A simple cam

[rlortie]

Path_finder,

Please take into consideration that I stated; 'It reminded me of', I make no ascertainable comment as to whether it will work or not.

I wish you luck with it, if anybody deserves gain in a sustainable design I consider you a the top of the list!

Ralph

[Richard]

well stated rlortie

PathFinder I'm glued and got the popcorn:-)

[triplock]

gimme a 'P'
gimme a 'A'
gimme a 'T'
gimme a 'H'.....

Well you get the idea son :-)))))

Chris

[path_finder]

Dear all,
Many thanks for the encouragement.
As promised, the first shots of the wheel, built in accordance with the drawing legsP4.png above.
The first shot is the first tested cam, with a shape exactly conform to the theory. The S point is the axis where the strings are rotating.
The second shot shows the cam inside the wheel without the springs at this step. The cam is keeling at 6:00 if you don't rotate the central axle for moving the cam at 3:00.
The third shot shows the constitution of the cylindrical weights: there is a roller in the middle of each weight, rolling around the outer rim of the cam.
The radial position of the weights during the ascending phase (left side if clockwise) is assumed by a couple of nylon wires (difficult to see on the shots but sometime illuminated).
In this state the wheel is completed, but the shape of the cam must be adjusted (few millimeters too large) and an handle shall be installed on the main axle (with a locking mechanism when the cam has been set at 3:00).
Other shots follow soon.

[triplock]

That really is a thing of beauty. It's like OU porn. Hmmmmm........................................

Puts my meccanno efforts to shame :-(


Chris

[getterdone]

Try to keep both hands on the keaboard while you're looking at those pictures Triplock.

Very nice work Pathfinder, thanks for sharing.

[Richard]

Path Finder

Beatiful

Triplock

Meccano..?

[path_finder]

Here is again the wheel with the internal cam at the right position.

In view to take the shot I was obliged to abandon the main axle, and to fix the cam in the right position with a sticker tape (see at 1:00).
The mechanism working well, I was obliged for the shot to lock the wheel (trying to rotate clockwise) by a kickstand at 3:00.
In the upper right corner is a detail of the mounting way of the rosettes on the cam at the point S.
There are two rosettes with eight pins each, one at each side of the cam.
The springs must be held between the axle of each weight and the corresponding pin of the rosette.
This way has been chosen for assuming a good mechanical equilibrium of the forces (nylon wires, weights, springs, wich are all doubled).

Until now everything is going well, but what is wrong?: we cannot attach the springs. Why?
If you are not a good observer, and cannot answer to this question, an important clue is given into the second drawing.
Don't cry. Be patient. There is a solution, coming soon.

[Richard]

path finder

would a fer de milone cam resolve the problem?

richard

[triplock]

I particularly like this design of cam. It seems to offer the greatest degree of offset, with the path of least resistance;

Animation:


http://commons.wikimedia.org/wiki/File: ... imated.gif

[path_finder]

Dear Richard,
What you mean with "fer de milone"?

Dear triplock,
Your suggested cam is this one implemented (see the rollers).

The solution is obviously a vilbrequin (I don't know if the english translation is correct), like in red in the following drawing

Nota bene: the above design seems to be very close from the Merseburg wheel.
If true, this is another confirmation for the presence of the elongated bearings in the Bessler's design. Remember this topic: http://www.besslerwheel.com/forum/viewt ... 1553#61553.
The main axle do not passing through the wheel, we need a strong fixation (and bearing) at the both sides of the wheel (what has been made in my wheel, see the double bearing cage at each side).

[Richard]

Path Finder

Brilliant:-))

The fer de milone is an axle assembly that constitutes two sides leaving the center open for just such a design as yours.

richard

[rlortie]

Dear Denker,

I apologize do not be explicite enough.

The cam is fixed at it's stable position by a shaft centered on the main axis and inside another hollow shaft, like explained in this old drawing:
http://www.besslerwheel.com/forum/download.php?id=6185.
On the other hand the main wheel's shaft is hollow and rotates around the first small shaft thanks a rollers bearing.
Therefore the both shafts do have the same axis but are independent.
This design is very close from what you can see on the Merseburg wheel, where the power is collected on the hollow tube thanks the rope.

In another post (http://www.besslerwheel.com/forum/download.php?id=6520 I expressed another way this design (the hollow tube) can be used.
But there is still an important question: why these two bearings are so much allongated?. A proposition is given in this old post (and the followers):
http://www.besslerwheel.com/forum/viewt ... 1553#61553

This forum is full of some important data (I don't speak specially for me, there are a lot of competent contributors).
I just regret that a big amount of useful data apparently are lost or forgotten, and few years after we are obliged to give again the same answer.
A good source of abundant data is the link 'Albums' in the index page (or here: http://www.besslerwheel.com/forum/download.php?m=1103), then select by name or date in the rolling list.

Dear Path,

Caution: your 'vilbrequin' or stationary crank shaft is not the answer you seek, with the external adjusting handle as explained in the quoted links. If not careful you will end up with a symmetrical wheel within a wheel. Here you will require the split hollow axle which is the same as positioning your cam

If confused you your wish more input on this, contact me by private mail and I can send you some pictures.

My suggestion is: you stay with the above cam approach. It has to be grounded. There are two ways to accomplish this; first is as described above. The second way is to suspend it on the axle and add enough counter weight in it to keep the lobe pointed to three o'clock. The axle need not be hollow and turns within it.

The latter I have used for keeping a 'snail cam' in position.

Ralph

[path_finder]

Dear riortie,

Thanks for your comments.
Many thanks also for proposing some drawings.
As explained earlier I publish systematically everything in the 'general discussion' forum, because IMHO all data shall be put at the disposal of everybody (even if a part of them don't have a sufficient level of Knowledge for understanding everything). So far, if your data are not confidential nor submitted to any secrecy restrictions, why not to publish here your drawings? Many thanks in advance.

Few personal remarks:
1. The use of an heavy counterweight at the opposite position of the excentered COG has been tested many time: the problem with this idea is to obtain a stable position, wich is not easy because the force supported by the cam is variable and the countertorque from the counterweight must follow exactly this variable value.
Nevertheless a solution could be possible (never tested yet by me) by the use of two ellipsoidal gears, as explained before here:
http://www.besslerwheel.com/forum/viewt ... 3115#63115

2. The way to oblige a weight to follow an ellipsoidal path was also here:
http://www.besslerwheel.com/forum/download.php?id=6281
In that case the stability of the cam may be better.

IMHO the solution shall be completely different and must be based on a mechanism starting from the outer rim of the wheel, like discussed before, see here:
http://www.besslerwheel.com/forum/viewt ... 2694#72694
But this is another story. For the moment I want to investigate deeply on the suggested design, in view to be sure do not forget something on the road (even if no success).

[rlortie]

Path,

The data I am willing to share is not confidential, it is from my own failed research. I have no problem sharing on open forum.

I will attempt to edit the pictures in a format suitable for posting here. It is not that I do not wish to share, I simply am inhibited by my knowledge of resizing pictures to allotted KB allowed.

Ralph