Air Pack question.

[swindad2]

So I decided to let my local machine shop tackle my air pack rebuild. I know, should have done it myself, but the combination of my health, work space, and too many other projects made the decision for me. So they called me and said a part was missing from the rebuild kit, to come and look at it. I agreed that it was not in the kit, but I received the kit, opened, with the truck, so I assumed maybe it was just missing. Ordered another rebuild kit, and it contains the same parts. The part in question looks like a bushing (metal core with rubber surround). It fits over the push rod shaft, inside a smaller housing, at the joint where the two halves of the pump meet. I have read through all the rebuild threads on the site, and looked at the TM/rebuild guide. You can see the part in the diagram, but nowhere does it mention removing or replacing it. It is not numbered in any of the diagrams. I assume since it is a rubber part, over the shaft, that it should be replaced. I have included pics to show what it looks like. It is pretty chewed up. Where am I going to find this thing, or should it have been left alone?

Or is this a combination of two of the seals I'm just not seeing. The metal part is throwing me off. It appeared to have been one part.



Here is the rebuild manual thanks to rustystud: http://www.steelsoldiers.com/showthread.php?118450-Air-Pack-Rebuild-Manual

 

[rustystud]

Is this from a long air-pac ? I've rebuilt both long and short style air-pacs and this part does not look familiar at all !
I've posted pictures of both style air-pacs disassembled and I cannot find this part you are talking about.

 

[rustystud]

Long style air-pac disassembled. Part 1.

 

[rustystud]

Long style air-pac Part 2



These are the major parts in a "Long Style Air-Pac". Part 2.

 

[rustystud]

Short style air-pac Part 1

This is a "short style air-pac" disassembled. Part 1 .

 

[rustystud]

short air-pac Part 2



This is the "short style air-pac" major parts disassembled. Part 2 .

 

[Floridianson]

Seems like it would have been one peice and funny it is not in the rebulid kit.

 

[swindad2]

Seems like it would have been one peice and funny it is not in the rebulid kit.

It is the long pump. I did have the thought "a stray part got mixed in?", but that appears to be the part in this diagram. I have another air pack. Thought about tearing it down and seeing if it is the same. But the part, with the arrow, is not something I have seen mentioned anywhere else.



Don't know how I got 2 pics in here, but.......

 

[gringeltaube]

It seems that we just found out there are two versions of the same part, called the pushrod bushing assembly.
The one pictured in post #1 must be pre-1955, since the ORD 9 SNL G-742 manual from that year already shows the one-piece bushing.

Actually I'd prefer to have the older version: at least it is much easier to replace that seal - which is probably a std. sized oil seal...?


G.



Edit: After further studying... I'll take that last sentence back. See my next post.

 

[swindad2]

So mine is an older version? If so, where do I get a replacement part? Or will one of the parts included in the rebuild kit work? I assumed this air pack was newer than the one on my truck. Bought it off fleabay for $70. It was very clean. Looked barely used. I looked at a lot of places online that sell the rebuild kits and they all looked the same. Bought the second kit from TNJ. It was actually half the price or less than most other places. Kind of glad now I didn't attempt this one myself, but the machine shop is waiting on me to tell them how to proceed.

On another note, pulled the master cylinder off today, disassembled and cleaned it. Much simpler to work on. Guess I'll open up the other original air pack in the next couple days and cross my fingers that it is the different one that will use my rebuild kits. I read a lot on the air packs before starting, but now I am more confused than ever.

 

[gringeltaube]

Yes, it can be confusing indeed... because that same manual first shows in Figure 112 a sectional view of what I think is a very early version, but then in Figure 114 there is the seal "S" which is exactly what the common 1-piece rod bushing takes. This is also clearly shown in Figure 133 - despite that washer not being removable, since it is crimped-on. They do explain though, how to pull the old seal out and to carefully "work" the replacement seal into its slot, inside the bushing.
Nowhere could I find anything mentioned regarding that two-piece pushrod bushing...!?

Now, in order to repair this "early-version-whatever"-airpack, we would need a rod seal (for a 7/16" rod) that would fit into what seems to be a metal carrier that inserts into that no-name, mystery cup, all well sealed in place. This cup then needs to be installed with a gasket, to stay airtight against the air cylinder shell...

Or... directly get a new, one-piece bushing replacement and discard the original parts.


G.

 

[rustystud]

I wonder if the "new" style of push rod bushing will fit in place of this "old" style one ? What does the bottom end of the main cylinder look like ? Anything like this ?

 

[rustystud]

It seems that we just found out there are two versions of the same part, called the pushrod bushing assembly.
The one pictured in post #1 must be pre-1955, since the ORD 9 SNL G-742 manual from that year already shows the one-piece bushing.

Actually I'd prefer to have the older version: at least it is much easier to replace that seal - which is probably a std. sized oil seal...?


G.



Edit: After further studying... I'll take that last sentence back. See my next post.

Actually the lip seal used in the push rod support bushing is really easy to change out once everything is cleaned. I'll take our newer style any day over that stamped steel thing.

 

[rustystud]

It is the long pump. I did have the thought "a stray part got mixed in?", but that appears to be the part in this diagram. I have another air pack. Thought about tearing it down and seeing if it is the same. But the part, with the arrow, is not something I have seen mentioned anywhere else.

View attachment 493590

Don't know how I got 2 pics in here, but.......

Swindad what is the manual number you got that picture out of ?

 

[rustystud]

Just a note. There is a metered orifice in the compensator body that must be open for the proper function of the compensator piston. If the orifice is plugged (everyone I've seen has been plugged) then the piston will not return properly due to a vacuum created. This will cause the air cylinder piston to "hang up" causing slow release of the brakes.

 

[gringeltaube]

I wonder if the "new" style of push rod bushing will fit in place of this "old" style one ?...

I bet it does. The only change- or say upgrade- was done at the air-side end. The new part is only longer, incorporating the seal.

The OP may be able to confirm that, once he has pulled the bushing out of his other airpack (and that one wasn't that same odd style, of course).

Swindad what is the manual number you got that picture out of ?

Ehh... Rusty, if YOU don't know the answer...??? Because that is what appears on Page 132 in the manual YOU have posted here...



G.

 

[mattgunguy]

Is there a way to test a air pack that isn't on a truck before rebuilding it. We were basically given a used long air pack yesterday that I'm keeping for a spare.

 

[swindad2]

So it appears that the "newer" pump turns out to be an "older" pump.? Tore the original air pack down today, and it looks like every other one I have seen on the site. Problem is, it was full of water. Pretty nasty on the inside. Won't know if it usable till I clean and hone the cylinder. The push rod and all the other components looked okay, just dirty.

No idea what the gunk is on the outside of the air pack. Looks like grease, full of sand. I thought it might have come out of the master cylinder boot. It had shrunk and pulled back from the end, and was full of some sort of heavy grease. I am hoping maybe the piston cylinder is the same on the other one and I can swap it out. It's still at the machine shop and I haven't looked that closely at it yet. It has already been cleaned and honed and looks great. I'll take the parts down in the morning and see if we can make one complete air pack. Here are some pictures in the mean time.



I do remember when I installed the purchased air pack, one of the fittings was different (can't remember which), and I had to pull one off the original. The crimped lines in the photos were on the pump I bought, for shipping purposes.

 

[rustystud]

I bet it does. The only change- or say upgrade- was done at the air-side end. The new part is only longer, incorporating the seal.

The OP may be able to confirm that, once he has pulled the bushing out of his other airpack (and that one wasn't that same odd style, of course).



Ehh... Rusty, if YOU don't know the answer...??? Because that is what appears on Page 132 in the manual YOU have posted here...



G.

I guess it's official, I'm going senile ! My wife has been saying that for years now !

 

[rustystud]

So it appears that the "newer" pump turns out to be an "older" pump.? Tore the original air pack down today, and it looks like every other one I have seen on the site. Problem is, it was full of water. Pretty nasty on the inside. Won't know if it usable till I clean and hone the cylinder. The push rod and all the other components looked okay, just dirty.

No idea what the gunk is on the outside of the air pack. Looks like grease, full of sand. I thought it might have come out of the master cylinder boot. It had shrunk and pulled back from the end, and was full of some sort of heavy grease. I am hoping maybe the piston cylinder is the same on the other one and I can swap it out. It's still at the machine shop and I haven't looked that closely at it yet. It has already been cleaned and honed and looks great. I'll take the parts down in the morning and see if we can make one complete air pack. Here are some pictures in the mean time.

View attachment 493887View attachment 493888View attachment 493889View attachment 493890View attachment 493891View attachment 493892View attachment 493893View attachment 493894View attachment 493895

I do remember when I installed the purchased air pack, one of the fittings was different (can't remember which), and I had to pull one off the original. The crimped lines in the photos were on the pump I bought, for shipping purposes.

Well swindad, it appears you got lucky ! You can use the newer style pushrod bushing . I have extra's, so if you need one let me know.