The drive wheels of small four-wheel tractors generally use shoe brakes, and some small four-wheel tractors have poor braking effect after a certain period of use. However, after adjusting the eccentricity of the eccentric shaft and the length of the brake lever, the braking effect is still not satisfactory. At this point, the brake pads can be replaced. However, if the friction plate is not exposed by riveting, there are no other abnormalities. Repair can be done as follows. First, set the eccentricity of the eccentric shaft to the minimum position, remove the brake lever, reset the brake cam, check the clearance between the brake drum and the brake lining, and then, according to the size of the gap, in each On the driving surface of the brake shoe cam, a piece of gasket with the same size and thickness as the contact surface is spot welded, and the surface of the weld and the gasket is polished and leveled on the grinder. After reinstalling, recommission the brake. If you need to replace the friction plate later, just remove the iron pad from the welding.