GRAHAM ESCAPEMENT ( dead beat escapement ):
Pictorial with explanation
	
	The dead beat escapement also known as the graham escapement is 
characterized by its action of lock and slide  as it operates. This type of system 
can be easily recognized by looking at the verge. Pay particular attention to the 
working faces of the verge, there will be a flat edge where the escape wheel tooth 
hits upon releasing from the opposite side and a sharp edge that the tooth drops off
from the flat part and an angled surface that the tooth slides along as it gives the
pendulum an extra push until it lets go and the whole thing starts again on the other 
side. This type of system is or can be quite accurate because the verge has significant 
control over how much power is delivered to the pendulum. If however there is too
much lock or not enough lock the accuracy and dependability will be questionable 
at best. The depth setting is not the same for all clocks although the principle is the
same. Generally speaking weight drive clocks with heavy pendulums are more 
sensitive and require somewhat shallow depth settings keeping in mind not to 
completely eliminate the  lock segment of the operation.
The following is a list of some of the sensitive clocks: 
seth thomas #2 regulators
most vienna regulators
most french clocks
jewelers regulators (large wall clocks and floor clocks with mercury filled pendulums)
		

 

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Copyright (c) 2002 David Tarsi. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being no invariant sections, with the Front-Cover Texts being no Front-Cover Texts, and with the Back-Cover Texts being no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".