Forklift drive axle should choose gear oil reasonably
1 Precautions for reasonable selection of gear oil for forklift drive axle
(1) Selection of gear oil
①Viscosity grade and selection. The viscosity classification of industrial gear oil is carried out according to the standard of GB3141-82 "Viscosity Classification of Industrial Lubricating Oils", which is determined by the linear speed of the gear pitch and the material and surface stress of the gear.
②Choice of quality level. The quality level is mainly determined according to the contact stress of the tooth surface, which can be selected according to Table 1. Generally speaking, the quality level should be as high as possible, high-grade oil can be used in low-grade occasions, otherwise it is not suitable.
③Gear oil used in our company's forklift drive axle. Imported forklift trucks all use Mobilgear gear oil (MD Gx-90), which meets the requirements of the American Petroleum Institute API quality classification GL-4. It is a versatile gear oil with good anti-corrosion and anti-rust capabilities. It is suitable for curved gears, manual gearboxes and high-speed passengers and trucks.
Domestic forklift trucks use 220# medium-load gear oil (GL-4), which is based on the anti-oxidation and anti-rust industrial gear oil and has improved extreme pressure and wear resistance. It is suitable for gears with medium load operation. For example, the transmission stress of closed cylindrical gears, helical gears and herringbone gears with contact stress of 500-1100N/mm?
(2) Precautions for using gear oil
① Pay attention to prevent impurities mixed with water
②Choose the appropriate viscosity grade oil according to the ambient temperature to ensure the lubrication requirements under high and low temperature working conditions. For example, the temperature difference between our company in the south, winter and summer is not as great as that in the north, and the temperature is not too long, and the temperature is not too low. Therefore, the forklift trucks of our company use the same brand of gear oil in winter and summer.
③ Always check the amount of oil in use. If the amount of oil is too high, the internal pressure will be high and oil will leak, which will cause damage to the half shaft oil seal and failure of the brake.
④ Check the performance index and pollution of gear oil in a timely manner, and replace it if it exceeds the standard. When changing the oil, the gear box should be cleaned and filled with new oil, and the amount of oil should be appropriate.
2 Gear oil performance indicators and pollution determination
(1) Determination of water content
A combination of qualitative analysis and quantitative determination can be used, usually expressed as a percentage. When the water content exceeds 0.2%, new oil should be replaced.
(2) Determination of viscosity
It can detect 40?C and 100?C kinematic viscosity of oil. When the viscosity change rate exceeds ±10%-15% of the viscosity of the new oil, consider replacing the new oil and find out the reason for the change in viscosity. If the lubricating oil used is MD Gx-90, when the kinematic viscosity at 40?C is lower than 153mm?/s or higher than 220mm?/s, a new oil should be replaced and the cause of the viscosity change should be ascertained. If the lubricating oil used is medium-load gear oil GL-4, when its kinematic viscosity at 40?C is lower than 168.3mm?/s or higher than 286mm?/s, it is necessary to replace with new oil and find out the reason for the change in viscosity.
(3) Determination of solid particles and pollutants
Spectral analysis and iron spectrum analysis can be used to identify the composition and content of solid particles and contaminants in oil. When the size of the steel sticky abrasion particles in the iron spectrum analysis is greater than 200 μm, or the content of the steel sticky abrasion particles with 60 μm is more than 10%, the oil behind should be replaced. When using spectroscopic analysis, if two consecutive samples are taken under the rated capacity of the lubricating oil to detect that the Fe element content is close to or exceeds 1000 ppm, the lubricating oil should be replaced.
3 Abnormal oil indicates the existence of the fault
Drive axle gear stains are less polluted and more difficult to sample, our company has less detection, but because our company has less detection, but because our company cooperated with Guangzhou Machine Tool Research Institute in the past few years to develop "Equipment Oil Condition Monitoring" 》The project is sampled and sent to Guangzhou Machine Tool Research Institute for testing.
Among them, the oil sample sent by B727 forklift on January 20, 1998 had a kinematic viscosity of only 67.4mm?/s at 40?C, and the oil sample sent on April 13, 1998 had a kinematic viscosity of only 50.2mm?/ at 40?C. s, and the concentration of Fe and Cu elements has a downward trend, and the normal value of the differential gear oil MDGx-90 at 40?C kinematic viscosity is 180-200mm?/s, which indicates that there may be transmission oil (MD1310, 40?C kinematic viscosity is 36.8mm?/s) into the differential. A similar situation occurred when detecting the differential gear oil of the B718 forklift. I flashed and inspected these two forklifts, and it turned out that the seal ring (transmission skeleton oil seal) at the connection between the transmission and the differential was damaged, causing the transmission oil to enter the differential.
The above examples show that oil monitoring can predict machine failures, and we should pay enough attention to it.
