An unloading system for an agricultural vehicle includes: a grain tank; at least one cross auger placed within the grain tank; a discharge tube having an inlet in communication with the grain tank and at least one discharge auger placed therein; and a drive system configured to drive the at least one cross auger and the at least one discharge auger. The drive system includes: a main driver; a discharge coupling continuously coupled to the main driver and the at least one discharge auger; and a variable speed coupling continuously coupled to the main driver and coupled to the at least one cross auger.