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Sunday 13 November 2011

Solving the problem with the Imperial Model D Portable Typewriter

A big thank-you to Rob Bowker, Richard Polt, "rn" and to Adwoa for their suggestions and encouragement with my efforts to get my "new" Imperial Model D Portable Typewriter working.
I think I have located the source of the problem, as the videos below will indicate. Anyone watching the videos might be able to spot the difference from a working Imperial Model B (black) and a non-working Model D (green).
I have removed the keyboards-typebaskets on the Model D and my Model B to see where the differences in the mechanisms are. And the inner workings of the Model B and the Model D do differ somewhat, as can be seen from the photos below. One obvious thing is that the B has a rounded, fairly wide plate under the typebasket which activates the pawl and the carriage movement.
Neither has a pawl to engage with the escapement rack, as such - not a round one, anyway. It is more like a three-toothed tomahawk head. Is there a spring missing from the D (green)? The spring on the Model B can be clearly see pulling the "pawl" forward.


Rob Bowker said...

They look so similar you'd think they'd share the same works. You can see where the spring isn't on the Model D. Hopefully that's your answer - great videos, by the way! There's a little recess on the corresponding screwheads. I wonder if swapping the spring from the B to the D would give you a conclusive diagnosis? Or just poke something in there with you free hand (:-))to bear on the pawl, see if it catches on the rack? Pretty convenient having two similar machines!

Robert Messenger said...

Thanks, Rob. Yes, I have poked at the pawl on the Model D and seemed to get one or two movements out of the carriage. For some reason, the pawl seems to me to be not engaging squarely with the rack, it seems to sit up a bit. I tried tightening and loosening the screw, but that just made the carriage move free. I had another look and there is a spring on the bottom right (looking from below) of the pawl, maybe that's the one that's not functioning. Can't see where a spring would attach on the top left, as in the Model B.

Robert Messenger said...

Sometimes these blessed vintage typewriters make me feel like a complete amateur! I remember I had to get Terry Cooksley to fix the mainspring on a Hammond, and it should have been straightforward! (Probably was for him)