128 the functional coordination of these valves provided in addition to the exemplary embodiment according to fig3 will be discussed in detail hereinafter in connection with one operating cycle of the viscous fluid pump 10 34 a situation is assumed in which the 34 right 34 feed cylinder of the viscous fluid pump 10 34 carries out its feeding stroke and the piston 13 1 of its drive cylinder 12 1 moves to the 34 right 34 in direction of the arrow 41 the driving chamber 114 1 of the right changeover cylinder 113 1 of the tube switch 111 is in this situation loaded with pressurized fluid the feeding chamber of the right feed cylinder is connected through the s tube 112 of the tube switch 111 to the feed line 22 the shutoff device 121 is open that is the bottom side driving chamber 122 of the differential cylinder 118 of the shutoff device 121 is relieved toward the tank 32 of the pressure supply plant 28 through the changeover control device 64 or 64 39 connected to the drive chamber 122 the control line 129 is connected to the changeover control device 64 or 64 39 and the opening control valve 124 and the closing control valve 123 are in their illustrated operating positions this situation was preceded by the transmission of the end position signal at the pressure outlet 117 1 of the right changeover cylinder 113 1 this signal is transmitted to the opening control valve 124 to cause valve 124 to.