broken stump grinder

[J_J]

When you get the new motor installed, just run it at maximum, and you will know by the vibration, if any.

IMHO, my observation is, that you have an unbalanced wheel. The nuts plus washer, gives more weight to that side.

 

[toy]

pictures looks like potmetal to me whats your opinion

Is it possible that the shaft that is on the hub of the grinder blade may have had a roll pin in it located just where it twisted off. The roll pin would have been driven in through that shaft and into the motor shaft to hold it on. If it wasn't put in or put in improperly that would have caused it to shear and as the blade worked itself off it egg shaped the the remainder of the blade shaft?

 

[J_J]

Toy,

He said that it broke/sheared off inside the motor, almost like something came to a sudden stop. What do you think would happen if some one flipped the switch on the PTO when the stump cutter blade was up to full rpm. That should be a motor spool valve.

 

[MossRoad]

Toy,

He said that it broke/sheared off inside the motor, almost like something came to a sudden stop. What do you think would happen if some one flipped the switch on the PTO when the stump cutter blade was up to full rpm. That should be a motor spool valve.

That would let the motor and blade freewheel when the valve was turned off, but would not prevent damage if the blade was stuck and the valve turned on, would it?

 

[J_J]

That would let the motor and blade freewheel when the valve was turned off, but would not prevent damage if the blade was stuck and the valve turned on, would it?

David, That is the way it is supposed to work, but if something did not function correctly, then maybe. I can see someone dropping the stump cutter suddenly and it twisting off. Maybe. With the heavier nuts on one side, the balance should have been off somewhat.

If the blade is down in the stump, and you started the motor, it should go to relief when the relief pressure rating is reached.

 

[washita]

checked balance of cutting wheel today, it is balanced equal amount of nuts on both sides of blade, short of putting it on a car style tire balancer all indications is that it is ok, not sure what inside the motor retains the broken shaft ( still a piece of hollow shaft in the motor), when the pto is shut off at full rpms the wheel normally makes a couple of revolutions before stopping, wheel was not jammed or stuck when the cutting wheel exited stage left, called terry this morning, he claimed to not seen that type of failure before and was wondering if it was a manufactures defect, will send motor and shaft to tazewell at next opportunity, he claimed that even when you stall a grinder the pressure relief normally protects the motor, train of thought now is to support cutting wheel on its own set of bearings with a belt drive, plus add another steel disk to increase the mass of the cutting wheel, plus a overrun clutch on the motor. I miss the old days a stick of dynamite =no stump

 

[J_J]

washita, not sure what inside the motor retains the broken shaft ( still a piece of hollow shaft in the motor),



I believe that there is a gear on the end of the shaft.

 

[ponytug]

Ahh.. the old days, the smell of dynamite, the stones and tree parts whistling through the air... Nothing quite like watching a three foot long hunk of solid oak frisbeeing through the air at breakneck speed. It was certainly fast. I think that I was always around amateurs, because it seemed like the charges tend to send stuff up and out, rather than down and in.

Then there was the time a distant relation tried to break up an ice dam on the river before the ice pushed the bridge piling down river. The family story goes as follows;
Picture the potbellied stove, the highway crew clustered around it drinking coffee warming up on a cold winter day. Someone comes running in and says "There's an ice dam out on county G and it looks like its going to take out the bridge!" They call their buddies at the neighboring highway crews, because this is going to be fun. Everyone drives out to the ice dam, caucuses for a bit and they decide to dynamite the ice dam. All according to plan.

Guy hikes on on the ice, plants a stick of dynamite at the down river center of the ice dam, lights the fuse and runs for shore. Just as he makes it to shore...
bang, water spouts, ice flying, but, ...ice dam still intact.
"Ahah" says someone "it's freezing out here, let's just put a case out there, and get it done."...Guys drag out a case, plant it on the ice, light the fuse, longer this time, and run for shore. Cue music, and then watch in horror as the ice starts shifting and moving and the case of dynamite slowly moves down river...How far?
You guessed it, right under the bridge. BOOM!!!

Neighbors who hadn't watched it happened wondered why highway crews from three counties were working on the repair...

Ahh, yes the good old days... Brings a smile to my face, just thinking about it.

Looking at your photos, and I am no expert, it looks to me like a manufacturing defect, do to the erratic nature and granulated look of the break. Good luck on the repair. I hope PT/the manufacturer come up with something.

All the best,

Peter

 

[RegL]

Think ya used enough dynamite there Butch?
TURNER CLASSIC MOVIES

 

[MossRoad]

Think ya used enough dynamite there Butch?
TURNER CLASSIC MOVIES

Ahahahhaaaaaahhahahahaaa!!!

Oh, man! I forgot about that. Thanks for the laugh.