The total efficiency of the gearbox is not only related to its design parameters, but also to its different working environment parameters. On the premise of determining the size of the gearbox, its total efficiency is mainly related to the input power P, the input speed n, and the lubricating oil kinematic viscosity ν， The lubricating oil submerges the tooth height multiple k, the sliding friction coefficient f between the tooth surfaces and the dynamic viscosity of the oil and gas mixture in the gear box μ And other factors.
The fixed value of input power and input speed is P=10 kW, n=10 000 r/min. The dynamic viscosity of the oil and gas mixture in the gearbox has no obvious effect on the efficiency, so take a fixed value μ = 0． 1 cP。
| Parameter name | Kinematic viscosity | Tooth height multiple | Friction coefficient |
| Symbol/Unit | ν /cSt | k1 | f |
| Fixed value | 60 | 0.8 | 0.06 |
| Variation range | 30 ～ 120 | 0.5 ～ 1.2 | 0.04 ～ 0.10 |
Study and select the main influencing parameter of the total efficiency of the gearbox – lubricating oil kinematic viscosity ν， The lubricating oil submerges the tooth height multiple k, and the sliding friction coefficient f between the tooth surfaces is a variable. The variation range is shown in the table.