A volumetric gear machine interacting with a working fluid comprising: - a first toothed wheel with helical teeth comprising a first tooth in turn comprising a first and a second flank (311, 312) opposite to each other; - a second toothed wheel with helical teeth having two opposite flanks, the first and the second wheel (3, 4) operatively connected in a meshing area; the helical teeth of the first wheel and second wheel being truncated at the tip; the first tooth periodically comes into contact with the second wheel only at the first and second flank (311, 312); at least one portion of the first and second flank (311, 312) being involutes of a circle; at least one portion of the flanks of the helical teeth of the second toothed wheel being involutes of a circle; at a portion of the meshing area, the first and the second flank (311, 312) being in simultaneous contact with the second wheel; said machine being a pump or a motor and being intended to convey a working fluid; characterised in that εTR - εEL≤ 1 wherein: εTR: transverse contact ratio: minimum value between εTR sx and εTR dx; εTR sx: ratio between the rotation of the first wheel necessary so that the point of contact between the first tooth and the second wheel travels the entire line of action of the first flank and the angular pitch; εTR dx: ratio between the rotation of the first wheel necessary so that the point of contact between the first tooth and the second wheel travels the entire line of action of the second flank and the angular pitch; εEL: helix contact ratio defined as the displacement of the helix with respect to the angular pitch, the helix displacement being equal to: S = 360 ⋅ L / ( 2 π ⋅ r b / tan β b) where: S: displacement; L: longitudinal length of the tooth; r b: base radius, assessed at the base of the involute; β b: helix angle at the base radius. - a first toothed wheel with helical teeth comprising a first tooth in turn comprising a first and a second flank (311, 312) opposite to each other; - a second toothed wheel with helical teeth having two opposite flanks, the first and the second wheel (3, 4) operatively connected in a meshing area; the helical teeth of the first wheel and second wheel being truncated at the tip; the first tooth periodically comes into contact with the second wheel only at the first and second flank (311, 312); at least one portion of the first and second flank (311, 312) being involutes of a circle; at least one portion of the flanks of the helical teeth of the second toothed wheel being involutes of a circle; at a portion of the meshing area, the first and the second flank (311, 312) being in simultaneous contact with the second wheel; said machine being a pump or a motor and being intended to convey a working fluid; characterised in that εTR - εEL≤ 1 wherein: εTR: transverse contact ratio: minimum value between εTR sx and εTR dx; εTR sx: ratio between the rotation of the first wheel necessary so that the point of contact between the first tooth and the second wheel travels the entire line of action of the first flank and the angular pitch; εTR dx: ratio between the rotation of the first wheel necessary so that the point of contact between the first tooth and the second wheel travels the entire line of action of the second flank and the angular pitch; εEL: helix contact ratio defined as the displacement of the helix with respect to the angular pitch, the helix displacement being equal to: S = 360 ⋅ L / ( 2 π ⋅ r b / tan β b) where: S: displacement; L: longitudinal length of the tooth; r b: base radius, assessed at the base of the involute; β b: helix angle at the base radius. εTR: transverse contact ratio: minimum value between εTR sx and εTR dx; εTR sx: ratio between the rotation of the first wheel necessary so that the point of contact between the first tooth and the second wheel travels the entire line of action of the first flank and the angular pitch; εTR dx: ratio between the rotation of the first wheel necessary so that the point of contact between the first tooth and the second wheel travels the entire line of action of the second flank and the angular pitch; εEL: helix contact ratio defined as the displacement of the helix with respect to the angular pitch, the helix displacement being equal to: S = 360 ⋅ L / ( 2 π ⋅ r b / tan β b) where: S: displacement; L: longitudinal length of the tooth; r b: base radius, assessed at the base of the involute; β b: helix angle at the base radius. S: displacement; L: longitudinal length of the tooth; r b: base radius, assessed at the base of the involute; β b: helix angle at the base radius.