50Hz vs 60Hz fixed drive speed ?

From: Guy Sotomayor <ggs_at_shiresoft.com>
Date: Wed Feb 18 10:07:46 2004

On Tue, 2004-02-17 at 13:12, Paul Koning wrote:
> >>>>> "Tom" == Tom Uban <uban_at_ubanproductions.com> writes:
> Tom> A friend and I were discussing 8" floppy drives recently, in
> Tom> particular that they often have two pulley sizes so that the
> Tom> rotational speed is 360rpm regardless of 50Hz or 60Hz operation,
> Tom> assuming that they are setup properly.
> Tom> The question then turned to whether or not a fixed hard drive
> Tom> would typically be designed in a similar fashion, such that the
> Tom> spindle would rotate at the same number of RPM when configured
> Tom> for 50Hz or 60Hz operation, or if they did not worry about the
> Tom> speed differences as the media was not removable?
> Looking at some DEC drives in the Peripherals Handbook.... the RS04
> fixed disk (head per track) drive spins slower with 50 Hz power.
> Various removable pack drives (RP04, RK03, RP03) all show a single RPM
> spec but two models, one 50Hz, one 60Hz. Of course, voltage is
> another consideration.
> A Maintenance manual would give more detail about whether there really
> are two different pulleys or the like, but the data suggest that this
> is indeed the case for the removable drives.

RK05's used a different motor pulley for 50/60Hz. The pulley (on the
motor shaft) is actually stamped with the frequency it's intended for.
DEC used the same motor in both cases, but used a smaller pulley for
50Hz so that the disk would spin at the correct speed.

> paul
TTFN - Guy
Received on Wed Feb 18 2004 - 10:07:46 GMT

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