Abstract: The invention relates to an external gear machine (1) in particular an external gear pump or an external gear motor, having at least two gears (3, 4) that mesh with each other in external engagement, wherein the gears (3, 4) are surrounded by a housing (10), wherein one gear (4) has at least one bearing journal (7, 8) and the other gear (3) has a driving or driven journal (5), which are in each case mounted in a bearing bushing (38) so as to respectively be rotatable about a rotation axis (13, 14), wherein a bearing sleeve pp with an anti-twist element is arranged in the bearing bushing (38). In order to improve the external gear machine, in particular with regard to the materials that can be used for producing the bearing bushings and/or the service life, the anti-twist element of the bearing sleeve is arranged in a through-hole of the bearing bushing and is combined with a filter device and/or throttle device via which a working medium of the external gear machine (1) reaches the bearing sleeve.

Abstract: The invention relates to an external gear pump (1) having a pump housing (2). An inlet (2a), an outlet (2b), and a working chamber (6) are formed in the pump housing (2). A first gear (11), which is arranged on a first shaft (21), and a second gear (12), which is arranged on a second shaft (22), are arranged in the working chamber (6) in such a way that said first and second gears mesh with each other. Both gears (11, 12) have teeth having a tooth width (b). The first shaft (21) is radially supported in at least one plain bearing (61), and the second shaft (22) is radially supported in at least one further plain bearing (63). The plain bearing (61) has a bearing diameter (D63), and the further plain bearing (63) has a further bearing diameter (D63). During operation of the external gear pump (1), a delivery volume (V) of a working medium can be conveyed from the inlet (2a) to the outlet (2b). The two bearing diameters (D61, D63) are selected in such a way that the ratio V/(D612*b) is less than 1.

Abstract: A gear pump (1) comprises a pump housing (2), wherein a working chamber (6) is formed in the pump housing (2). A first gearwheel (11) and a second gearwheel (12) are arranged meshing with each other in the working chamber (6). The first gearwheel (11) has a number of first teeth (13) and the second gearwheel (12) has a number of second teeth (14). A first tooth flank (13a, 14a) and a second tooth flank (13b, 14b) are formed on each of the teeth (13, 14). When the gearwheels (11, 12) mesh, the first tooth flanks (13a) of the first teeth (13) are meshed with the first tooth flanks (14a) of the second teeth (14). A coating (15) is arranged on each of the first tooth flanks (13a, 14a). The coating (15) and the first tooth flank (13a, 14a) are positively connected to each other.