What is the function of brake shoes in rail systems?

Brake shoes play a critical role in the functioning of rail systems by providing the necessary friction against the train wheels when the brakes are applied. This friction is essential for slowing down or stopping the train effectively. When a train operator activates the braking system, the brake shoes press against the wheel surfaces, generating the resistive force that limits the train's motion. The effectiveness of braking relies on this friction, which must be sufficient to overcome the train's momentum.

The other options, while related to the railway system, do not pertain directly to the function of brake shoes. Securing freight loads involves different mechanisms such as tie-downs or containers, connecting train cars is accomplished through couplers, and controlling train speed on inclines is managed through dynamic braking systems or throttle adjustments, not specifically through the action of brake shoes.