Underframe for tower crane

The utility model discloses an underframe for a tower crane, and relates to the field of hoisting equipment. The tower crane comprises a cement foundation, a cross-shaped base is pre-buried in the cement foundation, a tower crane body is arranged on the cross-shaped base, four tower legs are fixed to the lower end of the tower crane body, four fixing grooves are formed in the cross-shaped base, the tower legs are inserted into the fixing grooves, the tower legs and the fixing grooves are matched with each other, a cavity is formed in the cross-shaped base, and the cross-shaped base is fixedly connected with the cavity. Fixing rods are arranged in the cavity, fixing holes are formed in the tower legs and matched with the fixing rods, and a driving mechanism used for driving the four fixing rods to be close to or away from each other is arranged in the cavity. When the tower crane body is fixed, the fixing rod can be inserted into the fixing hole through the driving mechanism, and when the tower crane body is u