A gear (not now shown) pulls on the tray’s brown rack of teeth, drawing the tray into the drive.
On the underside of the tray, there is a curved rail, shown in white. As the tray closes, this rail pushes on a post sticking up from the blue cam. This drives the cam to the left where the teeth on its front edge engage the gear shown. The gear finishes driving the cam to the left.
The rotation motor assembly has two pins that fit through slots in the cam. As the cam moves left, it lifts the motor, driving its spindle through the hole in the center of the disk.