Very simple,'L' bracket on roof with hole in bottom,'L' bracket on inside of wall,with hole (half inch) a bolts goes through,a wing nut attaches underneath.there are 8 of these,very,very simple
I will post pics tommorow,too cold to go outside now.
Its a very simple system,with the bonus of adjustment for ground slippage,see the pic again,note the bolts and nuts,I can 'tilt' the roof if needs be about 5mm either way,(does this mean I have a 'tilt' train in my yard
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also,the castors have 5mm 'play',not that I have ever needed to call on any of this,never had an issue,never had any maintanance,a bit of CRC to stop rust colour.
Cant go wrong with this design,I have seen a set up like you mention,I nearly went that way,then we figured this was more simple,less likely for lproblems,Hope this helps,