Hello, I was studying double 3 legged gravity escapements. With a seconds pendulum does it take 6 seconds or 12 for an entire rotation of the escape wheel? I am not able to figure that out... Dandydude
As the pendulum is 1 beat per second and the escape wheel moves every beat and moves 6 times for one revolution it must be 6 seconds per revolution. Phil
Dear Phil, Thanks for that... In a graham dead beat style, each beat moves half a tooth forward right? (30 tooth Escape Wheel + 1 second pendulum = 1 RPM of Escape Wheel) Why would it be different in gravity escapements? Why would it move 1 tooth per beat and not half tooth? I have been finding some conflicting information online.
With a dead beat escapement each pallet operates on every one of the 30 teeth the escapement moves only half a tooth spacing per beat., whereas each three legged escapement in the double gravity escapement operates only on its corresponding pallet. It's effectively two separate 3 tooth escapements. Phil
Double 3-legged gravity escape wheel moves 60° each event so with a 1-sec pendulum you need a 10:1 gear reduction to drive a seconds hand.
The confusion may be because a single six legged escapement will rotate once every 12 beats whereas a double three legged every 6 beats. Phil
Thanks for that tok-tokkie... 1:10 wheel would be the fourth wheel... this would end up being larger than the 3rd wheel which is usually a 1:7.5... this is bit inconvenient, don't you think? Thanks a ton Dandydude
I suggest you read my 30-legged gravity escape thread. I give a detailed illustrated description of how a gravity escape works. There is a link to the Trinity College clock site which has an animation of a double 3-legged in action. It also has very thorough mathematical analysis of the dynamics of the escape. 30-Legged Gravity Escape Clock
