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.
