A Budd Rail Diesel Car, or RDC for short, is a train that has a special kind of engine called a diesel engine. The engine uses a special kind of fuel called diesel fuel to make it go. The RDC was made by a company called Budd Company and it was used in the United States during the 1940s and 1950s.
The RDC looks like a long metal box with windows on the sides. Inside, there are seats for people to sit on and a place for the conductor to sit too. The RDC was very important because it allowed people to travel from one place to another very easily without having to worry about changing trains or waiting for a long time.
The RDC is also called a "self-propelled railcar" because it can move on its own without needing another train to push it. This means that it is a very flexible train and can be used in many different places.
Overall, the Budd Rail Diesel Car was a very important invention that helped people travel more easily and quickly. While it may not be used anymore today, its legacy still lives on as an important part of the history of transportation in the United States.