Hemichallenger gave you the info I believe, in that it releases with equal pressure and applies upon loss of service pressure. The emergency air would apply the brake while service air is released. That would work great on a vehicle that works that way...but I don't think your 5 ton does. I believe pressure actuates on the 5 ton, which would be opposite from a brake that is operated by a release of pressure. Thus a miss-match and candidate for a tank and valve for pressure actuation (break away), I think.
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Air brake issues - please help!!!
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quickfarms
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Air brakes are fairly standardized. The red line is used to pressurize the system and release the spring brakes. The blue line sends a small amount of air to the relay valve that uses air from the tank connected to the red line to apply the brakes. If the air lines are correctly hooked up this system should work to a point.
hemichallenger
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This works on a 5 ton. The emergency air releases the parking brake that the spring applys. No air makes it apply and sevice air makes it apply. A tank and valve works the same way it is just added so that you have much more air to operate the system.
painter paul
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For now, just make sure you never undo those clamps around the air chamber! The springs can fly out and take off a hand, or even kill you. Looks to me like the blue should apply the brakes, and the red should either set the brakes as an emergency or release them and let the blue apply the brakes when driving. The cage bolt should be removed for normal service, and it should be caged to allow the trailer to be moved when there is no air hooked up to it, as in moving it w/o an air brake truck. Thanks, Paul
goldneagle
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Non of the Military trailers sitting in my yard have break-away features and they are legal.
Wait a minute, is entropy right about the brakes service application on the modulated release of pressure, like he stated above?... because I thought the 923 worked on the application of pressure...exactly the opposite (like your video hemichallenger).
Entropy455
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I appreciate the warning about not taking the air chamber apart. I don't like the idea of snapping a bone from an uncontrolled coil spring letting go. . . . If I do anything, I would simply replace the can.
Nonetheless, my main concern is figuring out how the darn air brakes work, and to determine whether or not the current trailer brake design is even compatible with my M923. Does the blue line provide a gentle control air signal, or does it provide powerful driving control signal. I.E. does the blue line increase in pressure as I hit the brake, or does it decrease in pressure? I have read a bunch of on-line references on this subject, and many sources are providing contradicting information.
Again, when I use shop air to pressurize the red line, the brakes engage fully. When I pressurize the blue line with shop air, nothing happens whatsoever. Thus if I un-cage the air chamber, will it make things better, or worse? I'm thinking the red line will continue to engage the brakes - - - will the blue line become functional???
This trailer was purchased at auction, which means it could have issues. It is possible that someone caged the air chamber to deliver the trailer to the auction house, using a non-air-brake truck. It is also possible that the air chamber is faulty. I'm also willing to acknowledge at this point (however remote), that this brake system might be complete hogwash - and is simply a non-functioning smoke & mirrors attempt to keep from getting ticketed by the state highway patrol for non-functioning brakes.
Nonetheless, my main concern is figuring out how the darn air brakes work, and to determine whether or not the current trailer brake design is even compatible with my M923. Does the blue line provide a gentle control air signal, or does it provide powerful driving control signal. I.E. does the blue line increase in pressure as I hit the brake, or does it decrease in pressure? I have read a bunch of on-line references on this subject, and many sources are providing contradicting information.
Again, when I use shop air to pressurize the red line, the brakes engage fully. When I pressurize the blue line with shop air, nothing happens whatsoever. Thus if I un-cage the air chamber, will it make things better, or worse? I'm thinking the red line will continue to engage the brakes - - - will the blue line become functional???
This trailer was purchased at auction, which means it could have issues. It is possible that someone caged the air chamber to deliver the trailer to the auction house, using a non-air-brake truck. It is also possible that the air chamber is faulty. I'm also willing to acknowledge at this point (however remote), that this brake system might be complete hogwash - and is simply a non-functioning smoke & mirrors attempt to keep from getting ticketed by the state highway patrol for non-functioning brakes.
This Thread is absolutely fascinating. Perhaps if you go to this thread about 5 ton brakes:http://www.steelsoldiers.com/showthread.php?107066-M931-Brake-issue , and get a clearer picture of your truck's brake operation, the trailer you have and it's operation may come clearer. I watched the videos about brake operation and learned a lot. Best of Luck to you on your brake quest.
In regards to your "emergency" red line issue, perhaps the parking brake being caged and perhaps a bad seal between the chambers is the culprit. I have never seen the inside of brake chambers, but it stands to reason the 2 chambers are sealed-separated from each other. Your red line, trailer air supply-parking brake release -E brake should, upon pressurizing (an uncaged chamber) seems to be intended to release the parking side of the chamber and should release the wheels.
With the parking side of the chamber released, the blue service line and it being pressurized should activate the service brakes.
I am making this reasoned guess from watching the videos from this thread and the other thread I mentioned.
opcorn:
In regards to your "emergency" red line issue, perhaps the parking brake being caged and perhaps a bad seal between the chambers is the culprit. I have never seen the inside of brake chambers, but it stands to reason the 2 chambers are sealed-separated from each other. Your red line, trailer air supply-parking brake release -E brake should, upon pressurizing (an uncaged chamber) seems to be intended to release the parking side of the chamber and should release the wheels.
With the parking side of the chamber released, the blue service line and it being pressurized should activate the service brakes.
I am making this reasoned guess from watching the videos from this thread and the other thread I mentioned.
opcorn:
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Yes trukhead, I think you have it right. The e brake takes pressure to release and the service line applies pressure for normal braking. If his brakes apply by putting air to the red line (e brake), then there may not be a spring inside that is "caged". Someone may have removed it. How else does he get brakes by putting air to the e-side? If he has a good, large vice or a spring compressor it might be worth checking out to see if a spring is in there. I want to stay on top of this as I have Dexter axles with hydraulic disks going into a dump trailer build for pull behind a 923 and need a similar setup.
One final thought...to apply the brake with pressure as a normal air brake, the pressure must go to the rod (service) side of the cylinder. Putting pressure to the emergency side would normally release the brakes...but that is not the case here, if one is to believe the attachment colors...which I doubt now. If air into the line marked as the service line does nothing, it must be going into the e side of the cylinder which is either caged or the spring is removed.
From USDOT "(b) Emergency brake requirements, air brakes. Every truck or truck tractor equipped with air brakes, when used for towing other vehicles equipped with air brakes, shall be equipped with two means of activating the emergency features of the trailer brakes. One of these means shall operate automatically in the event of reduction of the towing vehicle air supply to a fixed pressure which shall not be lower than 20 pounds per square inch nor higher than 45 pounds per square inch. The other means shall be a manually controlled device readily operable by a person seated in the driving seat. Its emergency position or method of operation shall be clearly indicated. In no instance may the manual means be so arranged as to permit its use to prevent operation of the automatic means. The automatic and manual means required by this section may be, but are not required to be, separate. (d) Breakaway braking requirements for trailers. Every trailer required to be equipped with brakes shall have brakes which apply automatically and immediately upon breakaway from the towing vehicle. With the exception of trailers having three or more axles, all brakes with which the trailer is required to be equipped must be applied upon breakaway from the towing vehicle. The brakes must remain in the applied position for at least 15 minutes."
Goldeneagle, If they have not got breakaway, (per the above) they are not legal for normal civilian use that is subject to a DOT inspection. There seems no choice but for entropy to make them work right, including the breakaway feature. In the double cylinder, the spring is used for that purpose upon release of emergency air. With a single cylinder, actuated by pressure, a tank and valve would be required. So when you sell a unit goldeneagle, unless it has the breakaway (a double cylinder (with spring) or tank and valve)...I would not represent it as meeting the DOT requirements.
quickfarms
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You need to I cage the brake can and recheck the function. It sounds like the air lines are reversed.
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Caging a normally used air brake chamber, will simply compress the parking/emergency spring. It leave the service brakes operational.
In the case of this trailer, I think he simply needs to cross his lines to get it to work. He actually only needs to connect and use the service line to the trailer to make it function.
That trailer's brake system is outdated and probably not legal to use.
Also, since your truck has air brakes, it would be wise to learn how they function. This is one benefit of having CDL training.
In the case of this trailer, I think he simply needs to cross his lines to get it to work. He actually only needs to connect and use the service line to the trailer to make it function.
That trailer's brake system is outdated and probably not legal to use.
Also, since your truck has air brakes, it would be wise to learn how they function. This is one benefit of having CDL training.
So if brakes apply by putting air in the red line, to make it work he must hook to the service line on the truck, which supplies pressure when the peddle is pressed. That makes sense. But he is not "legal", in that the breakaway is not functioning for over the road, knowingly, under DOT authority. He simply needs to fix it right, making sure a spring exists when "un-caging" it and hooking air to both sides to assure they are functioning properly with the correct ends for his truck. As I write this, he is probably doing the work. Hope so. Toby
Entropy455
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Can anyone please provide me with a schematic of an air-over-hydraulic trailer brake system? Something basic - non ABS - just what's required to get me up to code for a pre ABS trailer (built and titled in 1965). I found a few brake kits online, however they seem quite expensive.
The few schematics I did find failed to provide part numbers for the individual components (they want me to purchase their kits $$$). I can get my hands on an air cylinder, and I'm plenty capable of running air & hydraulic lines. I have a lathe & mill for fabricating the necessary mounting hardware/brackets.
Nonetheless, I'm not sure as to which trailer brake air control valve I should purchase, and whether or not I should upgrade my existing master cylinder and air chamber - with the new style that has the two components built into one. I'd rather utilize an existing design that is known to work, in lieu of trying to engineer a system from scratch. My end-use for this trailer is to occasionally transport a mini excavator (about 14-k pounds).
On a related note: I have seen with my own eyes, a large commercial flat-bed trailer break away from a tractor while on the freeway (I-5, just north of Tacoma). It was not pretty. Thankfully no one was hurt, however there were a lot of vehicles damaged - as even with the breakaway brakes functioning, it took a long time for the trailer to come to a stop, side-swiping cars as it drifted across several lanes of traffic. . .
The few schematics I did find failed to provide part numbers for the individual components (they want me to purchase their kits $$$). I can get my hands on an air cylinder, and I'm plenty capable of running air & hydraulic lines. I have a lathe & mill for fabricating the necessary mounting hardware/brackets.
Nonetheless, I'm not sure as to which trailer brake air control valve I should purchase, and whether or not I should upgrade my existing master cylinder and air chamber - with the new style that has the two components built into one. I'd rather utilize an existing design that is known to work, in lieu of trying to engineer a system from scratch. My end-use for this trailer is to occasionally transport a mini excavator (about 14-k pounds).
On a related note: I have seen with my own eyes, a large commercial flat-bed trailer break away from a tractor while on the freeway (I-5, just north of Tacoma). It was not pretty. Thankfully no one was hurt, however there were a lot of vehicles damaged - as even with the breakaway brakes functioning, it took a long time for the trailer to come to a stop, side-swiping cars as it drifted across several lanes of traffic. . .
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The TM for a M105 should have a schematic M105A2/ M103 1990 version
Where are you in the scope of things on this trailer?
How about:
Determning if the chambers are caged, and uncage them to see if the wheels turn or not, if they don't turn, there is a spring in there and the wheels are braked. If they turn with the chambers uncaged, well time to start the airbrake reconstruction project.
If previous step determines chambers were caged and wheels don't turn, then install red line to parking brake, chamber and attempt to pressurize it so the wheels now rotate freely. If wheels don't rotate freely, time to start the airbrake reconstruction project.
Now, if pariking brake chambers can be activated with the red line properly installed on the red gladhand, attach blue line to front-service brake chamber and to the truck blue glad hand and attempt to activate service brakes with truck brake pedal. If after all this, the brakes work , your golden, if the brakes don't work, time to start the airbrake reconstruction project.
However, if you are reconstructing and engineering a brake system that is not original, consider if you are ultimately liable for it instead of repairing what is on the trailer of another engineers design.
I'm getting am M931A2 tractor and I want to learn all I can about these brakes. I have a M1022 dolly, a M1061 trailer and fabbing up a dump trailer and would like to understand the various iterations of air brakes and such as wedge versus s-cam.
This has been a fantastic thread.
Good luck and success with your brake issue.
After all of this, you have no success consider an elector-hydraulic brake activator and an intertia controller like in the pickup trucks: http://www.easternmarine.com/Electric-Hydraulic-Brake-Actuators/
http://www.easternmarine.com/dexter-electric-hydraulic-drum-brake-actuator-k71-650-00
and install a solid state electronic brake controller in your truck.
All this elecric stuff is DOT-Federal legal as well!
How about:
Determning if the chambers are caged, and uncage them to see if the wheels turn or not, if they don't turn, there is a spring in there and the wheels are braked. If they turn with the chambers uncaged, well time to start the airbrake reconstruction project.
If previous step determines chambers were caged and wheels don't turn, then install red line to parking brake, chamber and attempt to pressurize it so the wheels now rotate freely. If wheels don't rotate freely, time to start the airbrake reconstruction project.
Now, if pariking brake chambers can be activated with the red line properly installed on the red gladhand, attach blue line to front-service brake chamber and to the truck blue glad hand and attempt to activate service brakes with truck brake pedal. If after all this, the brakes work , your golden, if the brakes don't work, time to start the airbrake reconstruction project.
However, if you are reconstructing and engineering a brake system that is not original, consider if you are ultimately liable for it instead of repairing what is on the trailer of another engineers design.
I'm getting am M931A2 tractor and I want to learn all I can about these brakes. I have a M1022 dolly, a M1061 trailer and fabbing up a dump trailer and would like to understand the various iterations of air brakes and such as wedge versus s-cam.
This has been a fantastic thread.
Good luck and success with your brake issue.
After all of this, you have no success consider an elector-hydraulic brake activator and an intertia controller like in the pickup trucks: http://www.easternmarine.com/Electric-Hydraulic-Brake-Actuators/
http://www.easternmarine.com/dexter-electric-hydraulic-drum-brake-actuator-k71-650-00
and install a solid state electronic brake controller in your truck.
All this elecric stuff is DOT-Federal legal as well!
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quickfarms
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Some one has changed the air brake can on the trailer in the past. You have a modern clamp ring air can on the trailer. The correct air can should be held together by a ring of bolts like on the M105, M1061, M146 and other military trailers.
This setup of using only the air can was not used after the late 50's. This trailer should have an air tank and relay valve on it. According to a DOT inspector I know.
You need to have a DOT certified brake mechanic sort out the brakes on this trailer.
This setup of using only the air can was not used after the late 50's. This trailer should have an air tank and relay valve on it. According to a DOT inspector I know.
You need to have a DOT certified brake mechanic sort out the brakes on this trailer.