The function of hydraulic cylinders is to convert hydraulic energy into mechanical energy. 

There are several main applications of hydraulic cylinders in pipe jacking: 

1. The main top oil cylinder is used to push the top distance machine forward. 

2. Correction cylinder, used to adjust the direction of the pipe jacking machine. 

3. The bypass valve cylinder is used to drive the closure of the ball valve switch 

4. The relay oil cylinder has the same function as the main top oil cylinder. Can drive the pipe jacking machine