Dryer drum drive motor. Includes pulley for dryer drum drive belt. Other shaft has reverse threads for blower wheel. Common symptoms of a bad drive motor are:
-Dryer stops turning during cycle
-Dryer won't start
-Dryer won't turn at all
Check out Repair Help for more information.
Dryer motor with pulley
Dryer motor w/pulley
Dryer drum drive motor with pulley for belt