An electric machine comprising: an internal stator provided with an internal surface; an external rotor coaxially mounted about the internal stator; a biasing assembly so configured and sized as to bias the external surface of the tubular body against the internal surface of the internal stator; and a liquid cooling arrangement comprising a tubular body, which is C-shaped, the liquid cooling arrangement being inserted in the internal stator, said electric machine being characterized in that: the tubuiar body is provided with first and second longitudinal ends and an external surface so configured and sized as to be applied to the internal surface of the internal stator; the first and second longitudinal ends include expansion slots open to one of the first and second longitudinal ends without reaching the other of the first and second longitudinal ends; the expansion slots (22, 24) allowing deformation of the tubular body; the tubular body also includes a cooling path provided with a fluid inlet and a fluid outlet; where at least three expansion slots are provided from the first longitudinal end, at least two expansion slots are provided from the second longitudinal end, the expansion slots provided from the first longitudinal end are open to the first longitudinal end but do not reach the second longitudinal end and the expansion slots provided from the second longitudinal end are open to the second longitudinal end but do not reach the first longitudinal end; where the expansion slots provided from the first longitudinal end and the expansion slots provided from the second longitudinal end are alternately arranged such that each expansion slot provided from the second longitudinal end has a neighbouring expansion slot provided from the first longitudinal end on each of its sides and the expansion slots provided from the first longitudinal end and the expansion slots provided from the second longitudinal end are provided in U-shaped portions of a serpentine cooling tube to allow a continuous cooling tube while providing expansion slots open to either longitudinal end of the body. an internal stator provided with an internal surface; an external rotor coaxially mounted about the internal stator; a biasing assembly so configured and sized as to bias the external surface of the tubular body against the internal surface of the internal stator; and a liquid cooling arrangement comprising a tubular body, which is C-shaped, the liquid cooling arrangement being inserted in the internal stator, said electric machine being characterized in that: the tubuiar body is provided with first and second longitudinal ends and an external surface so configured and sized as to be applied to the internal surface of the internal stator; the first and second longitudinal ends include expansion slots open to one of the first and second longitudinal ends without reaching the other of the first and second longitudinal ends; the expansion slots (22, 24) allowing deformation of the tubular body; the tubular body also includes a cooling path provided with a fluid inlet and a fluid outlet; where at least three expansion slots are provided from the first longitudinal end, at least two expansion slots are provided from the second longitudinal end, the expansion slots provided from the first longitudinal end are open to the first longitudinal end but do not reach the second longitudinal end and the expansion slots provided from the second longitudinal end are open to the second longitudinal end but do not reach the first longitudinal end; where the expansion slots provided from the first longitudinal end and the expansion slots provided from the second longitudinal end are alternately arranged such that each expansion slot provided from the second longitudinal end has a neighbouring expansion slot provided from the first longitudinal end on each of its sides and the expansion slots provided from the first longitudinal end and the expansion slots provided from the second longitudinal end are provided in U-shaped portions of a serpentine cooling tube to allow a continuous cooling tube while providing expansion slots open to either longitudinal end of the body.