The cooling test of small cranes shows that the main transmission gears and bearings of various engineering machines run in the lubricating oil of 5 Shan, which is 10-12 times larger than that of 3 Shan. However, when the temperature is too high, it will accelerate the deterioration of lubricating oil, such as oil temperature of more than 55-60 Shan, the temperature of each increase of 5 Shan, the speed of oil oxidation will increase 1 time times. To this end, the construction machinery in the process of use, one to prevent the low temperature overload operation, to ensure the normal operation of the low temperature stage, so that the machinery to achieve the specified temperature after the driving or work, not because there is no problem at the time to ignore its important role; second, to prevent the mechanical operation at high temperature, the machine in the process of constantly check a variety of temperature table values, found that the problem immediately stop the inspection, found fault in time to For a moment can not find the reason, must not be without treatment and still make mechanical disease work. In peacetime work, should pay attention to check the cooling system work condition.