A cutout relay is in effect a one way valve for the generator. When battery voltage exceeds the generator voltage, the relay prevents the battery from discharging into the wires of the generator to ground. When the generator voltage exceeds the battery voltage, the generator can charge the battery. (voltage and rate control are not included) A good cutout relay is equivalent to a high amp capacity Diode. When the generator was the only option, Solid state power capable diodes didn't exist. Thus a device that latches on when gen is higher than bat, and tripps off when it is lower. There are windings for both voltage and current surrounding the mechanism and when it detects reverse flow, the coils magnetism push the contacts apart.
A voltage regulator includes a cutout relay as an integel part. But the voltage control is separate from the cutout in every way. The "A" style generator uses a grounded field. (supply in in the gen) The regulation is based on a relay that opens and closes a set of contacts that ground the field. As they vivbrate several times per second, the field strength is made to fluctuate. This variability controls the voltage output of the generator. As the out put gets to the desired charging voltage, the relay vibrates more, reducing the field current. If the load increases (lights turn on voltage goes down) the contacts stay together longer allowing higher output voltage (keeping it charging) The cutout relay system depended on simplicity again, due to cost a simple low output generator was used that could only charge enough at full output to run the lights and charge nominally. Thus when the light switch (on many old tractors) was connected to the generator field, the generator is able to make full output when the field is directly grounded. (The light switch is not internally electrically connected to the gen. only the shaft is controlling two separate switches) When on L (low charge) the switch causes the field grounding current to go through a 2.5 or so resistor. In all other positions the field is full ground. on H the charge rate is high (for recharging the battery when it was cranked too long, or started repeatedly. On L or H it is also full ground, max output. The cutout prevents draw when shut off as described above. Regulators provide automatic charge regulation, better battery life, and less operator spawned errors. If the tractor has a LHDB switch it likely had a cutout. If it has a 3 position it likely had a regulator. (no guarantees on an old tractor, but the serial # break should be good to assess the issue. Best of luck with the project, a worthy effort. Hello to all, Jim
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Today's Featured Article - The 8N and the Fox - by Zane Sherman. Dec. 13 1998, Renfroe, Alabama. Last niht I dreamed about the day that I plowed the field of about 10 acres over on what Jimmy and Dandy called the Ledbetter field. I was driving the 1948 8N Ford tractor that Jimmy bought in 48 new This was prebably in about 1951 and maybe even befor the house was built. This would have made me to be about16 years old and I drove the tractor for nothing and would have paid to drive it if I had had any money which I didn't, but neit
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