The motor + fan group should be placed on the support frame and fixed.
There are two series of holes on the frame, each of which is adapted to different types of motors, that can be used and compensate for the difference in the depth of the hub.

Before tightening the screws completely, the fan must be centred with the air flow conveyor and check the perpendicularity of the axis with the beam by using the slotting of the holes to fix the motor.

ВОПРОС:

что значит "slotting of the holes"??? Проверить перпенд-сть оси с траверсой путём "slotting of the holes"? Ничего не понимаю.

Уважаемые специалисты, подскажите, пожалуйста.