Gear Transmission Characteristics And Gear Oil Working Conditions
The gear transmission efficiency is high, and the general spur gear transmission efficiency can reach 98%. Compared with the bearing, the equivalent curve radius of the gear is small, and the oil wedge condition is poor.
The gear drive teeth are in line contact with the teeth. Therefore, the contact area is small and the unit contact pressure is high. Generally, the contact pressure of the automobile gear unit can reach 2000-3000 MPa, and the hyperbolic gear is higher, up to 3000-4000 MPa.
Gear transmission not only wired contact, but also sliding contact, especially hyperbolic gear, which has a relatively high relative sliding speed between the teeth, generally up to 8m/o. Under high speed and heavy load conditions, the oil film may become thin or even partially broken, resulting in increased friction and wear, and even scratches and bites.
The working temperature of the gear oil is generally lower than that of the internal combustion engine oil, and varies greatly with the change of the ambient temperature. The temperature of the vehicle gear oil is generally not higher than 100'C. Modern cars use hyperbolic gears. Because of their large offset, the relative sliding speed of the gear wheel surface is high when the vehicle speed is high, so that the oil temperature reaches 160'C-180'C.