a vehicle multi - speed automatic transmission which comprises an input shaft and an output shaft ; first , second , third and fourth planetary gear sets ; at least third , fourth , fifth , sixth , seventh and eighth rotatable shafts ; and first , second , third , fourth and fifth shifting elements whose selective engagement , in combinations of three engaged shifting elements , defines different gear ratios , between the input shaft and the output shaft , for implementing eight forward gears and at least one reverse gear . when shifting from one forward gear into a successive higher or lower forward gear , only a single one of the first , the second , the third , the fourth and the fifth shift elements is disengaged and only a single one of the first , the second , the third , the fourth and the fifth shift elements is engaged .