Open synchronous belt transmission is a commonly used transmission method in agricultural machinery. It transfers the mechanical energy of the power machine to the working machine, so that the working machine can run and work normally. In the transmission with a power of less than 30 kilowatts, flat belt transmission is often used. The advantages of this transmission are: simple structure, convenient use and maintenance, elasticity and flexibility of the belt, can alleviate impact and reduce vibration, work balance, and less noise; When the load increases suddenly, the belt will slip on the pulley, which can protect the machine parts from damage; the transmission direction can be changed in many ways, mainly used for the transmission with a large distance between the shafts. Open transmission is the most common, it is suitable for power transmission between two wheels whose two shafts are parallel to each other and rotate in the same direction. In order to prevent the belt from slipping off the pulley, the rim surface of the large pulley is often made into a convex arc.

When the belt is running, the driving side (ie tight side) should be placed below and the driven side (ie loose side) should be placed on top, which is beneficial to transmission.

The running speed of the belt should also be controlled. The commonly used transmission speed is 5 to 25 meters per second, and the most appropriate transmission speed is 10 to 20 meters per second for agricultural machinery energy 2006.8 meters.

There are also requirements for the center distance of the timing belt wheel (open timing belt). The center distance between the two pulleys is small, which can make the transmission compact, but too small will make the small pulley wrap angle too small, and the belt will slip easily, reducing the transmission efficiency and service life. If the center distance is too large, the belt will flap, the work will be unstable, and the size of the machine room will be increased. The center distance of the two pulleys can be selected within the range of the sum of the diameters of 2 to 5 times larger and smaller pulleys.

Also pay attention to the belt wrap angle of the small pulley. The belt wrap angle refers to the central angle corresponding to the arc length of the belt and the pulley. In transmission, the larger the wrap angle, the better. The larger the wrap angle, the less easily the belt will slip on the pulley, which is beneficial for transmission. The belt has a wrap angle on the large and small pulleys. The wrap angle of the small pulley is smaller than the wrap angle of the large pulley, so only the wrap angle on the small pulley needs to be checked when calculating. The wrap angle of the small pulley of the open drive shall not be less than 150 degrees, otherwise the wrap angle of the small pulley can be increased by increasing the center distance.

In addition, the number of cycles of the belt is generally not more than 3 to 5 times per second. Too many cycles will shorten the belt life. If it exceeds, the length of the belt must be increased to reduce the speed of the belt.