Looking back I see I wrote something along the lines of this post back in 2009, 2012, 2019 and 2022! Why am I so hooked on making working models, after all a working model can be simmed and will be if one ever materialises?
But a suggestion on the Bessler wheel forum yesterday prompted me to re-examine my model and I saw a simple but crucial error that I might have missed on a sim.
Anthony (a newbie) has this signature “it’s not where you see the weights on the wheel that matters, its where the wheel (FEELS) the weights thats important”. Now that is a fact I learned so long ago that I almost forgot how important it is.
Imagine you place pendulum on a wheel with its pivot just below the axle, so the weight hangs downwards. If you rotate the wheel a few degrees clockwise, the pendulum rotates anti-clockwise relative to the wheel. The pivot bears the weight of the pendulum and as long as the pendulum moves relative to the wheel, the weight is pulling down on the pivot.
But if you place a stop in the path of the pendulum forcing it to stop and remain motionless, the weight is no longer felt on the pivot, but rather where the weight actually is, resting against the stop.
As soon as the pendulum is free to move again the weight is again felt at the pivot.
The error I found was a simple mistake. A supporting rod I had fitted into the mechanism was too short, meaning the part it was supporting did not have its pivot close enough to the axle to gain a big enough advantage? Unless you keep the fact mentioned in Antony’s signature in mind you might not even realise you’ve overlooked it. Like I did!
Actually I didn’t forget about it, but I was so intent on correcting what I saw as an unnecessarily long lever in a drawing, I shortened it too much.
JC
"...the weight is no longer felt on the pivot, but rather where the weight actually is, resting against the stop."
ReplyDeleteIt really does not matter where the stops are placed inside a pm wheel. A stop can be in direct contact with and supporting a weight or it can be closer to the axle and supporting the lever to whose end the weight is attached. What matters is the location of the weight itself. Try not to be misled by the locations of pivots and stops. It's only the locations of the weights that count.
Everybody knows this. If the pendulum is hanging so that it's COM is vertically beneath the pivot and it is free to move the weight is felt by the wheel at the pivot point as though the weight were there. As soon as the pendulum is resting on a stop or locked to the wheel the weight is felt where it is located.
ReplyDeleteThe locations of the weights, or where they’re felt don’t matter. The only thing that matters is that nothing was seen of the prime mover either in the demonstrations or the drawings. It was easy to hide the prime mover in the drawings. What prime mover would have been invisible at the demonstrations?
ReplyDelete"What prime mover would have been invisible at the demonstrations?"
DeleteAnthony & JC are talking about pivoted levers with weights inside a wheel and where the weight is felt if hanging verses locked. A Prime Mover structure is a different matter & it is hidden inside the covered interior of the wheel obviously. And it went around with the wheel because Bessler said everything must go around with the wheel and nothing hangs from the axle.