Sammendrag
Several maps of deformation functors of modules are given which generalise the maps induced by the Knörrer functors. These maps become isomorphisms after introducing linear equations in the target functor. In this manner the obstruction ideal for one module occurs as obstruction ideals for other modules over other rings. In particular we obtain a map to the deformation functor of the maximal Cohen-Macaulay approximation over a quotient ring defined by a regular sequence.