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Bob Nelson 11-01-2009 18:11:21 76.113.226.72 739391 Report to Moderator	Did a search but couldn't find an answer. I'm hoping someone has the patience to answer some novice questions. I'm studying the electrical diagram for a 6 volt 9N; single pole (1940). 1) what is the purpose of the cutout relay? Is that to keep from discharging the battery when the tractor is shut off? 2) The resistor block looks like it has 3 connections. Battery hot to center pole (thru ammeter) that also connects to light switch and ignition switch? 3) When the ignition switch completes the circuit, it looks like it activates the ignition system through a resistor? What is the purpose of the resistor? 4) I've owned this tractor for 15 years and never tried this, but it looks like the starter would turn the engine over even with the ignition key off? True? It also looks like you could turn the lights on even without the ignition on. Can't believe I've never tried either one!! HA! If there is a good site that answers these questions, just point me there. Thanks for any help. [Reply]   [Send Email]
Bob Nelson 11-01-2009 19:20:53 76.113.226.72 739400 Report to Moderator	Thanks Bruce in reply to Bob Nelson, 11-01-2009 18:11:21   Thanks Bruce. Bob   [Reply]   [Send Email]
Bruce (VA) 11-01-2009 18:24:11 24.125.26.10 739392 Report to Moderator	Re: Novice Electrical System Questions in reply to Bob Nelson, 11-01-2009 18:11:21   1) The cut out is just a switch. When the generator stops charging the battery (battery volts exceed generator volts) or when the engine stops, it opens. 2) Yea, that sounds right. But, I'm not looking at a wiring diagram & don't own a 9N. Just do a search in the archives on wiring diagrams. 3) Technology & materials being what they were in the 30's, that square coil would melt if it ran on much more than 4 amps for any length of time. (see tip # 38 for an example). In order to get a hot spark at the same time the starter was drawing max current from the battery, a ballast resistor was added in the ignition circuit. What that did was add about .3 ohms of resistance in the circuit, added to the 1.5 ohms of the coil. That got you 3.5 amps or so at start up. As the voltage increased when the engine was running to about 7.5 volts, the resistor heated up, adding more resistance in the circuit. 1.0 ohms hot, plus 1.5 ohms of the coil got you down to 3 amps or so to keep from melting the coil. 4) Yep, that's right. The thumb starter switch is there to prevent the tractor from starting in gear. The key switch just allows battery voltage to the coil for the ignition circuit. And, if you run the headlights through the key switch, you will melt the key switch. 50 Tips   [Reply]   [Send Email]