DC motor runaway

[magnewb]

Hello! Does anybody know what happens to a series- or shunt DC motor if it is intentionally exposed to a runaway? I know the motor overspeeds, but how does it stop? Does the winding insulation burn up pretty fast (and making it stop) or is it possible that the speed on the rotor can increase until the speed itself makes the motor shatter? The reason I wonder is because I want to test this just for fun, with a startermotor used in a car

 

[SirKit Breaker]

Go for it, stand back, and let us know what happens

 

[Knobhead]

Runaway in a DC motor is fun. Only ever seen it once.

Two things can happen.
1/ the armature windings can break free of the bindings and foul the stator.
2/ the armature segments break free and wreck the brush gear.

Fun and games all round!
Runaway in a DC motor is fun. Only ever seen it once.

Two things can happen.
1/ the armature windings can break free of the bindings and foul the stator.
2/ the armature segments break free and wreck the brush gear.

Fun and games all round!

Just to spoil your fun you’ll need at least 30V to destroy a 12V starter motor, there’re designed for no load running.

 

[magnewb]

Thanks for your answer. In which extent are they designed for no load running? Do they have some type of runaway protection like a centrifugal switch?

 

[Knobhead]

Take a starter motor to bits and see how well constructed they are.
They shouldn’t run unloaded but before the days of pre-engaged starters it was a common fault for the “Bendix” gear to jamb and the motor would run unloaded.

 

[malcolmsanford]

Take a starter motor to bits and see how well constructed they are.
They shouldn’t run unloaded but before the days of pre-engaged starters it was a common fault for the “Bendix” gear to jamb and the motor would run unloaded.

Nothing like a nice cold raining day under the bonnet ****ing the starter motor bendix with a hammer was there Tony.........

 

[Knobhead]

Nothing like a nice cold raining day under the bonnet ****ing the starter motor bendix with a hammer was there Tony.........

I made the mistake of buying a Maestro, what a pile of s**t. Cold weather the bendix would freeze. Got to the stage I would put the kettle before going out to the car so it was ready to thaw the starter out. Was quite happy when I wrote it off.

 

[malcolmsanford]

Hillmans were always a joy for the transverse engines and of course the bendix was buried under the engine, and with being so low to the ground getting under to hammer it was a joy ..............espicially on a date. But they always had a get out of jail starting handle for the extra cold mornings.