Silver SK312 knitting machine was manufactured in the very late 1960s. It is a standard-gauge knitting machine with 200 needles, 4.5 mm apart.
It has punchcard (with 24 holes in one row) reading capabilities, which allows automatic needle selection based on the wholes determining the patterns.
It might have been released to the Japanese markets only judging by all the Japanese writing on the carriage. The same model but on the Western markets is known as Studio SK312.
The machine has typical features of early Silver/Silver Reed punchcard-capable knitting machines: a detachable row counter, and a stand-alone toolbox.
Similar (more vintage) knitting machines with punchcard capabilities are Silver SK311, Silver SK313 and Silver SK315. The pdf file of the manual for those machines is available online for free.
Silver Sk312 is a but more advanced than its earlier counterpart, Silver SK311: the carriage for the Silver SK312 does not have buttons and the carriage for Sk311 indeed has them.
The carriages, especially when not in use, have problems typical for Silver/Silver Reed/Singer/Studio machines: the patterning drums “freeze up” and don’t move (which, however, can be fixed with enough Kroil oil and lubing).
Another interesting feature of Silver SK312 (which can be also found in Silver SK313 but not in later punchcard machines manufactured by Silver/Silver Reed) is the blue and red indicators (in the picture below both of them are blue) of the Russel lever position.
This machine has an interesting feature: when you knit for a while, and the pattern on the card is finished, a STOP word will appear on the display of the punchcard reader. This STOP word is actually from the punchcard itself. Thus, punchcards for this machine are very easy to distinguish by this giant STOP lettering.
Then you will have to rewind the card to the starting position. The manual describes this feature well. I am not sure if this is the feature of the cards themselves or of the reader. I am yet to work on one of those machines.
Note that this model still has only one lever on the pattern panel (lever with a silver cap in the picture above): only to release the punchcard so it advances when the machine knits patterns and is passed back and forth. Later models have two levers: one for card release and one to expand the pattern vertically by a factor of two.
Later knitting machines allow a constant reading of the card: the card is simply clipped and is ready circular over and over.
