24v DC gear motor usually come with requirements about high torque or low speed. For some small motors like N20 or N30, we merely do 24v. But for some bigger dc motors like 555 or 775, 24v is commonly seen. 24v dc gear motor is also including 24v brushless dc planetary gear motor like DM-42RPBL4260. These motors are usually applied some products with high power, like helical lifts. For these applications, it is no need to save energy. So 24v dc gear motor will provide more power.