Freightliner 70012

[ac6000cw]

There's some discussion of couplers in the comments on YouTube, including a reference to the "draught centre" being different between US and UK. That phrase means nothing to me (and search engines get diverted away into irrelevant draught excluders and draught beer ), but it might refer to coupler height.

AFAIK in the US the 'draft gear' is the shock absorbing mechanism behind the centre coupler ('draw gear' in the UK?). It fits in a space in the vehicle underframe (I think this space is sometimes called a 'coupler pocket'). So I guess the 'draft center' is the centre line of the draft gear i.e. the coupler height, as you suggest.

 

[norbitonflyer]

Yes, it's draught (or draft) as in pull (think of draught horses, or pulling pints of draught beer), rather than draught as in unwanted air movements. (although the derivation is the same - hence the airflow used to draw a fire)