Its upper end is drill pipe box or union, the nether end is casing pin. It is a crossover with hollow inside.
它是个上端为钻杆母扣或者由壬，下端为套管公扣，内空心的转换接头。
2
A coil compression spring is captured to the pin in the hollow core of a segment and urges the adjacent components together.
卷曲的压缩弹簧被固定在段的空芯内的销上，并促使相邻的部件互相靠近。
3
The built-in float pin rod comprises a hard and a soft slide rod, and moves only in the hollow holding handle, the bending spring, and the hollow casing for the rod body.