Roger Smith says co-axial escapement is 10x more efficient

Luxury and Independent Watch brands

Roger Smith says co-axial escapement is 10x more efficient

Postby koimaster » February 2nd 2018, 10:10am

In this diagram the green represents the angle in which the escape wheel is involved in the delivery of power through to the balance. A lever escapement spends 210 degrees of its rotation involved in the delivery of its power. A co-axial escape wheel spends an extra 45 degrees imparting its energy, which means that 255 degrees of its rotation is involved in the delivery of power through to the balance.


This is good and a gain……..In calculating this I found that for one revolution of a 4.5mm diameter lever escape wheel, 9.0 mm of sliding action (see red) takes place. For a co-axial escapement of the same diameter, there is only 1.1 mm of sliding action (see previous post) for one revolution of the escape wheel - the rest of the impulse is a simple frictionless pushing action. This equates to a 10x efficiency saving found in the co-axial over the lever escapement…..So for a watchmaker, this is wonderful news because these savings in energy are something that the watchmaker can use in order to further enhance the life of the mechanical timekeeper…….

So what are the benefits? Well it means that the vibrations per hour can be dropped down to a reasonable 21,600 or preferably 18,000 vibs per hour, and because this escapement is no longer reliant upon the use of a lubricant it does not have to hide the inefficiencies of the escapement and failure of the oil behind a high beat mechanism. We can go further and reduce the mainspring strength which will be required to drive the watch. This reduced power will reduce the effort that it takes in winding the watch and also the effort that the mechanism has to endure in restraining all this power and releasing it through its train of wheels etc……..

The real gain here is that the watchmaker can then extend the service intervals of their watches and reduce the running costs to the owner.


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