A device for breaking separation of at least one bearing cap of a corresponding thrust block in the bearing assembly of engine cases provided with bearing bores which are arranged in-line, in particular crankshaft cases for alternative piston engines is provided. The device includes an extension mandrel comprising two half-mandrels insertable into at least one of the bearing bores. The half-mandrels being distant from each other in order to produce breaking separation force between the thrust block and the bearing cap. The bearing cap is clamped in such a way that it is non-rotatable except in a limited manner in the direction of breaking separation between a corresponding half-mandrel and a fixing device.