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Tuesday, 16 October 2012

Anatomy of the Hall Typewriter

Some of those who expressed interest in the Salem Hall typewriter I posted on yesterday may like to know (vaguely) how it works. Here are some of the key components:
The Hall has a wafer-thin ink pad - more like an ink sheet than an ink pad, I suppose - that sits on the bottom of the typing unit. Each time the character pad moves and is depressed, it re-inks the characters. This ink pad was very dry - which is hardly surprising after about 120 years - but there were traces of a blue-ish purple ink still in it.
What is left of the character pad. I believe it is very rare to find a Hall with the character pad still intact. I don't know what this pad was made from, but as it dried and hardened over a century or more, it obviously became very brittle. Worse, it tightened and pulled in on itself, with the centre being drawn upward. Thus the break where the plunger (coming through the hole top right) has hit it.
The character sheet sits on top of the typing unit, under a holed plate. A scan of it is below:
This video demonstrates how the character pad moves as the characters are selected by the plunger (pointer):
video
This image shows the platen, with the measured paper bail drawn back. The bail is attached to a lever which emerges from the front centre of the typewriter. The typing unit, which can be partially seen bottom right, sits over the platen. The unit is moved along the threaded bar, seen right, by a tightly sprung brass wheel.The sprung levers release the unit upon each depression of the plunger and move it one space at a time.
With the paper bail drawn back on to the platen:
The various levers and wheels which operate the Hall:
I love this simple but effective way of taking the lid off the wooden case. The bar slips out from the hinge, allowing the user to remove the lid:

2 comments:

Scott Kernaghan said...

That's a curious machine you have there Rob. I love the design simplicity.

Ken Coghlan said...

That is absolutely fascinating, Robert. A great looking machine, and a great in-depth 'x-ray', if you will. I know I have heard of this typewriter before, but I don't think I have ever seen pictures that do it so much justice. Fantastic!