11-18-2015, 09:40 PM
BR60103 Wrote:Charlie: I don't know brakes. Is the 26 a development of the 6?I only know the ones I had, and the 26 is a later brake that has the passenger setting that allows a passenger train with the proper brake valves to do a partial release. Maybe an engineer is on here that can explain it because I never handled a passenger train equipped that way, but I think it was designed so you could go from a 20 pound reduction to a lower reduction causing a gradual release of the brakes, like easing up on the brake pedal of a car. The 26 also had a maintaining feature that kept the air in the trainline from reducing below what your application was. With freight equipment you must completely release the brakes and allow the air to build up in the train line before the next application or you can get into deep do-do. The 6 brake was on lots of older equipment originally including steam, and the 14 was just a little later version. If you make a 15 pound reduction with a brake that does not have a maintaining feature train line leakage will keep setting the brakes harder. I am not good at explaining it but if you normally have 90 psi of air pressure in the train line, the air brake reservoirs on each car will pump up to that pressure. That is why you have to build air when a train is made up. When all the pressures are equal the brakes will release. To stop you remove air from the train line and the air pressure in the reservoirs is higher and the brakes apply. A 15 pound reduction would thus bring the train line to 75 PSI and give a gradual stop. Dumping the train line puts the train in emergency and all the pressure in the reservoirs is used to apply the brakes. One other note, a car (or train not running) sitting long enough can lose all of the air in the reservoirs and the train line, which makes things equal and the brakes will release. That is why they need X number of hand brakes tied down before leaving cars or a train.
The 26 is also very easy to set up to MU or to tow an engine like they do when they have an unoccupied engine on one end of a local.
Regards
Charlie