upper casing

基本解释

Upper section composed of driving sprocket upper casing with rails(double chain) and discharging outlet.
上部区段，由传动链轮及带有轨道（双排链）的上部机壳、卸料口组成。
Applying pump pressure then activates a sliding collar that opens access ports, enabling circulation across the upper casing interval.
然后施加泵压，使滑动箍启动，于是使进入口开启，从而能够穿过套管上段进行循环。
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Upper casing, as a key part in the driving system of helicopter, is difficult to be formed owing to its complex geometry and high demand for property.
上机匣为直升机传动系统中的关键零件，几何形状复杂，性能指标要求高，成形难度大。