Balanced valve, hydraulic cylinder expansion control loop and crane

The invention provides balanced valve which comprises a main valve body (1) and a main valve core (4), wherein the main valve body (1) is provided with a positive oil outlet (A) and a reverse oil outlet (B); the main valve core (4) comprises a first acting surface (A1) and a second acting surface (A2) which are opposite to each other; the first acting surface is exposed in a first acting cavity (3) communicated with the reverse oil outlet; the second acting surface is exposed in a second acting cavity (17) communicated with the reverse oil outlet through a dumping groove (5); and the balanced valve further comprises a guiding control module which enables the second acting cavity to be selectively communicated with an oil draining port through a guiding control oil port (X). In addition, the invention also provides a hydraulic cylinder expansion control loop and a hydraulic crane. Due to the guiding control method, a large control ratio can be obtained through controlling the size of a guiding piston rod, the