Identify a common type of equipment used for moving railcars.

Selecting a locomotive as the common type of equipment used for moving railcars is correct because locomotives are specifically designed to haul trains over tracks. They are powerful vehicles equipped with engines that generate the necessary force to pull multiple railcars, making them integral to freight and passenger transport in the railway industry. Locomotives also play a critical role in facilitating the movement of heavy loads, as they can manage various types of railcars, including those used for transporting bulk materials, containers, and passengers.

In contrast, while tractors and flatbed trucks are utilized for moving cargo on roads, they are not designed for rail systems and cannot directly transport railcars. Cranes, although capable of lifting and moving heavier objects, do not have the means to transport railcars down tracks as locomotives do. Thus, the locomotive is specifically tailored for this function, making it the most appropriate choice in the context of moving railcars.