H16 External Motors
All Bolex H16 cameras can be driven by an external drive motor. Freeing the operator from having to wind the camera between shots which can be tedious and rather embarrassing in this day and age.
They also allow you to shoot shots lasting longer than 28 seconds at 24fps which was the limit of the spring motor.
Early cameras have a 8:1 backwind shaft which can be used with the first 3 motors to drive the camera. 8:1 means 8 revolutions exposes 1 frame of film.
Later cameras have a 1:1 drive shaft, the ratio was changed so that external motors could be added that could be sync locked to tape recorders for synchronous sound recording. Those being the last 3 motors.