Now if you want to try and rebuild the OEM switch yourself, here's a couple of things I've learned and would like to add to what Dwight has said:
Once you have removed the groove pin and found all the parts that went flying across the floor, simply flipping the contact disk is the logical approach for the first rebuild. Next time you can file or sand it smooth and clean. I sure hope you took that picture Dwight mentioned or have another disconnect laying around to use as a reassembly guide. There are two springs and several washers/bushings (some metallic and some non-metallic) that must be put back together in the proper order for the disconnect to work properly.
I also have carefully filed a little material off the rounded heads of the contact terminals (they are actually 1/4-20 copper alloy carriage bolts) to achieve more contact area with the disk. Once the handle/shaft and related parts are removed, filing the heads of the two contact studs is fairly easy. Use care in doing this as the same amount of material should be removed from both heads and those two surfaces must be in the same plane for optimum contact with the disk once it's been reassembled. I think it's best to file both of them at the same time while carefully holding the switch frame in a vice.
I prefer to chemically clean all of the copper alloy parts before reassembly. This involves removing most of the nuts & lock washers on all three studs and the fusible link. Be sure to use two 7/16 wrenches when loosening the nuts on either side of the fusible link's terminals. (The inboard wrench is going to have to be kinda thin, something like a tappet wrench or one of those cheap sheet metal wrenches you got with that Christmas toy you had to assemble last year.)
I do not suggest removing the bottom nuts that hold the two contact studs into the Bakelite body of the switch (learned that one the hard way). Chemically cleaning the exposed face of those two nuts and the threads of the studs with a Q-tip is sufficient. It's imperative that any and all surfaces that are going to conduct electricity be as clean as possible, or you could still have high resistance connections.
Pay close attention to the "tightness" of the crimped connections of the terminals on the fusible link, as I've found those to loosen over time with repeated heating and cooling cycles. Keep in mind that although some of us have replaced power cables with something like say #4 welding cable, every bit of power still goes through that little fusible link. So far I've not had to replace one, but it just looks to me to be a 2 1/4" long piece of #12 copper wire. After cleaning the fusible link assembly, I always recrimp those terminals to help insure a tight connection.
If I recall correctly, I've added a washer or two between the larger spring and the groove pin to increase the compression load of the spring against the disk and the two contact studs/terminals. When reassembling everything, take care as to how tight you make the threaded connections. Just remember that all of the threaded studs and nuts made of copper alloys and are rather soft and can't be tightened as if they were steel nuts and bolts. A liberal coating of a good dielectric grease on the contact disk and studs might be a good idea.
Mike in KYSide Note: I probably shouldn't say in this discussion group how I chemically clean the copper alloy parts because I'm afraid David Roden will turn me into the EPA or someone like that. Hell, I'm still getting unannounced inspections from my local County Electrical Inspector trying to see how I got my standby generator hooked up to the house. LOL
----- Original Message ----- From: "Hazen, Dwight L" <hazen indiana edu>
To: <elec-trak cosmos phy tufts edu> Sent: Wednesday, November 12, 2008 8:49 AM Subject: (ET) power disconnect switch
Not to spoil anyone's replacement disconnect business, I have had good luck repairing the disconnect switch. Water and then corrosion cause the spring loaded copper disk to hang on the shaft causing intermittent operation.You need to disassemble the switch (take a picture of it before you start) and clean all the parts, make sure you get the springs right when you reassemble (look at your picture). Lightly sand the disk, contacts and shaft if needed "less sanding is better than more" turn the disk over and use the other side if sanding will not work. A small amount of grease on the shaft will help the disk to move, careful not to get any grease on the disk or contacts. There is a little pin that rides on the cam that makes the detents. If that pin is bent the switch will not work correctly, straighten or replace.There is a right way and wrong way to put it back in the tractor, make sure when you are done the off position is down from the operator's position with the handle toward you. In an emergency you what to just slap the handle down to cut the power. Never force the handle that is how the pin gets bent.The switch is not a bad design and it seems to be made to take apart and fix. Most devices today can not be repaired just replaced.Try it you have nothing to lose. Dwight Dwight L. Hazen Indiana University, UITS, Networks Bloomington, In. 47408-7378 812-855-5367 Ham Radio wb9tlh arrl net http://wb9tlh.ampr.us _______________________________________________ Elec-trak mailing list Elec-trak cosmos phy tufts edu https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak