貫通制軔

Train brake is a braking system type designed as the primary method to stop or slow down entire {{pll|Rail Vehicle Types|trains]. A lot of braking force is needed to do that, so each individual vehicle in a train is equipped with compressed air brakes , which allow synchronous mechanical brake application throughout the entire train.

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

The same control device is used to release train brakes. Release functions by the brake pipe getting pressurized by main reservoir . The auxiliary reservoirs then 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 motorized vehicles, whether it a single one, or many in multiple-unit configuration , using the independent brake is a more responsive option.

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