Basicly, the two nutrunner are assembly in the gear blue. And the pinion (white) will receive a motor to rotate the gear to put the nutrunner in correct position (it's just a setup). The gear(blue) have a bearing.
I'm developoing one mechamical device, that we'll put two nutrunner in one gear. One spur gear will rotate the gear and put the nutrunner and one position. Each nutrunner will fix one bolt with 70Nm.
I need put one motor in pinion, but i need consider the moments to define de size of the motor...