Thread: To Yoke or not

If I understand what you are asking, then as I understand it the main advantage in using a yoke is that any part of the pendulum will rise and fall slightly vertically as it moves from side to side. You may need to engineer in some way of accounting for this rise/fall (maybe, I am not sure if it would be pronounced enough to matter). The yoke would be one way of doing this simply.

Russell are there clock designs that are yokeless? I too discovered that the yoke allows the pendulum rod to rise and fall during its arc length. Have you any prelim designs to share?

Dean.

Thank for the responses.
It must be Friday and the brain just refusing the follow what you are saying.

quote "the pendulum will rise and fall slightly vertically as it moves from side to side."

My problem with the above is if the rod is attached to a bearing at its pivot it can only move in line with the bearing not up and down Or am i missing some think here
I thought there might of been some friction or mechanical advantage by using a yoke.....is there?

Dean I have a new design but I will put it in a new build thread soon.

Russell

Russell the if you mark the pendulum rod where the yoke travels you will find that the yoke moves say 10mm in height variation; ie the low point is the verticle position of the yoke and the two "high" points are where the pendulum is stationery; ie at the end of its stroke eg extreme left and extreme right in the pendulum cycle. Hope that makes some sence.
Look forward to the new clock!

Dean.

Basically, the rod is supported at the top by some form of bearing or pivot, and moves side to side, but because it is attached to a pivot the motion is not purely side to side. If it was just side to side then the top and bottom of the rod would have to move sideways by the same amount, but the top can't move sideways. It is moving through an arc of a circle. Think of it this way. If you gave the pendulum a really big shove, it would move around in a complete circle. while it went around that circle, the bob on the end would move up and down as well as left and right. Every part of the rod between the two ends also goes up and down a bit as well to maintain the circular notion.

Sorry guys can't see it I just don't follow what you are getting at. I am on the wrong page here.
The hold thing is one piece attached to a bearing.....How do things move around when it's in motion?

Russell

I too do not fully understand what is going on - would love a diagram from somebody.
Is it the same as hanging mugs (by their handles) from a hook in the kitchen cupboard, rather than having them held by a piece of string?
Chris

Hi Chris
Do not know if I should be happy you do not follow the yoke fundamentals as well as me ... at least I do not feel along out here any more.

Still have not found any thing on google. Will try some emails next to clock people on the web.

Russell

Just got a reply to a email sent to Brain law
Russell

Congratulations on completing the project, it is always good to here you enjoyed the making of the clock and it is successful.

My honest answer is that I don't really know, when I designed my original clock some 20 years ago it was based on bits and pieces I had picked up from reading text books and looking at pendulum designs around me.
My feeling was that the friction of the knife edge in a groove was less than having it mounted on a pivot which was the only way to do it if you operated the escapement directly.
The other thought was that it was more efficient way to transfer the impact from the pallets into the pendulum. I might have to research this further now you have asked the question.

Any chance of getting a couple of photo's or video of the completed clock?

Regards

Brian Law

Hey good to hear that Brian replied."..have just emailed him myself. I will video the yoke and rod, marking the rod so that you can see that these two opponents move in relation to one another.
Dean.

Another reply from [email protected]

Dear Russel
The reason for the crutch is quite simple. The pendulum should be as free swinging as possible, which is why they mostly swing on a knife edge or they are sprung. if the pendulum where to be directly connected to the anchor arbor then the pendulum would have to swing on the anchor arbor, which would mean that the whole pendulum weight would hang on the anchor arbor bushing, which would increase the friction incredibly. The crutch is just a connector, as the pendulum and the anchor arbor have different methods of friction reduction.
This however is not always the case as 2 of my clocks do not have a crutch.
I hope that answers your question.
Yours Dave

I will reply to this email as it raise some questions in my mind.

Russell, I have considedred the yoke less design. From my plans I have decided that a yoke is not entirely necessary. For me, my pendulum is only 250gms so there is no reason why you could not pivot it on the the same shaft as the timing wheel. It would not increase "the friction incredibly" as far as I can see.
thats my opinion today!.
Dean.

Yes Dean there a lot to consider with the yoke but it does just boils down to friction... which has the less or least enough for the job at hand

Russell