ISO 81400-4:2005规定了功率为40kW至2MW的风力涡轮机齿轮箱的设计和规范。适用于所有此类平行轴、单级行星齿轮箱和组合式单级行星齿轮箱和平行轴封闭式齿轮箱。其规定基于具有上述功率容量和配置的风力涡轮机的现场经验；其指南可适用于更大容量的风力涡轮机，前提是对规范进行适当修改，以适应更大容量风力涡轮机的特点。寿命要求适用于最小设计寿命为20年的风力涡轮机。

ISO 81400-4:2005 establishes the design and specification of gearboxes for wind turbines with power capacities ranging from 40 kW to 2MW. It is applicable to all such parallel-axis, one-stage epicyclic and combined one-stage epicyclic and parallel shaft enclosed gearboxes. Its provisions are based on field experience with wind turbines having the above power capacities and configurations; its guidelines can be applied to higher capacity wind turbines provided the specifications are appropriately modified to accommodate the characteristics of higher capacity wind turbines. Life requirements apply to wind turbines with a minimum design lifetime of 20 years.