This paper proposes a controller for the cooperative task of 3-dimensional (3D) snake robots which have wheeled links with no side slip. We assume that the snake robot moves on a flat surface. First, we consider features of the kinematic redundancy caused by introducing wheelless links and derive a dynamic model of a 3D snake robot with introducing the shape controllable points for parameterizing its kinematic redundancy. Next, we extend it to the model for the cooperative transportation task of the robots and propose a controller which accomplishes this task by controlling internal forces and utilizing the redundancy. Simulation results show the validity of the proposed controller.