Re: Air Brakes

Another problem with straight air is that it puts a limit on train length as the air tank on the engine can only fill so many cylinders and so much pipe at a high eough pressure to operate the brakes. Of course Automagic air also has length issues but in general the couplings won't be able to take the strain before a train reaches the length that would be a problem. Exception to that, the northernmost lines have had problems caused by cold in Winter. CN, CP, GN & others have all used midtrain units to supply additional pressure to the read end. Sometimes old diesel units, sometimes gear installed in box cars.
hank