a composite profile 10 with a height h of 105 mm here and a maximum width b of 92 mm according to fig1 comprises a rail - like carrier profile 12 having a rail foot 14 and a continuous rail head 22 formed integrally on the latter by means of a rail web 20 . two longitudinal edges 17 with a height c of 10 mm defining the foot surface 16 of the rail foot 14 run parallel to each other at a distance b 1 of 80 mm here . from these longitudinal edges 17 , the two ridge surfaces 18 of the rail foot 14 , which are somewhat inclined towards them , are inclined slightly upwards to the cross - sectional centre axis q crossing the longitudinal axis a of the composite profile 10 , and merge with that axial rail web 20 with a height h 1 of approximately 30 mm and a thickness e of approximately 18 mm . adjoining the upper end of the rail web 20 are the lower surface 26 which extends to the longitudinal edges 24 of the rail head 22 and of which the width b 2 measures approximately 78 mm and of which the outside height n of approximately 28 mm defines the position of the rail head surface 28 . from each of the longitudinal edges 24 of the rail head 22 in fig1 , 2 extends an insertion slot 30 which is inclined upwards at an angle w of approximately 60 ° to the cross - sectional longitudinal axis q and which has a width a of 3 mm here and a depth t of 18 mm and of which the lower wall surface in fig2 merges with a kind of longitudinal rib 34 of the rail head 22 ; the outer side of the longitudinal rib 34 is formed by that lower surface 26 . in the longitudinal edge 24 is made a longitudinal recess 32 , forming a cross - sectional step 33 , as a three - dimensional extension of the cross - sectionally v - shaped slot 30 which also provides its width a . this rail or carrier profile 12 of the composite profile 10 is formed from a light metal material , in particular an aluminium alloy , in an extruder not shown in the drawings for reasons of clarity . the flat top or upper surface 28 of the rail profile 12 or its rail head 22 is in the final state spanned by a profile strip 40 with a thickness f of 6 mm which is made from a ferrous or non - ferrous heavy metal . this profile strip 40 is cross - sectionally channel - shaped , and its side arms 46 with a height c 1 of 18 mm , which extend from a base plate 42 and are parallel to each other and to the longitudinal axis b of the profile strip 40 , abut against the longitudinal edges 24 of the rail head 22 . in this position the flat outer surface 44 of width q of the profile strip 40 forms the surface of the composite profile 10 . associated with parallel axis with each side arm 46 of the profile strip 40 resting on the surface 28 of the rail head 22 is , on the inside , a channel - like insert rod 50 with an approximately v - shaped cross - section of an apex angle w 1 of approximately 60 °, of which the cross - sectionally linear channel arms 49 , 49 i provide a thickness a 1 which with slight play corresponds to the width a of the insertion slot 30 and here measures 2 . 8 mm , for example . the right channel arm 49 in fig3 of the insert rod 30 , which is also referred to as an anchor rod , is aligned in the fitted position with its outer surface — running parallel to the cross - sectional longitudinal axis q — with the inner surface of the side arm 46 of the profile strip 40 . the distance c 2 from the end edge 47 of the profile strip side arm 46 — and hence also the longitudinal edge 48 of a channel arm 49 of the insert rod or profile 50 , to the inner lower surface 45 of the profile strip 40 is 11 . 9 mm here ; the longitudinal edge 48 of the channel arm 49 which according to fig3 runs at only a short axial parallel distance i from the free end of the other channel arm 49 i is aligned in the fitted position approximately with the end face 47 of the profile strip side arm 46 . the end face 47 of the profile side arm 46 is sealingly welded to that longitudinal edge 48 of the channel arm 49 by a weld seam shown at 52 . the latter runs on that end face 47 of the profile strip side arm 46 and on the outer surface of the outer channel arm 49 in such a way that its outer surface 51 — forming a sloping surface — is inclined at an angle y of approximately 40 ° cross - sectionally to the insert rod 50 . preferred is a cross - section of the weld seam 52 after the fashion of a right - angled and isosceles triangle of which the two arms defining the right angle are therefore of approximately the same length ; the sloping surface 51 is then a hypotenuse . each side arm 46 of the profile strip 40 forms a fixed unit , owing to the position of the weld seam 52 described , with the latter and the insert rod 50 . in fig5 the weld seam 52 and its sloping surface 51 extend from the outer edge of the end face 47 . here the cross - sectional width z of the weld seam 52 measures approximately 3 mm , and so corresponds approximately to the thickness a 1 of the wall of the insert rod 50 . in fig6 the cross - sectional width z of the weld seam 52 e is smaller , because here the sloping surface 51 attaches to the end face 47 at a distance from its outer edge 43 . a maximum of 1 / 10 mm to 2 / 10 mm is left free at the end face 47 so that the welding material can take up the aluminium . the other channel arm 49 i is inserted in the adjacent slot 30 of the rail head 22 . the angle γ here measures approximately 45 °. in fig6 is shown as a further embodiment at 54 a counter - bead of the weld seam 52 e which is formed continuously on the inside of the closed gap between the side arm 46 and the insert profile 50 owing to a through - gap existing between the two parts 46 , 50 . this counter - bead 54 can be formed both on this weld seam 52 e and on the weld seam 52 of fig5 . a permanent and tight bond of the two composite partners 12 , 40 of the composite profile 10 which is under mechanical prestressing is formed . this prestressing between the composite partners determines their capacity for use ; for this prestressing is vital for the contact resistances , the corrosion behaviour and hence for the life of current transmission . in fig7 can be seen the head region of the carrier profile 12 , on a larger scale than fig2 , with a top casing 60 which spans its top surface 28 — as stated , preferably made of steel — and of which the cross - section is formed from the covering profile 40 , the two insert rods 50 and the weld seams 52 connecting the latter into a unit . with the arrows at d , uniform delivery of current from the topic casing 60 to the rail head 22 is symbolised . by way of examples , cross - sectional values of the materials used , aluminium ( number i ) and steel ( number ii ), are compiled below : fig8 to 12 illustrate the manufacturing method according to the invention . first the two insert rods 50 made of special steel are delivered to the extruded rail profile 12 as in fig8 and their inner channel arms 49 i are inserted in the respective insertion slots 30 . then all the special steel profiles , that is , the insert rods 50 and the covering profile 40 , are pressed on , the latter against the top surface 28 of the rail or carrier profile 12 ( fig9 ). then these parts are welded under pressure p ; welding jets used are marked 70 . as already mentioned , the insert rods 50 formed from steel are modified in such a way that lateral welding through to the aluminium of the carrier profile 12 takes place . welding through to the aluminium leads above all to the contact resistance being uniformly good over the whole length — that is , regardless of tolerances — and current collection can take place uniformly over the whole steel surface . also the possibility of the steel or profile strip 40 sliding on the carrier profile 12 due to thermal stresses is excluded . resting on a lower contact pressure roller 72 t in fig1 is the unit consisting of covering profile 40 and rail profile 12 with which — not visibly — the two insert rods 50 are associated . an upper contact pressure roller 72 is associated with the foot surface 16 of the rail foot 14 . these special rollers 72 , 72 t which are mounted on parallel shafts 74 and adapted exert the necessary vertical pressure , while lateral pressure plates 80 which are rotatable on bearing arms 76 of a ridge frame 78 inclined on axles 79 of holding plates 77 exert pressure on the insert rods 50 . this is a modified roller straightening machine for light metal profiles . in order to achieve optimum prestressing here , welding is carried out between the contact pressure rollers 72 , 72 t made of non - magnetic material — and in fact the two sides are worked simultaneously . fig1 shows an essential detail of the conductor rail 10 according to the invention which provides the required prestressing . a corner region of the rail head 22 with insertion slot 30 can be seen and , lying stationarily in the latter , an insert rod 50 which on the other side is joined to the side arm 46 of the profile strip or covering profile 40 and is pressed during the welding operation by those pressure plates 80 , which are held at an angle of inclination w 2 of approximately 35 °.