A plane at an oblique angle to the horizontal. This angle is usually called the rising angle. Bevel is a simple machine. It is hard to lift a heavy object along the vertical line. If you put a heavy object on an inclined plane, it will save effort to pull it up along the inclined plane. Dutch mathematician S Steven studied the balance of objects on an inclined plane and put forward the triangle theorem of force and the principle of inclined plane. Let an object with a gravity of W be placed on an inclined plane AB with an elevation angle of α (Figure 1a). When an object is stationary or moving in a straight line at a uniform speed, if the friction force is not considered, it can be known from the condition of static equilibrium that gravity W, pulling force F along the inclined plane and normal reaction force N of the inclined plane form a closed force triangle (as shown in figure 1b). F=Wsinα. Let f be the input force and w be the output force, then the mechanical benefit м a = w/f = 1/sin α = s/h, that is, the ratio of the output force to the input force is equal to the ratio of the hypotenuse in the right-angled triangle ABC to the same right-angled side (Figure 1a). This is called the triangle theorem of force or the principle of inclined plane. The inclined plane principle is widely used, such as the inclined plane conveyor belt and material conveyor of Panshan Highway.