Ok, it looks like you have USA plastic wheels along with early Charles Ro hook and loop couplers. How I can tell these are Charles Ro hook and loop couplers is due to the silver screws which use a flat head screw driver to install. The later USA hook and loop couplers used black srews which were install with a phillips head screw driver, a fact not too many people know. That curvy piece is actually the spring which gets install with the hook and loop couplers. You'll notice one coupler has a loop with a hook and then a loop without a hook, very common in the USA train world on the American series. The screws actually mount these hook and loop couplers onto whats called the truck of the rail car. Most people hate these type of couplers and replace them with either a USA knuckle coupler or as I seen on a few of your rail cars, kadee couplers, that coupler is like the king in any model scale.
