Magnets instead of balls


George Hofmann
 

A little while ago there was some discussion here of remote uncoupling for Sergents. Replacing the ball bearing with a magnetic cylinder was mentioned. This modification would allow an electromagnet under the track to push the cylinder upwards thru magnetic repulsion, something that can't be done with the nonmagnetized ball. One end of the wand could still be used to attract the cylinder up just like the ball. Possibly the other end of the wand could be used to push it up as well, which could be useful if a diaphragm was in the way above the coupler, for example.

The concept was intriguing to me although I expected it not to work. I expected the magnet to be attracted to ferrous parts within the car and thus bind in its bore hole. I had to try it however. I ordered some 1mm diameter cylindrical magnets which were also advertised to be 1mm in length. Here's a picture of what I received. One of the stock ball bearings is stuck to the end of this stack of magnets.



The magnet nicely fit in the hole where the ball normally goes. The coupler parts assembled as usual. I was excited.

But then my hopes were dashed. While it seemed to work normally thru a few cycles it began to lockup. Investigation revealed that the cylinder actually was able to tumble within its space such that it got crossways. I'll leave it to others to prove geometrically how this is possible. This phenomenon seemed to be worsened by trying to use the other end of the wand to push the cylinder up. Rather than moving up smoothly, the cylinder attempted to swap ends just as a magnet in free space would do. 

So, I give up on this project. The concept seems great but I don't see how it can be accomplished without some kind of modification to the coupler assembly itself.

George
Edgewood, WA


Steve Wintner
 

Makes me wonder if a magnet that was, say, 1 mm Dua and 3 mm long would work. You'd have to deepen the hole in the coupler, not sure if there's 3 mm of space there...

Very interesting, thanks George!

Steve


On Wed, Nov 3, 2021 at 14:28, George Hofmann
<george.hofmann@...> wrote:
A little while ago there was some discussion here of remote uncoupling for Sergents. Replacing the ball bearing with a magnetic cylinder was mentioned. This modification would allow an electromagnet under the track to push the cylinder upwards thru magnetic repulsion, something that can't be done with the nonmagnetized ball. One end of the wand could still be used to attract the cylinder up just like the ball. Possibly the other end of the wand could be used to push it up as well, which could be useful if a diaphragm was in the way above the coupler, for example.

The concept was intriguing to me although I expected it not to work. I expected the magnet to be attracted to ferrous parts within the car and thus bind in its bore hole. I had to try it however. I ordered some 1mm diameter cylindrical magnets which were also advertised to be 1mm in length. Here's a picture of what I received. One of the stock ball bearings is stuck to the end of this stack of magnets.



The magnet nicely fit in the hole where the ball normally goes. The coupler parts assembled as usual. I was excited.

But then my hopes were dashed. While it seemed to work normally thru a few cycles it began to lockup. Investigation revealed that the cylinder actually was able to tumble within its space such that it got crossways. I'll leave it to others to prove geometrically how this is possible. This phenomenon seemed to be worsened by trying to use the other end of the wand to push the cylinder up. Rather than moving up smoothly, the cylinder attempted to swap ends just as a magnet in free space would do. 

So, I give up on this project. The concept seems great but I don't see how it can be accomplished without some kind of modification to the coupler assembly itself.

George
Edgewood, WA


George
 

Could you use two of the magnets stacked?


On Nov 3, 2021, at 6:02 PM, Steve Wintner via groups.io <steve_wintner@...> wrote:

Makes me wonder if a magnet that was, say, 1 mm Dua and 3 mm long would work. You'd have to deepen the hole in the coupler, not sure if there's 3 mm of space there...

Very interesting, thanks George!

Steve


On Wed, Nov 3, 2021 at 14:28, George Hofmann
<george.hofmann@...> wrote:
A little while ago there was some discussion here of remote uncoupling for Sergents. Replacing the ball bearing with a magnetic cylinder was mentioned. This modification would allow an electromagnet under the track to push the cylinder upwards thru magnetic repulsion, something that can't be done with the nonmagnetized ball. One end of the wand could still be used to attract the cylinder up just like the ball. Possibly the other end of the wand could be used to push it up as well, which could be useful if a diaphragm was in the way above the coupler, for example.

The concept was intriguing to me although I expected it not to work. I expected the magnet to be attracted to ferrous parts within the car and thus bind in its bore hole. I had to try it however. I ordered some 1mm diameter cylindrical magnets which were also advertised to be 1mm in length. Here's a picture of what I received. One of the stock ball bearings is stuck to the end of this stack of magnets.

<IMG_20211103_135605657_HDR.jpg>


The magnet nicely fit in the hole where the ball normally goes. The coupler parts assembled as usual. I was excited.

But then my hopes were dashed. While it seemed to work normally thru a few cycles it began to lockup. Investigation revealed that the cylinder actually was able to tumble within its space such that it got crossways. I'll leave it to others to prove geometrically how this is possible. This phenomenon seemed to be worsened by trying to use the other end of the wand to push the cylinder up. Rather than moving up smoothly, the cylinder attempted to swap ends just as a magnet in free space would do. 

So, I give up on this project. The concept seems great but I don't see how it can be accomplished without some kind of modification to the coupler assembly itself.

George
Edgewood, WA
<IMG_20211103_135605657_HDR.jpg>


George Hofmann
 

Steve:
Deepening the hole and using a longer magnet is the modification to the coupler that I was thinking would be required. I doubt that it would be possible let alone practical.

The other George:
Two magnets would not work since just one fills the hole completely. You wouldn't be able to open the knuckle.

I really was not expecting the tumbling action. I sure didn't think a cylinder would be as free to rotate as a sphere.

G


Todd Sullivan
 

George,

Cylinder 'tumbling' happens when the diameter of the cylinder and the length of the cylinder are equal or almost equal.  So, your thought about having a longer cylindrical magnet was on the right track.

Todd Sullivan
who learned about that from a smart friend many years ago


prandn
 

Am I correctly understanding that cylindrical magnets. not spherical magnets are being used?
If so are spherical magnets not available?

loren martell
Aloha, OR 97007


George Hofmann
 

On Thu, Nov 4, 2021 at 07:28 PM, prandn wrote:
Am I correctly understanding that cylindrical magnets. not spherical magnets are being used?
If so are spherical magnets not available?

loren martell
Aloha, OR 97007
Spherical magnets would not allow movement by repulsion which is the only point of this exercise. The goal would be upward movement of the magnet through use of an electromagnet under the rails.

G


George Hofmann
 

On Thu, Nov 4, 2021 at 09:14 AM, Todd Sullivan wrote:
George,

Cylinder 'tumbling' happens when the diameter of the cylinder and the length of the cylinder are equal or almost equal.  So, your thought about having a longer cylindrical magnet was on the right track.

Todd Sullivan
who learned about that from a smart friend many years ago
Well that is an interesting bit of knowledge that 99.999999% of the world's population is not aware of. :-)
G