Big arm device

The utility model discloses a big arm device which comprises a big arm support, a moving platform and a hydraulic cylinder, the big arm support is of a three-dimensional frame structure, and the three-dimensional frame structure is formed by connecting two parallelograms which are arranged in parallel and a connecting rod in a hinged mode. The bottom of the big arm support is installed on the basethrough a hinge base. A hydraulic cylinder is arranged on the base close to the big arm support, one end of the hydraulic cylinder is fixed to the base, the other end of the hydraulic cylinder is connected with the big arm support, and the big arm support swings by 0-90 degrees under the action of the hydraulic cylinder. The moving platform is installed at the top of the big arm support and is kept horizontal when swinging along with the big arm support. The mechanical arm can move leftwards, rightwards, forwards and backwards on the platform at the upper end of the big arm, after equipment is transported to a well s