Dennis explains:
The purpose of this is so the bolts pass through the fascia of the car, making the nuts accessible from
outside the car. This means that damaged roof panels can be replaced from outside the car; no need to
disturb the lining or insulation, or load, for that matter.
Ah ha! After my post’s initial crickets, I got out my (borrowed) copy of the ‘31 CBC, and began to think,
without the benefit of the correct reference drawing, that perhaps the roof used a lag screw going into the
wooden plate for the same reason Dennis gives above- access to the underside of the roof would have been
nigh impossible. But a standard bolt would be much more inline with standard construction techniques.
Thank you for sharing that.
And I’d completely agree that, consequently, there would be no use for such a fastener position on an Xm.
Last thing, perhaps for you Bill: when was the first application of these roofs? Pieter’s given me the
indication that they really aren’t appropriate for 1930, the rebuilds being from the later 1930’s.
Earl Tuson