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Guys, please help me. I am working on my Graphophone AT, completing the motor.
Does the crank turn while playing?
I am thoroughly confused!
Many thanks!
Graphophone AT
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Teak
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Onlinephonogfp
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Re: Graphophone AT
Yes, the crank turns while playing, as the mainsprings unwind. That's why Columbia provided a "fall-off" type crank for this model.
George P.
George P.
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Lucius1958
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Re: Graphophone AT
That's another question: why didn't they just leave the crank to unwind without falling off?phonogfp wrote:Yes, the crank turns while playing, as the mainsprings unwind. That's why Columbia provided a "fall-off" type crank for this model.
George P.
Bill
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Django
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Re: Graphophone AT
Lucius1958 wrote:That's another question: why didn't they just leave the crank to unwind without falling off?phonogfp wrote:Yes, the crank turns while playing, as the mainsprings unwind. That's why Columbia provided a "fall-off" type crank for this model.
George P.
Bill
My guess is that because the crank shaft is horizontal, a large portion of the rotation would involve resistance caused by the weight of the crank arm. This and the additional driving force as the weight has the opposite effect as it uses it’s weight to help drive the motor on the way back down could rob power on the upstroke, increase power on the downstroke and stress the drivetrain during the transition between the up and downstrokes. The main purpose was probably to prevent the loss of power on the upstroke.
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Onlinephonogfp
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Re: Graphophone AT
The loss of power on the upstroke is a good point, but my simple mind is drawn to the possibility of a rigid crank stopping at the 12:00 position and posing a hazard to removing the cylinder. I don't know...
George P.
George P.
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Jerry B.
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Re: Graphophone AT
With disc models the fall off crank would fall before it interfered with a large record. Jerry B.