Starter on B7500

[Chanceywd]

Yes. 9N/2N/8N same as my B7200 - starter is a direct drive series wound DC motor. Looks like the US industry switched to gear reduction PM motors in early 90s and Japan may have been earlier. B7500s were built 2000-2004 and no field coil shown in the starter parts disgram....

Dan

I worked with DC motor drives in the past and until you mentioned I forgot about the difference between the 2 types of motors, Thanks for waking this old 70 yo brain up!

 

[TheOldHokie]

I worked with DC motor drives in the past and until you mentioned I forgot about the difference between the 2 types of motors, Thanks for waking this old 70 yo brain up!

That sort of stuff seems to have a habit of going into secondary/tertiary storage when not used for a while

I should have looked at the specifics of the B7500 before running my mouth.....

Dan

 

[Henro]

Please note I revised my comment about polarity and direction pf rotation. I was assuming a series wound motor but after looking at the parts breakdown it looks like its probably a PM motor.

In any event something about this problem description is fishy

Dan

That's why I am wondering if the OP somehow put the original starter back in, in place of the "new" one. Might be possible if he is referring to a used replacement as the "new" to him starter.

Original problem could be a failure of the linkage that pushes the gear shaft into the flywheel.

Perhaps the most important question to the OP would be is the replacement new, or or a "good" used item?

 

[TheOldHokie]

That's why I am wondering if the OP somehow put the original starter back in, in place of the "new" one. Might be possible if he is referring to a used replacement as the "new" to him starter.

Original problem could be a failure of the linkage that pushes the gear shaft into the flywheel.

Perhaps the most important question to the OP would be is the replacement new, or or a "good" used item?

The possibilty of reversed battery polarity keeps bugging me.

If its a PM motor it would run in reverse. Its also fairly common to use a sprag clutch to prevent the newly started engine from over driving the starter motor. So if the starter motor is running in reverse the sprag clutch wont engage?

That seems to explain all of the symptoms including a new starter....

Dan

 

[Chanceywd]

That sort of stuff seems to have a habit of going into secondary/tertiary storage when not used for a while

I should have looked at the specifics of the B7500 before running my mouth.....

Dan

Me too with 8n comparison !
And now you mention sprag clutch I worked with loss in weight feeders that used them so the permanent magnet motor could be reversed and drive a faster speed of gears with the auger still driving the same direction
Brain is starting to wake up.
Bill

 

[GeoHorn]

Just to confirm that reversing polarity with Dan. In changing an 8N to 12 volt you change from positive to negative ground. You can get 12 volt starter but the old 6 volt will work fine.

Bill

The bendix on an “N”-Ford operates by centrifugal force (threaded armature)…not by an electric solenoid-and-arm. When the motor armature spins…it thrusts the starter-gear forward to engage the flywheel)…. So reversing polarity has no difference to the starter.

 

[TheOldHokie]

The bendix on an “N”-Ford operates by centrifugal force…not by an electric solenoid-and-arm. So reversing polarity has no difference to the starter.

It has nothing to do with the bendix. Its a function of field and armature design.

Dan

 

[GeoHorn]

It has nothing to do with the bendix. Its a function of field and armature design.

Dan

Are we discussing the same thing..?? The little Kubota starter has a cylindrical solenoid/actuator mounted upon the starter-motor. The N-Ford does not and relies upon motor activation to throw the engagement-gear into the flywheel.

 

[TheOldHokie]

Are we discussing the same thing..?? The little Kubota starter has a cylindrical solenoid/actuator mounted upon the starter-motor. The N-Ford does not and relies upon motor activation to throw the engagement-gear into the flywheel.

I am intimately familiar with the N-series bendix style starter and how it differs from a more modern solenoid design.

Short snswer is NO you are not talking about the same thing.as the rest of is.

Go back and read the last 10 posts in this thread. The discussion of polarity has been around how it affects the direction of motor rotation. Nothing about starter drive design. So to catch you up:

An N-series starter is a series wound motor with direct coupled bendix drive. Reversing battery polarity has no effect on motor rotation or drive operation.

A B7200 starter is a series wound motor with dircy coupled solenoid drive. Reversing battery polarity has no effect on motor rotation or drive operation.

A B7500 starter is a permanent magnet motor with a planetary gear reduction solenoid drive. Reversing polarity will reverse motor rotation but drive will still extend and mesh with ring gear. However engine may not spin because of one way sprag clutch in the drive.

Dan

 

[GeoHorn]

I am intimately familiar with the N-series bendix style starter and how it differs from a more modern solenoid design.

Short snswer is NO you are not talking about the same thing.as the rest of is.

Go back and read the last 10 posts in this thread. The discussion of polarity has been around how it affects the direction of motor rotation. Nothing about starter drive design. So to catch you up:

An N-series starter is a series wound motor with direct coupled bendix drive. Reversing battery polarity has no effect on motor rotation or drive operation.

A B7200 starter is a series wound motor with dircy coupled solenoid drive. Reversing battery polarity has no effect on motor rotation or drive operation.

A B7500 starter is a permanent magnet motor with a planetary gear reduction solenoid drive. Reversing polarity will reverse motor rotation but drive will still extend and mesh with ring gear. However engine may not spin because of one way sprag clutch in the drive.

Dan

My post was purely in response to Chancywd who was questioning why reversing polarity on a 8N would still result in proper operation of that N-Ford starter. It was a sub-topic of this thread. Sorry for the thread-drift.

 

[North Idaho Wolfman]

OLD GAR needs to verify that the battery connections and polarity is correct.
It would also explain why its blowing fuses, because the other systems require the correct polarity too.

 

[OLD GAR]

Due to "Murphy Being Always On The Job" I've missed most of the posts in between my first posts about the starter issue on my B7500! I appreciate all the convers about what could be the problem. Funny enough there were a couple that were close but other stuff just made me look in another direction. An 'impossible to recreate' showed up quite by accident. In the suggestions to use the 'test meter' without the battery cables being connected did puzzle me but 'what the heck' I'll try that. Same results EXCEPT ~0^0~ ! Probe to the +post to -post 12.7V. OK ? BUT upon an "up close" look at the meter reading there is a little " - " in front of the 12V number! So back down to the cable from the battery to the starter and the same " - " in front of the 12V reading! This is WTF! reaction when trying to understand this! ! ! WELL GUESS WHAT? This battery is less than a year old but in the hurricane of several other crisis, the B7500 got to sit out of the shed with the key left on. May have been 3 or 4 weeks! So bring the Schumacher charger and hooked it up. Charger indicated 12.8V. WTF? Starter spins but the engine isn't turning over. Then to avoid having to take the starter off, we towed it to the garage. Even tried a rolling start while towing it but it wouldn't even let the wheels turn the engine over. So on to the garage where the starter exchanges started. All a waste of time! When the culprit finally was uncovered it was a kick in my a$$! ! ! How I discovered it was to take the battery off my old Massy210-4 and switch it to the B7500.
WAIT FOR IT! THE DAMN THING WORKED LIKE IT WAS SUPPOSED TO! No amount of reasoning for a good battery going dead, would result in that battery reversing polarity! The upscale Schumacher charger, connected in the correct way, should have charged the battery in the correct polarity. RIGHT? WRONG! ! ! Explain that if possible.

 

[Chanceywd]

Due to "Murphy Being Always On The Job" I've missed most of the posts in between my first posts about the starter issue on my B7500! I appreciate all the convers about what could be the problem. Funny enough there were a couple that were close but other stuff just made me look in another direction. An 'impossible to recreate' showed up quite by accident. In the suggestions to use the 'test meter' without the battery cables being connected did puzzle me but 'what the heck' I'll try that. Same results EXCEPT ~0^0~ ! Probe to the +post to -post 12.7V. OK ? BUT upon an "up close" look at the meter reading there is a little " - " in front of the 12V number! So back down to the cable from the battery to the starter and the same " - " in front of the 12V reading! This is WTF! reaction when trying to understand this! ! ! WELL GUESS WHAT? This battery is less than a year old but in the hurricane of several other crisis, the B7500 got to sit out of the shed with the key left on. May have been 3 or 4 weeks! So bring the Schumacher charger and hooked it up. Charger indicated 12.8V. WTF? Starter spins but the engine isn't turning over. Then to avoid having to take the starter off, we towed it to the garage. Even tried a rolling start while towing it but it wouldn't even let the wheels turn the engine over. So on to the garage where the starter exchanges started. All a waste of time! When the culprit finally was uncovered it was a kick in my a$$! ! ! How I discovered it was to take the battery off my old Massy210-4 and switch it to the B7500.
WAIT FOR IT! THE DAMN THING WORKED LIKE IT WAS SUPPOSED TO! No amount of reasoning for a good battery going dead, would result in that battery reversing polarity! The upscale Schumacher charger, connected in the correct way, should have charged the battery in the correct polarity. RIGHT? WRONG! ! ! Explain that if possible.

Never would have figured that but as IWM said polarity needed to be checked. Thanks for the update and glad to hear you got it figured out. Sorry about me leading off about the 8N starter in trying to understand .
Bill

 

[Henro]

Short explanation of what apparently happened:

"So let me restate: The only way for a battery that has a positive charge, to reverse itself, is for the battery to be completely discharged, and then reversed charged. We have seen this happen a couple of times, and it would be considered the more common of these rare situations.

For all intents and purposes, the battery will be ruined. You could technically charge it up, negatively, and continue to use it, but your plates are designed with the positive plates being lead dioxide, and the negative being composed of a sponge lead, which would now be reversed. Because the reversed battery is no longer formatted correctly, it will only work to a limited degree. The fact of the matter is, a lead acid battery cannot reverse its own polarity without an external stimulus. It is just not possible."

Taken from:

Battery Myth | Can a Battery ‘Reverse’ its Polarity?

Guilty As Charged Blog Post touching on the battery myth of reverse polarity. Can a battery, after installation, reverse its own polarity? Not by itself, but with external stimulus, it is possible.

www.batterystuff.com

 

[85Hokie]

the battery off my old Massy210-4 and switch it to the B7500.
WAIT FOR IT! THE DAMN THING WORKED LIKE IT WAS SUPPOSED TO! No amount of reasoning for a good battery going dead, would result in that battery reversing polarity! The upscale Schumacher charger, connected in the correct way, should have charged the battery in the correct polarity. RIGHT? WRONG! ! ! Explain that if possible.

Batteries in general can have the appearance of being "good" yet not be!!!!!!!

My wife' s CR-V would start fine if somewhat "warm" - outside temps in the 40's. But once it dipped into the 20's - it would just clicky-clicky.

I said hell, I will fix this right up!!! Cleaned the terminals and charged the battery and it started right up..... well that was fixed!!! O hell no it was not!!!!!!

I ordered on of those battery testers - the kind that places a load on it and tests the internal resistance and all those good things......... CAME UP in big bold letters ......... REPLACE!!! the life was at 32% the charging ability was 12% or something like that ........ but it still showed 12.5 volts with a meter.

Moral of the story - you can have 12 volts across a human hair wire - but it will never deliver the amp amount to turn the starter - and in my case the volts were there BUT the ability to deliver amps was not.

AND for what it is worth - many a "dead battery" cannot be helped via a high amp charger.

I replaced her battery with a new one at wally-world and bullya - starts right up.

 

[OLD GAR]

Is this problem the same as you were having before you changed the starter motor?

If so, I would check the voltage between the battery connection at the starter and the starter case, to see if it was equal to battery voltage at the battery posts (not the battery clamps, but the posts themselves) and report back. Also report what the voltage is at the battery posts unloaded and when you try to start the tractor and the starter motor spins but doesn't engage the flywheel.

Maybe someone else has better ideas, but this is what I would do myself as a first step to evaluate the issue.

Some will advise changing things like the battery cables, but I personally favor taking measurements first rather than the shotgun replacement approach.

Never would have figured that but as IWM said polarity needed to be checked. Thanks for the update and glad to hear you got it figured out. Sorry about me leading off about the 8N starter in trying to understand .
Bill

 

[OLD GAR]

The suggestions that polarity could have been a reason. My aged eyesight just overlooked an indication that all wasn't well. The numeric display on my test meter actually showed the obvious " - " in front of the 12.8V but I didn't see it until way late in the search! But so far no explanation has covered the phenom of a newer battery reversing polarity.
Another thread by me is being posted about another problem on this same Kubota B7500!