John Harrison RAS Regulator 'Replica' - Video 5 of 13

Apologies for the brief 'DVD Video RAM' message at 2 mins 10 seconds: please don't be mislead into thinking that the video has ended. Spielberg need have no fears of competition from me, that's for sure.

This video shows the first stages of construction of the 'replica' of Harrison's masterpiece, beginning with the creation of the large, main movement plates, associated pillars, some subsidiary small pillars and their 'bridges' (one rectangular, one an inverted 'U' shape) and the escape wheel, supported and running freely upon its 'anti friction' assembly.

The two anti-friction wheels, in view in the latter part of the video, support the rear end of the escape wheel 'arbor' (axle). The front end of the arbor is supported by an almost identical anti-friction arrangement, out of sight behind the movement plates. The anti friction wheel hubs are of 'lignum vitae', which is an extremely hard, naturally greasy wood, used extensively by Harrison as a maintenance-free bearing material. As cleverly used throughout this regulator, it requires (in fact, demands) no lubrication, generates almost zero resistance to motion and reportedly lasts for centuries without significant wear (a tower clock by Harrison at Brocklesby Park, Lincolnshire has been running with lignum vitae bearings virtually continuously since the early 1700's). The freedom of rotation of the escape wheel assembly and any similar assemblies thus supported has to be experienced to be believed. Later videos will demostrate the amazing freedom throughout the movement, which all contributes towards unsurpassable timekeeping performance.

At this point it begins to become apparent that, over many centuries, horologists have invented some wonderful (albeit occasionally obscure) names for clock components and assemblies. What part matches which name is fairly obvious in this video, although just to be sure, the 'movement' is the complete assembly of plates, pillars, arbors (axles), wheels (big gears) and pinions (small gears), remontoire (shown in videos 2 and 3) and escapement (shown in video 4) and any other bits and pieces completing the 'clockwork'. Later videos will introduce any components not shown thus far. A well-aimed Google of any vague terms will reveal a rich and absorbing supply of descriptions and explanations.

For further information, please see http://soptera.blogspot.com and
http://www.hsn161.com/HSN/Heskin.php
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Category:

Science & Technology

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• John
• Harrison
• RAS
• regulator
• grasshopper
• escapement
• remontoire
• maintaining
• gear
• clock
• pendulum
• gridiron
• time
• longitude
• H1
• H2
• H3
• H4
• wooden
• lignum
• vitae
• glathoppa