A.50~70mm B.70~100mm C.100~120mm D.>120mm
A.1/4H B.1/3H C.1/2H D.2/3H
A.爬升→下降→安裝 B.爬升→安裝→下降 C.安裝→爬升→下降 D.下降→安裝→爬升