Troubleshooting of common faults of the hottest ge

Troubleshooting of common faults of gear pump

at present, CB-B gear pump is widely used in the operation mechanism of dump truck and construction machinery. Now its common faults and troubleshooting methods are introduced as follows for reference

1. Causes and elimination of vibration and noise

(1) inhale air

① the pump body of CB-B gear pump is in direct contact with the end covers on both sides. If the flatness of the contact surface cannot meet the specified requirements, the pump is easy to inhale air during operation; Similarly, the end cover and gland of the pump are also in direct contact, and air is also easy to invade; If the gland is made of plastic, it will be damaged or deformed due to temperature changes, which will also make the seal loose and enter the air. The way to eliminate this kind of fault is: when the flatness of the pump body or pump cover cannot meet the specified requirements, you can grind it back and forth with steel sand on the flat plate according to the "8" line, or you can grind it on the surface grinder to make its flatness not exceed 5 μ m. The perpendicularity between the plane and the hole shall be ensured; The leakage at the pump cover and gland can be sealed by coating epoxy resin and other adhesives

② the pump shaft is generally sealed with a skeleton oil seal. If the spring clamping the lip falls off, or the oil is encapsulated reversely, or its lip is strained and aged, the rear end of the oil seal will often be in a negative pressure state and inhale air, which can generally be solved by replacing a new oil seal

③ if the oil quantity in the oil tank is insufficient, or the oil suction pipe orifice is not inserted below the oil level, the pump will suck in air. At this time, oil should be added to the oil tank to the oil mark; If the oil return pipe orifice exposes the oil level, sometimes the air will be backfilled into the system due to the instantaneous negative pressure in the system, so the oil return pipe orifice should also be inserted below the oil level generally

④ the installation position of the pump is too high from the oil level, especially when the pump speed decreases, because the necessary vacuum in the pump suction chamber cannot be guaranteed, resulting in insufficient oil suction and air suction. At this time, the relative height between the pump and the oil surface should be adjusted to meet the specified requirements

⑤ the oil suction filter is blocked by dirt or its capacity is too small, resulting in increased oil suction resistance and air suction; In addition, the larger diameter of oil inlet and outlet may also bring in air. At this time, the oil filter can be cleaned, or the oil filter with large capacity and appropriate inlet and outlet diameter can be selected. In this way, it can not only prevent the inhalation of air, but also prevent the generation of noise (electromechanical reverse transfer to destroy the oil pump)

(2) mechanical reasons

① the connection between the pump and the coupling produces vibration and noise due to non-compliance with the specified requirements. The coupling shall be adjusted according to the specified requirements

② noise is generated due to wear and tear of gears and other components caused by dirt in the oil entering the pump. Replace the oil, strengthen filtration, disassemble the pump and clean the characteristics of less peripheral circuits; The gears with serious wear must be repaired or replaced

③ serious damage or wear of parts in the pump will produce vibration and noise: such as large tooth profile error or circumferential pitch error, poor contact between the two gears, high tooth surface roughness, out of tolerance of the common normal length, too small tooth backlash, and the contact area of the two meshing gears is not at the unfair degree circle position of the pressure point, etc. At this time, the gear can be replaced or grinded. At the same time, the damage of the needle cage of the bearing, the wear of the long and short shaft journal and the needle can lead to the poor rotation of the bearing and produce mechanical noise. At this time, it is necessary to dismantle and repair the gear pump and replace the needle bearing

④ the axial assembly clearance of gear is too small; The burrs on the sliding joint surface between the gear end face and the front and rear end covers were not carefully removed before assembly, so the joint surface was strained during operation, resulting in large internal leakage and reduced output flow; Dirt enters the pump and wedges into the gap between the gear end face and the front and rear end covers, straining the mating surface, causing the high and low pressure cavities to be connected due to radial straining grooves, reducing the output flow. The following measures should be taken to repair the above situations. Disassemble the gear pump, appropriately increase the axial clearance, that is, grind the end face of the gear; Grind the front and rear cover end faces and gear end faces with a surface grinder, and remove the burrs on the gear teeth (chamfer is not allowed); The depth dimension of the unloading groove on the end face of the front and rear end covers after plane grinding will change, and the width should be appropriately increased

(3) other reasons

the high viscosity of the oil will also produce noise, so the oil with appropriate viscosity must be selected

2. Insufficient output flow

① high oil temperature will reduce its viscosity, increase internal leakage, and reduce the pump output flow. Find out the causes and take measures; For medium and high pressure gear pumps, check whether the sealing ring is damaged

② if the viscosity of the selected oil is too high or too low, the output flow of the pump will be reduced, and the oil with qualified viscosity should be used

③ CB-B gear pump generally cannot be reversed. If the pump body is installed reversely, it will cause local short circuit between the oil pressure chamber and the oil suction chamber, so that its flow will be reduced or even it will not be able to suck oil. At this time, check the rotation direction of the pump

④ the engine speed is not enough, resulting in reduced flow. The cause should be found out and eliminated

to avoid impurities such as water