貫通制軔

In order to stop or slow down, trains need a lot of braking force. For this reason each individual vehicle in a train is equipped with compressed air brakes , which allow synchronous brake application throughout the entire train. This is called a train brake.

Train brake is applied by a control device found in motorized rail vehicles. Applying brakes on a fully charged train functions by getting air dumped from the brake pipe to the atmosphere. This forces auxiliary reservoirs to feed their stored pressure to brake cylinders , pressing brake shoes against the wheels and braking the train.

Train brake is released by the same control device. Releasing brakes on a fully charged train functions by the brake pipe getting pressurized by main reservoir . This forces auxiliary reservoirs to recharge from the pipe and no longer feed the brake cylinders, depressing the brake shoes from the wheels and no longer braking the train.

貫通軔機通常透過位於動力車輛上的貫通軔機司軔閥（自閥）手柄操作。如果一組列車中有多架動力車輛，壓力將受到「自動保壓」式司軔閥或是位於更高緊軔位的司軔閥主導。

Train brake should be used when a train contains cars . If the train only contains a single motorized vehicle, or multiple ones in MU configuration , using the independent brake is a better option.

To aid the train brake and prevent brake shoes from overheating , some motorized vehicles are equipped with dynamic brakes , too.