http://projects.wasatch-rr-contractors.com/?page_id=189

Questions:

1.) Am I correct in understanding that there is a rubber diaphragm that is the cause of the relatively short maintenance period with UC's.

2.) Do you lose any special features that the older equipment has in converting?

Doubt that it is due to a rubber diaphragm in the UC-12. The UC-12 valve uses the technology of the 1920s which is slides and rings. Because if wear, lubricate stiffening, etc. these are periodically cleaned and tested. These are complex and heavy valves and difficult to get replacement parts for.

The ABDX valve uses the more modern o-ring and diaphragm technology. The current concept is to buy the valve and it is good for 15 years and then you scrape (or repair) it. The railroad industry (manufactures and users) are doing its best to keep the maintenance forces and facilities to a minimum.

Undoubtedly, features of the UC-12 are lost due to its replacement with a freight valve. I suspect that would include the graduated release.

It is most interesting that the Boone and Scenic illustration shows a UE-12 installation. I guess this is probably a former electric commute car. The UE-12 system was set up to be electro-mechanical activated system with the traditional pneumatic automatic pipe system as a back-up. On most pipe brackets this third face is blanked.

I noticed that the Brake Cylinder also seems to be converted to a Freight car brake Cylinder which looks like a 10" or 12 " cylinder. Were the brake level ratios changed so the car would have the same brake shoe forces as it orginial did with the orginial brake cylinder which probably was a 14" or 16 " cylinder. Most ABDW conversations use a relay valve arrangement for proper brake shoe forces.

If the original MU car was a motor and not a trailer; then the smaller cylidner would be required in order to make up for the reduced weight of the motors and other propulsion gear that was removed for tourist trailer service. I have converted quite a few Lackawanna MU motors, and they required a new blanking plate for the magnet valves, a choke ajustment, and several new holes drilled in the brake levers to correct the brake ratio.

Steve

Guys,

Nice observations based on the photos on our page. Thank you for taking the time to review them. The comments made on this thread are all correct. Let me tell you what we have found.

A relay valve is a good thing to use. In most of the cases of these conversions the brake rigging systems have been very worn out. Wasatch has taken the approach of watching the cars in normal service and reading the temperatures of each wheel’s to determine which are braking hard and which not so hard. I became acquainted with the practice during the 2002 Winter Games when the State of Utah decided to run the same test on one of our Heber Valley Trains. The result was shocking. Though the brake valves of the cars were functioning, the shoes were not applying equal pressure on the wheels. What I learned from this is that a good brake system has as much to do with equal pressures on wheels as it has to do with a good and reliable brake valve system. Hence, when we make conversions we spend a lot of time figuring out which aspects of the linkage need the most attention for equal shoe application as well as focusing on brake cylinder pressure and so on.

The conversions we have done are individual and handled on a case by case basis. We strive to look at the entire system and give the customer the options. In the cases on our web page, the customers chose the options that you see. Again, the observations about the coaches are all correct.

The number one reason for this conversion above all other reasons is life of valve. The cost and frequency of changing a UC valve makes this conversion pay for itself in less than one year! The big picture is the cost savings on valve change out and frequency.

One car conversion takes about 8 hours. FINISHED

www.wasatch-rr-contractors.com

Merry Christmas from all of us at WRC

JohnE.

Others have all made very good points which all should be considered for a conversion. I believe one of the reasons for the wear on the U-12 is that the piston, piston rings, and the brass slide valves operates vertically, as opposed to horizontally as compared to, say, a D-22 system. Supposedly gives uneven and/or accelerated wear. But as many have noted, the 15 month COT&S period is a pain, and expensive to boot. Rubber diaphrams, checks, and "O" rings are cheaper and easier to maintain, and lighter, too...

One of the benefits of incorporating a relay valve in a freight brake conversion is that with the addition of an H-5 relayair valve and a safety valve you can incorporate a “Service Limiting” feature into the system. This is the feature the safety valve on the U-12 and D-22 perform and I think it has value particularly on cars in high speed or heavy grade service.

Service Limiting was also included on the old AB-1B system that most passenger equipped head end boxcars had. If memory recalls there was a filling piece with a Service Limiting safety valve that was picked up when the old air signal line was pressurized.

In looking at Amtrak’s operating practices on the NEC that require full service brake applications at speed I would not run a car with Freight Brake in this service unless it incorporated Service Limiting.

E.B. Levin

For those of us a little weak in the area of technical knowledge on air brakes, what is service limiting and how does it work?

It seems to me that the current standard in brakes for modern passenger equipment is the 26C system. Given that the ABDX system does not have the "rapid response" or graduated release features of the old UC system, when we talk about converting/upgrading/modernizing a car with UC brakes, why not convert over to a 26C system?

The 26C system is still a three year valve (four years only on Amtrak, commuter and other 49CFR238 regulated railroads), they are generally more expensive to acquire on the used market, and if you are stuck with a valve failure in the middle of nowhere and do not have a spare in your battery box, you are outa' luck (recent actual experience). Also, there are about sixteen different types of 26C/F valves, not all amenable to passenger service. ABD and ABDW are relatively easy to get used, and can be serviced anywhere the RR services its own equipment. BTW, Part 238 allows ABD variants six years in 238 covered passenger service; while freight (and tourist/historic) allows til failure, as long as it gets a SCT every time it hits the repair track.

Steve