We are working on the brakes on a caboose with AB brakes. The train line comes up right away but the brake cylinder pressure is slooooow to come up. Is there something in the brake control that could be plugged? If so where would we look. We have an extra AB brake but we do not know if it is good or not.
Is there a way to bench test the AB valve without having to hook up in the caboose.
Any help would be great!
THANK YOU for any help.

Without a lot of knowledge on the internals, I would ask: Do you intend on doing any interchanging or shipping of the cab? If so, before spending any money to rebuild or find a replacement, it might be a good time to work at upgrading the schedule on the brake. From what I've read, they were outlawed in interchange this last year?

Joe

It will be used in Tourist service only on our own track. That is why we would like to clean and reuse if we knew that it would work after we work on it.

Make sure nobody has monkeyed with the retainer valve or other parts of the equipment and that the brake cylinder is in good shape, packing cup, spring, etc. If you end up taking the brake cylinder apart (and you should if it hasn't been serviced for a while), get a manual and follow the instructions. Normally, only the non-pressure head needs to come off but there's a big whacking spring in there and you need to secure the head to the piston tube.

Use only AAR spec brake cylinder lube in the cylinder. It is available from Interlube in 5 gal. pails. There may be other suppliers that I am not aware of.

If you are not overly familiar with the equipment, suggest sending control valve portions out to a recognized air brake shop, make sure you get new pipe bracket gaskets at the same time. There a lot of things in air brake components that can easily be damaged or lost if you don't have much experience with it. There should be several shops that can handle AB. Off the top of my head, PABCO, Strasburg or Multi Service Supply.

As noted, an upgrade to more modern equipment might be worth some research.

Gord

Only if you have (and know how to use) an AB test rack. :)

Test racks were made by the air brake companies and utilized in railroad air brake shops and once often in car shops and roundhouses. These are complex devices that are designed to test individual chambers and actions within the brake valve. There were performance standards for new valves, refurbished valves, acceptable valves and condemnation.

With a test rack an specific problem can be found and diagnosed, while simply cleaning a valve and putting it on a car and setting the brakes may only give you a "go/no go" situation.

The air brake shops mentioned above will clean, service and test the air brake valve.

How slow is slow? Does it take long to apply after a brake reduction, or do you mean it takes long before the brake cylinder actually works? The train line shouldn't take any time to come up because it's just a pipe running the length of the car. The brakes on the other hand have to charge up the aux reservoir. It would be best to take both the service and emergency portions off of the pipe bracket to ensure it is not gummed up. You will need new gaskets though. There is that little thimble-like strainer, and a paper filter that may be gummy. While you're at it, check and adjust the brake travel.

Remove the AB's and at least install ABD.........both service and emergency that have been cleaned in an AAR approved air brake shop. Clean the dirt collector/cut out cock (replace if it is plug type) and replace the filter in the pipe bracket. Use new service and emergency mounting gaskets. You will likely need at least one new pipe bracket stud if you are removing an AB service and putting an ABD service on in it's place. You may also have to remove the filling piece between the brake cylinder line and the pipe bracket. You'll have to replumb the brake cylinder line. Install a brake cylinder pressure tap and test the car with an in-date single car test device. Report the air brake test date in the UMLER file. This will keep you legal if you are operating the caboose and your railroad is connected to the general rail system.

And regarding the rule on AB in interchange.........no they are not outlawed yet by the AAR. But if you remove an AB you are not allowed to reapply it and if you remove one portion then you have to remove the other as well.