We have been having some reoccuring problems with our 24RL brake systems. With a 20# reduction and the brake stand cut out (after giving sufficient time for the pressures to equalize of course) the equalizing reservoir begins slowly climbing, around 1 or 2 psi per minute. Since the brake pipe is already reduced (and holds steady with the brake stand cut out), I can only imagine that the air that causes the equalizing reservoir to climb can only be coming from the main reservoir.

Possibly unrelated, I also have a steady blow at all times from a port on the service application portion of the brake stand (right next to the cut out cock). I have replaced the entire brake stand with freshly rebuilt components and the problems persist.

We dealt with these problems on one particular locomotive on and off for several years. It seemed that replacing brake stand components repeatedly would eventually mitigate the problem for a while, but that may have been coincidence. I also cleaned and hydro'd all of the reservoirs. Eventually, we solved the problem by replacing the 24RL with a 26 system.

Now, I have a different locomotive exhibiting the same symtoms. I plan to eventually upgrade it to a 26 as well, but it's not in the budget for the near future, and my curiosity wants to find out what is causing these problems.

Any air brake masters want to offer suggestions as to what could be causing this?

Eric

Eric, this almost sounds like one of the combined reservoirs has an internal partition leak. Probably the first one to check would be the combined equalizing and reduction limiting reservoir, vent one side and pressurize the other and watch for leak off. A rusted partition in the combined reservoir could lead to cross bleeding between pipe 22 and pipe 5. Most older equipment has never had the partitioned reservoirs changed out, and the chambers are subject to water accumulation that can result in pinholes in the partition.

Testing the reservoir remember to leave one side vented to atmosphere when you put some pressure on the other side, then cut off the fill and wait a while to see if the charge gradually bleeds off.

Unfortunately I seldom work with 24 brake, everything recently has been 26 brake with LUL racks or 30A-CDW with 26 LUL. So everybody else please feel free to find fault with me, I am strictly guessing on this one.

PC

PC,

Thanks for the reply.

I thought the same thing about the Combined Reduction Limiting Reservoir and Equalizing Reservoir. However, my notes say that the RLR is only used during first service (which we do not use), is uncharged normally, and only becomes charged during first service to equalize with the equlizing reservoir. So, I don't think that it would ever be charged higher than the equalizing reservoir to have a positive bleed, unless the RLR is being charged incorrectly. I may break the line and see if there is actually pressure on it.

On my previous locomotive, I did Pressure test the Combined reservoir and did not notice a leak, but also may not have let it sit long enough for a small one to present itself.

I also am more familiar with the 26 system, having actually been to a Wabtec class. Unfortunately, the 24 was not covered in that class.

I should also note that we are using the brake system in Passenger Position with Graduated Release.

Eric

Beyond that it would seem like places where the 5 pipe passes through gasket interfaces and is on one side of a diaphragm would be likely places for cross feeding, those would include the application portion, the equalizing portion, and several gaskets in the valve body. Good luck with the troubleshooting.

There is also a 5 pipe over at the control valve but I think that is strictly auxiliary air and not related to the problem you are describing. Unfortunately the Wabco diagrams for 24 system are very difficult to read, there are a lot of passages in the valves and they are drawn and labeled very small.

I often thought it would be interesting to develop and teach a 24 brake training class, but who wants the burden of having to carry large amounts of liability insurance for the rest of your life just to do teaching of a subject that has so few remaining applications, and some of those being relatively high risk tourist passenger service.

PC

Eric,

Drop me your email and I'll send you my 24RL cheat sheets.

Eric Levin