Whether the thread connection on the vehicle is firm will directly affect the normal use of our car, and it is also one of the effective assistants to ensure driving safety. Today, the editor is here to take stock of the five major measures to prevent the loosening of car threads, and I hope it will be helpful for the majority of car owners.
The spring washer should have good elasticity and suitable size. The spring washer is easy to install, low manufacturing cost and widely used in automobiles. It uses the elastic deformation of the washer to make the thread pair axially tensioned, while the bevel tip of the washer also helps to prevent loosening. However, this gasket will lose its due elasticity in use due to heat or prolonged compression. Therefore, before installing the spring washer, its elasticity should be checked for failure. The method of inspection is to see whether the two ends of the washer interface are staggered at a certain Angle, if the staggered Angle is small or not staggered, the washer has failed. At the same time, the size of the washer should correspond to the size of the corresponding bolt, and the outer diameter of the washer is slightly smaller than the outer diameter of the nut.
The cotter pin length should be appropriate if the engine connecting rod big head connection bolt is loose, it will cause the connecting rod bearing to be loose, make the engine produce abnormal sound, and even damage the engine related parts. When breaking down and checking some connecting rod bearing abnormal noise failure, it is often found that the cotter pin of the locking nut on the connecting bolt of the individual connecting rod has been gone, which is mostly due to the cotter pin being too long, scratching and breaking with the crank arm during high-speed movement, and finally falling off. The method to determine the correct length of the cotter pin is to insert the cotter pin into the corresponding hole of the lock nut, and after striking in place with a hand hammer, the extension length of the cotter pin does not exceed the plane of the crank arm, and then lock the cotter pin as required.
The assembly direction of the dish spring gasket should be correct. The dish spring gasket will not produce more scratches on the surface of the machine, so the use of the dish spring gasket is increasing, but if it is improperly installed, it will not play a role in preventing thread loosening. For example, the dish-shaped spring gasket installed between the rear flange lock nut and the flange of the second shaft of an automobile transmission will cause the nut to loosen if improperly installed, which will cause the speedometer driving gear to slip, and the speedometer speed indication and the number of miles traveled will produce an error. At the same time, the third gear jumps due to the forward and backward movement of the second shaft. The correct installation direction should be the concave side of the dish spring washer towards the connector and the convex side towards the nut. In this way, after the nut is tightened, due to the deformation of the dish spring gasket, the supporting surface is subjected to the reaction force and plays a locking role.
Some parts of the car chassis (such as the connection bolt of the transmission fork and the transmission fork shaft) use the safety wire to prevent the thread from loosening, which is often used for the thread of the bolt group. The safety wire is more reliable, but the installation should pay attention to the selection of safety wire specifications and the tightening direction after entering the screw hole. The safety wire is too thick and not easy to pass through, the diameter should be slightly less than the diameter of the perforation, and a little resistance can be inserted. The way to distinguish whether the safety wire is inserted in the correct direction is: if a bolt is loosened, the safety wire is in a tight state, that is, the two screws adjacent to it are tightened when a bolt is loosened, otherwise it is incorrect.
The lock piece should be locked on the side plane of the nut. The nut lock of the larger part on the car is often used as a lock piece, such as the car steering knuckle lock nut and the front end lock nut of the second shaft of the transmission. After the nut is tightened according to the specified torque, the lock plate should be folded to a plane on one side of the nut, and at the same time, it should be pressed tightly by hammering. Never attach the lock piece to the edge of the nut, which will not play a good role in preventing loosening.