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Winter Small Crane Maintenance Should Pay Attention To The Problem


Today, Shandong China Coal Group crane to everyone about the crane, small crane maintenance of some small knowledge, crane friends in the leisure time can have a look. These are small problems that we usually don't notice, if there are some mistakes we are still walking, then should pay attention to.


1-- > avoid oil only add not change


Oil is essential in the use of small crane diesel engine, mainly plays a role in lubrication, cooling, cleaning. Therefore, many crane drivers will pay attention to check the oil amount of lubricating oil and add it according to the standard, but ignore the inspection of lubricating oil quality and the replacement of spoiled oil, resulting in some engine moving parts always run in poor lubrication environment, thus accelerating the wear of each part.


2-- > bogey butter daub in small crane


(1) butter cylinder pads. Butter is commonly used in small crane repair grease, can play the role of lubrication and sealing. Therefore, when some repairmen install the cylinder gasket, they will put a layer of butter on the cylinder gasket, thinking that this can increase the tightness of the diesel engine. However, this has affected the performance of the diesel engine.


(2) butter the tire nuts. In order to easily tighten the nuts and prevent corrosion, many repairmen in the tire of the nuts and bolts oil. In fact, this is a mistake. Because after the tire nuts are tightened, the threads have the characteristic of self-locking.


This is because the screw Angle is less than the equivalent friction Angle between the threads. In a given bolt connection, the helical raising Angle is a certain value, while the equivalent friction Angle varies with the friction state between the threads. Obviously, the equivalent friction Angle between threads decreases after oiling, and the self-locking performance of bolt connection becomes worse. Never grease or oil the bolts and nuts of the tires. This, on the contrary, will loosen the nut and even lead to an accident.


3-- > avoid cylinder liner and new piston installation without selection


When replacing the cylinder liner and piston, it is considered that the new cylinder liner and piston are standard parts with interchangeability and can be used when installed. In fact, the cylinder liner and piston dimensions have a certain tolerance range. If the maximum size of the cylinder liner with the minimum size of the piston, will make the clearance is too large, resulting in compression weakness, difficult to start.


4-- > avoid not checking plunger stroke allowance


In the trial of plunger injection pump, many maintenance personnel do not pay attention to check the plunger stroke margin. The so-called plunger stroke margin, refers to the plunger by the CAM on the camshaft top to the stop point, can continue to move up the amount. After adjusting the start time of oil supply, it is necessary to check the travel allowance because the travel allowance of plunger is related to the wear of plunger and sleeve. After the plunger and the sleeve wear out, the plunger has to move up a little more to start the oil supply, thus delaying the start time of the oil supply.


5-- > bogey cylinder clearance measurement is not accurate


When measuring the cylinder clearance, it is not possible to measure in the direction of the piston skirt perpendicular to the piston pin hole, but in the other direction. The structure of the aluminum alloy piston is small on the top and large on the bottom, which is a cone, and the section of the skirt is oval, so the cylinder clearance along the circumference is not equal. In the measurement, the clearance in the direction of the long axis of the ellipse shall prevail, that is, the clearance in the direction of the piston skirt perpendicular to the piston pin hole shall be measured. This measurement is more convenient, accurate, and in the reciprocating movement, piston skirt perpendicular to the direction of the piston pin hole due to the action of lateral pressure wear larger, so, when measuring the cylinder clearance, should be measured in the direction of the piston skirt perpendicular to the piston pin hole.


6-- > avoid piston open fire heating


Because the piston and piston pin is interference fit, so when installing a piston pin, should first make the piston thermal expansion, at this time, some of the maintenance personnel will put the piston on the flame heating directly, so it is very wrong, because each part of the piston, uneven heat bilges cold shrink degree would be different, firing can make the piston balance, easy to cause deformation; The surface of the piston will also adhere to carbon ash, reducing the life of the live.


7-- > avoid polishing the bearing bush with emery cloth


For some inexperienced repairmen, tile is a difficult work, because tile technology is difficult to master, so it is not easy to meet the technical requirements, for this, someone in the replacement of the bush, in order to increase the contact area between the bush and the crankshaft, with sand cloth polishing to replace the tile. This method is extremely undesirable in the actual maintenance, because the abrasive on the emery cloth is hard, and the bearing alloy is soft, so the sand is easily embedded in the alloy when grinding, diesel engine work will accelerate the wear of the journal, shorten the service life of the crankshaft.


8-- > avoid screw too tight


In the process of crane disassembling and assembling, many parts of the bolts are specified torque requirements, such as the transmission box, cylinder head, wheel hub, connecting rod and front axle, tightening torque is specified in the specification, must not be changed at will. However, many users mistakenly believe that tightening is safer, but tightening too tightly will cause the screw or bolt to break, and may also cause failure due to the thread sliding buckle.


9-- > avoid high tire pressure


The tire pressure of small crane is an important factor to determine its service life and work efficiency. Too much or too little tire pressure can affect its service life, and it is also bad for safe driving, especially in the hot summer. Scientific inflation standards should be: the standard tire pressure as a benchmark, with the temperature changes, the tire pressure is slightly adjusted. For example, the summer should be 5% to 7% lower than the winter, because considering the summer temperature is high, gas heating, pressure increase, on the contrary, the winter must reach the standard pressure or a little lower.


10-- > avoid water tank pot suddenly add cold water


Crane engine overload, poor heat dissipation or water shortage of the tank will cause the tank to open, if you immediately add cold water, it will lead to the cylinder head and cylinder block burst. Therefore, once found in the use of water tank open pot, should take emergency measures to stop the operation, so that the diesel engine cooling water cooling.