towards the connecting rod 34 the disc 83 is itself freely rotatably arranged on the first shaft 16 the ratio between the number of teeth on the driven gear 79 and the drive gear 78 is preferably 1 1 the first shaft 16 rotatably mounted at two upright support embers 88 89 see fig1 carries the conveyor arrangement 17 following the disc 83 in the axial direction as shown in fig9 and 10 the conveyor arrangement 17 comprises a wheel 90 which is fixedly connected to the first shaft 16 that is to say which is non rotatatably arranged on the first shaft 16 on its face and in the proximity of its outer periphery the wheel 90 carries containers 91 which are arranged pivotably on the wheel 90 a control lever 92 co operates with each container 91 of which for example there are provided eight uniformly distributed at the periphery of the wheel the containers 91 and the control levers 92 are each fixedly connected to each other by way of a respective pin 93 engaging through the wheel 90 from one face to the other so that the container 91 follows a pivotal movement of the control lever 92 the conveyor arrangement 17 transports a liquid medium for example water from a lower supply or storage container 73 lower level into the upper liquid container 69 upper level provided in the proximity of the upper liquid container 69 is a control plate 95 on to which the control levers.