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Old 17th Dec 2022, 12:04 am   #1
Chris Don
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Join Date: Sep 2008
Location: Montreal, Canada
Posts: 7
Default Tandberg 64 - PAPST motor - help needed

Hi all,

This is a sketch of the synchronous PAPST motor HSZ 32.50-4-440, that one can find on Tandberg 64 tape recorders (made in 1965).

I have seen that a few guys here have significant knowledge about these motors, as appears in an old thread: https://www.vintage-radio.net/forum/...t=90880&page=2

As is common with PAPST motors, the bell-shaped rotor is outside the stator.
Two sleeve bearings guide the axis.
Downward, the rotor is held by a thrust (1 ball) bearing.
Upward, the rotor movement is limited by a steel washer in contact with the (stator's) sleeve bearing.

My problem is: the thing (marked with ? on the drawing) that used to maintain this washer has completely deteriorated, and I can't figure out what it was. Couldn't figure out if what remained was dust (from some kind of felt?) or rust. Looked like rust, hard and brittle.

Could anyone familiar with these motors tell me what this mystery element was? Felt or spring?...

Without this, the motor runs smoothly when vertical (gravity holds the rotor in contact with the thrust bearing) but not when horizontal (and yes, these tape recorders could be used vertically i.e. with motor horizontal).

I have contacted the EBM-PAPST manufacturer in Germany in the hope that they can still unearth a documentation of their antique motors, but I guess there is little chance they do...

Thanks for your ideas 8)
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