QUOTE(WCO @ Nov 23 2007, 10:42 PM)
Here is drawing of a screw press used in Russia.
http://www.picatom.com/b/1-967.htmlDrawing was made in 1830-s. Rittenhouse, what do you think, was there rotational momentum on an upper die? How movement from screw was passed on a die?
WCO,
I'll need to be brief here, I'm working to deadlines on two major articles, one for JRNS.
Thank you very much for the neat picture, I downloaded and added to my refs. Cooper had few Russian images. Do you have any others? I don't read Russian but will have translated. I am particularly interested in the die/collar articulation. There were two basic schemes for this - raise the die or depress the collar - but several different articulation for accomplishing.
The press is counterweight type - note the heavy ball weight attached to the curving lever in the side view. Interesting mechanism there, too. Hadn't seen that particular style before. Anyway, the weight/lever held the upper die block (or slider) against the bottom of the screw. The die block is the big rectangular block in the middle of the press to which the upper die holder is attached. It is indicated by the highly stylized "d" in the drawing.
As the screw descends it pushes down on the upper die block causing it and the upper die to descend and effect the strike. The upper die block isolates the upper die from the torque of the screw. The two cross-members (not indicated by a letter) prevent the upper die block from twisting due to the screw torque. This was a fairly common arrangement as can be seen from the leaf spring and counterweight style press images I posted.
It is, however, an older design and was superceded in most mints by the early 1800s with the improved, lighter weight mechanical assemblies seen in the Boulton and 1801 French press images. These designs had significant advantage since they didn't have the heavy and cumbersome counterweight flopping around. The weight reduction and smother mechanical operation resulted in significantly improved coining rates over the counterweight design.
If this drawing is from 1830, it is not a coining press since, as RWJ notes, they were replaced over 2 decades prior by the Bouton press. Screw presses were retained for use in striking medals and proofs and, of course, hubbing dies.
The pull-strap, check rope and collar shown in the drawing does establish that the press as shown was set up for coining proofs or medals. One or more men would pull on the pull-strap ("a") to effect the strike. Another man would likely have been opposite to assist in opening the press and returning the arm to the pressmen for another strike. The check rope shown on the opposite arm (again no letter) was tied off to an anchor bolt sunk into the floor to as a safety precaution - it checked the swing of the arm. The really neat thing about this is that this operating scheme is actually docmented in the historical record by George Eschol Sellers!
If the press had been set up for hubbing the collar mechanism, pull strap and check rope would be removed. The press was then operated like a giant vice to impress the die. This operation is likewise documented in the historical record and Cooper actually shows a photo from an Eastern European mint where a screw press was still being used for hubbing in the mid-20th century! Coopper did tell me the where and when of the photo, but I can't recall off-hand. Maybe Hungary like 1950s or 60s?
The press has a couple other intersting features. First, it's obviously a bruiser - very heavy, probably cast iron or low carbon structural steel. Although it could be bronze. The historical record does document the use of bronze frames in the Paris mint cast from cannon captured during the Napoleaonic war. But, both the sheer size and style of the press tend to indicate cast iron or steel.
Also note the faint outline of the screw and T-shaped nut in the front view (on left). This is a common design feature of screw presses. The mating threads for the screw were not cut into the press frame itself, but rather a large T-shaped nut which was then fit into the press frame and pinned in place. The head of the T nut was also typically a hex shape to further resist twisting. This enabled replacement of the nut when the threads wore out. Otherwise they'd have had to re-bore the press frame. Clever, huh?
Since the press is Russian, I'd really like to do an article for JRNS on it. Could you please supply a reference to the source? I'd also like to credit you with supplying the image so could you please post or PM your name.
Thanks again for the image - very, very cool
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