A watch must rotate at 2 or 3 revolutions per minute.  The speed reduction shown provides that, with the last reduction being a chain drive.  The chain drive isolates the watch from the vibrations of the motor and gearing, as vibration tends to loosen the screws.
The first assembly provides a way of securely grasping the watch without scratching, and placing it to rotate on a vertical plane.   Also, the watch is lifted high enough to be easy to install and remove.  The chain allows the space separation.  An idler sprocket is required to ensure good 'wrap' and no slippage.
	The second assembly is the motor, first stage speed reduction, and angle sensor.  The purpose of the angle sensor is to allow a stop at the end of each Watch revolution and also to count total Watch revolutions.  Fortunately, the angle sensor, set to stop at a count of 56, also stops at -56, simplifying the program, somewhat.
Finally, the RCX is placed horizontally on the back, providing a substantial counterweight, so not to tip forward when installing the Watch.   Notice that there is a pilot lamp (green thing) and a push-button (grey thing) which are operating controls.

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