When is a train's brake system considered "kept charged"?
GM1361 When is a train's brake system considered "kept charged"?
After the Initial Terminal Brake test has been performed and the 'Air Slip' has been prepared to document the results of the test - Air, either from a engine consist or ground air plant must remained attached. If the cars are 'off air' - for whatever the reason, for more than 4 hours then the Initial Terminal Brake Test must be done and documented again when a air source is returned to the cars and they are to be moved on a train.
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why should trains be kept charged?
GM1361Why should we keep trains kept charged?
The Initial Terminal Brake test takes time - The trainline must be charged to at least 75 psi which takes time no matter if the source is a locomotive consist or a ground air system. The brakes must be applied and a qualified person must walk the train and verify that the brakes are applied to each car in the train (or cut of cars) and that the brake piston travel is within the acceptable limits and that all cars have brake shoes that are not worn beyond the acceptable limits. The air leakage of the trainline must also be measured and must be less than 5 psi per minute, if greater then the cause must be fournd and corrective actions taken. After the application has been walked and verified, then the brakes must be released and the train (or cut of cars) walked to verify that the brakes have released on each car. The time required to properly perform the initial terminal brake test will easily require a hour or more on a reasonable mile long size train - if there are problems that have to be repaired, much longer.
Once a Initial Terminal Brake test has been performed on a train or cut of cars - you want to keep the trainline charged so the procedure doesn't have to be repeated as is required when the train (or cut of cars) has been off the source of air for more than 4 hours. Needless to say, the longer the train (or cut of cars) the longer it takes to perform the test.
GM1361How much air pressure should be(acceptable) in the trainline after two hours?
When a active train makes a stop and part of the train is cut away from the remainder of the train, the anglecock on the head end of the remainder of the train should be left open and thus the trainline is vented to atmosphere. The trainline pressure should be ZERO.
Closing the anglecock on the head end of the remainder of the train is known a bottleing the air and is prohibited by most carriers - with air bottled, it is 'possible' for a faulty brake valve on a car in the remainder of the train to release the contents of it's car's brake resevoir to the trainline and thus create a increase in trainline pressure and thus cause all the other brake valves on the remainder of the train to 'think' the engineer has put air into the train line and all the brake valves release their brakes. Cuts of cars with bottled air, without being secured by hand brakes, have repeatedly run away, that is why bottled air is prohibited. If the trainline is vented to atmosphere, a defective brake valve releasing its resevoir will not raise the trainline pressure and cause the other brake valves to release their brakes.