It had it's connecting rods removed, and a vacuum pipe cable tired from one end to the other so it was through braked. This pipe also seemed to have a valve near the cab window to allow the people on Mallard's footplate to stop the train if need be.
Mallard was moved on the mainline when it was taken to Doncaster works open day some years ago, and they did the same thing then as well with it's rods.
Which raises a quesion in my mind to which I really SHOULD already know the answer, but don't, or else I DID know once but now I've forgotten -
How were steam locos designed to be dragged?
Surely there was a mechanism to equalise pressure of both ends of each cylinder to atmospheric pressure?
(That would permit passive movements without any resistance from the un-fired steam pressure drive.)
Was that a valve controllable from the footplate, or was it an external job to open and release pressure?
And more specifically, when
Mallard had to be dragged back from Peterborough to Doncaster, after having destroyed one of her 3 "big end" piston bearings during that mad breaking-of-the-speed-record, what were the arrangements to allow her to be dragged back?
Did they have to remove the con rods then?
And was she dragged back north backwards?
How ignominious.