Pump and blocking element

A pump comprising:

• a rotor rotatable about a rotation axis and comprising a rotor hub and a rotor collar, the rotor collar extending from the rotor hub in a radial direction and encircling the rotor hub in an undulating manner;
• a pump housing forming a pump duct with the rotor, said pump duct connecting a first inlet/outlet space to a second inlet/outlet space;
• and
• a blocking device arranged between the first inlet/outlet space and the second inlet/outlet space and comprising a blocking element, the blocking element blocking the pump duct in an axial direction on both sides of the rotor collar,
• wherein the blocking device has a first seat for the blocking element and a second seat for the blocking element, the first seat for the blocking element disposed on a side of the first inlet/outlet space, the blocking element abutting against the first seat by way of a first contacting face in a first operating direction for pumping from the first inlet/outlet space to the second inlet/outlet space, the second seat for the blocking element disposed on a side of the second inlet/outlet space, the blocking element abutting against the second seat by way of a second contacting face in a second operating direction for pumping from the second inlet/outlet space to the first inlet/outlet space, and
• wherein a spacing between the first seat and the second seat in a circumferential direction relative to a point disposed on an axis of the pump is greater than a spacing between the first contacting face and the second contacting face of the blocking element in the circumferential direction.