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Then perhaps 'AZ Deuce', YOU are the guy that needs to volunteer with a little dirty knee time and let us know what is hooked to what and where!
(pretty please!!)
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Airbrake hand controller 'Trolley valve' install assistance needed.
- Thread starter zebedee
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(pretty please!!)
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Zbd: In any system, as we know it today, the Service line, merely conveys a "signal", if you will, to the trailor/towed vehicle. That "signal" causes relay valves to open supplying the actual air, that does the actuial braking in the system. When the driver is done with the brakes, he returns the valves (treddle or toggle hand brake), to zero/closed/neutral. The air is exhaused by not just one, but several "quick release valves", located all along the Service line (and the brake pots themselves). You want that air out of there, and the brakes OFF, fast. Otherwise you will feel they are dragging.
I can't comment about your bench test, and supply coming straight out the exhaust. I do know, there are several models of those valves, that look the same, externally.
In your truck, what are the air lines made of? DOT plastic air brake line? If they are hopefully, get a handfull of extra tees & couplings, and fittings , and tap into the system at a joint, and test that way. Hey man, who ever heard of a valid, nice clean bench test, anyway? Tests aren't valid unless you have dirt and grease up to you arm pits, and your hair is all messed up.....
I can't comment about your bench test, and supply coming straight out the exhaust. I do know, there are several models of those valves, that look the same, externally.
In your truck, what are the air lines made of? DOT plastic air brake line? If they are hopefully, get a handfull of extra tees & couplings, and fittings , and tap into the system at a joint, and test that way. Hey man, who ever heard of a valid, nice clean bench test, anyway? Tests aren't valid unless you have dirt and grease up to you arm pits, and your hair is all messed up.....
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I don't have any 809 series trucks here without the trolley brake, but I can look and tell you were they are connected in the M818 or M819.
Unfortunately it is snowing pretty good here right now, so it won't be right away.
Unfortunately it is snowing pretty good here right now, so it won't be right away.
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I will let you know when I get to it.
jesusgatos
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I'd like to remove the trolley brake setup from an M931A2 and add it to an M923A2 that I'm turning into a long(er)-wheelbase tractor. Anything I should be aware of when swapping parts around between trucks, besides the obvious?
quickfarms
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The trolley valve is only used to tug test the fifth wheel engagement.
In a correctly set up and adjusted air brake system there is no need to use the trolley valve.
Excessive use of the trolley valve can lead to brake failure on the trailer or towed vehicle.
I would advise you not to modify the brake system unless you know what you are doing. If you do not have the knowledge and experience it is best not to modify the system. If you want to have the valve added you should take it to a dot certified brake mechanic.
On civilian trucks there is more to it than just teeing into the lines. There are multiple differences between a straight truck with air brakes and a semi tractor with the trolley valve.
In a correctly set up and adjusted air brake system there is no need to use the trolley valve.
Excessive use of the trolley valve can lead to brake failure on the trailer or towed vehicle.
I would advise you not to modify the brake system unless you know what you are doing. If you do not have the knowledge and experience it is best not to modify the system. If you want to have the valve added you should take it to a dot certified brake mechanic.
On civilian trucks there is more to it than just teeing into the lines. There are multiple differences between a straight truck with air brakes and a semi tractor with the trolley valve.
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jesusgatos
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Appreciate that, but I want to learn more about air brakes - how they work and how to work on them. Other than the trolley brake and the 5th wheel gladhands, how to the air brakes on the tractors differ from the air brakes on the cargo trucks? Doesn't seem like it should be too difficult, swapping parts around. What am I missing?
quickfarms
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We are in the process of doing a cab swap on a civilian truck. The truck is a tractor and the doner cab came from the same type of truck except it was a straight truck. There were so many subtle differences in the airbrake system that we ended up swapping the entire system from cab to cab. The main differences were the trolley valve, the trailer supply and parking brake valves, the tractor protection valve and a whole lot of subtle differences. There were even differences in how the foot valve was plumbed. The tractor had additional air pressure sensors.
I posted a civilian air brake manual in the manual section.
jesusgatos
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Well sure I can see how that would turn into a nightmare, but I'm talking about swapping parts between two versions of the same vehicle (M931A2 & M923A2).
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I still have not done my m923A1 but I looked at it and it looks looks it will not be to bad.
Need to add the Trailer Air supply valve and a Tractor protection valve. Then tee in to the wet tank and the
brake supply line.
Let us know how it goes and what you did, take some pics!!
I think the hard part is going to be going though the fire wall of the truck. LOL
Need to add the Trailer Air supply valve and a Tractor protection valve. Then tee in to the wet tank and the
brake supply line.
Let us know how it goes and what you did, take some pics!!
I think the hard part is going to be going though the fire wall of the truck. LOL
quickfarms
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That is what we thought when we did the cab swap. The donor was identical to the tractor except it was not a tractor.
jesusgatos
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Just finished swapping over all the tractor-specific airbrake stuff from three M931A2's onto hightop M923A2's. First one took awhile, but it's really not that difficult. Working on the rest of the tractor conversions.
Bringing it back.
Installed one on my M923. Takes about an hour or so. I did not use anything from a 931 or 818 truck other than the valve itself. Everything else was easily sourced from NAPA or a Parker store.
Items needed:
Trolley Valve
1/4" pipe to 3/8" DOT pushlok fitting
1/4" pipe to 1/4" push lock DOT Fitting x 2
3/8" DOT pushlok T connector
Haldex KN23000 One way check valve
35' of 1/4" air line
5' of 3/8" plastic air line
3 way T 1/2" NPT
1/2" pipe to 3/8" DOT pushlok fitting x 2
1/2" pipe male nipple.
1/2" pipe bushing
1/2" to 3/8" bushing reducer
3/8" pipe to 1/4" DOT pushlok fitting
Use the remaining 1/4" air line for routing your exhaust vent on the trolley valve. Military trolley valves use a 1/4" pipe fitting on the valve side. Very simple install and pretty beneficial. You have to have that KN23000 one way valve to prevent the air from going up the line to the axle control valves and engaging the brakes on the truck when the handle is charged.
Installed one on my M923. Takes about an hour or so. I did not use anything from a 931 or 818 truck other than the valve itself. Everything else was easily sourced from NAPA or a Parker store.
Items needed:
Trolley Valve
1/4" pipe to 3/8" DOT pushlok fitting
1/4" pipe to 1/4" push lock DOT Fitting x 2
3/8" DOT pushlok T connector
Haldex KN23000 One way check valve
35' of 1/4" air line
5' of 3/8" plastic air line
3 way T 1/2" NPT
1/2" pipe to 3/8" DOT pushlok fitting x 2
1/2" pipe male nipple.
1/2" pipe bushing
1/2" to 3/8" bushing reducer
3/8" pipe to 1/4" DOT pushlok fitting
Use the remaining 1/4" air line for routing your exhaust vent on the trolley valve. Military trolley valves use a 1/4" pipe fitting on the valve side. Very simple install and pretty beneficial. You have to have that KN23000 one way valve to prevent the air from going up the line to the axle control valves and engaging the brakes on the truck when the handle is charged.
Added a video. Would not link up correctly on the other post. In the video i call it a treadle valve on accident.
https://www.youtube.com/watch?v=hg_YIkMBkvA
https://www.youtube.com/watch?v=hg_YIkMBkvA
74M35A2
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Vid is good, thanks. I have one question: If hand trolley valve has exhaust port to bleed down pressure on brake service line when handle is up or in full off position, what would keep air pressure from going up through the hand valve exhaust when the regular foot valve is used?
I get that the check valve isolates the abs relay from hand valve pressure, but it seems like you would almost need one on the hand brake line to the rear also, but then how could the trailer brake service line pressure drain if the hand brake valve was used then released?
I can’t seem to solve these both at the same time. How does your hand valve not hiss air when your foot pedal is used?
I get that the check valve isolates the abs relay from hand valve pressure, but it seems like you would almost need one on the hand brake line to the rear also, but then how could the trailer brake service line pressure drain if the hand brake valve was used then released?
I can’t seem to solve these both at the same time. How does your hand valve not hiss air when your foot pedal is used?
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The trolly valve handles all that. Think of it like a front axle engagement dash valve, but with infinite adjustment. The dash valve does the same thing but only has On/Off capability.
When the trolly valve handle is applied, supply pressure to the valve is allowed through the valve to the brakes and the vent is closed. When the handle is released, supply through the trolly valve is cut off and any pressure in the lines to the brakes is vented. Any handle position between full On and full Off gives partial application pressure.
74M35A2
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How does it dump trailer service line pressure when the hand valve is released, but does not also dump service line pressure when the foot pedal is used?
74M35A2
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Why is the trolley valve not venting air when the foot brake is used?
I get the pressure application part of all of it. But, you need to bleed pressure off the trailer service line in order to release trailer brakes. How is that accomplished in each case, once this hand valve and check valve are installed?
When you use the foot pedal and release it, where does the trailer service line pressure vent to the atmosphere?
Then, when you use the hand valve and release it, where does the trailer service line pressure vent to the atmosphere?
I re-read this tread, and my questions are same as the original posters. No offense, but I don’t think it is really understood. Apology for wanting to understand it before I cut brake lines on my truck. With the way it has been explained so far, I see trailer brakes turning on, and then just staying on. Or, air venting out the hand valve anytime the foot pedal is applied.
The only part that started to make sense was “quick release valves”, and Simp saying the hand valve sweeps through an exhaust phase before going to full close in the full up position. That, combined with if a quick release valve dumps all air with a service signal input of say less than 60psi or so, would start to make sense. But, as video’d, trailer service brake air signal could not be dumped when foot pedal is used, because that signal line now has a check valve on it.
I get the pressure application part of all of it. But, you need to bleed pressure off the trailer service line in order to release trailer brakes. How is that accomplished in each case, once this hand valve and check valve are installed?
When you use the foot pedal and release it, where does the trailer service line pressure vent to the atmosphere?
Then, when you use the hand valve and release it, where does the trailer service line pressure vent to the atmosphere?
I re-read this tread, and my questions are same as the original posters. No offense, but I don’t think it is really understood. Apology for wanting to understand it before I cut brake lines on my truck. With the way it has been explained so far, I see trailer brakes turning on, and then just staying on. Or, air venting out the hand valve anytime the foot pedal is applied.
The only part that started to make sense was “quick release valves”, and Simp saying the hand valve sweeps through an exhaust phase before going to full close in the full up position. That, combined with if a quick release valve dumps all air with a service signal input of say less than 60psi or so, would start to make sense. But, as video’d, trailer service brake air signal could not be dumped when foot pedal is used, because that signal line now has a check valve on it.
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I see what you're saying and I'm not sure on that point. Wes would have to answer that one.
I'm considering adding one, but for a different purpose. I would do the same thing but eliminate the check valve, because I want the service brakes on the truck applying with the spring brakes. The parking brake on the truck only engages the spring brakes. When winching another object or vehicle I want the service brakes applied so that I also pick up braking from the front axle.
The trailer side doesn't matter too much to me and I might just put the check valve on the other side of the Tee to eliminate that completely. For the trailer I just want a dump valve to dump trailer air to apply the spring brakes since the cargo trucks don't have this. But that's a different topic...
I'm considering adding one, but for a different purpose. I would do the same thing but eliminate the check valve, because I want the service brakes on the truck applying with the spring brakes. The parking brake on the truck only engages the spring brakes. When winching another object or vehicle I want the service brakes applied so that I also pick up braking from the front axle.
The trailer side doesn't matter too much to me and I might just put the check valve on the other side of the Tee to eliminate that completely. For the trailer I just want a dump valve to dump trailer air to apply the spring brakes since the cargo trucks don't have this. But that's a different topic...
74M35A2
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10-4. I’m starting from ground zero to better understand how all of this works, something I have been wanting to do anyway. I’m ready to add this once I fully understand it.
Good point on the front brake actuation when winching. I have wanted that more than once.
We tested a brand new KW truck a while back, and I was playing with the trolley valve it had. It was a spring return type, but I noticed it returned bery slow, and wondered why. If it passes through an exhaust/vent window before going full closed, then it would make sense. Just not sure how to do the check valve then, to still make sure the trailer brake service line dumps all pressure when the foot pedal is used.
Good point on the front brake actuation when winching. I have wanted that more than once.
We tested a brand new KW truck a while back, and I was playing with the trolley valve it had. It was a spring return type, but I noticed it returned bery slow, and wondered why. If it passes through an exhaust/vent window before going full closed, then it would make sense. Just not sure how to do the check valve then, to still make sure the trailer brake service line dumps all pressure when the foot pedal is used.
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