Pressure Bar Reduction Gearing

[Huw Eastwood]

It's a real interesting topic this one- it's the Cleveland Fed door that's had me baffled, the fact they spin that massive capstan handle for what seems ages- and fast as well, you see the guy putting his hand against it (bad idea?) as a friction brake.

All that shouts worm gearing to me, as I can't see how spur or planetary gearing would have enough difference on the ratios to allow that many revolutions and that much speed. The problem with worm gearing though, is the offsetting that wylk mentioned. Not easy to cram all of those types into the housing drum since the offsetting takes up a lot of space and bearing in mind the actual bearings and supports would need to be massive. I can't remember what the One King West door is like- I'm assuming it's lack of capstan handles on the hand wheel possibly means it's turned slower and for less revolutions?

On the One King West door, one thing that will determine if the 2 pressure bars are separate is they will rotate in opposite ways. If it's a single bar straight through the housing driven by a single crown and pinion gear then it'll turn it one way. If the pressure bars are individual and each is driven by its own gear on opposing sides of the drive gear, then the left bar will rotate in the opposite direction to the right. Not an easy thing to determine from even the clearest of videos though, I think you'd need to be there and try it! My guess is crown and pinion bevel gearing on the One King West door, but the Cleveland Fed I'd love to know. Doug, what's your chances of pulling the front cover off the drive housing lol

[wylk]

Placing the pressure system under the crane hinge instead of over it seems to be a rather late development. One advantage I can see is that the pressure-bar anchors will not stick out of the frame as far, reducing the problem of tripping over them and bumping into them.

Based on a quick skim of images, it appears to have been done by Herring-Hall-Marvin. By this time I think they were subcontracting Diebold for the actual manufacturing but I didn't find any Diebold examples (I did say it was a quick skim). Here is a nice example in Festus, Missouri:



Notice the doorstop's latch on the door, something we were discussing earlier in another thread.

Here is another round example in Saint Louis:



But HHM wasn't the only adopter of this new arrangement. Here is one of my favorites, 510 Fifth Avenue NYC which is a Mosler from 1954:



I always think the crane hinge shape is "awkward". Note the door stop in the corner.