Mould for producing a casting core, which illustrates coolant channels as well as coolant inflows and outflows (3, 4) of a cooling jacket of an electric motor using casting technology, with a core box space to be filled with core material, which is designed substantially cylindrically around a central axis, and the external wall of which is formed by an external mould and its internal wall by an internal mould completely enclosed by the external mould, wherein components of the internal mould are: - two first mould shells and two second mould shells, all four of which together delimit the internal wall of the core box space, wherein the second mould shells are each arranged between the first mould shells, - a first demoulding mechanism, which is arranged between the first mould shells and is formed for moving these towards each other, wherein the first demoulding mechanism comprises a shell support that is longitudinally moveable in the direction of the axis, with two guides arranged on the same, wherein one of these is displaceably mounted in one guide, and the other one of the two first mould shells on the other guide, and wherein the longitudinal directions of the two guides converge towards each other, - a second demoulding mechanism, which is arranged between the second mould shells and is formed for moving these towards each other, wherein the second demoulding mechanism comprises a shell support that is longitudinally moveable in the direction of the axis, with two guides arranged on the same, wherein one of these is displaceably mounted in one guide, and the other one of the two second mould shells on the other guide, and wherein the longitudinal directions of the two guides converge towards each other, wherein one of the shell supports including the guides arranged on the same is a one-piece design and the other shell support including the guides arranged on the same is a two-piece design consisting of two support sections (20A, 20B) arranged one behind the other in the direction of axis. - two first mould shells and two second mould shells, all four of which together delimit the internal wall of the core box space, wherein the second mould shells are each arranged between the first mould shells, - a first demoulding mechanism, which is arranged between the first mould shells and is formed for moving these towards each other, wherein the first demoulding mechanism comprises a shell support that is longitudinally moveable in the direction of the axis, with two guides arranged on the same, wherein one of these is displaceably mounted in one guide, and the other one of the two first mould shells on the other guide, and wherein the longitudinal directions of the two guides converge towards each other, - a second demoulding mechanism, which is arranged between the second mould shells and is formed for moving these towards each other, wherein the second demoulding mechanism comprises a shell support that is longitudinally moveable in the direction of the axis, with two guides arranged on the same, wherein one of these is displaceably mounted in one guide, and the other one of the two second mould shells on the other guide, and wherein the longitudinal directions of the two guides converge towards each other,