Knowledge Sharing Of Outboard Gear Oil

Outboard gear oil is the structural material of gear devices. When designing a gear transmission device, it is necessary to calculate the strength of the gear. Oil viscosity and load-carrying capacity are important parameters. The development of the automobile industry has promoted the upgrade of vehicle gear oil, and the increase in the load of automobiles and boats has increased the power of the drive axle gear transmission. However, the geometric dimensions of the drive axle gears have not changed greatly, leading to increased tooth surface pressure and temperature rise, especially the continuous improvement of the overall design of automobiles and boats, which makes the aerodynamic performance more reasonable. The air resistance of the car or boat is reduced during the driving process, and the air flow through the outer surface of the drive axle is reduced. The heat dissipation becomes worse, the frictional heat is difficult to dissipate, and the use conditions become harsher. If the load is doubled again, there is not enough lubricating oil film protection, or the oil film ruptures, after dry friction occurs, the instantaneous friction heat generated is enough to melt the uneven processing marks on the tooth surface. Sintering and scratches occur.

The following unified lubricating oil illustrates this problem from the relationship between the lubrication characteristics of the gear oil and the amount of additive and the gear rack.

The radius of curvature of the gear is small, and the conditions for forming an oil wedge during lubrication are poor, and the oil film needs to be re-established every time the gear teeth mesh. In addition, the meshing surfaces do not match, and the flow is also sliding, which deteriorates the oil film operation. The main function of outboard gear oil is to reduce friction and wear between gear pairs. The friction lubrication process generally includes fluid lubrication, elastic lubrication, mixed lubrication and boundary lubrication. When the lubricated tooth surfaces come into contact under load, plastic deformation occurs, and the lubricating oil sinks between the metal surfaces. The composition, performance and chemical state of gear oil dominate the whole process of friction lubrication.

The damage of the gear surface includes gluing, scratching, dot decoration, peeling, abrasive wear, etc. The ability of gear oil to prevent the above damage is called the bearing capacity and scratching capacity of the gear oil, which is closely related to the viscosity of the base oil. Also affected by temperature. When the oil temperature rises, the viscosity decreases and the oiliness weakens, making it difficult to form a firm oil film, increasing the chance of metal contact; too low viscosity can also cause gear fatigue and wear, and even tooth root fracture. The oil film thickness of various viscosities under specific working conditions is shown in the figure

To maintain the fluid lubrication between the tooth surfaces, to prevent and reduce boundary friction, it is necessary to maintain a specific oil film degree and strength. Oil film thickness and strength. The thickness of the oil film is determined by the oil viscosity (ŋ), operating speed (N) and load bearing (P), which is determined by the dimensionless parameter ŋ·N /P. Usually, to increase the thickness of the oil film, a high-viscosity base oil is used.