Threaded fasteners are widely used on motorcycles, and they cannot be removed during normal maintenance and repair. During the disassembly and assembly process, due to the unreasonable use of the tool, incorrect assembly and disassembly methods, or rusting of the threaded fasteners, it is difficult to disassemble and install, which brings a lot of inconvenience to the maintenance. I have summarized some experiences in disassembling and threading fasteners through practice, which are described below.
The wrench for disassembling the threaded fastener in the maintenance of the motorcycle includes: an adjustable wrench, a wrench, a wrench, a socket wrench, and the like. Commonly used screwdrivers are: a word screwdriver, a cross screwdriver and so on.
Whenever possible, when removing a hex head bolt or hex nut, the preferred tool should be a socket wrench and a wrench, followed by a wrench. Try not to use or use the adjustable wrench.
When removing the screw, the blade of the screwdriver should be completely matched with the groove of the screw. Otherwise, the screw thread or the screwdriver knife will be damaged. a. When the bolts, nuts and screws are grouped on the disassembly joint surface, they should be scored in the order of the cross. Loosen the fasteners until they are not preloaded.
If the thread fastening still has a certain preload, it can be tapped with a hammer before disassembly.
This will weaken its preload and facilitate disassembly. However, be careful not to use too much force when striking, so as not to deform the threaded fasteners. If you have a vibrating screwdriver on hand, you can disassemble it better (the vibrating screwdriver can be used with the sleeve, crosshead, and head). When using a vibrating screwdriver, the first hammer should be accurate and powerful.
Apply kerosene or gasoline for a period of time before disassembling the rust fasteners. During the soaking process, the hammer is gently tapped by hand, which is beneficial to the depth of penetration of kerosene or gasoline into the rust wire, and reduces the disassembly torque of the threaded fastener, which is more convenient for disassembly.
When removing the hex head bolt, if there is a sliding edge, you can do the following: repair with a file as shown, and then remove it with a wrench.
Use a hacksaw to saw a slot on it, not too deep. Then use a vibrating screwdriver to remove (eg).
Use a small sleeve to remove it. If the original 19mm sleeve is used, the 18mm sleeve is now used, and then hammered with a hammer, so that it is firmly put on the bolt or nut, and can be unscrewed.
However, this may damage the sleeve.
If the bolts are thick, the method of tweezing can also be taken in case of emergency, as shown. At this time, the force should not be too large, and the angle of the dice should be noted.
If none of the above methods solve the problem, the welding method can be adopted under the premise of safety, as shown in the figure. It should be noted that the welding can not be disassembled immediately, and it must wait for a while, and the temperature of the welded bolts is lowered and then unloaded. The reason for this is that the bolts and components are not the same material, so the expansion coefficients are inconsistent. After cooling, the mutual stress can be reduced and the mechanical strength of the welded joint can be improved. This method is also suitable for the disassembly of the screw.
Disassembly of bolts and screws. Broken bolts and screws are divided into two cases, as shown in the figure. If the situation arises, the fifth method can be used for disassembly. If it happens, it will be more troublesome to repair. The commonly used methods are: surfacing. The specific method is to first use a suitable diameter electrode and the corresponding current. Start welding at the break. Solder a little pause and re-weld, be patient. Solder to a height of about 5 mm above the workpiece surface and shape into a cylinder. Then, a suitable nut sleeve is welded to the welded body, and after cooling for a while, tap and screw the broken screw. When using this method / be careful not to weld the workpiece, so the electric welding technology must be good. In addition, this method is only suitable for breaking bolts that are shallower on the working surface.
Drilling method. When encountering a bolt that is broken deep in the surface of the workpiece, only the drilling method is adopted, that is, the hand drill is used to punch the hole in the center of the broken thread. When punching, first hit with a drill with a small diameter, and then gradually change the diameter. Larger drill bit, slowly reaming. When approaching the broken thread, insert a square pyramid with a suitable diameter and rotate the quadrangular pyramid to remove the broken wire. When the wire is broken by this method, if the hole is deflected during the punching, the internal thread of the component is damaged, and the hole must be re-punched and tapped. Of course, this will increase the trouble. Therefore, be careful.
When installing, first put the bolts and nuts on the thread by hand, and then use the tools to tighten them several times. In the process of tightening, in addition to the method of cross-assembly, attention should be paid to the torque of different threaded fasteners. Generally, the tightening torque of the threaded fastener can judge the degree of tightening by feeling; the important threaded fastener can be checked by the torque method. Therefore, for professional maintenance personnel, it is necessary to have tools for measuring the tightening force, and also to know the correct method of use and the torque parameters associated with it.
It is important to remember that the damaged threaded fasteners cannot be reused. Otherwise, it will not only affect the safety of the motorcycle, but also cause trouble for the next disassembly.
Many scooters use self-tapping screws in many places. If the number of disassembly is too high, the buckle will be even lost. In this case, you can cut a piece of iron or aluminum alloy, and make a hole with a diameter slightly smaller than the diameter of the screw, and tighten the self-tapping screw.
(Editor: Zhang Shuli) Yan Qing 43
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