Pull pin mechanism, bolt type telescopic boom and crane

The utility model relates to the technical field of engineering machinery and discloses a pull pin mechanism, a bolt type telescopic boom and a crane. The pull pin mechanism comprises a boom pin, a return mechanism and a swing rod. The boom pin can be arranged on a lateral wall of the telescopic boom in sliding mode, the return mechanism is used for keeping the boom pin to be in an extending state, the swing rod is hinged to a lateral wall of the telescopic boom in dead axle mode, one end of the swing rod is connected with the boom pin, and the other end of the swing rod can be pushed by a cylinder pin. In an embodiment of the pull pin mechanism, by arranging the boom pin, the return mechanism and the swing rod having a leverage effect on two lateral walls at the tail portion of the telescopic boom, when a mandril of the cylinder pin is in an extending state, the boom pin is in a retracting state, when the mandril of the cylinder pin is in an retracting state, the boom pin is in an extending state, and back and forth switching between a locking state of the cylinder pin and a locking state of the boom pin is achieved, so that the structure is simple, assembling is facilitated, machining difficulty of parts such as a cylinder head is reduced, and installing precision of parts such as the boom pin is reduced.