What aspect of the axles is regulated by the radius rods?

The regulation of the axles by radius rods primarily affects the position of the axles under the vehicle. Radius rods are essential components in railway car design that help maintain the correct alignment and positioning of the axles as the train moves. By connecting the axle assembly to the main frame of the vehicle, radius rods provide a way to control the spatial relationship between the axle and the body of the train. This positioning is crucial for the overall stability and safety of the train during operation, especially when navigating turns or encountering varying track conditions.

Proper axle positioning ensures that the wheels maintain optimal contact with the rails, which is vital for performance, efficiency, and safety. Therefore, the role of radius rods in maintaining the proper position of the axles is a fundamental aspect of train operation.