John Harrison RAS Regulator 'Replica' - Video 9 of 13

The previous video explained the principles of the remontoire mechanism in some detail.

In this video, the aerodynamic fly has been added, which slows the action down to a more typical speed. To be more precise, a combination of air drag and inertia (reluctance to be moved) are responsible.

Towards the end of the video, testing with the grasshopper escapement installed is achieved by virtue of manual torque applied to the remontoire wheel ; the input applied in this example generates a rapid action, but the purpose is served. The grasshopper is in hyperactive mode because there is no pendulum to impose a pace of one-beat-per-second (the small pendulum-like object you see in the video is the 'crutch', which merely connects the escapement to the pendulum without friction in the complete regulator).

As mentioned in Video 3, the fly is driven via a friction clutch. When fly acceleration is low, such as during release (but before arrest) the amount of friction is adjusted to be sufficient to prevent slippage. At the instant the fly is locked by the remontoire detent, potentially damaging peak loading is considerably reduced by clutch slippage, thus protecting the mechanism from deterioration over many millions of cycles (in fact, just over 105 million cycles at 30 second intervals per century).

The friction clutch also prevents bounce of the fly locking arm on the remontoire mechanism detent : it simply stops 'dead' upon contact. The previous video demonstrates how bounce occurs in the absence of frictional damping (albeit influenced by the greater speed of action and lighter rotating mass without the fly fitted).

Detailed explanations or links to descriptions are provided at https://soptera.wordpress.com
.
.