Expansion device having a readjustment unit for a drum brake

An expansion device for expanding brake shoes of a drum brake for a vehicle along an expansion axis, comprising:

• a housing having a readjustment unit for compensating an expansion travel increased due to brake lining wear,
• wherein the readjustment unit comprises a readjusting screw, which is arranged coaxially with the expansion axis and has a thread which brings about an axial movement of at least one expansion piston in the expansion direction by rotation in a first circumferential direction and the rotation of which in an opposite circumferential direction can be blocked by a spring-loaded latching unit, wherein the latching unit allows a defined idle rotation of the readjusting screw, which is defined structurally by a first stop acting in a first direction of revolution and a second stop acting in the opposite direction of revolution, and
• wherein the readjustment unit has a blocking member, which is arranged in a manner elastically preloaded axially against the readjusting screw, and the latching unit is arranged between the blocking member and the readjusting screw.