Hi all,
Anyone know how to isolate and secure the motor of a 1981 Mantua 4-6-2 DC Locomotive? It is screwed to the chasis which is the right rail pick-up.
https://imgur.com/gallery/QqD51YU
Gary
I'm not well-versed in DCC, but did do a DCC "dead-rail" installation for a friend.
To isolate the motor from the frame (and the boiler, too), I applied Kapton insulating tape to the bottom of the motor, and also to the top of the underframe, and, as a precaution, to the inside of the boiler, too, as the upper clearance between the motor and boiler was fairly tight.I then removed the steel screw which holds the motor to the frame, replacing it with a nylon screw (available from Kadee).
Wayne
Typical open frame motors. On the fiber board with the spring. The coiled spring pushes on the lever holding the brushes. You will see one brush lever with the wire soldered on has a piece of insulation on the spring. The opposite brush lever there is no insulation. Strip about a 3/16 piece of insulation from a piece of wire and insulate the spring with the stripped piece of insulation. Then you will need to solder a wire to the motor brush lever like the one going to the draw bar.
The open frame motors draw a lot of power. It would behoove you to replace the iron magnet with a super magnet. That would give your decoder an easier life if not save it from failure. It also slows the top speed and increases torque and slow speed response.
Pete
wrench567Strip about a 3/16 piece of insulation from a piece of wire and insulate the spring with the stripped piece of insulation.
Exactly what I did to this two-motor PRR DD1 model from Alco —
DD1-DCC1 by Edmund, on Flickr
While that red insulation looks like ordinary PVC wire insulation it is a stiffer material removed frome a high-temperature wire. There's a possibility of the spring pressure eventually displacing ordinary plastic especially with a little heat.
You can see I have the gray and orange DCC wire soldered directly to the brush holder:
DD1-DCC2 by Edmund, on Flickr
That's all the isolation you need.
Good Luck, Ed
Thanks all,
Ed. The motor screws into the frame. If I isolate teh brush springs as you show will the mounting screw cause any problem?
gdelmoroEd. The motor screws into the frame.
As far as I've experienced on several other open frame motors of this type I've isolated no, there wasn't any problem with metal contacting the rest of the magnet and motor frame which, of course, carries one side of the rail pickkup.
As with any decoder install, use Kapton tape and shrink tubing on the exposed wiring or PC board solder points.
Isolated brush holders like this are similar to what you'd find in a later-style "can" motor where the brushes are also fully isolated.
Thank you
Pete, thanks for your reply, not sure which part is the magnet or where i get the super magnet.
Hi Gary.
I buy most of my magnets from K& J magnets. Measure the iron magnet and compare the length and width. The thickness between the steel motor plates is important. I use stacks of 1/8 and 1/16 inch thick magnets to make the right thickness. Usual size is 1/2 wide by 5/16 deep by 1/8 inch thick. Yours may very.
I have seen them listed in Micro Marc.
Pete.
Gary.
I found an old invoice from K & J magnets. Apparently I purchased 6 of a part number B842-N52 and 6 of a B841-N52. I think that did two motors and a couple of under track uncoupler magnets.
Thanks Pete, ill let you know how I make out.
Like Wayne said earlier, I've used a thin layer of tape and then secured the motor back down with plastic/nylon screws, 2-56 IIRC? I think mine were made by Walthers.
At one time Mantua made a kit to replace the open frame motor with a Mashima can motor, if you hunt around online you might find one of them. You'd still need to do the tape/nylon screw deal though.
Hi Pete, I ordered the magnets but i can't figure out where they go! The existing magnet is formed around the coil. Can you send a picture?
The magnet is on the opposite end of the worm gear. Usually around a a screw. I usually just loosen the screw and slide the week iron block magnet out. You will find the new super magnets to be really strong. DO NOT let them slam together. When they break they shatter. If you find the motor to be not fast enough just replace one or more of the stack with a steel shim the same thickness.
I don't have any pictures. I found an old thread that has a picture of a Bowser DC71 that has the super magnets. https://cs.trains.com/mrr/f/744/t/283009.aspx?sortorder=desc It's about 4 posts down. Posted by garya. Last picture in the post.
Pittman-type open frame motor:
Pittman-type by Edmund, on Flickr
If you have the "flat-can" style like an early Athearn motor you might have a hard time finding curved magnets.
Garya's photo:
https://imgur.com/e6VgklX
Regards, Ed
Here's a Mantua mike with an isolated motor and supermagnets:
The Mantua magnet can be pried out and replaced with 4 of the 1/2 x 1/4 x 1/8 magnets. I isolated the brushes with insulation as Ed does.
Thanx guys! That really helps.
One more question (I hope). Does it matter how the magnets are inserted? Do I just stack them so they stick to each other and then put them in the open space?
Stack them like the picture shows. You can take up any gap with a thin piece of steel or another magnet. The magnet is charged through the thickness. If they were charged through the length then they would not be able to stack. Remove everything metal from your workspace before you handle them. The most frustrating thing is trying to tighten the end screw.
gdelmoro One more question (I hope). Does it matter how the magnets are inserted? Do I just stack them so they stick to each other and then put them in the open space?
That's what I do. Mantua motors take 4 magnets. I just push them in. Bowser motors take 5 and a shim. The aforementioned picture:
Before I replace the old magnet, I test the motor to see which way it turns when powered up. I put the new magnets in and test it. If it runs backwards I flip the stack of magnets.
Great pictures! Thanks to all for the help.