Working principle of trenchless directional drilling rig

It has an incident angle, and there is also a guide instrument that leads the drill rig to go. When it reaches a certain angle, the guide worker will tell the operator to level the angle of the drill pipe, then drill, and so on to adjust the angle. It will come out when it is adjusted to the incident angle. It has an expander and a transfer case to pull the pipe from the other end. It is very simple, but the machine is too expensive and costs hundreds of thousands.