Dial Drive Slipping in Models 116, 640, 641, 650, 660, and 680
There
are two points that can be adjusted on the Model 116 dial drive in the event
that there is any slipping or roughness [Assembly Part No. 31-1563 - Also
used on models 116, 640, 641, 650, 660, and 680].
First
remove the lock spring "A" from the assembly and then, by pulling
on the Speed Shaft "B", both the speed shaft and the
vernier shaft, as well as the bearings and the tension spring "E",
can all be removed from the housing. Through the use of two blades, placed
at each end of spring "E" and expanding with pressure, this spring
can be stretched. Normally the spring measures 9/16 inch, and after stretching
1/8 inch, this will be sufficient to increase pressure on vernier shaft
"F" when re-assembled. Part number of inside tension spring is
28-8366.
The
second adjustment is effected when tightening the upper bracket of the drive
in place (not illustrated). When enmeshing the semi-circular ring with the
drive mechanism, place the bracket in such a position as to allow the ring
to fit well into the spring slot, but not all the way. This allows for any
irregularity in the ring itself and completes the necessary adjustment.
From the Philco Serviceman - September, 1935.
