If the working pressure of the engine oil of a wheel loader is less than 0.2 MPa (or varies with the speed) during operation, it should be shut down immediately to investigate the cause and wait for fault detection before continuing to work. Otherwise, it may cause important mechanical accidents such as tile explosion and engine cylinder pulling. The main reasons for low oil pressure are detailed below.
(1) There is not enough remaining oil in the engine oil. If there is not enough remaining oil, it will reduce the amount of oil in the oil pump, causing a decrease in oil pressure and exacerbating damage to the engine crankshaft, rolling bearings, cylinders, and piston rods.
(2) The temperature of the car engine is too high. If the temperature of the car engine is too high, it not only accelerates the aging and quality change of the engine oil, but also easily causes the engine oil of the Jingong small loader to become thinner, resulting in a decrease in steam pressure.
(3) The oil pump stops running or the oil pump volume is insufficient. The breakage or detachment of the fixed pin between the transmission gear and the transmission shaft of the oil pump, as well as the blockage of the oil pump transmission gear due to the suction of dirt by the oil pump, will cause the oil pump to stop running and the oil pressure to drop to 0. When the clearance between the oil pump shaft and the shaft sleeve, the clearance between the transmission gear port and the pump cover, the tooth side clearance, or the axial clearance exceeds the specified value due to damage, it will cause a decrease in oil pump volume and result in a decrease in oil pressure.
(4) The clearance between the engine crankshaft and the crankshaft rolling bearings is too large. After long-term use of car engines, the clearance between the crankshaft and crankshaft rolling bearings of second-hand excavator engines will gradually increase, and the oil pressure will also decrease.
(5) The oil filter is blocked. When the oil cannot circulate due to blockage of the oil filter, the valve built in the oil filter base is pushed open, and the oil enters the main oil passage directly without filtration. If the opening pressure of the valve is adjusted too high and the oil filter is blocked, the valve cannot be opened immediately, resulting in an increase in the working pressure of the oil pump, an increase in air leakage, and a decrease in the amount of oil provided by the main oil passage, causing a decrease in steam pressure.
(6) The return valve is damaged or malfunctioning. If the torsion spring of the return valve becomes soft due to fatigue or the adjustment is unreasonable, the mating surface of the high-pressure gate valve is damaged or stuck by debris, the return capacity increases significantly, and the steam pressure in the main oil passage decreases.
