Is the axle a labor-saving machine?

F 1R=F2r Axle is a simple and labor-saving machine. (The wheel radius is large and the shaft radius is small, which saves labor. )

The essence of the shaft is that the lever can rotate continuously. When using an axle, the lines of action of the forces acting on the wheel and the shaft are tangent to the wheel and the shaft, so their arm of force is the corresponding wheel radius and shaft radius.

Because the radius of the wheel is always greater than the radius of the shaft, when power acts on the wheel, the shaft is a labor-saving lever (the first picture below). Practical example: Bicycle pedals and roulette wheels (big gears) are labor-saving axles. When power acts on the axle, the axle is a labor-saving lever (Figure 2 below). Practical examples are: frisbees (pinions) on the rear wheels and wheels of bicycles, and fan blades of ceiling fans.