Apparatus blanks were used to fill the space in the housing when a dial was not needed for several reasons including:
"APPARATUS (DIAL) BLANK DESIGN FOR THE WESTERN ELECTRIC 500,"
by Russ Cowell and Paul Fassbender in Singing Wires, March, 2009.
Thanks also to Carl Bennett for application suggestions.
Blank in Set
||95A Apparatus Blanks were used in early soft plastic housings.
They would only fit in the housings for desk sets, not in the "new" wall or keyset set types.
Apparatus Blanks came out in 1954 to fit the various models being
introduced in the 500-series.
The smaller metal bracket was an obvious cost saver.
had to mount to the housing of the wall set to permit the housing to be
removed and installed over the cradle.
The blank attached to the bracket using a single screw in the blank's center.
||95C Apparatus Blanks appeared in about 1967, and were cost
reduced to eliminate the metal bracket completely.
The tabs sat on the unused dial mounting brackets in all 500-series sets.
Larry reported that later 95Cs eliminated the posts projecting from the back.
The 95C sat a bit flusher with the housing than the 95B blank.
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