On Sat, 17 Feb 2018 10:28:42 +0000, Dave Plowman (News) wrote:

In article ,
Andrew Gabriel wrote:
Larger diameter motors have lower max speeds above which the forces on
the armature will break it. Larger diameter motors also allow space for
more poles giving lower speed higher torque characteristics. To
increase torque with a given diameter, the motor body can be made
longer.

Yes - remember a pretty advanced design of 1/4" tape recorder. Had twin
capstans with direct drive. And they stopped turning when the tape
stopped running. They were pancake motors. Had a very fast start up
time. That would explain it.

The fast startup times were more probably the result of employing
solenoid operated pinch wheels. I'm sure the capstan motors were more
likely kept spinning all the time the machine was powered up and ready to
go.

--
Johnny B Good