View single post by timeforwalkies
 Posted: 05-28-2007 08:42 pm
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Joined: 05-24-2006
Posts: 79
OK all.  Since I didn't get an answer, I decided to do a little research into the problem.
Turns out this little brake cylinder uses what is called a bowed e-ring.
For those of you unfamiliar with the double acting cylinder it has a machined shaft which is cast into the casting.  It goes through the mounting plate and the e-ring secures the cylinder in place with a spring pin keeping it from turning in the hole.
The machined shaft diameter is .62 so the groove size should be .485 dia, but appears to be .562.  Plus or minus that is .08 oversize.
Ah, but it gets better.  The e-ring provided is actually for a .75 shaft so should have a groove diameter of .58 which is still to small for the snap ring.  Using an oversized e-ring should not be a problem since there is no real load on the ring, but the groove diameter should still be correct or the ring will stretch and possible deform.
I also noticed when I removed the original ring that it had been permanently stretched.  I believe that even if the ring breaks and the cylinder is free in the hole, it will probably not fall out since there is tension in the brake return spring and that should hold the cylinder in place.  Additionally the oil line does place a little tension on the cylinder.
If you are going to use the e-ring provided you are going to stretch it and in my case destroy the thing.
Unfortunately I still don't have a solution.
I am going to take the cylinder to a machine shop and ask about turning the groove.  My only concern is that the oil line mounts there and machining will reduce the material remaining between the groove and the major diameter of the threads.  I will do this first on one of the origionals.
Hope this helps anybody with a similar problem.
Edit for 5/29/07
OK.  That's what I get for eye balling it.
Went to my machinist friend today and made a couple of interesting discoveries.
The shaft diameter is actually .678 and the groove is .63, both  caliper measured.  So I did miss both but it makes no difference.  The e-ring still gets stretched, just more.  My friend has a tool designed for opening 5100 series rings.....the type with holes that expand the ring to go over the shaft end.  With this tool we were able to open the e-ring enough to get it over the shaft end, but not without distorting it so it was a loose fit.  It will work, but this is an incorrect application and design for this e-ring.
The conclusion is that a tool is necessary, but the tool normally used for an e-ring is designed to push the ring over the groove diameter which is how I destroyed the first ring.  With the tool he loaned me you can stretch the ring just enough to get it over the end.
Case closed at least for now.  I haven’t actually installed the cylinders yet, but will let you know if this doesn’t work.
I did make one other mistake.  The hole I described as the inlet for the brake line is actually the the bleed valve hole.  Well it wasn't totally my fault since that is how it was shipped to me.  No matter. The line will still hold the cylinder in place....somewhat.
Edit for 5/30/07
Done, but two final comments.
1. Now I am not sure if I have Girling or Lockheed.  The brakes say Lockheed so I will go with that.  Either way the cylinders are double acting.
2. In the process of trying to get the e-rings in place I discovered that the e-ring supplied with the cylinder would be impossible, at least for me, to install even with the tool I borrowed.  The cross section of the ring is to big to allow the tool to fit between the shaft and the ring on installation.  But since I had destroyed the first one, my machinist gave me a couple of  e-rings made in China.  With half the cross section they went on smooth as could be.
On to the master.  And good luck to all who try this.

Last edited on 05-31-2007 12:52 am by timeforwalkies