CREATE TABLE table_20866024_3 (model_designation VARCHAR(255), gvw__kg_ton_ VARCHAR(255), axle_ratio VARCHAR(255))
What's the model designation of the model with GVW of 2828/2.78 kg/ton and axle ratio of 9/47?
    
SQL: SELECT model_designation FROM table_20866024_3 WHERE gvw__kg_ton_ = "2828/2.78" AND axle_ratio = "9/47"