Nice SD Série Instructions Et Avertissements Pour L'installation Et L'utilisation page 14

DIMENSIONED DRAWINGS OF GEARMOTORS FOR SECTIONAL DOORS
Gearmotors with chain-operated emergency mode activation
SD-100-24-KE2
SD-120-20-KE2
SD-140-20-KE2
When assembling gearmotors with 31.75 mm
diameter shaft from the left, the tab is to be blocked
only with a fixing ring because using a screw could
break the shaft.
12 – English
Only with the 0.55­20 gearmotors
Hollow shaft diameter: 25.4 or 31.75 mm.