Page 5 of 7 FirstFirst 1 2 3 4 5 6 7 LastLast
Results 41 to 50 of 67

Thread: CTIS and Arduino

  1. #41
    Colonel
    Join Date
    Aug 2018
    Location
    Port angeles wa
    Posts
    297
    Thanks
    37
    Thanked 189 Times in 113 Posts

    Default

    So you are using the wet tank pressure switches 115 PSI closed to 90 PSI open points to control the inflate timing? I thought about using that switch to control an indicator light on my manual panel to indicate wet tank pressure, but I find I can do it prettywell by ear. Dryer purge = full, inflate for a few seconds then pause till I hear the purge. I havnt timed it, but filling in similar pulses by hand, I am pretty sure it does not take 30 minutes to go from 20 to 80 PSI. I will time it, but 30 minutes sounds like an awfully long time for something bad to happen. If it is inflating in pulses, it should return comparable steps in pressure that could be checked as an expected result.

    I would suggest something in the code to cope with leaks, like an expected pressure reading witin a certain range when you check pressure initially.

    You could also read the pressure 3-4 times over a few seconds after opening the wheel valves, looking for a change in the reading. If you have one tire that is leaking, as soon as you close control and send a shot of air to open the wheel valves, the pressure measurement at the PCU will be unstable as the tire pressures equalize amongst themselves. Have seen this watching the pressure gauge connected to the PCU before I fixed a leaking wheel valve. That took care of most of the change, but I was still seeing a change in pressure after opening the valves which led me to a leak at the T fitting down by the transmission. So reading out of range(unable to open wheel valves?) or unstable indicates a leak...
    Last edited by Ronmar; 01-12-2019 at 18:28.

  2. #42
    4 Star General Steel Soldiers Vendor m-35tom's Avatar
    Join Date
    May 2007
    Location
    eldersburg maryland
    Posts
    2,769
    Thanks
    109
    Thanked 583 Times in 373 Posts

    Default

    Remember inflating at engine idle speed is much different than at 1500 rpm or more. At a higher rpm the wet tank switch does not cycle.
    tom bauer m-621
    air conditioned - 28 air
    6 wheel drive - 3 air lockers
    power steering - hydraulic - over 250 kits sold
    fast - now 1 of 43 with .69 od !!!
    m-35 transmission expert
    avatar - 64mph @ 2400 rpm with 14.5R20XL

  3. #43
    Sergeant Plasa's Avatar
    Join Date
    Aug 2017
    Location
    Italy
    Posts
    83
    Thanks
    22
    Thanked 41 Times in 16 Posts

    Default

    Hello Ronmar.
    No, I don't use the wet tank switch for inflation time. Only for starting the system. Here are the steps:

    - open control valve
    - after 3 seconds: open inflate valve
    - after 3 seconds: close inflate valve
    - after 30 seconds: check pressure
    - if too low: inflate:
    -- open inflate valve
    -- after 30 seconds: close inflate valve
    -- after 5 seconds: check pressure, if too low, continue inflate, otherwise:
    -- close all valves
    -- after 30 seconds: open control, after 3 seconds inflate valve, after 3 seconds close inflate valve wait 30 seconds, read pressure
    - if too high: deflate
    -- open deflate valve
    -- after 15 seconds close deflate valve
    -- after 2 seconds open inflate valve, after 2 seconds close inflate valve, wait 10 seconds, read pressure. then same as inflate...

    The idea for air leaks is good, I will include something to check pressure for 5 seconds, if changes there is a leak. Maybe on every initial pressure check...

    Thank you Ronmar!

    Christian

    Quote Originally Posted by Ronmar View Post
    So you are using the wet tank pressure switches 115 PSI closed to 90 PSI open points to control the inflate timing? I thought about using that light to control an indicator light on my manual panel to indicate wet tank pressure, but I find I can do it prettywell by ear. Dryer purge = full, inflate for a few seconds then pause till I hear the purge. I havnt timed it, but filling in similar pulses by hand, I am pretty sure it does not take 30 minutes to go from 20 to 80 PSI. I will time it, but 30 minutes sounds like an awfully long time for something bad to happen. If it is inflating in pulses, it should return comparable steps in pressure that could be checked as an expected result.

    I would suggest something in the code to cope with leaks, like an expected pressure reading witin a certain range when you check pressure initially.

    You could also read the pressure 3-4 times over a few seconds after opening the wheel valves, looking for a change in the reading. If you have one tire that is leaking, as soon as you close control and send a shot of air to open the wheel valves, the pressure measurement at the PCU will be unstable as the tire pressures equalize amongst themselves. Have seen this watching the pressure gauge connected to the PCU before I fixed a leaking wheel valve. That took care of most of the change, but I was still seeing a change in pressure after opening the valves which led me to a leak at the T fitting down by the transmission. So reading out of range(unable to open wheel valves?) or unstable indicates a leak...

  4. #44
    4 Star General coachgeo's Avatar
    Join Date
    Nov 2010
    Location
    North of Cincy OH
    Posts
    2,407
    Thanks
    854
    Thanked 626 Times in 484 Posts

    Default

    If Im not mistaken the 939 trucks had 80psi controllers also..... AND different wheel valves to match... not sure about valves in between. Something to consider if you up the pressures. Something to look into maybe is... did the wheel valves and other valves part #'s on the MTV's that had higher pressure controllers have the same part #'s for all the other valves that the LMTV did... or were they different? If different.... why? Maybe they were mean to match the higher pressure demands?
    One does not get troubles in life... just character building opportunities. Build on with a smile

    Moderator: Orange Tractor Talks & AmbulanceRV

    Daily driver- 99 VW TDI or 2002 KLR DIESEL w/cvt... weather permitting
    Projects: 96 M1078, 97 Triumph Tiger w/3cyl Diesel Kubota
    Sold: 1962 Dieselized Unimog 404, 1984 Int. 24foot Flatbed, 97 Jeep TJ heavily Modified, Datsun Roadster(s) & 510(s)

  5. #45
    Sergeant Plasa's Avatar
    Join Date
    Aug 2017
    Location
    Italy
    Posts
    83
    Thanks
    22
    Thanked 41 Times in 16 Posts

    Default

    Yes, quite sure that there are diffrent wheel valves, transducer and ECU. I have a ECU with highway pressure about 95psi on a M1078, perhaps it's a 80psi ECU for a 939 or M1089 truck. With that ECU my CTIS was not able to get highway pressure and tires went overinflated...

    Christian

    Quote Originally Posted by coachgeo View Post
    If Im not mistaken the 939 trucks had 80psi controllers also..... AND different wheel valves to match... not sure about valves in between. Something to consider if you up the pressures. Something to look into maybe is... did the wheel valves and other valves part #'s on the MTV's that had higher pressure controllers have the same part #'s for all the other valves that the LMTV did... or were they different? If different.... why? Maybe they were mean to match the higher pressure demands?

  6. #46
    Colonel
    Join Date
    Aug 2018
    Location
    Port angeles wa
    Posts
    297
    Thanks
    37
    Thanked 189 Times in 113 Posts

    Default

    Tom my switch still cycles at high RPM untill the tire pressure reaches somewhere over 65PSI. At that point the wet tank outflow to CTIS decreases closer toward what the inflow from the compressor is. At 40 PSI in the tires, I can go from a full wet tank to the 90PSI wet tank switch opening with a 4 second shot of CTIS inflate. It is only around 5 seconds to drop the tank to the 90PSI switch point at full RPM...

    IMO I think there is a reason they chose a wet tank switch with those closed and open contact actuations. I think there are some advantages to using that wet tank switch to control the fill. If you just turn the control and inflate valves on at low RPM or low tire pressures, the tank will quickly empty to the point where the rubber diaphram and spring in the protection valve start regulating the flow as the tank hovers around the 85PSI protection valve setpoint. Having watched this on a pressure gauge at the PCU, the gauge needle starts to flutter as the tank empties. Not sure what effect this will have on the protection valve long term. At higher RPM and pressures it would allow you to maintain longer duration fill pulses. I suspect the CTIS designers used a combination of this switch and a max inflate pulse duration, to insure the tank fills full periodically to maintain brake pressures.

    Christian: If I can make some suggestions, you can shorten some of your times. It dosnt take a 3 second shot of air to open the wheel valves and you should be able to check tire pressure immediatly after the fill valve closes. At low pressures, a 3 second shot of air is the entire volume of the wet tank

    I would suggest you use the wet tank switch to control the inflation cycles which will keep the tank pressure cycling between 115PSI and 90 PSI and would automatically accomidate different outflow rates with differing pressure and differing supply flow due to engine RPM while keeping air peaks in there to maintain brake supply.

    I wanted to fix a leak so after that I timed a deflate and a fill on my manual system. It took about 4 minutes to deflate from 60 to 20PSI checking pressure every 60 seconds. To inflate, It took 9 minutes from 20 to 40, another 9 minutes from 40 to 60 and 11 additional minutes from 60 to 80PSI with the engine at idle. I filled in 3-4 second shots of inflate, with 9 seconds of recovery time between each shot. As the tires fill above 60PSI I can increase the inflate durations as the outflow to the tires slows, but it still takes about 9-10 seconds for the tank to recover to 120PSI. Tank recovery is a lot faster at higher RPM
    Last edited by Ronmar; 01-12-2019 at 21:59.

  7. The Following User Says Thank You to Ronmar For This Useful Post:

    tennmogger (01-13-2019)

  8. #47
    4 Star General coachgeo's Avatar
    Join Date
    Nov 2010
    Location
    North of Cincy OH
    Posts
    2,407
    Thanks
    854
    Thanked 626 Times in 484 Posts

    Default

    Quote Originally Posted by Plasa View Post
    Yes, quite sure that there are diffrent wheel valves, transducer and ECU. I have a ECU with highway pressure about 95psi on a M1078, perhaps it's a 80psi ECU for a 939 or M1089 truck. With that ECU my CTIS was not able to get highway pressure and tires went overinflated...Christian
    Others have swapped the ecu only and had no problems... it just ran highway at higher pressure. Last conversation on your truck seemed to be left that alot was changed on your truck so its hard to measure from it..
    One does not get troubles in life... just character building opportunities. Build on with a smile

    Moderator: Orange Tractor Talks & AmbulanceRV

    Daily driver- 99 VW TDI or 2002 KLR DIESEL w/cvt... weather permitting
    Projects: 96 M1078, 97 Triumph Tiger w/3cyl Diesel Kubota
    Sold: 1962 Dieselized Unimog 404, 1984 Int. 24foot Flatbed, 97 Jeep TJ heavily Modified, Datsun Roadster(s) & 510(s)

  9. #48
    Sergeant Plasa's Avatar
    Join Date
    Aug 2017
    Location
    Italy
    Posts
    83
    Thanks
    22
    Thanked 41 Times in 16 Posts

    Default

    On my truck only the ECU was changed, for sure. All the rest is original and never touched. But anyway, now with the new self made ECU works, and that is the most important thing...

    Thanks and regards from Italy!

    Christian
    Quote Originally Posted by coachgeo View Post
    Others have swapped the ecu only and had no problems... it just ran highway at higher pressure. Last conversation on your truck seemed to be left that alot was changed on your truck so its hard to measure from it..

  10. The Following 4 Users Say Thank You to Plasa For This Useful Post:

    319cssb (01-13-2019), Ohiobenz (01-13-2019), tennmogger (01-13-2019), Third From Texas (01-14-2019)

  11. #49
    Sergeant Plasa's Avatar
    Join Date
    Aug 2017
    Location
    Italy
    Posts
    83
    Thanks
    22
    Thanked 41 Times in 16 Posts

    Default

    Hello Forum. Time is running and project is going on. I finish the configuration mode that enable (when you short a contact inside) to manually inflate / deflate the tires and to save the actual pressure as new default pressure for the 4 diffrent modes. I also add a switch to cutoff the power in chase of emergency/malfuncion.
    The P<> is a error message that something is wrong with the pressure transducer: ambient pressure is out of range...
    For information, the original pressure transducer should be a 100psi transducer (a map(0,1023,0,103) conversion) shows the right pressure. In the next 3 weeks I am travelling through Europe, testing also the software. When it is usable and reliable I will put the sources on github.

    IMG_20190214_110656.jpgIMG_20190214_102005.jpg

    Christian

  12. The Following 7 Users Say Thank You to Plasa For This Useful Post:

    Awesomeness (02-15-2019), coachgeo (02-14-2019), Dock Rocker (02-14-2019), firefinder (02-14-2019), patracy (02-14-2019), Ronmar (02-14-2019), Third From Texas (02-14-2019)

  13. #50
    Colonel
    Join Date
    Jun 2016
    Location
    Austin
    Posts
    291
    Thanks
    54
    Thanked 29 Times in 23 Posts

    Default

    Awesome!

    Cant wait to see it! Have a good trip.


    Sent from my iPad using Tapatalk

  14. The Following User Says Thank You to ramdough For This Useful Post:

    Plasa (02-14-2019)

Page 5 of 7 FirstFirst 1 2 3 4 5 6 7 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •