6V Generator Motoring Test Question

Kerwin · Sep 8, 2010

I was bench testing the 6V generator from my M and could get it to motor with the F terminal grounded, but it did not want to speed up when I removed the jumper from the F terminal. In fact, it will usually continue at same speed for a while and then slow down.

A couple of questions:

I was using a battery charger with a 6V/10A setting to provide power. Would using a fully charged 6V battery make a difference?

There is some back end noise in the generator, even after oiling. Could a bad bearing, etc., cause enough resistance to keep generator from picking up speed?

What else can I look for in the generator to determine cause of motoring problem? I did a search and found reference to a troubleshooting chart by John T, but not sure where the chart is located.

Thanks for the help.

Janicholson · Sep 8, 2010

Your test should be made with a fully charged battery. That being said, the f terminal grounded slows the rotation.
John T list

John T · Sep 8, 2010

Usually a smooth even RPM when you jump voltage to the ARM post and case/frame (with FLD grounded) means the Armature, Brushes and bearings/bushings are in "decent shape" Then if it increases RPM when FLD is ungrounded that means the Field windings are at least intact. If she dont change RPM at all I question if the Fields are bad such as open or shorted internally. An ohm meter can provide an indication if the fields are open or shorted.

That noise may be a bearing/bushing "going" bad although it isnt bad enough yet to allow the armature to drag.

I prefer a battery for the motor test but still think it should act about the same as above unless the charger can barely supply enough amps to begin with.

Heres my non chargign troubleshooting

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=665110

John T
John Ts Non Charging troubleshooting

JMOR · Sep 8, 2010

(quoted from post at 08:37:40 09/08/10) I was bench testing the 6V generator from my M and could get it to motor with the F terminal grounded, but it did not want to speed up when I removed the jumper from the F terminal. In fact, it will usually continue at same speed for a while and then slow down.

A couple of questions:

I was using a battery charger with a 6V/10A setting to provide power. Would using a fully charged 6V battery make a difference?

There is some back end noise in the generator, even after oiling. Could a bad bearing, etc., cause enough resistance to keep generator from picking up speed?

What else can I look for in the generator to determine cause of motoring problem? I did a search and found reference to a troubleshooting chart by John T, but not sure where the chart is located.

Thanks for the help.

"Could a bad bearing, etc., cause enough resistance to keep generator from picking up speed? "

As I recall, the answer is yes, because even though reducing the field will increase speed, torque is reduced. So the extra torque needed to overcome a bad bearing is not present with reduced field.

Bob M · Sep 8, 2010

Hey John - I think you got it there. If memory serves it takes 15 - 20 amps to spin up a 6 volt generator. A 10 amp charger is not gonna do it.

Kerwin: Recommend testing again using a fully-charged 6 volt battery in place of the charger.

Also.....some noise (buzzing, squeaks, etc) out of the commutator of a spinning generator is pretty much normal. You simply don't ordinarily hear it on a tractor on account of all the other mechanical racket nearby!

Kerwin · Sep 9, 2010

I tried the motor test on the generator using the battery and it worked. Thanks for all the help.

6V Generator Motoring Test Question

Kerwin

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Janicholson

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John T

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JMOR

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Bob M

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Kerwin

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