SMK Alps mount lock
|Family||SMK second generation|
|Switch type||Alternate action|
|Sense method||Metal leaf|
|Total travel||3.5 mm|
|Keycap mount||Alps mount|
|Switch mount||Plate mount|
SMK Alps mount lock is the alternate action switch in the SMK second generation series.
The operation is very similar to that of SMK lock, where a swivelling pin follows a track. Where the J-M0404 series version used an external module to house the pin and a track on the slider, the second generation design reverses this: the track is in a separate block, and the pin fits into the slider. The position of the track block inside the switch explains why the left-hand retention clip is offset to the back of the switch.
The pressure spring that supports the follower pin is small, at 4 mm long and 1.38 mm in diameter; this is larger than the equivalent spring in RAFI full-travel key switch, which in RS 74 M is a mere 2.7 mm long.