1. Use tools correctly
1) When disassembling and assembling the assembly, connecting bolts of parts and components and various shafts, bearings, gears, etc., use appropriate tools. It is not allowed to pick with a chisel or cut with electric or gas welding, nor to knock with a movable wrench instead of a hammer. If it is necessary to hit with a hammer, soft metal punch or lining plate shall be padded to prevent damage to parts or matrix.
2) Avoid damaging the working surface of the parts when disassembling and assembling the parts. For the parts that can be disassembled and assembled with tension and compression tools, tension and compression tools shall be used, and hard smashing or random knocking is not allowed.
2. When the assembly or parts are disassembled, they shall be marked.
1) When disassembling all assemblies and parts, the dual assemblies, rotating parts and non interchangeable parts shall be checked for assembly marks before disassembly. If not, they shall be marked again (such as marking the installation position of tires and rims of high-speed vehicles), so as to prevent damage to the original fit or balance state due to wrong assembly. As the saying goes: repairman, how to dismantle and install, not afraid of missing parts for a long time, but afraid of forgetting how to install.
2) If the installation direction is required, the original direction shall be valued or marked to prevent reverse installation. For example, it is very important to mark the piston, cylinder gasket, connecting rod, etc.
3. Parts cleaning
1) When cleaning rolling bearings, the temperature of the cleaning fluid should not be too high.
2) The following parts cannot be cleaned with alkaline solution:
① Rubber parts, oil seals, non-metallic friction plates, etc.
② Various bakelite gears and plastic parts, aluminum alloy, zinc alloy and other parts.
After the parts are cleaned with chemical solution, wash them repeatedly with purified water to clean the surface chemical solution. After the assembly and parts are cleaned, clean them with clean test cloth or dry them with compressed air.
3) After the parts are cleaned, they shall be prevented from damaging the finish machined surface. If they are not in a hurry to assemble, they shall be coated with a protective layer to prevent rust corrosion.
4) The interior of oil pipe and gas pipe shall be thoroughly cleaned to ensure smooth pipeline. When installing the pipe joint, it is not allowed to wind cotton yarn and other objects to prevent blocking the pipe.
4. Fastening of bolts
1) Bolts with torque requirements shall be tightened according to the torque specified in the repair or operation manual or tightening operation requirements.
2) When reassembling bolts and nuts, add washers consistent with the bolt diameter as required, and the inner diameter of the washers shall not be too large.
3) The length of the reassembled bolt shall be appropriate, and the exposed part shall not be too long or the screwed part shall not be too short. The bolt shall be screwed on after the oil, water and sundries in the screw hole are cleaned.
4) For bolts and nuts with high technical requirements, the thread condition and self-locking ability shall be carefully checked, and other bolts (female) shall not be used arbitrarily.
5) When assembling the joint surface connected by several bolts, it shall be tightened several times and with different torque according to the specified sequence. If there are no special requirements, it shall be tightened cross symmetrically and evenly. Do not tighten a bolt (female) at one time to prevent deformation or loose combination of parts.
6) Reliable locking. For the bolt locked with the locking pin, pay attention to the proper matching between the diameter of the locking pin and the inner diameter of the lock hole. Buckle one piece of the locking pin on the square plane of the nut and cannot be bent on the bolt end. If it is locked with iron wire, the lock wire shall be tightened and locked according to the direction. Copper plated or self-locking bolts and nuts shall not be used repeatedly to prevent locking failure.
5. Disassembly of connecting parts
1) When disassembling threaded connectors, attention shall be paid to the rotation direction of threads. For multi bolt connectors, attention shall also be paid to the disassembly sequence. The stud bolt can be tightened with two nuts on the screw rod and then removed with a wrench. The rusty bolts can be disassembled by repeated advance and retreat method, hammer knocking method, kerosene immersion method or blowtorch heating method. When removing the threaded connection, the relay rod shall not be added arbitrarily to prevent the bolt from being broken. In case of broken bolt, if the broken head is higher than the base, file the higher end into a square or weld a nut to screw it out; If the broken head is in the machine body, a hole smaller than the bolt diameter can be drilled at the bolt end, and then one side can punch or tap the reverse thread, and then screw out the broken head bolt with a tap or reverse bolt.
2) For the disassembly of interference fit parts, special tools such as tension and compression device shall be used as far as possible. When there is no special tool, soft metal or wood block can be padded for knocking and disassembly. It is not allowed to directly hit the part surface with a hammer to prevent the part from being damaged.
3) The riveted parts are generally not removed during repair. If the rivets are loose or the riveted parts need to be replaced, the rivets can be drilled or chiseled off.
6. Installation of oil seal and gasket
1) Pay attention to the coaxiality between the rotating shaft and the oil seal hole, and the material and thickness of the gasket shall meet the requirements to prevent looseness or poor sealing. In addition, the selection of oil seal shall meet the requirements.
2) The thickness of the sealing gasket shall be appropriate so that after installation, the oil sealing can be completed without looseness or deformation of relevant parts.
7. Use of Jack
1. Never start the engine when the vehicle is jacked up by the jack, because the vibration of the engine or the rotation of the wheels will cause the vehicle to slide down from the jack, causing danger.
2. In order to ensure the safety of various types of vehicles, there are generally fixed positions when using the jack, and the jack cannot be supported on the bumper, beam and other parts.
3. Maintenance personnel cannot work under the vehicle without support. When changing wheels, passengers cannot stay on the vehicle because their movement may cause the vehicle to slide off the jack.
Post time: Nov-04-2021