What is a distinctive feature of the Standard (*F-type*) coupler?

The distinctive feature of the Standard (F-type) coupler is its squared corners. This design element is significant because it ensures a more secure coupling mechanism between rail cars. The squared corners aid in providing a stable connection that can handle the stresses encountered during train operations, particularly in terms of separating forces and side sway. This design is important for maintaining stability and safety, especially when trains are in motion or during tight maneuvers.

In contrast, rounded corners are typical of other coupler designs, which may not provide the same level of stability during operation. The use of lighter materials and designs for high-speed trains refer to specific applications or alternative coupler systems, which are not features that define the Standard (F-type) coupler itself. Therefore, the squared corners distinctly identify the Standard (F-type) coupler and reflect its intended function and reliability in rail transport.