What happens to the spring brakes when the air pressure is lost?

When air pressure is lost in a vehicle equipped with spring brakes, these brakes automatically engage to help stop the vehicle. This is a crucial safety feature designed to ensure that if there is a loss of air pressure, such as from a compressor failure or a leak, the vehicle can come to a stop effectively. The spring brakes rely on large springs that are engaged when the air pressure is depleted, meaning they do not require any manual activation. This automatic engagement provides an essential fail-safe for heavy vehicles, preventing them from rolling uncontrollably due to a sudden loss of air pressure. The design ensures that the vehicle is brought to a stop, prioritizing the safety of the driver and others on the road.