The transmission will keep your motor in the proper power band at different speeds.

变速器将使电机在不同的功率范围内保持在适当的功率范围。

My dear Alphonse, I will send you a proper power of attorney under which you can make these sales.

亲爱的阿尔方斯，我会寄给您一份适当的授权书，您可以根据该授权书进行这些销售。