On these cranes, the hydraulicRAMS that extend to raise up the crane do not push on the boom, but instead on a pivoting link-bar.
这些起重机，液压冲力并不是作用于吊杆上，而是作用于一个铰链连接杆。
2
The skylight is raised by two hydraulicrams. It has in-built sensors that prevent it from closing on obstructions, but that activate closure during sudden gusts of winds.