motor fan sheave

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[quote="brianj"]Right]

I am having trouble visualizing what you described. The only way I can think of the idler shaft/bearing being pulled into the headstock is if the control sheave siezed to the shaft. But that does not explain what is forcing the whole shebang to migrate into the headstock.

The quadrant gear is notorious for having 'jammed' teeth caused by either adjusting towards slow with in NOT running, or adjusting too fast in that direction while running. Most likely the teeth were 'mashed' to begin with.

Normally the control sheave is always pressing against the quadrant arm.

The small loop spring on the end of the control sheave is quite weak and I cannot imagine it pulling the shaft in. Its only purpose is to prevent the inner race of the button bearing from rotating.

It is possible that the pop pop was caused by the control sheave hitting the speed control(high speed adjustment 'too fast'. If it bent the leg enough for the quadrant to move away from the control sheave that would cause the control sheave to go too far out on the idler shaft.

Another possibility is the idler pulley opened up too far and the motor belt got jammed between the sheaves.

If it jammed while running(fast) that would be a major shock to the entire drive train. How that would pull the idler shaft inward I do not know but it maybe the cause since the belt would likely be in contact with the shaft and jammed in one or both sheave vanes.

I would be very careful bringing this back up. I would not go to fast without careful observation of everything moving as the speed is adjusted upward.

I would run it only after running the speed control through its full range while rotating the shafts manually with no problems.

Pix of the damaged parts might shed some clues as to what happened.

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In your first post, you mentioned both sheaves were seized. Did you mean the motor pulley was seized also? If so in what position were both pulleys seized?

When you ran it up to fast, did the speed actually increase. If so the sheaves were not seized(sluggish most likely).