Thirty-Legged Gravity Escape Clock. Here is a video of the clock. Some comments. It will get a stainless bezel. The holes for the swing scale can be seen. Yet to be made. At 2m43 I say pendulum clock instead of pendulum cock. At 4m23 you can see some solder wire on the escape wheel & also on the last train wheel a bit later. I had completely forgotten about them. I am not at all embarrassed about them. It exemplifies that this is a real amateur clock. I also like the amateurishness of the video. It is slick stuff that I don’t like to be associated with. Picture shows the escape on the back of the clock. Clock is sitting on a 12V alarm battery. I started in about 1996 with precious little to guide me. I will not go into how I arrived at this layout but it is more like a tower clock. Basically the Huygens drive is on the hour arbor with 12:1 gearing to the minute arbor and then 60:1 gearing to the seconds arbor. The arbors are concentric. There are four triangular frames. I am a mechanical engineer & simply designed the mechanism that I thought would best accomplish the job – not knowing anything about horology. I had a Photostat of Grimthorpe’s book about Big Ben and chose to use his double-three-legged gravity escape. When I tried the clock it needed vast weight to make it run. That escape turns 60° each tick so there was originally a further 10:1 set of gears from the escape to the second’s arbor. I realised that 1 gram at the escape wheel would require 10x60x12= 7200 grams at the drive. So I decided to make a 30-legged version of the gravity escape and dispense with the 10:1 gearing. That is the origin of my gravity escape – needing to reduce 7200 grams to 720 grams. When I first got it to work I wanted to publicise it as I was astonished that it seemed to be a novel idea. By this stage I was on the internet & had found the Mini Lathe Horology group on Yahoo. So I took a video of it working, posted it on YouTube and wrote about it on HLH. Gravity Escape 30 legged That was January 2012. Right now when I went to get the link two other important gravity escapes are listed. Mudge had done one 1795 Thomas Mudge's Gravity Escapement, circa 1795 Bloxham too in 1853 Bloxham's Gravity Escapement In the comment beneath the Bloxham version is a long extract from Grimthorp’s book (The diagram appears after 13 secs). He claims that the fault with the escape is its propensity to trip and thus break teeth. I have seen Bloxham’s clock for it is in the Science Museum in London – I was delighted when I discovered it there. In his book Grimthorpe says the problem with the Mudge escape is it too is likely to trip. The difference between Mudge’s version and mine is essentially where the left hand pallet lifting tab is. Mudge has it at the locking face whereas mine is far away below the center of the escape wheel. I considered placing it as per Mudge but the line of action points almost directly at the pallet pivot so there is a very short mechanical lever arm – it needs a very large force to raise the pallet with that geometry. Placed as I have done the forces are very modest. I ran a thread asking about the power (weight & drop) required by various clocks. The thread has lost some of its data tables and much of its formatting since the last upgrade of this site but here it is: http://mb.nawcc.org/showthread.php?108078-What-power-needed-to-drive-various-clocks&p=822282#post822282 In the second last post the data is still there. The power is micro Watts but the micro symbol does not show. My clock now runs on 14 micro Watts whereas Tinker Dwight’s dead beat grandfather clock runs on 67 micro Watts. (JHE your final posting in that thread of 1.2474 kg falling 46.055 mm in 12 hours is 13 micro Watts.) Despite what Grimthorpe says my clock simply never trips. Baron Grimthorpe (unaffectionatly know as Lord Grim) had three names during his life; christened Edmund Beckett Dennison but he dropped the Dennison which was something his father had added to his own name. When his father died he inherited the title so became Baron Grimthorpe. He went to Trinity College in Cambridge. On his death he bequeathed funds for a clock using his escape to replace the clock in the tower at Trinity. That clock has been the subject of serious research which is reported at their website. They refer to Grimthorpe as Dennison – probably because that was his name when he was a student there. The Trinity Clock Click the Escapement tab on the left & you will get a nice animation of the double three-legged escape in action. I draw your attention to this quote on that page: What Grimthorpe had done when he designed the Big Ben clock was make it be massively over powered so that it could deal with wind loads and ice loads on the hands on the four faces of the clock. He fitted a big air brake (air governor) to the escape shaft to limit the speed so the action of the clock was prompt but not violent. The big advantage was if the load increased because of ice or wind the fan (air brake) had less work to do but the speed and action remained the same so the clock worked fine. But the crucial other advantage of his design was that the actual force applied to the pendulum was not changed at all as well as the pendulum being entirely disconnected from the loads imposed by the hands. So there were three aspects to his design 1) there was a big reserve of power which was automatically controlled to match the load & 2) the pendulum was completely isolated from those varying loads & 3) the pendulum was always given the identical impulse. But it is that quote by Schoof saying how wasteful of power the clock is which is quantified as twelve times the required power that I want to discuss. That is what my design eliminates. There is no power dissipating air governor on my escape. As shown above my clock runs on 16 uW whereas a conventional dead beat clock needs 67uW (four times as much). But that is not a fair comparison because my clock uses ball bearings for all the arbors so I should compare it to dead beat clocks with ball bearings. JHE’s second clock has ball bearings & runs on 13uW with a dead beat escape (am I correct about the ball bearings because you stated that you planned on jewelling it but is that for the train arbors or the escape arbour?). JHE’s earlier pin wheel escape regulator with ball bearings runs on 38uW. Rex Swensen has made a very elegant dead beat Vienna style clock with 1 second pendulum and ball bearings his clock runs on just 5.72 uW (Rex Swensen's Web Site Vienna Regulator Page) . So my clock is pretty good and certainly no power hog.