In addition to my previous post, the following Ken Kuo animation should also be of interest and value:Unilateral twin pivot Harrison compliant grasshopper escapement: https://www.youtube.com/watch?v=fBfp9riiJxc
All currently known written, illustrated and/or physical evidence attributable to John Harrison indicates that he invented and constructed three configurations of the grasshopper escapement: the twin pivot, the single pivot and the twin balance. There is, however, currently no written, illustrated or physical evidence that Harrison ever identified, recorded or constructed a fourth configuration, which will be referred to as the ‘unilateral twin pivot’ or ‘UTP’ grasshopper escapement.
Ken Kuo's geometry, but not the entirety of the mechanical arrangement, are based upon the description in the 'Downloads' section at http://soptera.wordpress.com
(please see my opening post, above). This geometry therefore complies exactly with Harrison's final intentions, recorded close to the time of his death (i.e. in his 1776 manuscript 'Concerning Such Mechanism...' and an apparently associated, contemporary illustration, currently catalogued as 'MS3972/3' in The Worshipful Company of Clockmakers library).The comments section of this video may be read in full, by left clicking 'SHOW MORE', located a few lines below each video.
To avoid misunderstandings, please note my comment re pallet nib bounce, which is unnecessarily excessive in the video.
My response to misleading comments by 'KEvronista' should also be read in full by left clicking 'View all 3 replies' below his first post. KEvronista eventually acknowledges his error, although I do worry that some observers will be lead astray if they don't read the entire exchange.
Should the link fail or become out of date (as they all too often seem to do), please visit www.youtube.com
and search for username 'Ken Kuo'. Then search within Ken Kuo's videos for 'Unilateral Twin Pivot Grasshopper Escapement (UTP Grasshopper Escapement)'.