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About Locks and Drops

bangster

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Because I still haven't fully internalized this stuff, and don't find it in easily available form in any of my books, I've looked through the archives and assembled what I think are the basic definitions and instructions. I'm posting them here so they'll all be in one place.

bangster
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ABOUT LOCKS AND DROPS

•DROP is the amount of rotation of the escape wheel as one tooth is let off the anchor and another is caught.
• There are normally two drops that must be measured and adjusted, entrance and exit drop. They should be equal.

•The ENTRANCE DROP is adjusted by varying the distance between the entrance and exit pallets.
•Closing the pallets will decrease the entrance drop while opening them will increase the entrance drop. This doesn't effect the locks or exit drop.

•The EXIT DROP is adjusted by varying the distance between the pallet arbor and the escape wheel.
•Moving the pallet arbor farther away from the escape wheel increases the exit drop (and decreases the entrance and exit locks.)

•LOCK is a measurement of the overlap between the pallet face and the escape wheel tooth at the moment the tooth is "caught".
•Just like drops, there two locks...entrance and exit lock.

•Varying the EXIT DROP adjusts both entrance and exit LOCK.

•RUN is the measurement of the amount of travel of the escape wheel tooth up the pallet face following lock. It is visible in the motion of the pendulum as over-swing or the extra swing of the pendulum following the tick or tock. If you don't have any run (over-swing) your escapement isn't healthy and the clock will eventually stop.

•The sequence of events is...(1) entrance drop, followed by (2) exit lock, followed by (3) run (recoil in a recoil escapement), followed by (4) slide (impulse in a recoil), followed by (5) lift or impulse (in a deadbeat), and then (6) exit drop.

•The drops should be as small as they can be and still have the escapement be reliable. In other words, the drops should be large enough to account for the inaccuracies in the escapement, like poor tooth spacing and an out-of-round escape wheel.


•The more lock you have the better the action of the pendulum. But, it is possible to have too much lock where the power to the pendulum isn't enough to swing it to unlock.

•Unequal drops will sound like the movement is out of beat and too much drop is wasted energy. If they are equal you will insure a proper tick-tock sound and a more efficient escapement.

•Minimizing the drops will maximize the lock and thus increase the amount of swing of the pendulum necessary to unlock the escapement.

•Start with the entrance drop. Adjust it by opening or closing the pallets as necessary. Opening the pallets will increase the entrance drop and closing them will decrease the entrance drop. When you have the entrance drop adjusted to where you want it, then adjust the exit drop.

•The exit drop is adjusted by increasing or decreasing the distance between the pallets and the escape wheel. Increasing the distance will increase the exit drop and decreasing the distance will decrease the drop. Adjusting the exit drop shouldn't change the entrance drop.

•If you shorten the swing of the pendulum to the extent that there is no over-swing (run), the pallets may not release the escape wheel and the clock stops.
•At the other extreme, say a 30 degree swing (15 degrees from center) will cause errors due to the pendulum not swinging in a perfect arc.
 

LaBounty

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Hey Bangs-

Sounds good! The only correction I'd make is that adjusting the entrance drop will change the locks slightly but not as much as adjusting the exit drops. Adjusting the exit drops will greatly change the locks.

I'm probably the one who suggested changing the entrance drop won't effect the locks but that's not quite right :).

Hope that helps!
 

shutterbug

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Nice summary! I'll bookmark this one :)
 

RJSoftware

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Hey Bang. I assume this is heading toward another sticky. Good going..!

Only thing I can think of correction wise is you did not mention setting depth to assure palette lands on the locking area.

I say locking area cause some deadbeat type arrangements have impulse face on the ew tooth (ex. pin palette) and others have the impulse on the palettes. The locking area is generally just after the impulse face.

Sooo, proper lock is within the range of the locking area.

RJ
 
Last edited:

Scottie-TX

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Yeah; PAINS me to admit it, but searched carefully and could make only LAB's observation. I'll keep looking tho. SURELY I can find something else to fault. SHEESH.
 

bangster

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Most of it came from two or three people in the course of a very informative thread.
 

bangster

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No, I missed that one in my search. But it's a good, informative link. Thanks.

bangster
 

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