Hub bolts are high-strength bolts that connect the wheels of a vehicle. The connection position is the hub unit bearing of the wheel! Generally, level 10.9 is used for minicars, and level 12.9 is used for large and medium-sized vehicles! The structure of the hub bolt is generally a spline gear and a threaded gear! And a hat! The T-head hub bolts are mostly grade 8.8 or higher, and bear the high torque connection between the vehicle hub and axle! Double headed wheel hub bolts are mostly of grade 4.8 or higher, and bear the relatively light torque connection between the outer wheel hub shell and the tire of the vehicle.
Fastening and self-locking principle of hub bolts
Automotive hub bolts generally use fine pitch triangular threads, with bolt diameters ranging from 14 to 20 mm and thread pitch ranging from 1 to 2 mm. In theory, this triangular thread can be self-locking: After the tire screw is tightened to the specified torque, the threads of the nut and bolt fit together, and the tremendous friction between them can keep the two stationary, that is, self-locking. At the same time, the bolt undergoes elastic deformation, tightly fixing the wheel and brake disc (brake drum) to the wheel hub. Using fine pitch can increase the friction area between threads and have a better anti loosening effect. Nowadays, more and more cars use fine thread, which has a better anti loosening effect.
However, when a car is running, the wheels are subjected to alternating loads, and the tire screws are also subjected to continuous shocks and vibrations. In this case, at a certain moment, the friction between the tire bolt and the nut disappears, and the tire screw may become loose; In addition, when accelerating and braking a vehicle, a “loosening torque” will occur due to the opposite rotation direction of the wheels and the tightening direction of the tire screws, which will lead to the loosening of the tire screws. Therefore, tire screws must have reliable self-locking and locking devices. Most of the current automotive tire screws use friction type self-locking locking devices, such as adding elastic washers, machining a matching cone or spherical surface between the wheel and the nut, and using spherical spring washers. They can compensate for the gap caused by the instant the tire screw is impacted and vibrated, thereby preventing the hub bolt from loosening.
Post time: Mar-17-2023