is a repair yard that specialises in diesel engines. It is the diesel equivalent of the Sodor Steamworks. When it was first introduced, the Dieselworks was run down and shabby, with insufficient and damaged equipment. After a fire broke out in the main building, it was rebuilt. Den, Dart and Diesel 10 live and work at the Dieselworks.
The company's logo is a picture of a diesel engine, of similar appearance to Den's class. Both Den and Dart have this logo on their liveries.
In the nineteenth season, the small warehouse, that serves as an extension to the main Dieselworks building, is shown to house a large smelting foundry, where all the broken parts are melted down and reused again, to build new parts.
Equipment at the Dieselworks includes:
- An elevating turntable
- A crane named Happy Hook
- A set of lifting jacks
- An on-site smelting department
- A five-road shed with a turntable to accommodate the diesels
- A special shed for Diesel 10
- A giant vice
- A scrapped model of Charlie's cab is seen inside.
- The Dieselworks is located in a desert-like area, not far from Vicarstown.
- A scrapped Marklin engine has been seen at the Dieselworks in Blue Mountain Mystery.