Internet Horology Club 185
Graham Deadbeat

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October 02, 2015, 09:29
Moses Gingerich
Graham Deadbeat
Hello All Ye Experts,
Been gone for a while but glad to be back. I have a question:
Can anyone describe what the drop and lock sides are in the Graham Deadbeat movement? I seem to get confused how to detail which one. Of course the deadbeat is defined as having the escape wheel "stop" as in dead motion. But which is the drop and which is the lock?

October 05, 2015, 01:12
David E. Booth, Jr.
This is what "Scottie-TX" over at Nationals says about "lock and Drop", in a discussion about recoil scapements:

"Semantics, and I'll not try to convince you there is lock on a recoil as first, I couldn't do it and second, it would be non-productive.
Like many call the anchor a verge. There is a verge. It is for a verge escapement that has recoil. But when someone calls an anchor a verge - I still know the part referred to is an anchor. Some call 'em gears. I know they're referring to wheels. Semantics.
Even the experts differ on lock and drop.
When discussing, "lock" of a recoil escapement, Penman calls it "bite".
Conover avoids giving it a name at all - only describes the event.
Balcomb calls it, "engagement".
Whatever you wanna call it. We all know of the event being described.
Experts differ on the meaning of drop - well - not the meaning but which is entry and which is called exit.
The most accepted is inside and outside - inside being entry and outside, exit.
The difference comes when one describes exit drop as the time and space preceding tick heard on exit face. Most would call this, "entry drop", i.e. the drop apparent after tooth leaves the entry pallet and until the tick of it dropping to the exit pallet.
So when discussing drops it is important to know how YOU regard it or describe it because exit drop is changed by a procedure different from that of entrance. "

But I agree with Scottie and with Laurie Penman that "drop" is the amount of free movement of the escape wheel between palets. So, in a Graham deadbeat escapement, the escape wheel tooth hits an entry (locking) pallet, then slides across it to an impulse face, the wheel freely travels through a certain "drop", and the next engaging tooth "locks" on the exit pallet. That tooth then slides across the exit pallet, and down the impulse face, allowing drop to once again occur, until the next tooth encounters the entry pallet, and the escapement is locked once more.

Some people refer to the sharply angled pallet in an American recoil anchor escapement as a "drop" pallet, and the pallet at a (nominal) right angle to the anchor as a "lock" pallet. To my way of thinking, all that does is unnecessarily confuse the issue. If we consistently refer to pallets as entry and exit, and to faces as either locking, recoil, or impulse, and reserve the word "drop" to mean the arc of free travel of the escapement wheel, a great deal of confusion can be avoided, regardless of the type of escapement under consideration.
October 05, 2015, 09:42
Mike Benda
This may be helpful.
Graham deadbeat
October 06, 2015, 15:11
Mike Benda
And here The link to an escapement model. Within the same site is a model that can be adjusted.
This is an excellent learning tool.

Graham model
October 27, 2015, 22:39
Moses Gingerich
Thanks David and Mike. You are appreciated.