Brake van had two additional functions:
- The guard would use the brake van's brakes to assist with keeping the train under control on downwards gradients and whenever he could see that the locomotive's crew was attempting to slow the train.
- The brakes were left set on at a low setting all the time to ensure that the loose chain couplings often used between unfitted cars were kept taut, to minimize the risk of snapped coupling chains from the locomotive "snatching" or jerking, which was particularly problematic in the days of steam locomotives. Brake vans thus had a significant amount of ballast weight built into their structure to increase the available braking effort.
These days brake vans are only used in certain special cases, for example in trains with unusual cargoes or track maintenance trains, and are consequently very rare.