Initial Terminal Brake Tests (Class I / Class II / Class III)
The three classes
A Class I brake test is the initial terminal test. It is the most complete: 100% of cars inspected, brake pipe leakage test, brake application and release test, and inspection of piston travel and brake rigging. A Class II test is performed at a location other than the initial terminal - for example, a yard where the train is received, or where cars are added or removed. It still requires inspection of all cars and an apply-and-release test, but it is not the originating Class I. A Class III test is a trainline continuity test performed en route when a train is picked up and no Class I or II has been performed; it verifies that the brake pipe is continuous, angle cocks are in the correct position, and the trainline is not blocked. It is not a substitute for a Class I when cars are added.
What the tester actually does
For a Class I, confirm the train is charged, perform the leakage test, make a full service application and release, and observe that brakes apply and release on each car. Measure piston travel and inspect brake rigging, hoses, and angle cocks. Record the test and any defects.
Worked example
A train originates at an initial terminal: Class I. It later picks up 15 cars at an intermediate yard. Those cars and the trainline require a Class II test before movement. If the crew only performs a Class III continuity check, the added cars have not had the required apply-and-release inspection.
Traps that cost marks
Treating Class III as a full brake test. Performing a Class II when the train originates at an initial terminal. Failing to test after adding cars. Skipping piston-travel measurement on a Class I. Not documenting the test.