Does anyone has a place that still sells the old non electronic tester? Anyone has plans for building one?

Thanks

You can buy them from the brake shops and manufacturers already ported for the type of brakes you’re testing. They ain’t cheap, though. You may be able to build your own to spec with ball valves but you still need it periodically certified at a brake shop. HRA was looking into that. Home build is something I may look into.

Last I heard, per the FRA, a freight tester cannot be used on a passenger car brake system, and a passenger car tester cannot be used on a freight system.

Correct. The porting for airflow characteristics is different for different types of brake valves.

Not sure it will help for passenger brake valves, but HRA has recently posted guidance and best practice regarding single car test devices for freight valves. This was developed in coordination with FRA and contains recommendations for an alternative air brake
single car test device that may be constructed and used with the test
code instructions as outlined in the guidance.

https://heritagerailalliance.wildaprico ... resources/

MD Ramsey

Prices on these have actually come down in recent years. Especially the freight testers since few railroads use them anymore. It can be somewhat costly to keep them "in date" though.

duplicate post

The UP rip track at the yard where I work recently tossed their old, original MKT RR "mechanical" brake testing hardware in the scrap dumpster. They've had the new electronic stuff for a few years and had this stuff laying around in the storeroom... their young "manager" came through and went on a spree and made them get rid of everything they didn't use.... along with the test equipment~ the sets of adhesive letters they'd apply to cars that had their COTS, AB tested dates (these days, they don't update the info on the individual cars, it's all electronic), an ancient old platform scale with weights, 3 ancient Lincoln "torpedo" motor-generator welders, mechanical reefer cooling system repair parts.... everything old is gone....

Bad Order -

And did this "young manager" even think of offering any of this to railroad preservation folks? My guess is that he did not.


Les

These guys don't have any inkling that there is such a thing as donating, and probably wouldn't have any idea of how to get someone else on the case to make a donation of it. They're so overwhelmed with paperwork and taking ass chewings on the multiple daily calls that something like this wouldn't even register.

I put one together a few months ago using the HRA guidance.

Here are the relevant standards developed by the HRA:

REVISED AIR BRAKE STANDARDS (2022)

SINGLE CAR TESTER STANDARDS (2022)

Here is a quick clip of the leak test from when I finished putting the tester together:

Rochester & Genesee Valley Railroad Museum Single Car Test Device Quick Leak Test

It only cost about $600 in parts from McMaster-Carr and about 15 hours in machining and assembly. I took my time putting it together and it took a few tries to find quality drill bits for the smaller diameter valve chokes, but honestly it wasn't too much of a nightmare.

We just tried it out last weekend on a caboose and everything worked as expected.

Thanks again to the working group that put together that HRA recommended practice, and got it approved for use on museum equipment!

I've had to make many test racks and fixtures for extremely obsolete traction air brake equipment and this includes making chokes. One thing to watch carefully: the shape of the choke can have a significant effect on the pneumatic properties. My first attempt was to take an ordinary hex socket pipe plug and drill, for example, a 1/16" hole through it. Well, that did NOT give timing perfornance the same as a WABCO choke, that's for sure!

The upstream and downstream approach to the orifice hole needs to be gradual and smooth. This can be done, for example, with a countersink. The actual length of the nominal restriction (in this example 1/16") should be about 5 times the diameter, and never more than 10 times. The definitiion of a "choke" in a pneumatic (compressible) application is that flow reaches the speed of sound and therefore can't get any higher, no matter what the upstream pressure rises to. (This is true until the downstream pressure reaches about 89% of the upstream pressure expressed in absolute pressure). If the L/D ratio is above 10, it is no longer an orifice, rather, it becomes a capillary, and the flow rate changes with downstream pressure.

The difference between sharp-edged orifices (chokes) and those with gradual entrance/exit regions can throw the flow rates off by almost 50%

That's why testing of the test device is important. A typical test is to bring some known volume to a certain pressure, such as 70#, and then open the exhaust via the orifice being tested. Measure the time for the pressure to drop a fixed amount, e.g. from 70 to 50 psig. Compare this to the test spec.

I'm curious when you built this device, did you get the chokes from McMaster too?

Justin,
Glad to hear regarding your efforts on assembling an HRA device. I think you're the first I've heard of assembling one outside of our initial "guinea pig", and it's good to hear all went well.

Jeff H,
Thanks for your notes on orifice form; good points.

Maria,
I had some contact with a fellow railroad about 10 months ago expressing their interest in obtaining both a manual freight device and manual passenger device. Surprisingly, upon inquiry, Wabtec did still offer these new, though admittedly long lead time and lots of $$$. Given recent changes in AAR Interchange Rules, I suspect demand for the manual devices is going to diminish drastically, particularly on the big railroads, so I wouldn't expect Wabtec or any other manufacturer to continue producing these too much longer. If anyone wants one new from the factory, now is probably the time to order (if it's not too late already).

Further, if anyone in the preservation field knows of used manual devices available as surplus from a railroad or shop, PM me or do what you can to secure and save them. (There was some talk of us securing a source or a used lot of manual devices when we were drafting the HRA RP, but we just didn't quite have the "bandwidth" to follow through with that thought at that time.) Bottom line is I would hate to see any get thrown in the dumpster, as with so much other equipment our modern world considers obsolete but we consider gold and still very useful.

-Erich Armpriester
Strasburg Rail Road Mechanical Services

Couple questions on the above....

What changed in the AAR rules concerning testing?

Does anyone have specs for making/buying the orifices?

Eric,

On the AAR Interchange Rules, see Rule 3, Item 4 of the current manual. In short, modern interchange freight cars are now required to be "4 port" automated single car tested.

On the chokes/orifices, so long as the HRA device is plumbed together such that it meets overall form and volume requirements, there is no specification on orifice form other than diameter. See Figure 3 of RP-002 for construction details. So long as the device is air tight, and charges and exhausts air at the proper rates from a fixed volume as called out in the test code, it will perform its function properly - just the same as OEM manual devices are tested for proper function. This allows a railroad some flexibility (within limits) to use equipment and tooling that is available to them to construct the device.

-Erich Armpriester