[AT] Farmall starter switch

Dean Vinson dean at vinsonfarm.net
Thu Aug 7 19:11:59 PDT 2014


Been using the Super M quite a bit lately, and sure enough, the difficulty starting returned pretty quickly.   I'd pull the ring and just nothing would happen, no click, no sound, no sense that it was trying to do anything.  That didn't quite make sense to me, assuming the starter pinion gear was locking up in the ring gear teeth...seems like I'd be able to hear or feel some indication of that.  Then I noticed that the tractor would start if I pulled the starter ring harder, or jiggled it around a little.  Over the past several days that pattern became very consistent... no response if I just pulled the ring normally, but it'd start every time if I pulled hard enough or wobbled the rod a little while pulling hard.   So, back to my initial theory about the switch contacts themselves being worn down and not making clean contact any more.

Thanks to the magic of the internet and credit cards, Bates Corporation sent me a new switch.   I put it on tonight, and the tractor started immediately with just a gentle tug on the ring.  So now I'm thinking it must have had both problems:  Poor electrical contact inside the switch, plus banged-up ring gear teeth interfering with the starter pinion.   I'll see how it behaves as time goes by, with that new switch on it.

By the way, I was impressed with Bates Corporation.   In addition to the switch I decided to replace the drawbar, since the one on the tractor was original and the holes were seriously oblonged and worn at both the front end where it attaches to the tractor and at the implement end.   Never bothered me enough to do anything about it when the tractor lived in my suburban garage, but now with regular use I wasn't happy with it.   I've looked at new drawbars before on the OEM Tractor Parts website so figured I could get one there, and the starter switch as well, but when I went to their website I saw that they just recently went out of business.   So I browsed a couple of other options before finding Bates' site.   Their system emailed me an immediate confirmation of my order, and then about 18 hours later I received a shipment notification email with a tracking number, and about 18 hours after that the new drawbar and starter switch showed up at my house.   They weren't the cheapest source but I'm happy with the service.

Dean Vinson
Saint Paris, Ohio

> ...The spring-loaded copper contact plate inside the switch and the 
> copper post on top of the starter motor are both all chewed up where 
> they come into contact when the switch is pressed.   I assume an 
> electric arc occurs when I make or break that connection, probably 
> boosted quite a bit by the tractor’s 12-volt conversion, and over time 
> those arcs have removed enough material that the contact plate 
> simply doesn’t reach the copper post any more so the starter
> motor never receives the “go” signal.    
> ...
> Got to thinking, "That might just be a bit too easy," so I went back
> out, reconnected the starter cable to the battery, and touched the 
> other end of the cable to the bare post on top of the starter motor.   
> Big sparks but no response from the starter motor--so my theory 
> that the switch simply wasn't making contact appears to be incorrect.  
> Time to take the starter motor off, but that's a task for another evening.
> ...
> Gentlemen, you hit the nail on the head with the idea about rocking 
> the tractor... Put  the tractor back in 5th gear and rocked it some
> more to rotate the ring gear a little, put the starter back on, hooked
> everything back up, climbed up, switched on, pulled the starter rod, 
> and the tractor fired right up like nothing had ever been wrong.







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