So where do you start with something like this?
The Sentinel Drivers' Club (SDC) has a drawings' archive and drawings can be obtained via the SDC archive page for a nominal sum. It's not quite that straight forward as first you need to know the drawing number required. This can take some time to work out but is not too difficult if an assembly drawing is available.
As such, the ashpan assembly drawing number for Sentinel 7109's boiler is 11815 although there is a simpler type under drawing 10634. As 11815 is a design which makes emptying of the ashpan more straight forward and doesn't tend to empty itself wherever it likes, that is the one that will be used.
|Ashpan 11815 Drawing|
(Courtesy Sentinel Drivers' Club)
|Detail Drawing Numbers (1)|
|Detail Drawing Numbers (2)|