Northern Territory pics

[motto]

The application of the word drug to this type of transport would have to derive from the word drag and it may not have had widespread usage at any time and may spring from an individuals dialect.
I have a book on the early days of heavy haulage in Scotland and the north of England in which there is text and photographs relating to loads of up to 130 tons. The trailers on which these loads were carried usually had no steering as that would have increased the height of the load to an unacceptable level. These trailers had to be 'dragged' or skidded around corners.
Another comment made in the book is that the trailers didn't have any form of braking and that the wheel bearings had that much rolling resistance that motion would cease when you stopped pulling.
If that doesn't constitute a 'drag' I don't know what would.

David