Main plate gearwheel kit (B)
The main plate gearwheel kit is attached to the main plate. It defines the upper axis of the timing belt linear guide.
There are two bearings set in the main plate. The axle with a small pulley is inserted in the front, at the back you have to insert a washer and the large pulley. All is held in place with a pin which is set in the plate surface of the large pulley.