The pump for liquids has two identical crank spaces (2', 2") adjacent to each other. In each of them a crank disk (3) is placed on a central pin (9), fitted with a piston rod pin (12). The piston rod pins (12) are connected by means of a piston rod, consisting of a piston rod shank (8) and piston rod eyes (11). Between the crank spaces (2', 2") a groove (6) is made, with a sliding sealing element (7), which may be fitted with a rotating sealing roller (13) with a shank opening (14). The piston rod shank (8) passes through the sealing element (7) of the first crank space (2') into the second crack space (2"). The input channels (4) and output channels (5) for medium lead to the space between the crank spaces (2',2"). The sealing element (7) separates the first crank space (2') from the second crank space (2") and the piston rod shank (8) separates the area of the input channels (4) from the output channels (5).