Geared motor, and method for installing a geared motor

A geared motor comprising:

• a direct current motor having a motor shaft;
• a planetary gear unit with a first sun wheel, the planetary gear unit having at least one planetary gear unit stage;
• a ring gear having teeth;
• first planetary gears engaged with the teeth of the ring gear;
• a gear unit casing;
• a gear unit output shaft;
• and
• a first pinion cage;
• a second pinion cage with a secondary sun wheel;
• secondary planetary gears secured to the second pinion cage;
• a plate for axially holding the first and secondary sun wheels, the first and secondary planetary gears and the first and secondary pinion cages in the gear unit casing, the plate provided with a shaft passage to form a preinstallation module;
• the first sun wheel having a central shaft receptacle which is formed with a positive fit contour acting in the rotation direction and coupled in a rotationally fixed manner with the motor shaft via a corresponding positive fit contour;
• and wherein, in the preinstallation module, an engagement of teeth of the first sun wheel with teeth of the first planetary gears is provided both before and after a final installation of the direct current motor at the preinstallation module.