How would this arrangement be compensated for temperature variation? A change in temperature would alter the lengths of the LH and RH pendulum arms. The lifted weights would therefore act at a greater moment arm about the pendulum pivot point and each weight, when lifted, would apply increased impulse to the pendulum. Simultaneously, the period of the pendulum over a complete cycle would alter due to (putting it simply) a change in the polar moment of inertia. It is certain that the change with temperature of this latter alteration in period would not be related to the previously described alteration in the period in any simple way and would, therefore, be resistant to being entirely compensated.
Regarding temperature compensation I have two suggestions: 1) Make the arms/weight supports and, indeed, other parts of the escapement from a thermally stable material such as carbon fibre. Incidentally, carbon fibre is a very good material from which to make pendulum rods. 2) Incorporate temperature compensation elements into the escapement, such as described by Broughall, UK Patent 215,947, 1924. In this patent, the impulse weights are lowered onto thermally expansive stops. The Broughall Patent is the electro-magnetic forerunner of the purely mechancal SeeSaw Gravity Escapement. Regarding your comment, 'resistant to being entirely compensated': You are probably right. The question is: How does its overall performance compare with other escapements? At the concept stage I made no attempt at optimization. I am currently working on a more efficient version that will indicate seconds directly, using a one-second pendulum and Riefler-type escape wheel. If it works, I will design a complete clock, and at that stage will address outside affects, including temperature variation in detail.
I'm struggling a bit to understand it. When the impulse weight is lowered by the pendulum onto the see saw, you would expect the see saw to be pushed down. Instead, it lifts up. I cannot see how this is happening.
A roller on 1, 3, or 5 pushes on the (pawl?) T shaped piece with another roller at its top which pushes that side of the see-saw up (using the small ramp on the bottom of the see-saw).
Hello Ken: What a lovely surprise - you animated my SeeSaw Gravity Escapement. That must have been a very tricky job. I really admire your understanding of escapements and your skill as an engineer and animator. Kind regards - Roger PS th-cam.com/video/A1yH9vJN__w/w-d-xo.html shows the concept model working
roger, you've secured your place in the annals of horology with your brilliant design. how has it been received by the horology community (i mean the one outside of youtube, of course!)? KEvron
KEvron, thank you for those kind words. 'The SeeSaw Gravity Escapement' was published in the Horological Journal, March/April 2011 (British Horological Institute), and in the Watch & Clock Bulletin, October 2011 (US Journal of the National Association of Watch and Clock Collectors). I'm not a member of those institutions, so I don't know if there has been any feedback - good or otherwise. In addition, the SGE is described on modelengineeringwebsite.com/SeeSaw.html together with general arrangement drawings of the concept model modelengineeringwebsite.com/SeeSaw_drawings.html. I have given talks on the SGE to several horological societies in the UK. The response has been very positive. My patent for the SGE was granted in March 2014 (Oscillatory Mechanism, GB2483867B). I am currently working on a version designed to tick seconds directly, using a one-second pendulum and Riefler-type escape wheel. Incidentally, I'm most impressed by your Lego clocks. Kind regards - Roger
Regarding 'wood screw pivots': I describe the use of wood screws and other practical aspects of the concept model in: modelengineeringwebsite.com/SeeSaw2.html Regarding the Arfield escapement (J. Anfield, Horological Journal, Oct 1987): Compared with conventional gravity escapements, the Arnfield obviates pendulum-related friction in unlocking the escape wheel, but pendulum-related friction still acts at the gravity arm pivot and lifting lever. In the SeeSaw Gravity Escapement, the pendulum controls the escapement, but, paradoxically, the pendulum is 'unaware' that the escapement exists - apart from providing frictionless impulse. As far as I know, this is the only mechanical escapement to achieve this. There are a number of other advantages over previous escapements, and these are described in 'Discussion', Part 4, of the above link.
![เจ้าผู้เดียว - ดิด คิตตี้ [OFFICIAL MV]](http://i.ytimg.com/vi/q0NLCYKBOTo/mqdefault.jpg)
How would this arrangement be compensated for temperature variation? A change in temperature would alter the lengths of the LH and RH pendulum arms. The lifted weights would therefore act at a greater moment arm about the pendulum pivot point and each weight, when lifted, would apply increased impulse to the pendulum. Simultaneously, the period of the pendulum over a complete cycle would alter due to (putting it simply) a change in the polar moment of inertia. It is certain that the change with temperature of this latter alteration in period would not be related to the previously described alteration in the period in any simple way and would, therefore, be resistant to being entirely compensated.
Regarding temperature compensation I have two suggestions:
1) Make the arms/weight supports and, indeed, other parts of the escapement from a thermally stable material such as carbon fibre. Incidentally, carbon fibre is a very good material from which to make pendulum rods.
2) Incorporate temperature compensation elements into the escapement, such as described by Broughall, UK Patent 215,947, 1924. In this patent, the impulse weights are lowered onto thermally expansive stops. The Broughall Patent is the electro-magnetic forerunner of the purely mechancal SeeSaw Gravity Escapement.
Regarding your comment, 'resistant to being entirely compensated':
You are probably right. The question is: How does its overall performance compare with other escapements? At the concept stage I made no attempt at optimization. I am currently working on a more efficient version that will indicate seconds directly, using a one-second pendulum and Riefler-type escape wheel. If it works, I will design a complete clock, and at that stage will address outside affects, including temperature variation in detail.
I'm struggling a bit to understand it. When the impulse weight is lowered by the pendulum onto the see saw, you would expect the see saw to be pushed down. Instead, it lifts up. I cannot see how this is happening.
A roller on 1, 3, or 5 pushes on the (pawl?) T shaped piece with another roller at its top which pushes that side of the see-saw up (using the small ramp on the bottom of the see-saw).
Hello Ken:
What a lovely surprise - you animated my SeeSaw Gravity Escapement. That must have been a very tricky job. I really admire your understanding of escapements and your skill as an engineer and animator.
Kind regards - Roger
PS th-cam.com/video/A1yH9vJN__w/w-d-xo.html shows the concept model working
Hello Roger:
Thanks for your response.
Ken
roger, you've secured your place in the annals of horology with your brilliant design. how has it been received by the horology community (i mean the one outside of youtube, of course!)?
KEvron
KEvron, thank you for those kind words.
'The SeeSaw Gravity Escapement' was published in the Horological Journal, March/April 2011 (British Horological Institute), and in the Watch & Clock Bulletin, October 2011 (US Journal of the National Association of Watch and Clock Collectors). I'm not a member of those institutions, so I don't know if there has been any feedback - good or otherwise. In addition, the SGE is described on modelengineeringwebsite.com/SeeSaw.html together with general arrangement drawings of the concept model modelengineeringwebsite.com/SeeSaw_drawings.html. I have given talks on the SGE to several horological societies in the UK. The response has been very positive. My patent for the SGE was granted in March 2014 (Oscillatory Mechanism, GB2483867B). I am currently working on a version designed to tick seconds directly, using a one-second pendulum and Riefler-type escape wheel.
Incidentally, I'm most impressed by your Lego clocks.
Kind regards - Roger
Regarding 'wood screw pivots': I describe the use of wood screws and other practical aspects of the concept model in: modelengineeringwebsite.com/SeeSaw2.html
Regarding the Arfield escapement (J. Anfield, Horological Journal, Oct 1987): Compared with conventional gravity escapements, the Arnfield obviates pendulum-related friction in unlocking the escape wheel, but pendulum-related friction still acts at the gravity arm pivot and lifting lever. In the SeeSaw Gravity Escapement, the pendulum controls the escapement, but, paradoxically, the pendulum is 'unaware' that the escapement exists - apart from providing frictionless impulse. As far as I know, this is the only mechanical escapement to achieve this. There are a number of other advantages over previous escapements, and these are described in 'Discussion', Part 4, of the above link.