<p>A motor shaft direct drive is known as a simple and low cost scheme for small toy vehicles, however the mechanism how it produces propelling force has not yet been explained nor discussed in detail. A trivial idea that a small dent is formed on the road surface just under the shaft end due to static weight takes us to the unexpected result. Brief calculus reveals that the propelling force vector of the system directs somewhat forward with respect to sagittal plane which includes motor shaft slant axis. It suggests that the motor alternative cw and/or ccw rotation generates gradual forward movement, i.e. the vehicle moves perpendicular direction with respect to that of right-left swinging motion. The forward motion is confirmed experimentally with single motor shaft direct drive vehicle, and also discussed in details.</p>