Grasshopper Escapement

Here is a version of Harrison's famous grasshopper escapement. Uploaded with permission of the Yahoo clockmakers' group.

Category:

Entertainment

Tags:

• Harrison
• grasshopper
• escapement
• clock

[VinnyMartello]

Is that like a semi propetual motion machine?

[bshallard]

This is the timekeeping part of a clock, called the escapement. Various types of escapement were invented seeking the most accurate timekeeping, and this one was invented by John Harrison, made famous by the book and BBC mini-series "Longitude". His famous sea-clocks are on display at the Greenwich Observatory. This particular escapement was built by a hobby clockmaker who's name I forget just at this instant.

[xwizbt]

I came here after wanting to find out more about the Corpus Clock. Thank you for providing an image of another grasshopper escapement - albeit not a chronophage! - and as for all the idiots posting comments like 'dat wus horrible', let us all doff our caps for natural selection. Pataleero - you're doomed.

[aldoaldoz]

At last I understood how the grasshopper escapement works. I first read about it on Dava Sobel's "Longitude" book. In her book there were some descriptions, but no pictures. Since then I'm looking for running images of John Harrison's mechanisms... thanks for posting this!

By the way, are there some videos about the H1 clock? I could only find photos, nothing running!

[BenVanDeWaal]

What is the use of the second (smaller) scapewheel? If the pendulum pivot (with the grasshopperframe) would be raised (about 1/2 the radius of the large wheel), both palletarms would be tangent to the SAME wheel. The arm-lengths should be adapted.

[TheDigit100]

Hi;

Love the clock, your input would be appreaciated in Gearotic Motion upcoming plans for this same typ ofe escapement.

Cheers

[Vlad3000]

@jonfraz

I'm only starting to look into this now but from what I've gathered so far the answer is yes.

Answer B is that a coiled up spring is what gets the gears going. This is what you wind when you wind a clock.

Without the escapement the spring would uncoil to quickly.

[gramule]

@glathoppa good to see Harrison's grasshopper movement. i have read sobel's longitude, and seen an actual harrison at prescott museum of clocks.

[jonfraz]

Am I right in understanding that the escapement releases the gears and allows them to move forward a short distance each time? And that this also restores some energy to the pendulum and reduces the effects of friction/air resistance? If so, what is propelling the gears to rotate in the first place? I hope someone can help!

[Axbent]

@MrLeonard55 In Model Engineer you can find a series on this, currently running.

[MrLeonard55]

Can i get some plans for it?

[MrLeonard55]

Are there any plans available for this clock?

[glathoppa]

This is a copy of an escapement by an American writer of clock construction articles.The escapement shown is not something John Harrison would ever have made. The torque delivery characteristics ignore Harrison's stipulations as comprehensively as any I've seen.