Twin Pivot Grasshopper Escapement - invented by John Harrison

Four minute escape wheel
No sliding friction, no wear, no lubrication
Entry angle = 90 degrees
Exit angle = 89.73 degrees
Thank you, David Heskin. More information refer to: www.hsn161.com

[@glathoppa]

Further to my previous comment, Ken Kuo's video 'Two Pivot Grasshopper Escapement - John Harrison' incorporates pronounced recoil, which results in a crystal clear demonstration of the principles of operation. Many thanks, Ken.

[@kenkuoescapement]

Dear Glathoppa, Actually, the composers lift form their resting positions. KZbin converts uploaded videos to mp4 files automatically that will lost some frames. You can't see the composers lift form their resting positions on KZbin but I can see that on my SolidWorks. Based on past experience, the pendulum should clearly overswing. I don't know why the pendulum overswing only 0.01-0.05 degrees. It is too small so that it is not clearly.

[@kenkuoescapement]

Thank you so much for all you have done for me.

[@carmelpule6954]

It is obvious that the pendulum inertia gives it its oscillating characteristic due to its mass and gravity effect. In a compound pendulum, there is the inertia effect which is more pronounced than the simple gravity pendulum and hence the reason why the compound pendulum is not so accurate but it is the reason why the grasshopper escapement has a recoil when the pallet homes on the tooth. There is no simple pendulum with a point mass and a no mass suspension arrangement to achieve a perfect simple harmonic motion shown in the video. I would have thought that the two arms of the rocker which hold the twin pivot have some inertia and so they will not stop so abruptly and recoil will take place. I do not think that it would be difficult to modify the software to show a little recoil motion. Congratulations on the presentation.

[@Blacksmith-Joe]

This is very cool! Will you release the file? I want to 3d print it. I've tried to draw one from the soptera link you posted but its a bit to 'wordy' for simple me.

[@pgvsmith1]

clever

[@glathoppa]

Is it possible to model some clearly visible escape wheel recoil, induced by pendulum overswing, please? The current animation (at 23rd July 2014) incorporates no recoil, which is incorrect. As a consequence, the composers fail to lift from their resting positions and the means by which pallet nib locking corner capture and release is achieved is not clearly demonstrated. There certainly must be recoil in practice, or the escapement will fail to function reliably.

[@glathoppa]

Ken Kuo, have you considered the creation of an animation of Harrison's twin balance grasshopper escapement, also explained in the Downloads section at soptera.wordpress.com Videos of my Harrison RAS regulator 'replica' on KZbin (search glathoppa) include his spring remontoire, which would be another challenging animation, most especially if combined with a 17.5 tooth spaces mean span, 120 tooth escape wheel, 3 to 2 mean end/start ratio single pivot grasshopper escapement. I can provide all component dimensions and forms, albeit based upon observation rather than prohibited direct measurement. Realistically reproducing the 'slipping' friction drive to the fly would be especially demanding, I suspect.

[@colbysmith447]

Ken Kuo, I'm making a wood gear timepiece and want to incorporate this grasshopper movement. Are there any drawings with dimensions for this that I could use to help me develop my escapement? Thank you.

[@kenkuoescapement]

Hi Colby, Download glathoppa's grasshopper escapement document at soptera.wordpress.com/downloads/