text: throughout all the figures , same or corresponding elements are generally indicated by same reference numerals . turning now to the drawing , and in particular to fig1 there is shown a longitudinal section of a stator according to the present invention , including a stator housing 6 in the form of a stack of laminations of sheet metal . the stator housing 6 has a longitudinal stator bore 7 , defined by a longitudinal axis 9 , for receiving a , not shown , rotor , and is formed with , not shown , slots to support a winding , whereby winding end portions 2 are disposed outside the slots and respectively jut out from opposite axial end faces of the stator housing 6 . cover slides 5 are further provided to engage the slots and thus to mask the slot structure . the cover slides 5 are circular in structure and arranged in surrounding relation to the stator bore 7 and project beyond the end faces of the stator housing 6 . the stator housing 6 is placed in a cooling jacket 8 of steel . motor connection lines 10 are routed through the right - hand opening of the cooling jacket 8 to the winding . as the winding end portions 2 on the opposite axial end faces of the stator housing 6 are of an identical construction , only one of the winding end portions 2 will hereinafter be described in detail . it will be understood by persons skilled in the art that a description of the area of one of the winding end portions 2 is equally applicable to the area of the other winding end portion 2 . fig2 shows hereby an enlarged detailed sectional view of the area around the left - hand winding end portion 2 of fig1 . each winding end portion 2 has an axis - confronting inner surface which is abutted by a tubular insulator 1 made , for example , of a thermoplastic material , thereby forming with the cooling jacket 8 and the respective end face of the stator housing 6 a mold having a cavity in which the winding end portion 2 is disposed , whereby insulating casting material , e . g ., resin , is poured into the cavity to fill out the area between the tubular insulator 1 and an inner surface of the cooling jacket 8 . thus , the mold , called “ lost mold ” because of its one - time use only , remains attached to the potted winding end portion 2 . [ 0023 ] fig3 shows in more detail one embodiment of the tubular insulator 1 . in this embodiment , the tubular insulator 1 has a substantially cylindrical cross section and is made , preferably , of thermoplastic material , such as polyamide , e . g . pa 66 gf 30 . in order to improve handling , for example , when the winding end portions 2 are not in exact parallel relationship , the tubular insulator 1 may have a slight truncated cone shape by slightly chamfering the end face that is to be inserted in the direction toward the confronting end face of the stator housing 6 or by providing this end face with a slightly smaller diameter than the opposite housing - distal end face . as shown in fig3 the housing - distal end face of the tubular insulator 1 is formed with a circumferential ridge - like reinforcement 11 , whereby the reinforcement may have a generally triangular configuration , as shown by way of example only . the tubular insulator 1 is so sized as to fit precisely against the inner surface of the winding end portion 2 , confronting the axis 9 of the stator . care should be taken that the tubular insulator 1 is properly centered in the stator bore 7 . accordingly , the tubular insulator 1 is provided at its end face to be inserted in the direction of the end face of the stator housing 6 with a centering ring 4 . suitably , the centering ring 4 forms an integral part of the tubular insulator 1 . referring again to fig2 to describe the function of centering ring 4 , it can be seen that the centering ring 4 supports the tubular insulator 1 against the confronting backside of the cover slide 5 to thereby center the tubular insulator 1 in relation to the stator bore 7 . in addition , the centering ring 4 provides a sealing in radial direction by abutting against the backside of the cover slide 5 and in axial direction by bearing against the slot flanks , not shown , of the last lamination of the stator housing 6 so as to prevent escape of casting material 3 when poured into the cavity for potting the winding end portion 2 . the casting process is carried out with the stator housing 6 being disposed in upright position to allow pouring of the casting material 3 into the cavity . the circumferential reinforcement 11 of the tubular insulator i provides hereby not only a mechanical stabilization during the casting process , but serves also as indication whether the required filling height of the casting material 3 has been reached so that the winding end portion 2 is completely covered with casting material 3 . the dimension of the reinforcement 11 is selected to provide a tolerance as far as the pouring height of casting material is concerned . as soon as the casting material 3 reaches the reinforcement 11 , upon correct placement of the tubular insulator 1 , the winding end portion 2 is completely covered with casting material 3 . care should be taken that casting material 3 is not poured beyond the outer rim of the reinforcement 11 to prevent casting material 3 from overflowing into the stator bore 7 . after finishing one side thereof , the stator housing 6 is turned around to allow potting of the winding end portion 2 on the other side of the stator housing 6 . while the invention has been illustrated and described as embodied in a stator for an electric drive with a tubular insulator as lost casting mold , it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention .