In this paper, the dynamic load-carrying capacity (DLCC) of cooperating mobile robots is investigated. The term, cooperating mobile robot, means a wheeled mobile base with multiple arms where end-effectors of the arms are connected to each other for holding and manipulating an object. In order to compute the load capacity of an arm, it is necessary to extract applied torques of motors in the joints. The cooperating feature of multiple manipulators is identified by applying proper constraints on dynamic models of the manipulators. These constraints are used to model the connections between the end-effectors, which imply that all the manipulators should grasp an object simultaneously. In that case, there exists a redundancy in corresponding dynamic equations, which can be solved by introducing new equations from optimal load distribution technique. This optimization is based on Lagrange multipliers method, considering the applied constraints. In this research, by virtue of cooperating models and by deriving the torques equations, the problem of DLCC is extended to multi-arm mobile manipulators. The general modeling is presented for a multi-arm manipulator with m arms where each arm has n degrees of freedom. For appreciating the advantages of the cooperative model, a simplified model of this general formulation is simulated and the results are discussed. Moreover, the cooperating model of the problem is simulated and conferred with an alternative model. The alternative model is called “free”, in a sense that it does not contain the constraints on the end-effectors for simultaneous grasping. The corresponding results prove the improvement in DLCC for systems with constraints and additional internal forces induced by it.