The local stops, the brakeman uncouples the train, the engineer pulls forward past the switch and then backs into the siding to pick up three boxcars. Are the air hoses connected and the air brakes pumped up at that time or does the engineer wait until coupling to the rest of the train; or does it really matter?
They wait untill they couple back up to the train, AAR rules(I Belive) State something like: Everytime you uncouple anything from the train you have to recharge and pump up the brakes.
Its GCOR but yea, we dont always follow that, especially when we are switching. Other times we just use a Class 3 air brake test whcih is usually sufficent. Once we get the whole train we will do a Class 1 terminal air brake test.
Engine goes into the siding and couples up to the three cars. The trainman would probably couple up the air and start charging the system. Walk down the cars to see if the hoses are made and anglecocks opened between the cars and closed on the last car, and hand brakes released.
Why? One. If there is still air in the brake cylinders, you either manually bleed it off or have to charge the system to move the cars. Two, you are going to have to make the air connections eventually, might as well do it now and save some steps. Three, if there is no air left in the resevoirs, they can be charging while you go back to the train. You have to have a certain amount of air pressure showing on the rear end gauge before beginning the air brake test. On a short train you could be up to the required pressure on the gauge without having sufficient pressure in the resevoirs on the new cars to set the brakes.
The system doesn’t have to be fully charged for the brakes to release or to move. Handling a small number of cars, the engine should be able to control speed and stop the movement. On a larger cut of cars, at times you may want to wait a bit to let the cars have enough pressure on them to help slow or stop movement. Depends on local conditions, how far your going to go back to the train, etc. Again, that wouldn’t have to be a full charge.
Once back on the train with everything recoupled and the train line properly charged, do your brake test and take off.
Jeff
Usually you would want to make up the air right away, especially if it is cold out. If the place is nice, the cars were spotted without uncoupling and the air would still be made up. The ground man would still want to check out the cars for any large defects while making up the air. Then when pulling out to the main, he would be in position to throw the switch and tie back on to the train.
Sometimes, the ground man would have a hand air gauge. Put it in, walk a set up, inspecting the other side. Check the release while pulling over the switch. Then, while doing the leakage test, the ground man would have plenty of time to walk back up to the engine.
I heard somewhere that when there is no air pressure in the system, the brakes would be set, and it takes positive pressure to release the brakes. Is that true?
Mr. B. That is correct (unless manually released) it takes positive pressure to release the air brakes. However, if the cars sit long enough, the pressure in the brake cylinder will gradually bleed off, and release the brakes.
In most cases, the crew would make the hoses and try the air (the Class 1 brake test) when they gather up the cars at the industry. Then when they return the train, preform the Class III (brake pipe continuity) test - which can be do using the EOT, so no has to be at the rear. After that checks out, away they go.
Nick