I have spent hours and hours pouring over diagrams in patents and repair manuals. I am fascinated by them to the point of losing entire afternoons.
Here are just a few of those I've found. I've led with some of my favorite Sheaffer diagrams culled and compiled from official Sheaffer repair manuals as well as patent documentation. The last one is from a 1939 US patent for a nice looking telescopic piston filler by a couple of German fellows.
An extensive list of Sheaffer patent numbers may be found by searching Fountain Pen Network for "Sheaffer Patents". The actual patent documents may then be downloaded from patents.google.com. Remember that I've warned you about the almost certain loss of the remainder of your day.