The transmission mechanism of the existing lawn mower is installed on the frame, and its structure includes a frame, a transmission shaft assembly, and a gear box. The frame is provided with a first mounting seat and a second mounting seat, and the gear box is fixed on the first mounting seat. On the mounting seat, one end of the transmission shaft assembly is connected with the output end of the gear box, and the other end of the transmission shaft assembly is installed on the second mounting seat through the bearing seat, and a cutter shaft is arranged on the frame, and the cutter shaft and the transmission shaft assembly pass Belt drive connection. When working, the power output by the tractor is transmitted to the gear box, the gear box transmits the power to the drive shaft assembly, and the drive shaft assembly is then transmitted to the cutter shaft through the belt drive mechanism, so that the cutter shaft rotates.

In order to adjust the tension of the belt transmission mechanism, since the position of the cutter shaft cannot be moved, only the position of the transmission shaft assembly can be adjusted. For the transmission mechanism of the above structure, a waist-shaped hole is provided on the first mounting seat, and the bolt passes through it. The waist-shaped hole is connected with the gear box, so that the gear box is fixed with the first mounting seat. When the distance between the drive shaft assembly and the cutter shaft needs to be changed to adjust the tension of the belt in the belt drive mechanism, loosen the bolts that fix the gear box, move the gear box to change the position of the gear box, so that the drive shaft assembly The position of one end is changed; the installation position of the bearing seat on the second mounting seat is changed, so that the position of the other end of the transmission shaft assembly is changed. Therefore, the tension of the belt is adjusted by adjusting the position of the drive shaft assembly.