Hi again Asaszn,
Direct drive means coupling the motor to the driveline with one ratio, as opposed to a multiple ratio transmission. Some will argue this and say it means having the motor turn at wheel speed. Convention for the past 30 or so years has "direct drive" including a single ratio, including 1 to 1. And, direct drive generally infers the absence of a clutch.
Connecting motors directly to the half shafts without any gear reduction is a bad idea. Wheel speed is too low. And the torque from reasonable sized motors at reasonable current is too low. A gear reducer (or belt or chain) will get the motor speed up and multiply motor torque to the wheel.
DC motors have excellent torque at low speeds and can do well in direct drive. Compared to the same motor with a multispeed tranny, the direct drive systems generally run a higher current limit for more torque off the line and up-hill. Once up to top speed, direct drive is equivalent to the multigear system in hi gear.
Regards,
major
