Brake test step by step
How to check that the brakes work on the entire train — not just on paper
When wagons are coupled together and brake hoses are connected, the train still isn't ready. The brakes work through a continuous compressed air line—often called the main line or main air tank line—that runs the entire train's length. A single unconnected hose, a closed valve, or a leak can mean the brakes fail on parts of the train even though they work fine up front. So the brake test isn't a formality but the control that actually determines whether the train can run. Historically, failing brakes have been among the most common causes of serious railway accidents worldwide, and this is part of the background for why the brake test today is a fixed, documented process with clear tolerances—not an individual assessment case by case.
§Why it is not enough to just connect the hoses
The compressed air must be able to flow unobstructed from the locomotive or control car and all the way to the last car. This is typically checked by walking backwards along the train while the system is pumped up, and finally opening an air valve at the back and letting air out until the rear car's brakes respond. This way it is confirmed that the compressed air actually has free passage through all cars — not just that the hoses look connected.
§Phases of the brake test
- 01Inspection of coupling and air passage — ensures that compressed air reaches all the way back
- 02Inspection of vehicle condition — visible damage, wear and faults in brake equipment
- 03Leak test — measures whether the pressure in the main line stays within tolerance
- 04Braking inspection — brakes must respond consistently across the entire train
- 05Inspection of solution — brakes must also be able to release again without getting stuck
- 06Issuance or renewal of brake certificate when the train is approved.
§The leak test: how much can the pressure drop?
During the leakage test the supply to the main line is closed and one watches how quickly the pressure drops. A slight drop is normal because no joint is one hundred percent tight but if the pressure drops too quickly there is a leak somewhere in the system that must be found and fixed before the train can be approved.
| Control point at pressure test | Requirements (Banedanmark train preparation rules) |
|---|---|
| Brake line pressure before the test | 5,0 bar |
| Maximum permitted pressure drop | 0.5 bar per minute |
§The brake certificate is your written proof
When the brake test is completed with an approved result it is documented in a brake certificate. The certificate shows who performed the test and that the train in its current configuration has passed. If the train's configuration changes – for example when a carriage is decoupled or coupled – the brake test should generally be repeated because the previous certificate no longer covers the new configuration.
§When should the test be repeated?
A full brake test is not something you only do once during a shift. As a general rule it must be repeated whenever the train's composition changes — for example when a car is coupled or uncoupled or when the train's braking system has been disconnected from the compressed air supply for a longer period. However if the train has been assembled and connected without interruption there may in certain situations be a more limited check rather than the full test. But it is still a fixed defined rule set — not an individual assessment — that determines when the full brake test must be performed again.
§The routine is your safety
For an experienced train preparer the sequence of phases can seem like sheer routine but it is precisely the routine that prevents a single step from being skipped on a busy day. A brake test that skips the sealing test to save five minutes is not a faster brake test — it is not a brake test.
“The one who signs off on a brake test vouches for it that the entire train can stop — not just the front car.”