need a t shirt or a fun day hanging out with CM dudes. I am looking for a method to provide self help and assistance to the community. I've already started reverse engineering the system to document it and publish. BTW, it's a pretty sad design, as was stated by others in this forum.

The system is in the public domain, so anything the public can discern is not controlled. I'm really starting to hate the thing as an example of a good idea done poorly.

Huh? Not sure what that's about, but yes, public domain is not controlled. Propreitary data is, and cannot be disseminated or released. I controlled millions of dollars worth of propreitary data for 25 years, used it for internal use by permission from the contractor, but had to protect it and it was illegal to publish, or disseminate it. You don't have propreitary data on this one, and need it to get to where you're going, but you're not going to get it is about the just of it. I wish you could. I would love to have all the specification control drawings on this one. If I did, and it is not propreitary, I would give them to you. Problem solved. Heck, we could even make it better than original with those drawings.

About all you can do is reverse engineer it.

 

[motomacguyver]

Well I tried the CTIS system again. And found Gear lube all over the back-back dif case. Looks like I'll need a seal in there sometime soon. Anyone have any experiance with sourcing/replacing these seals?

 

[mktopside]

Well I tried the CTIS system again. And found Gear lube all over the back-back dif case. Looks like I'll need a seal in there sometime soon. Anyone have any experiance with sourcing/replacing these seals?

I don't have any experience with the seals.

However, you can backfeed the truck with an air compressor through the emergency gladhand. Hook that up, turn the power on to the truck (leave the engine off), then turn the CTIS on. Crawl under the back, and see if you can hear where it's leaking from.

 

[glcaines]

A few weeks ago I saw a procedure in the TM for testing the axle seals to see if they hold pressure, and now I can't fid it. I'll keep looking. I do remember that the procedure included installing a pressure gauge, pressurizing the system and seeing how long the system held pressure. There are also detailed instruction in the TM for replacing the seals.

I printed out the Operators Manual, but I also need to print out the other TMs. Digital copies are great for searching key words, but I find it easier to read from paper.

 

[saddamsnightmare]

March 8th, 2011.

Good luck in your reverse engineering on the A3 CTIS. The Russians had a more reliable system, and in theory CTIS IS a great idea, but like a lot of complex ideas, they don't hold up in the real world of operations on a day to day basis. At least that is one less thing to fail on an A2, but I will say looking over your shoulders are going to be interesting.

 

[jesusgatos]

What about the Russian system was so much more reliable? Is it an inherent flaw in the way the system seals at the hubs or something? Can see how something like that might be difficult to overcome. I'm looking at all this from a distance, never having even seen the CTIS system on the A3's up close / apart.

 

[Dodge man]

Huh? Not sure what that's about, but yes, public domain is not controlled. Propreitary data is, and cannot be disseminated or released. I controlled millions of dollars worth of propreitary data for 25 years, used it for internal use by permission from the contractor, but had to protect it and it was illegal to publish, or disseminate it. You don't have propreitary data on this one, and need it to get to where you're going, but you're not going to get it is about the just of it. I wish you could. I would love to have all the specification control drawings on this one. If I did, and it is not propreitary, I would give them to you. Problem solved. Heck, we could even make it better than original with those drawings.

About all you can do is reverse engineer it.

You guys are assuming that the design is proprietary. It may not be. The drawings and technical information might not be in the TMs simply because the Logistics Analyst thought* the system was too reliable to justify writing the maintenance procedures OR that it wasn't justified to include in the TMs because the necessary test/support equipment was too expensive to justify the costs of maintenance at the lower levels OR because the troubleshooting and repair tasks were too complex for the technicians. Speaking from experience, there are LOTS of drawings that get delivered to the prime contractor (the one that usually writes the manuals) but that never end up in the TMs for various reasons. Instead of debating it, someone should simply call CM and ask if the design is proprietary and then go from there.

* Most of what goes into TMs is decided based on the Logistics Analyst's experience and on a new design it's common to leave things out or to include items that seldom fail simply because the Logistics Analyst has no experience with that system.

 

[glcaines]

I have now talked with two people at CM Automotive. They are quite proud of their CTIS system on the M35A3 and state that it is very reliable and simple. Both people told me that it is not fair that people are buying these trucks at auction and complaining, because these CTIS systems are approaching 20 years of age for the oldest ones. The rubber seals have deteriorated and preventive maintenance in the military was minimal. Most were issued to ANG and Army Reserve units where they have been left in motorpools for years without being driven or serviced. I have to admit, they have a point.

 

[Rustygears]

Gee, there are aircraft in inventory that are over 50 years old that still work fine, well beyond the design service life. We can really laugh about some of the maintenance **not** done on airframes. I used to be in that business as a civilian for DoD and got the **** out over 20 years ago after seeing how our dollars were really spent. I also worked in mil aerospace on 'the other side of the fence' and saw exactly what an earlier commenter pointed out. The loggies at DoD made maintenance level decisions based on many aspects.

Despite the offer of CM to troubleshoot my truck (not what I asked for) and to 'sell me replacement parts at reasonable cost' (again, not what I asked for and I wonder in whose judgement will define reasonable since there is no depot or 'I'-level maintenance of subassemblies aside from swap'em and trash'em) and that 'we are making additional and lower level manuals for the military' - no data has been forthcoming. Once I'm home for over a week and it's not raining, I'll have at it.

Let the games begin.... BTW - Big quake in Japan today. Center was 300km from Tokyo and the skyscrapers here still shook like jello for more than 5 minutes. At first, I thought it was just my hangover making me dizzy