Need help hooking up a trolley brake in an M809 series

[acesneights1]

I have an M813 that is being turned into a tractor.
Can someone with either an M818 or M52a2 tractor post a few pics of how and where the trolley brake is piped in ?
it is more complex due to air over hydraulic so a 900 series will not help.
thanks.

 

[74M35A2]

Air brake truck should work, since the towed interface and hand brake valve are both air only?

If so, Simp just did an explanation on it, and I have since updated the post with the appropriate 2 way shuttle valve to do so as an add-on. Simplier than I thought once I got into it, once you understand that this line and valve is a control signal only to the towed item, not brake apply pressure itself (that comes from the “emergency” side connection).

 

[BKubu]

SIMP's video is on YouTube. I'd recommend you subscribe to his channel; lots of good videos.

 

[simp5782]

Thanks guys. Same as a 939 truck you just get your supply air for the valve right from the tank.or T off your gauge line if its plastic already. The airline on the frame rail serves the same purpose its feeding air to the trailer.
https://youtu.be/hg_YIkMBkvA

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[acesneights1]

It's not that easy on an 809 series. There needs to be an extra check valve and I am not sure where to tie in on the air pack. The attached diagram kinda shows it but if I could get some pics of an 809 or M39 series that would help a lot.

 

[acesneights1]

Basically have to make sure the air pack does not backfeed through the trolley when trolley is off , but also have to make sure the trolley applies air to the trailer brakes only. This is where is gets tricky on an air over hydraulic system. Placement of that third check valve. All air over hyd seem to have 2 checks already but the tractor variation has a third.

 

[acesneights1]

It would seem I would need a check on the trolley line to brakes but also a check in the trailer brake line and tie the trolley in afterwards.

 

[acesneights1]

This was my original ideal but air will get trapped and not released. On a normal air brake system you can tie into the foot valve with one check. This is not so easy.....

 

[74M35A2]

The intricate part about this is the air sent down the service brake trailer pipe needs to be able to bleed off at the same source it came from when released. This is what a double check valve does, it is not just simply two one-way check valves. It is actually a shuttle valve that lets air bleed back in the direction it came from, without pressurizing the “other” line. The trolley valve has a bleed off function on it’s travel back up to the off position. I posted the NAPA p/n of such shuttle valve, can you just plumb them in as required to match the diagram? Third port on the hand trolley is just a vent relief line, so that is why diagram only showing 2 lines to it.

 

[acesneights1]

Then I thought this but again same problem and also will apply airpack as well. I have no idea how it was done but I know it can be . I had an M52a2 with a trolley. I need to see someone's truck.

 

[simp5782]

On the frame rail T you would just add another kn23000 on the delivery from the trolley valve activation line. You would then install a kn23000 on whatever port on the tank you used to constant supply so it cant back feed



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[acesneights1]

If I am reading the diagram from the TM right, it "looks" like the trolley IS applying air to the airpack but this would be with no brake pressure applied from master Cyls since my foot would not be on brake if using the trolley so what would applying air to the airpack with no applied brake pressure result in ? Damage to air pack ??
i am lost here....

 

[74M35A2]

From looking at the diagram you posted, it will not apply air pressure to your air pack. #20 is the double-check "shuttle" valve NAPA part. Is there a reason you can't simply configure it as your diagram shows?

 

[acesneights1]

From looking at the diagram you posted, it will not apply air pressure to your air pack. #20 is the double-check "shuttle" valve NAPA part. Is there a reason you can't simply configure it as your diagram shows?

That is what I want to do but I am having difficulty understand the diagram. I highlighted yellow as supply and green as service application but the lines I did not highlight I don't understand direction of flow. Perhaps if I knew the direction of the double check ?

 

[acesneights1]

The lines in blue are the ones I am not sure which direction air should flow. I mean seems simple that air needs to head towards the air pack but the tee's are confusing me.

 

[simp5782]

You are overthinking this. You only need a constant air supply to the trolley valve. The dash gauge would work. Or off the emergency gladhand side line on the frame rail. The air pack does not care whats going on beyond it. You are just sending air after it with the valve. In the video i posted. Think of the air pack as the abs module valve on the 939s. You have to have the check valve or it would apply the truck brakes when the handle charged.

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[acesneights1]

I think I have a better grasp on is. I took one of the check valves off another frame and played with it on the bench. Seems like it works more like a spool valve. Air can be applied from either side . Then it pushes a valve that closes the other side and air can flow either direction from the center to the side that had the air applied. Then if you apply air to other side, same result. That makes more sense to why it can work.

 

[acesneights1]

I'm gonna update this with some pics later but the diagram from the TM is correct. What makes it confusing is unless you know how these double checks operate it seems like it won't work but the valves are more like spools . Three of them are nessicary to make it work properly. A non tractor air over hydraulic 5 ton(809/m39) has two. A third needs to be added and it must be a double check like the two already on the truck. The prevents the trolley from applying the airpack and also prevents air from escaping the front service side glad hand or the service side glad escaping through the trolley in off position.

 

[acesneights1]

Sorry these are not very good but basically there is a tee where the service line comes from the front of the truck and that is where the dual check goes. Basically like the TM shows.

 

[acesneights1]

I also piped in a Tractor protection valve for the trailer brakes. This truck is an M813. I turned it into a Tractor. The tire crane looks cool on an 809 series I think.