Would anyone be able to give me a quick rundown of the differences from earlier airbrake system designs (say, 1900 - 1930) and modern 26L( ?) types?Further, what would be the major advantages to replacing such an early system on restored equipment? Would it simply be better compatibility, or FRA regulations?Thanks all!

.

Tim, both the C&TS and the D&S use 6ET to bring trains down their steep grades.The only reason I can think of for upgrading would be if you were planning to be on a Class 1 mainline, where employees were familiar with the 26L but not with older valves, and where you might need to prevail on a local shop for repairs. That is one reason that 611 got a 26L stand in 1982, for example.If you're talking about an engine in captive tourist line service, where you train your own engine crews, I see no reason to switch.But then, I have more cab time on vacuum brakes (2 hrs.) than air brakes (0 hrs.), so take it for what it's worth.JAC

I would suggest going to your college library and looking for any old issues of the now-defunct 'Railway Mechanical Engineer' magazine, formerly published by Simmons-Boardman. There was a wealth of air brake material to be found in those publications. To this day, the publisher has for sale quite a bit of material pertaining to 26L and newer air brake systems.As the WABCO offices in Wilmerding are not far from Pittsburgh, there may some other air-brale related materials to be fouind in the library. Of course, a secondary source for this type of thing would be EBAY.The 24RL system was not marketed for a very long time, and was superceded by the 26L primarily for reasons of initial cost, operational flexibility and ultimately-maintainability. Some 40 odd years later, both WABCO and NYAB can still supply new 26L equipment.

Hi Tom,The Lancaster, PA and Phila chapters NRHS joint restoration committee just completed upgrading the original 24RL brake systems on both restored Reading FP-7 locomotives 902 and 903 to to 26L.We decided to make the change for those reasons already stated in previous posts to this thread, but mainly to give us potential operational flexiblity in the future. We ran into issues of engineer qualification on the 24RL along with their lack of operational experience with it. This would be the case if you needed to operate on a Class 1 Main, but not necessarily for short line or tourist lines. The 26L also a much "cleaner" system installation wise to troubleshoot if you run into problems. Fortunately we were able to obtain and install "Unirack" manifolds for centralized control and check valve installation, along with using FRA approved plastic flex tubing and brass push connect fittings. This really saves a lot of work having to otherwise bend copper tubing for your air supply/control lines to the brakestand and reservoirs.Dave

One advantage of 26 over 6 is the pressure maintaining feature. If you are operating on long downgrades this feature can be very handy. The use of a standard set of cars like many tourist railroads use can greatly reduce the need for pressure maintaining if the brake systems do not have much leakage. If you are handling any freight with the locomotive pressure maintaining will make it easier to handle the trains downgrade.If you are running steam some railroads seem to have a lot of trouble with the oil from their compressors gumming up the valves of 26 equipment. Oil seperators and extra cooling capacity in the brake system can reduce the problems but they still seem to have more trouble than the old 6 systems. John Bohon

A lot of good info here, but no one has addressed the first part of Tim's question, which seems to ask for a list of obsolete brake schedules. I'm certainly no air brake expert, but I've run into a few, and with the help of some locomotive diagram books, I'll give it a shot:6ET The most common schedule on steam in the twentieth century, offered by both Westinghouse and New York.8ET Improved system used on some modern steam.14EL Similar to 6ET, for use on electric locos, boxcab Diesels, and early Diesel switchers.6DS Early Diesel switchers.6SL Early Diesel switchers.6BL Early road switchers.All of the above are non pressure maintaining, and handled the independent in multiple unit consists by exhausting all the cylinders through the lead unit.6BLC A conversion system that could MU with either the earlier 6 and 14 style independent brake system or the system used on 24RL and later.24RL F-units and other early road locomotives; non pressure maintaining, self lapping independent.24L Later road units, pressure maintaining; both automatic and independent self lapping.26L Current production, same operating attributes as 24L.That's all from memory. Anyone who sees an error, feel free to chime in and correct it.

Kelly is correct when he talks about ease of maintenance. All of the brakes mentioned, with the exception of the 26L system involved a lot of lapped valves, cylinders, piston rings, etc. These were very labor intensiveand costly to maintain (overhaul). The 26-series brakes use "O" rings, rubber diaphrams, etc. Much easier to produce and install. There is a "6N" modification for the old 6 system which is a modern update and features a modern automatic brake valve in the cab and an "O-ring" and diaphram distributing valve which replaces the old one under the floor One last thing, the FRA favors the newer more reliable systems with longer intervals in some of the periodic maintenance. Interestingly enough, while attending a training session at WABTEC (the "new" name for WABCO) last year at Wilmerding, we saw the machine which is still used to produce the piston rings for the older style brake valves. A number of us were fascinated by the machine, which was probably at least 80 years old, which still functioned and was cranking out piston rings. The worker who was operating the machine couldn't figure out why we were interested, but kindly explained the operation and then demonstrated the process slowly for us. Generally, the manufacturers support their products when there is a market for them. Some of the smaller contract air brake shops around the country have a pretty good supply of parts set back, as well.G.F.PayneBaltimore

Thanks for the great information everyone, it's appreciated. Being the first person in the Botti family to NOT work for WABCO in some degree (my dad and uncle worked summer jobs through college there, grandfather was a machinist), I should have thought that the company itself would be a good source for information. I'll check into that one.Cheers!

While performing the due diligence for the air brake conversion (24 to 26)on the New Haven 0401 FA-1 project, I spoke with a whole host of supplier, builder and railroad reps. in order to get a handle on the subject.One of the most interesting things that I learned is that air quality within the confines of a diesel locomotive carbody was much more favorable to a 24 system than a 26 system. Consider the fact that diesel locomotives tend to eventually leak all their working fluids (fuel oil , lube oil, cooling water, exhaust) into the airstream within the carbody. So, when air compressor is loaded, it tends to draw this stuff into the intake-with the only line of defense being a pair of crude wire mesh filters. Applied downstream of the compressor was something called a 'H' filter, which used a simple horsehair or wire mesh filter element.Of course, the oil/water vapor present could conceivably serve to lubricate the various metal/metal interfaces within the brake portions.On the 26 system, this vapor could negatively impact performance/service life of the rubber o-rings, diaphrams...and so on present within 26 equipment.The first line of defense is to improve the quality of compressor intake air. This was done by applying a two stage filter-a wire mesh panel to catch the 'big stuff' and a paper filter for the 'fines.'The next line of defense was to condition the output of the compressor. For many years, the 'gold standard' was the 'Salem 824'-which provided both an inertial separator for the heavy stuff (water and oil droplets) and a paper filter for the fines. This device was a great improvement over the H filter. On EMD road locomotives with 26 brake, I believe a secondary filter (Salem 818) was applied to condition air for sanders, horn bell, wipers, etc.Believe that Salem could supply a coalescer version of the 824 for use in older locomotives.And yes, the presence of automatic drain valves on the MRs helps to remove water from the system.On the newer locos with computer controlled brakes, Salem supplies a very sophisticated air dryer known as the 'Twin Towers'. Dave

Tom,Let me add a word for historic preservation. a given locomotive or car had a specific air brake system that was from its historic period. If you are going to display the item it should have the correct air equipment; just as it should have the correct bell, heatlight, generator etc.This is one reason that museums have their own tracks to demonstrate their trains. As time goes by the changes between modern Class 1 Railroads and what the museums preserve will be more and more dramatic. To say nothing of FRA mandated items like striping and ditch lights, which were not there in our historic periods.Thanks,Ted Miles

Ted,I wholeheartedly agree. Part of preserving technology is preserving the skills required for its use.That being said, I can see where operators who need to make use of mainline railroads have issues with the personal they have to work with, and I see why they feel they need to upgrade to more current equipment. I prefer to think of this as adaptive re-use, rather than preservation, and I hope that all the parties concerned understand that by doing this they may get to run the artifact today, but leave it less valuable for future generations.

If the operators/owners of 'big steam' were as doctrinaire (with respect to the air brake question) as the previous two posters-how many of these leviathans would have seen the rails over the past 20 years ?Dave

At least one steam leviathan is still getting over the road with its 6ET system intact: Pere Marquette 1225. At the Huntington NRHS convention of 1991 our enginemen used this brake schedule to handle a 32-car passenger train with perfect ease. Although the pressure-maintaining feature of modern systems might be useful in some situations it wasn't needed here, and we have no intention of modifying the brakestand of the 1225.The automatic train stop (ATS) system installed on this engine by the Pere Marquette has been amputated, however. This was partially in compliance with rules that say that all equipment on the locomotive must be maintained, and partially to make room for the engineman's feet. As built, the electropneumatic doohickeys that operated this system occupied all the space where the engineer's feet would normally go. The low-hanging inductor was removed from the tender truck for fear it would snag on something at trackside.