Looking at sevral kits that I’m interested in purchasing I noticed that sevral descriptions said that the model is equiped with K brakes, or this model is equiped with AB brakes. What is the difference? And what are the time periods they each were used? Thanks for the help guys. Dave
For a quick reply, the difference is the castings of the brake actuating valves and the piping going to it. Not my specialty, but I think all the visible difference is on the bottom of the floor.
The difference was and is in the control valve, rigging and construction. Do not confuse a control valve (one per car) and a brake valve (on the locomotive). Generally, and without going into gigantic detail, K valves are outlawed, having been some of the earliest control valves in use, common thoughout the 30’s and 40’s as were D-series valves. Westinghouse AB, ABD, ABDW and ABDE valves are improvements upon the K design and the ABD, for example is an improvement on the AB, and so on. There are specialized valves for certain service, but leave it suffice to say that we are near the end of the lifespan for the basic AB valve as well.
Hello Dave, The most obvious visual difference is that the most common K brake system, the KC brake, had the actuating cylinder, air reservoir, and control valve combined in one unit. Some K brake installations, especially on hopper cars, used the two-part KD system with the cylinder mounted separately from the reservoir/control valve unit. The AB system has a separate cylinder, two-part reservoir, and control valve. K brakes were in use from the end of the 19th century until the 1950s. They were finally banned from interchange service in 1953 (several earlier cutofff dates were extended because of the Depression, WWII, and postwar production delays) but could still be found on MOW equipoment and other cars that stayed on home rails into the early 1960s. The AB system was introduced in 1930 and adopted as the standard for all new freight car construction in 1933. It’s been updated with newer types of control valves and a variety of installation options – including truck-mounted cylinders incorporated into brake beams – but is the basis of freight car brake systems still in use today. so long, Andy
So if I understand you guys right, since I’m modeling the mid 30’s it doesn’t matter which brake my models have because they are both correct for the period and they’re on the bottom of the car where nobody will really see it anyway. Thanks for the help guys. Dave