DC Starter motor reverse rotation?!?

[stoy@n]

Hello every one,

I am new in this forum and hope i can get some answers regarding my question.

Recently I have repaired a damaged starter motor from Caterpillar engine.The motor it self was OK and only the coil which is connecting the starter to the fly wheel was burned.That was the only replaced part in the motor but nothing to do with the direction of rotation of the motor.The starter was working til the coil burn out.After replacing the coil and test the starter I found that the motor is not turning in proper direction which really twist my brain.This type of motors the reversing is possible only by changing the polarity of either the armature or the field but not both.
Does any body have an idea what could cause this motor to change the direction of rotation without changing any connections?!?

Regards,
Stoy@n

 

[hurk27]

I can only think of 5 more besides the one you mention.

1. swap ends of the armature windings (almost impossible unless you press the shaft out and back in backward)
2. swap ends of the field casing or winding Carrier (Not possible with most starters)
3. install the brush wires on the wrong terminals inside of the starter
4. wrong wiring of the field windings
5. Armature rewound backward
I pick 3, 4, or 5

 

[stoy@n]

I can only think of 5 more besides the one you mention.

1. swap ends of the armature windings (almost impossible unless you press the shaft out and back in backward)
2. swap ends of the field casing or winding Carrier (Not possible with most starters)
3. install the brush wires on the wrong terminals inside of the starter
4. wrong wiring of the field windings
5. Armature rewound backward
I pick 3, 4, or 5

The motor was not disassembled.It has been changed ONLY the coil which is connecting the rotor to the flywheel.The motor is quite big so swapping of brush wires is not possible.There was no change on the armature.The wires of the field are tick enough and also can not be mistaken.

Regards,
Stoy@n

 

[hurk27]

Well I know of no other way, When I had my 38' Chris Craft which had 2 counter rotation 327 Chevy motors (twin screw), I had removed both starters to rebuild them, I made the mistake of not marking them as to which motor they came out of, and installed them on the wrong motor, and in this case both were trying to start the engines backward? about the only other thing that comes to mind?

 

[iwire]

Any chance the battery was reconnected backward?

 

[Don Randall]

Any chance the battery was reconnected backward?

That could apply if they were permanent magnet motors, (PM fields). Don

 

[stoy@n]

If they has changed the polarity of the batteries the starter will not change the direction but they will damage the control of the engine.It is medium size Caterpillar engine with 24V starter.The motor is running in opposite direction and there is no chance to connect to fly wheel....
I have change in the past the rotation of motor starter to modify it for boat engine, but i have done change in the armature which is not only changing of two wires by mistake.....
It is a real mystery for me .....:-?:-?:-?
Any way the engine is now with new starter and run well.Also i have compared two motors just to verify the connections are proper....
It is very very strange and it is drive me crazy when i don't know what is the reason for the fault???

 

[hurk27]

I have change in the past the rotation of motor starter to modify it for boat engine, but i have done change in the armature which is not only changing of two wires by mistake.....

Try to find a counter clockwise drive for a Chevy starter, reversing the motor is not a problem but finding that drive can be!

If you figure it out let us know what it was