We prove that the value function of a deterministic unbounded control problem is a viscosity solution and the maximum viscosity subsolution of a family of Bellman Equations; in particular, the one given by the hamiltonian, generally discontinuous, associated formally to the problem by analogy with the bounded case. In some cases, we show that this equation is equivalent to a first-order Hamilton-Jacobi Equation with gradient constraints for which we give several existence and uniqueness results. Finally, we indicate other applications of these results to first-order H. J. Equations, to some cheap control problems and to uniqueness results in the nonconvex Calculus of Variations. © 2016 L'Association Publications de l'Institut Henri Poincaré