<Li> Keith Wickham (UK / US; Misty Island Rescue onwards) </Li> <Li> Naoki Tatsuta (Japan; seasons 6--8) </Li> <Li> Ryuzou Ishino (Japan; season 9 onwards) </Li> <P> Den is a Diesel engine who runs the Dieselworks when Diesel 10 is not around . He is very thoughtful and thinks hard before he speaks . When Den does speak, it is very slow . This gives the appearance that he may be a little slow, but nothing could be further from the truth . Engines can wait a long time for Den to give his insight, but it is worth the wait . </P>

What are the engines called in thomas the tank engine