In designs which involve several shiftable ratios, the planetary transmission can be shifted under load by employing adherent shift clutch agents. In realized transmissions, these shift elements consisting of multi-disk brakes and clutches as well as band brakes (see figure) for the most part are hydraulically operated.
In order to keep the number of shift clutch agents low in gearboxes with high number of gear ratios and to freely design the relationships of the individual gear ratios against each other, coupled planetary transmissions are used.