The use of cranes and precautions

The use of cranes in factory engineering construction is very extensive, especially when lifting some goods, it plays a big role, so if there is a fault during use, how should I repair it? The following is the repair for you I hope that the method of the crane failure can help you.　　How to repair crane failure

　　1 Engine oil can only be added and not changed

　　 Engine oil is indispensable in the use of diesel engines, mainly for lubrication, cooling, cleaning, etc.

Therefore, many drivers pay attention to checking the amount of lubricating oil and adding it according to the standard, but they neglect the inspection of lubricating oil quality and the replacement of deteriorating oil, resulting in some engine moving parts always in poor lubrication Operation in the environment, thereby accelerating the wear and tear of various parts.

　　Under normal circumstances, the loss of oil is not large, but it is easy to pollute, thus losing the role of protecting the diesel engine. During the operation of the diesel engine, a lot of dirt (soot, carbon deposits and fouling, etc., produced by incomplete fuel combustion) will enter the engine oil.

　　 For new or overhauled machinery, there will be more impurities after trial operation. If you just add it and not change it, you will rush to use it, which will easily cause accidents such as tile burning and shaft holding.

　　 In addition, even if the engine oil is changed, some drivers will not thoroughly clean the oil passage due to lack of maintenance experience or save trouble, so that mechanical impurities still remain in the oil pan and oil passage.

　　 2 Random use of butter

　　 Put butter on the cylinder head gasket. Butter is a commonly used grease in crane repair, which can play a role of lubrication and sealing.

　　 Therefore, some repairers will put a layer of butter on the cylinder head gasket when installing the cylinder head gasket, thinking that this can increase the sealing performance of the diesel engine. As everyone knows, doing so will affect the working performance of the diesel engine.

Cylinder head gasket is the most important seal between the cylinder block and cylinder head of a diesel engine. It can not only seal the high temperature and high pressure gas generated in the cylinder, but also seal the cooling water and lubricating oil in the cylinder head and cylinder block. When disassembling the cylinder head gasket, pay special attention to its sealing quality.

If grease is applied to the cylinder head gasket during installation, when the cylinder head bolts are tightened, part of the butter will be squeezed into the cylinder water passage and oil passage. When the butter between the cylinder head gasket is working in the cylinder, part of it will flow due to the influence of high temperature. The human cylinder burns, and the other part remains on the joint surface of the cylinder block and cylinder head, causing gaps between the cylinder head gasket, cylinder head, and the plane of the block. High-temperature and high-pressure gas can easily hit the cylinder head gasket from here, destroying the cylinder head gasket and causing leakage. gas.

　　 In addition, the butter will produce carbon deposits when exposed to high temperature for a long time, which will cause premature aging and deterioration of the cylinder head gasket. Therefore, do not apply butter when installing the cylinder head gasket.

　　3 new cylinder liners and pistons can be installed without matching

　　 When replacing the cylinder liner and piston, it is considered that the new cylinder liner and piston are standard parts, and they are interchangeable, and can be used after they are installed.

　　In fact, the size of cylinder liner and piston has a certain tolerance range.

　　 If the largest size cylinder liner is fitted with the smallest size piston, the fitting clearance will be too large, resulting in weak compression and difficulty in starting.

Therefore, the size grouping code of the standard cylinder liner and piston must be checked when reinstalling. The installed cylinder liner and piston must make the size grouping code of the standard piston and the standard cylinder liner the same. Only in this way can the difference between the two be guaranteed. With standard fitting clearance.

In addition, when each cylinder is installed with liners and pistons of the same group code, attention should be paid to the inspection of the cylinder plug gap before installation. In order to ensure the assembly standard, a test should be carried out before installation to prevent counterfeit and inferior products from being installed. .

　　 4 cylinder clearance measurement is not accurate

　　 When measuring the cylinder clearance, it failed to measure in the direction of the piston skirt perpendicular to the piston pin hole, and measured in other directions.

　　The structure of the aluminum alloy piston is characterized by a small upper part and a larger lower part. It is a cone, and the skirt section is elliptical, so the cylinder clearance in the circumferential direction is not equal.

　　 When measuring, it is stipulated that the clearance in the direction of the long axis of the ellipse shall prevail, that is, the clearance between the piston skirt and the direction of the piston pin hole is measured.

This measurement is more convenient and accurate. In the reciprocating motion, the direction of the piston skirt perpendicular to the piston pin hole is greatly worn due to the side pressure. Therefore, when measuring the cylinder gap, the piston skirt should be perpendicular to the piston. The direction of the pin hole is measured.

　　5 piston open flame heating

　　Because the piston and the piston pin have an interference fit, when installing the piston pin, the piston should be heated and expanded. At this time, some maintenance personnel will directly heat the piston on an open flame.

This approach is very wrong, because the thickness of each part of the piston is uneven, the degree of thermal expansion and contraction will be different, the heating of an open flame will cause uneven heating of the piston, which is easy to cause deformation; the surface of the piston will also adhere to charcoal, reducing the piston Service life.

　　 If the piston cools naturally after reaching a certain temperature, its metallographic structure will be damaged and the wear resistance will be greatly reduced, and its service life will be significantly shortened.

　　When installing the piston pin, the piston can be evenly heated in hot oil to make it expand slowly. Never use an open flame to heat it directly.

　　6 Use emery cloth to polish the bearing

　　 For some inexperienced repairers, scraping is a relatively difficult job. Because the scraping technology is difficult to master, it is difficult for the bearing to meet the technical requirements.

　　 For this reason, when someone replaces the bearing bush, in order to increase the contact area between the bearing bush and the crankshaft, they use emery cloth instead of scraping bushes.

This method is extremely undesirable in actual maintenance, because the abrasive grains on the emery cloth are harder, while the bearing alloy is softer, so the sand grains are easily embedded in the alloy during grinding, and the wear of the journal will be accelerated when the diesel engine is working. Shorten the life of the crankshaft.

　　 7 bolts are too tight

In the process of crane disassembly and assembly, bolts in many parts have specified torque requirements, such as transmission box, cylinder head, wheel hub, connecting rod and front axle. The tightening torque is specified in the manual, and must not be arbitrarily change.

　　 But many users mistakenly think that tightening is safer, but tightening too tight will cause the screws or bolts to break, and may also cause malfunctions due to the threaded sliding buckle.

　　 8 The tire pressure is too high

The tire inflation pressure of a wheeled crane is an important factor that determines its service life and work efficiency.

　　 The tire pressure is too high or too low will affect its service life, but also not conducive to safe driving, especially in the hot summer.

　　 The scientific inflation standard should be based on the standard tire pressure, and with the change of temperature, the tire pressure should be slightly adjusted.

　　 For example: Summer should be 5%-7% lower than winter. Taking into account that the temperature in summer is high, the gas is heated and the pressure increases, on the contrary, it must reach the standard pressure or slightly lower in winter.

　　9 Do not check the plunger stroke margin

　　In the ironic test of the plunger fuel injection pump, many maintenance personnel did not pay attention to checking the stroke margin of the plunger.

　　The so-called stroke margin of the plunger refers to the amount of movement that the plunger can continue to move upward after being pushed to the top dead center by the cam on the camshaft.

　　 After adjusting the fuel supply start time, the reason for checking the stroke margin is because the stroke margin of the plunger is related to the wear of the plunger and sleeve.

　　 After the plunger and sleeve are worn, the plunger has to move up for a while to start oil supply, which delays the start of oil supply. When the adjusting bolt is unscrewed or a thicker adjusting pad or gasket is used, the lowest position of the plunger moves up, so that the stroke margin of the plunger is reduced.

　　 Therefore, when repairing and debugging the fuel injection pump, the stroke margin should be checked first to determine whether the fuel injection pump is still allowed to be adjusted.

　　 During the inspection, the following different methods should be adopted according to the different structure of the fuel injection pump:

　　A) Rotate the camshaft, push the plunger to the top dead center, remove the delivery valve and valve seat, and measure with a depth vernier.

　　B) After the plunger is pushed to the top dead center, use a screwdriver to pry the spring seat of the plunger spring to raise the plunger to the highest point.

　　 Then insert a thickness gauge between the lower plane of the plunger and the tappet adjustment bolt to measure. The standard stroke margin of the plunger is about 1.5mm, and the limit stroke margin after wear should not be less than 0.5mm.

　　 10 water tank, boiling water, add cold water

　　 Engine overloading, poor heat dissipation, or lack of water in the water tank will cause the water tank to boil. If cold water is immediately added at this time, it will cause the cylinder head and cylinder block to burst.

　　 Therefore, once the water tank is found to be boiling during use, emergency measures should be taken to stop the operation, so that the diesel engine cooling water can cool down by itself.
　　 Attention to the maintenance of cranes

　　1. Daily maintenance: Carry out inspection and maintenance records before each shift.

　　 1. Check the oil quantity of each reducer. If it is lower than the specified oil level, it should be refueled in time. The oil must be clean. No corrosive agent and unclean oil should be mixed in. Filters should be used when refueling.

　　Each reducer oil mark: lifting mechanism reducer: 70# industrial gear oil

　　 Rotary structure reducer: 90# gear oil

　　 traction mechanism reducer: 70# industrial gear oil

　　 2. Check the lubrication of the bearing of the hoisting mechanism reel and the bearing at both ends of the traction mechanism reel. If necessary, add No. 2 calcium-based grease to ensure that there is oil in the oil cup.

　　 3. Apply grease to the slewing mechanism, large and small gear pairs and slewing rolling bearings.

　　 4. Check whether the power cable is damaged, whether the connection is loose or worn, and remove the dust from the electrical equipment.

　　 5. Check the contact and corrosion of each contactor and the contact of the controller.

　　 6. Check whether the connecting bolts have fallen off, and tighten and supplement them in time.

　　7. Check the lifting wire rope and traction wire rope. If the number of broken strands exceeds 5% or the nominal diameter wear exceeds 5%, the wire rope should be replaced. Check whether the fixed end of the wire rope is firm and whether the rope clamp bolt is loose, and deal with it in time.

　　 8. Check the safety devices, if they fail to work, they should be adjusted or repaired in time, especially when the lifting torque is limited to the lifting weight limit, and its reliability should be ensured.

　　 9. Check the braking efficiency of the lifting mechanism and the slewing mechanism. If it is not sensitive and reliable, it should be adjusted in time.

　　 2. Regular maintenance: once every half a month, and check the warranty records.

　　 1. Carry out daily maintenance.

　　2. Inject No. 4 calcium-based grease into the places where the lifting guide pulley and the tie rod and the support are matched, the pulley and wheel of the luffing trolley, the pulley of the hook group, the slewing ring, etc.

　　3. Since the length of the lifting and luffing wire rope is elongated after a period of use, it is necessary to re-adjust the luffing wire rope, and readjust the lifting height limiter and luffing limiter.

　　4. Tighten the bolts or nuts of the connecting bolts of each part, the wire rope pressing plate and the rope clamp once, and replace them if necessary.

　　 5. The insulation of all power-consuming or power-transmitting equipment must be reliable without leakage.

　　3. Regular inspection: Make inspections and record the handling of problems once every six months.

　　 1. In the process of transportation and storage, the metal structural parts should be prevented from being damaged, and the structural parts should be prevented from deforming. If it is found to be damaged, the whole is distorted and deformed. It should not be used without repair.

　　 2. Check all metal structures and parts, whether there are cracks in the welding area or materials, and check whether the structural parts are corroded. If found, they should be treated in time, and they should not be used without repair.

　　3. If excessive wear or deformation of each connecting bolt and pin is found, it should be updated.

　　4. Clean each reducer and refill lubricating oil, disassemble each rolling bearing to clean and clean the sliding bearing, add or apply grease when assembling.

　　 5. Apply grease to the rotary open gear pair.

　　 6. Check and adjust each brake and each safety device.

　　7. Overhaul or replace some parts that are worn out, such as: trolley running wheels, pulleys and sliding sleeves, rotary machinery pinions, etc.

　　 8. Repair and replace lifting and luffing wire ropes.

　　9. For each controller in the electrical operation, the rotating parts should be lubricated, and the arc pits of the moving and static contacts should be polished. Check and repair the distribution box, remove the dirt and dust on the wedge iron of each contactor, and check the insulation of the coil.

　　 10. Repair and replace various wires and cables.

　　11. After the completion of each project, each part must be painted once to prevent corrosion of the crane in fixed use. Paint once within six months to one year.

　　4. Maintenance of hydraulic jacking system:

　　 1. The hydraulic oil used in the hydraulic pump station shall be filled and replaced in strict accordance with the instructions of the hydraulic system, and the oil tank shall be cleaned regularly.

　　 2. After the pressure of the overflow valve is adjusted, it shall not be changed at will. Before each jacking, an oil pressure gauge must be used to check whether the pressure is normal.

　　 3. Always check whether the pipe joints are tightly tightened, and no oil leakage is allowed.

　　 4. The oil filter should be checked regularly for clogging and whether the adjustment value of the safety valve has changed.

　　 5. Leaks in the oil pump, oil cylinder and control valve should be checked and repaired in time.

　　6. When starting in winter, it should be started and stopped, and repeated several times. After the oil temperature rises and the control valve is sensitive, the operation will be carried out.

　　7. Every time you start the oil pump after the final assembly and overhaul, you should first check whether the outlet and inlet are connected reversely, whether the motor rotation direction is correct, and whether the oil suction pipe is leaking, then turn it by hand for a test run, and finally turn to start and test according to the regulations.