The Siemens 3RV1946-2B is a SIRIUS door-coupling rotary operating mechanism designed for heavy-duty operating conditions. It is specifically suited for use with circuit-breakers size S3 — the same frame as the 3RV2 series breakers up to about 40 A motor protection or 52 A for feeder duty. Mounting is by screw fixing in any position, and the gray handle extends through the enclosure door so the breaker can be switched without opening the panel. The mechanism is rated for up to 151 operating cycles per hour, which covers frequent manual isolation on a production line.
The mechanism measures 75 mm wide by 75 mm high by 78 mm deep, with an overall length of 300 mm from the back of the operator to the end of the coupling shaft. That 300 mm reach means it can bridge a standard enclosure depth and still engage the breaker rotary switch without an extension. The shaft has zero offset in all directions (upwards, forwards, backwards, downwards, to the side all listed as 0 mm), so the handle sits directly over the breaker's rotary axis. The 40 mm diameter of the handle bezel is the cutout dimension you need for the enclosure door.