which are located side by side are sealed by four seals 20 21 in relation to the internal drum 11 quasi each seal 20 21 forming part of each end wall of the external drum 19 the seals 20 21 are realized identically in the exemplary embodiments shown they are however oriented differently namely they are assigned in a rotated or mirror inverted manner to the oppositely situated end faces of the external drums 19 the two seals 20 21 between two adjacent external drums 19 are also oriented in opposite directions thus the seals 20 on the left hand end faces of the external drums 19 are oriented in an opposite direction to the seals 21 on the right hand end faces of the external drums 9 each of the identically realized seals 20 21 u2014 apart from the partially different orientations u2014 has a sealing lip 22 and a foot portion 23 which is integrally moulded thereon the entire seal 20 or 21 that is the sealing lip 22 and the foot portion 23 of the same are formed from an elastic material such as an elastomer rubber or the like the foot portion 23 and the sealing lip 22 extend at an angle with respect to one another such that an approximately l shaped profile of each seal 20 21 is created the sealing lip 22 extends for instance in a plane parallel to the partition wall 16 such that it forms quasi part of an end face of the respective external drum 19 in contrast the foot portion 23 extends parallel to the lateral surface of the external drum 19 overlapping the outside of an edge region of the same which proceeds from the end.