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John Stevenson
05-24-2007, 12:46 PM
The reason I ask is I have been making a Christmas tree.
Christmas tree's are the name given to a stack of slip rings to take or give power to a rotating item like a crane slew gear.

Some electric motors have three of them to handle the current to the armature.

They are made up of layers of brass and insulation with some method of getting the current in or out, also insulated.
Local rewinders got a set of 12 rings in with a short on 3 rings. They started to strip it down to replace the insulation but found out that this one was a weird one in that they had used brass tube with wires soldered on to the terminal bolts and filled the whole lot with resin ?

Quite how they had done this and kept everything concentric given the thin sleeves is puzzling, perhaps they were jigged up up to do these ?

Anyway it was all scrap at this point.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/xmastree1.jpg

My idea was to turn all the rings off and leave a resin sleeve on the alloy tube and the original end but the resin is flawed with the wires being cast in and it flew all over, bounced off the dog and smashed the cup handle [ note to self, bill for 38 piece dinner service to customer ]
So back to square one, again...................

Pic shows the build up during assembly, 4 rings fitted.
Each ring has one tapped hole to take the brass threaded stud with nylon tube over it for insulation. Other holes are clearance for the nylon tube, more holes as you get higher. Brass rings require drilling at this point, just popped at this stage. Nylon separators are top hatted to located the brass rings and centralise the whole job.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/xmastree2.jpg

Finished job after skimming in the lathe to true up the insulators and rings.

Started this yesterday dinner and finished it this dinner time. Would have been quicker but having no handle on the cup slowed the job up a bit :D

.

LastOldDog
05-24-2007, 02:40 PM
The reason I ask is I have been making a Christmas tree.
Christmas tree's are the name given to a stack of slip rings to take or give power to a rotating item like a crane slew gear.

Some electric motors have three of them to handle the current to the armature.

They are made up of layers of brass and insulation with some method of getting the current in or out, also insulated.
Local rewinders got a set of 12 rings in with a short on 3 rings. They started to strip it down to replace the insulation but found out that this one was a weird one in that they had used brass tube with wires soldered on to the terminal bolts and filled the whole lot with resin ?

Quite how they had done this and kept everything concentric given the thin sleeves is puzzling, perhaps they were jigged up up to do these ?

Anyway it was all scrap at this point.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/xmastree1.jpg

My idea was to turn all the rings off and leave a resin sleeve on the alloy tube and the original end but the resin is flawed with the wires being cast in and it flew all over, bounced off the dog and smashed the cup handle [ note to self, bill for 38 piece dinner service to customer ]
So back to square one, again...................

Pic shows the build up during assembly, 4 rings fitted.
Each ring has one tapped hole to take the brass threaded stud with nylon tube over it for insulation. Other holes are clearance for the nylon tube, more holes as you get higher. Brass rings require drilling at this point, just popped at this stage. Nylon separators are top hatted to located the brass rings and centralise the whole job.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/xmastree2.jpg

Finished job after skimming in the lathe to true up the insulators and rings.

Started this yesterday dinner and finished it this dinner time. Would have been quicker but having no handle on the cup slowed the job up a bit :D
.
John, nice looking stack. In the fire dept., we had those at the turntables on the ladder trucks and the snorkels. Occasionally, stress/distortion would cause intermittent continuity, the fix was three towers of brush holders, at 120 degrees about the circumference. All controls were electric over hydraulic. I think some were 8 circuit. Lloyd

Weston Bye
05-24-2007, 03:23 PM
Nicely done!

One question, John, is the aluminum tube part of the assembly, or just for setup? OK, another question, will the nylon compress or creep over time?

LastOldDog
05-24-2007, 05:57 PM
Nicely done!

One question, John, is the aluminum tube part of the assembly, or just for setup? OK, another question, will the nylon compress or creep over time?

Wes, the hygroscopic properties of Nylon along with thermal expansion are well documented. As long as each component is selected and configured to accommodate the differing conditions all should be well. Duration loading is merely a minor consideration. However creep is to be noted.
Lloyd

jimmstruk
05-24-2007, 07:09 PM
Thanks again John, good pics and as always an interesting job. JIM