Just scored a nice 282 gantry crane from Ebay. Works great, some cosmetic issues, but I'm an operator (with my 6yr old grandson) not a colector. The magnet picks up small stuff fine. I made culverts out of an old 1/2" metal broom handle... the crane doesn't always hold them. my auxiliary system is controlled by a small (entry level set) transformer set about midway. I don't want to burn out the motors by setting too high. How else can I increase the magnet power.? Thanks.
The unit can take full transformer voltage just like a locomotive. The service manual states the crane can hoist a weight of 4 ounces. That seems to be the limit unless you want to wind your own electromagnet.
Larry
Thank you, Larry for the quick reply. I will see what full transformer will do. I think I did do that and did not notice any difference in the magnet strength, but I will pay close attention this time. I had not thought about winding my own magnet... I might be able to add winding to the current magnet, or create a new one.
As hoped, the forum provides excellent information. Thanks.
I am pessimistic that simply rewinding the magnet coil can make any improvement. I expect that the space available is already substantially filled with copper, in a structure that allows it to dissiplate a certain amount of heat without damage.
Suppose you want to double the number of turns. To make room, you would have to increase the wire gauge by 3, approximately halving the wire's cross-sectional area. This would quadruple the resistance--doubled because the wire is smaller, and doubled again because the wire is twice as long. With 4 times the resistance, you would have to halve the current, since power goes as the resistance times the square of current. Half the current through twice as many turns as before produces the same magnetic field as before.
On the other hand, if you redesign the whole thing from scratch, making it bigger and using the most permeable iron (which Lionel also would have done) you might be able to do better.
As for increasing the current (by increasing the voltage), if it doesn't get too hot, and if the magnetic core doesn't saturate, the force that the magnet produces increases as the square of the current. So a modest increase in transformer voltage could yield a disproportionately large increase in lifting force.
Bob Nelson
Here's a thought: Suppose that we embed a modern rare-earth permanent magnet in the electromagnet core, then operate the electromagnet on DC, with the polarity that cancels the permanent magnet's field. Then the magnet holds its load all the time, except when the coil is energized. To drop the load, only a short pulse of current is needed, which can therefore be much more current than the electromagnet's winding would be able to withstand in the long term, allowing us to use a rare-earth permanent magnet that is that much stronger.
Exactly cancelling the permanent field may be a little tricky.
I appreciate all the input. I have saved it in my "round tuit" file. Right now , the crane works and grandson is happy. And I have more important things on my plate.... gotta get the place ready for the Oregon Rains..... they will come... inside stuff can be done when it's too nasty outside.... But some great ideas for a tinkerer to ponder. Thanks.
A nifty simple project.... I used slices of 3" to 4" diameter logs.... Then.... paint, wood burn or whaterver "TUIT " in the middle... once was my Jr High shop projects.... Students forever asked what a "TUIT" was...
Thanks.. I was "training" until I left for college, then some more when the son was 10 - 15,, now I back to "training".... keeps us young.
I made my own electromagnet for my Lionel modern reissue gantry crane, using a steel bolt for the core and winding it with #28 magnet wire. The magnet can easily lift objects that weigh several ounces. I am using DC to power the magnet and crane, I don't know if powering yours with DC instead of AC would make a more powerful magnet or not, but you might try it and see.
Here is a video of my crane lifting all sorts of loads.
I ran my postwar gantry crane on DC. The magnet was stronger, and the mechanism made less noise. I quickly learned that I needed a switch to bypass the rectifier to run the crane on AC once in a while to get rid of residual magnetism caused by the use of DC.
The strength of the magnetic field and the heat generated depends only on the amount of current flowing through the coil. However, you should get more current for the same voltage on DC than AC, because the DC current is opposed only by the coil resistance; while the AC current encounters an impedance in series with the resistance. I expect that you could get the same increase in lifting force--and the same increase in heating--just by using a higher AC voltage.
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