Set oranges and pineapple aside.
Place in a saucepan and bring to a boil; pour over gelatin in a large bowl. Stir until gelatin dissolves.
Stir in sherbet until smooth. chill until partially set (watch carefully).
Fold in oranges, pineapple and bananas. Pour into an oiled 6 cup mold.
Chill until firm.
Serves 8 to 10.