Abstract: A device (1) making it possible to apply at least one thread (2) to a supt (3) and characterized by the following features:it has a front clamp (4) and a rear clamp (5) along a direction of advance (F.sub.1);it has means (6, 7) for opening and closing said clamps (4, 5);it has means (8) permitting the displacement of the rear clamp (5) in the direction of advance (F.sub.1) or in a direction (F.sub.2) opposite to the direction of advance (F.sub.1); andit has means (9) for displacing the thread (2) in transverse directions.a reinforcing ply for a pneumatic tire having reinforcing threads applied on a support in a sinuous pattern having vertices.

Abstract: The insulating coating for an object such as a rocket motor casing is formed by wrapping a strip of insulating material upon the surface of a rotating mandrel. By means of this invention, it is possible to wrap a strip of malleable material such as rubber from an extruder onto a complex shape while exercising precise thickness control, thereby eliminating the need for machining the outer surface. The strip is run through a forming mill of unique construction which shapes the strip during the wrapping process to conform most precisely with the topography of the mandrel. The mill automatically varies both the taper and the width of the strip. The final wrapped product has a smooth outer surface that requires minimal finishing.

Abstract: The elements described refer to an apparatus for the manufacture of a tire einforcement from a single cord. Each lever 2 of the apparatus is provided at its end with a groove 3 which describes a partial oval. The cord is hooked therein. A recess 28 serves as a template for the installation of a bead wire.

Abstract: The apparatus concerns the manufacture of tires having at least one reinfement formed from a single thread. It is of the type comprising two coaxial crowns 1 of levers 2 the ends of which bear means 3 for retaining the thread and comprising means 5 for presenting the thread 4 to said retaining means 3. The presentation means 5 comprise a presentation head 50 carried by a flexible belt 55 mounted on two guide pulleys 51, the axes of rotation of which are perpendicular to the axis of the crowns 1, said guide pulleys 51 being arranged in the vicinity of the retaining means 3. The presentation means 5 also comprise an orifice 53 conducting said thread 4 substantially in the plane of and within the loop formed by the belt 55.

Abstract: A method of winding a reinforcement layer of a pneumatic radial tire, which comprises providing at circumferentially spaced locations opposite to a front face of an outer peripheral surface of a building drum, a pair of traverse devices each having a fiber cord feed guide and constructed so as to be reciprocated along the axial direction of the building drum; and moving the pair of traverse devices by independent driving devices along the axial direction of the building drum while rotating the building drum, thereby simultaneously feeding rubberized fiber cords respectively from each feed device to a reinforcement belt on the building drum.

Abstract: A device (1) making it possible to apply at least one thread (2) to a supt (3) and characterized by the following features:it has a front clamp (4) and a rear clamp (5) along a direction of advance (F.sub.1);it has means (6, 7) for opening and closing said clamps (4, 5);it has means (8) permitting the displacement of the rear clamp (5) in the direction of advance (F.sub.1) or in a direction (F.sub.2) opposite to the direction of advance (F.sub.1); andit has means (9) for displacing the thread (2) in transverse directions.The invention also concerns the process used in the device (1) as well as the assemblies obtained with this device (1) and this process, these assemblies being, for instance, reinforcing plies used in pneumatic tires.

Abstract: The rubber products forming a part of the structure of a tire are laid onto a rigid core by means of a volumetric extruder having an outlet orifice of small size positioned close to the surface on which the rubber is to be applied. The rubber products are built up by a meridian displacement of the orifice relative to the receiving surface with the extrusion of a controlled volume of rubber.

Abstract: A process for producing a tire reinforcement is characterized by the fact that each reinforcement cord is projected individually into its place in the reinforcement. For this purpose, a machine is used which comprises laying members comprising essentially a rotary conduit which projects the cord by a radially outer extremity of the conduit and rollers which impose a linear speed of laying of the cord.

Abstract: A method and device for securing the ends of a single reinforcement cord to the unvulcanized core (7) of a tire utilizing two jaws (10, 11) which clamp the cords arranged at the starting end (41, 42) and terminating end (43, 44) of the reinforcement. A cutting blade (13) cuts the cord which then, without loosening the jaws, are pressed against the core (7) in order to immobilize the cord (4) due to the layer of raw rubber with which the core (7) has been previously covered.

Abstract: The present invention is directed to a tire comprising a three-dimensional wound reinforcement formed from a continuous sheathed filament running diagonally over the region upon which the tread is located and alternating from one tire foot to the other, said filament (i) crossing back and forth over said region, (ii) running into the tire foot tangentially, (iii) running for a relatively long distance in the tire foot, and (iv) crossing over itself over the entire tire shape, said reinforcement resisting forces radially and circumferentially, and an elastomeric material surrounding said reinforcement and to a method of manufacture thereof.

Abstract: Apparatus is provided for weaving a woven endless tire reinforcing belt on an endless weaving surface in a zig-zag pattern. The apparatus comprises input means for receiving information defining said zig-zag pattern; means for storing said pattern-defining information; central computer control means for reading said stored information and controlling the weaving of said belt as defined by said information; at least one endless weaving surface upon which said belt is woven; said weaving surface being continuously rotatable about an axis; means for continuously rotating said weaving surface about said axis, said rotating means being responsive to said central computer control means; at least one reinforcement guide means for supplying cord reinforcement to said weaving surface; and at least one means for reciprocating said guide means to effect the laying of said cord reinforcement on said weaving surface, said reciprocating means being responsive to said central computer control means.

Abstract: A guide device (11) for feeding cord (2) from a source, such as a reel, to a mandrel (1) via an application roller (8). The device (1) has a body (12) housing a knife (10) for cutting the cord (2), and also houses a cord end retaining means (24) for holding the severed end of the cord from the reel after cutting. The retaining means is a resilient roller (24) which is biased against the application roller (8) to hold the severed cord end between the two rollers. Such a guide device can be used during the manufacture of a cord reinforced elastomeric ply for a pneumatic tire.

Abstract: A process for producing a tire reinforcement is characterized by the fact that each reinforcement cord is projected individually into its place in the reinforcement. For this purpose, a machine is used which comprises laying members comprising essentially a rotary conduit which projects the cord by a radially outer extremity of the conduit and rollers which impose a linear speed of laying of the cord.

Abstract: Apparatus for making a reinforcement for a tire including:(a) cord retention means disposed in two circles which are a distance apart which corresponds to the length of the path of the cord from one side of the reinforcement to the other so that the cord, disposed in this way, defines a cylinder by a plurality of passes back and forth from one retention means to another,(b) by a suitable movement of the retention means, the cord which is disposed in this way is folded back on and around a core defining the shape of the inner surface of the tire,(c) the anchoring of the cord being assumed, the retention means are released.

Abstract: This invention concerns the manufacture of a layer of elastomeric material to form part of a pneumatic tire, and the manufacture of a reinforced elastomeric layer.According to the invention a layer of elastomeric material is formed as a progressive helical winding along a mandrel. The layer may be transferred in cylindrical form to a tire carcass building former to constitute an inner lining for a tire carcass, or a reinforcement filament may be wound over the layer producing a cylindrical reinforced layer which is cut to produce a ply of coated fabric.

Abstract: A system for manufacturing a ring-shaped body where linear material is fed to a curved constituent member for forming said ring-shaped body substantially along a normal line of the constituent member at a winding point where the linear material is wound around said constituent member. The linear material is helically wound with a predetermined tensile force around a periphery of said curved constituent member while rotating said constituent member.

Abstract: A bead seal ring for use in the retreading of radial tires by use of a bead sealing ring unit that provides positive mechanical pressure for sealing the curing envelope between the bead sealing ring unit and the bead area of the tire by a radial force. In its relaxed or initial condition, the bead sealing ring unit has a diameter smaller than the bead diameter of the tire. The bead sealing ring unit is placed into sealing position and then expanded by a locking device secured to a metal band which is part of the bead sealing ring unit.

Abstract: The object of the invention is to simplify the production of woven, endless tire reinforcing belts by enabling rapid, economical changes in belt size and simplified removal of the belts from the weaving apparatus.The invention provides a method and apparatus for forming reinforcing belts which meet this objective by employing an endless weaving surface comprised of a flexible belt supported by means rotatable about spaced, parallel axes. By moving the supports apart, the weaving surface is tensioned for the weaving operation; and, by moving the supports toward one another, the weaving surface is relaxed to permit removal of the woven reinforcing belt. The circumference of successive reinforcing belts can easily be changed by changing the flexible belt comprising the weaving surface.

Abstract: Apparatus for manufacturing tire breaker fabric comprising a cord feed unit, guide means for guiding a single cord between two sets of retaining means attached one to either edge of an endless belt to form an elongate sheet of parallel closely spaced cords laid in zig-zag fashion such that the edges of the sheet are formed by a series of folded cord edges which are held by the retaining means. Stepwise drive means advances the belt and cord assembly to elastomer applying means for applying elastomer to one surface of the cord assembly.

Abstract: Apparatus for and method of manufacturing tire breaker fabric comprising an elongated sheet of parallel closely spaced cords formed from a single cord laid in zig-zag fashion such that the edges of the sheet are formed by a series of folded cord edges. The apparatus comprises a cord laying head for laying a single cord in zig-zag fashion between a pair of spaced-apart edge forming units each comprising a holding pin engageable with a folded cord edge and a pincher head engageable around the pin to crimp the folded cord edge. A collector and holding unit collects the zig-zag cord assembly so formed and is operable to feed each traverse of cord in sequence to a device for applying elastomer to the cord assembly.

Abstract: An apparatus for molding a tire with an annular reinforcement below the tread surface includes a first set of molding segments for molding a tire, a winding mechanism for winding a flexible reinforcement band or thread about the molded tire under tension and a second group of molding segments for molding a tread surface portion about the reinforced tire body.

Abstract: An apparatus and method of manufacture for making tire breaker cord fabric comprising a tire cord laying head to lay a zig-zag assembly of a single cord, edge loop holding units and drive means for relatively moving the cord assembly to an elastomeric material coating device.

Abstract: Apparatus for gripping a tire bead, moving the tire vertically and axially over an extruder nozzle die to a position within the tire chamber where a continuous extruded strip is applied to an inside surface of the tire as the tire is rotated. The extruded strip may be applied in a plurality of side-by-side turns connected by angular portions provided by axial indexing of the tire in a predetermined amount for a predetermined time. Means are also provided for spreading the tire beads and pressing the strip against the tire surface without interfering with the movement of the tire over and around the extruder nozzle die.

Abstract: A shuttle driving assembly (10) including an open shuttle (22) rotatably driven on an automatically opened support frame (16) by a plurality of drive roller assemblies (85,87) carried by the frame (16). Each drive roller assembly (85,87) has a drive roller pulley (84) and at least one with plural belts (192,191,190,188,186) driving groups of the drive roller assemblies. The drive rollers contact a groove (115) on the shuttle (22) to provide a positive and responsive power transmission therebetween. The shaft (82) of each drive roller assembly (85,87) is mounted in a non-concentric bearing in a web (30) of the support frame (16) to provide adjustment of the position of the drive rollers (92) relative to the shuttle (22) for centering the shuttle (22) relative to the frame (16).

Abstract: A tape-applying apparatus (10) is advanced toward a body (15) upon which a strip of tape (16) is to be applied to urge a plurality of stitching rollers (72,74) against the body (15). Further advancing of the apparatus (10) will move an applicator roller (42) and the end of the tape (16) into engagement with the body (15). As the body (15) is moved past the tape-applying apparatus (10), the tape (16) is pulled over the applicator roller (42) and is stitched to the body (15) by the stitching rollers (72,74). When sufficient tape (16) has been applied, the housing (20) of the tape-applying apparatus (10) is urged away from the body (15) which moves the applicator roller (42) out of contact with the body (15). A brake apparatus (94) on the housing (20) is activated by a cam recess (80) on the holders (50) for some of the stitching rollers (72). The brake apparatus (94) engages the applicator roller (42) to arrest further feeding of tape (16) to the body (15).

Abstract: An apparatus (30) and method is provided for holding and tacking an elongate material (12) onto a body (14), which body (14) may be toroidal in shape. The material (12) is applied to the body (14) by means of a shuttle (22) rotating about the body (14) in a plane transverse to a plane containing the body (14). The apparatus (30) includes a tacker arm (76) having a clamping means (104) for clamping and unclamping the end of the material (12), extending from the shuttle (22), to the arm (76). The arm (76) is pivotally mounted on a carriage (58) for movement between a first position, wherein the material (12) clamped to the arm (76) is held against the body (14), and a second position, spaced from the body (14). In the first position of the arm (76), the body (14) will move the arm (76) until the clamping means ( 104) unclamps the material (12) whereupon the arm (76) is pivoted to the second position.

Abstract: An apparatus (16) is provided for winding inextensible flexible elongate material, such as cable (15), on a carcass (10) of a body while maintaining the tension on the elongate material (15) substantially uniform. A shuttle (20) carries at least one compensator arm assembly (30,130) resiliently supporting a housing (44,144) having a sheave (50,150) in line with an energy-dissipator (80,180) on the side of the sheave (50,150) closest to the carcass so that the elongate material (15) being fed from a spool (28) under tension and passing over the sheave (50,150) as the shuttle (20) is rotating around the torus-shaped body will apply the elongate material to the carcass (10) under substantially uniform tension as the arm assembly (30,130) stores up elongate material (15) during periods of low material demand and pays out elongate material during periods of high material demand.

Abstract: An apparatus (10) is provided for positioning an driving a toroidal body (11), such as a sand core or the like, during the building of portions of the body. The apparatus (10) includes a height adjusting mechanism (16) for raising the horizontal mid-circumferential plane (A',A") of the body so that it will intersect the rotational center (A) of a shuttle (15) which rotates in a plane transverse to the mid-circumferential plane of body (11). The apparatus (10) includes a centering and driving mechanism (17) which includes idler roller devices (18,20) and a drive roller device (22) whereby the body is positioned and driven with the rotational center (A) of the shuttle (15) lying not only on the horizontal mid-circumferential plane (A',A") of the body, but also coinciding with the center of a cross section of the body formed by a plane of the shuttle (15).

Abstract: A low pressure, pneumatic tire is provided with a flexible tread belt that extends outwardly beyond the sidewalls respectively adjacent thereto when the sidewalls are flexed under normal load. The configuration and stiffness of the belt is such that the load carried by the tire is effectively spread beyond the width of the flexed torus. At the same time, local deformation of the belt can take place in such a way to fold up over the flexed sidewalls to prevent them from damage by shock or abrasion caused by objects striking the sidewalls.

Abstract: A tape-applying apparatus (10) is advanced toward a body (15) upon which a strip of tape (16) is to be applied to urge a plurality of stitching rollers (72,74) against the body (15). Further advancing of the apparatus (10) will move an applicator roller (42) and the end of the tape (16) into engagement with the body (15). As the body (15) is moved past the tape-applying apparatus (10), the tape (16) is pulled over the applicator roller (42) and is stitched to the body (15) by the stitching rollers (72,74). When sufficient tape (16) has been applied, the housing (20) of the tape-applying apparatus (10) is urged away from the body (15) which moves the applicator roller (42) out of contact with the body (15). A brake apparatus (94) on the housing (20) is activated by a cam recess (80) on the holders (50) for some of the stitching rollers (72). The brake apparatus (94) engages the applicator roller (42) to arrest further feeding of tape (16) to the body (15).

Abstract: Carcass plies for radial-ply tires are prepared by coating individual reinforcing strands with a rubber composition, and winding the coated strands in a winding machine with relatively weak transverse circumferential strands into a continuous cylindrical tube in which the reinforcing strands are substantially parallel to the tube axis and circumferentially spaced, and are connected by the circumferential strands of weaker material. Axial sections are cut from the tube, and only the axially central, annular portion of each section is expanded radially during shaping of the carcass, thereby stretching or breaking the transverse, circumferential strands.

Abstract: Improved method and apparatus for winding tread stock onto a tire by stretching the relatively thin strip of vulcanizable strip as it is being applied to a rotating tire wherein the windings of the strip overlap each other in a stretched condition to provide a uniform contour at any cross section of the tire eliminating air pockets and enhances bonding of the adjacent and overlying stock.

Abstract: The process for manufacturing pneumatic tires comprises as essential step the manufacture of a tire body by winding cords or cables (3, 23, 35). The cord or cable is withdrawn from a supply reel (7) under constant tension and laid around and anchored to the bead cores (2; 22; 36; 39) arranged at both sides of the tire. In addition a peripherally extending belt is applied which again can be formed by winding cords or cables, and the tire is completed by injection molding or die casting elastomeric material. An apparatus suitable for performing said process comprises in addition to an interior mold (1, 21, 38) two sets of outer molds, the first set allowing the shaping of an inner tire layer provided with protrusions serving as spacers for the winding of cables or cords and the second set corresponding to the external shape of the tire (FIG. 2).

Abstract: PCT No. PCT/US79/00450 Sec. 371 Date June 26, 1979 Sec. 102(e) Date June 26, 1979 PCT Filed June 26, 1979 PCT Pub. No. WO81/00096 PCT Pub. Date Jan. 22, 1981A braking apparatus (36) is provided for a supply spool (30) whereby material (12) drawn from the spool (30) will have a relatively uniform tension. The braking apparatus (36) includes a follower roller (40) in contact with the material (12) on the spool (30) and a brake portion (38) in adjustably controlled braking contact with a brake rotor (102) mounted for rotation with the spool (30). The follower roller (40) follows the decrease in the diametral amount of material on the spool and simultaneously moves the brake portion (38) toward the center of the brake rotor (102) wherein a uniform braking force on the spool (30) is maintained.

Abstract: A control system for an elastomer extrusion and application apparatus (10,16) including an extrusion rate measuring device (60,200) for receiving a ribbon (12) of extruded elastomer and for providing a signal representing the rate of extrusion, a drive (18) for moving an article (14) to have the ribbon of extruded elastomer applied thereto in a predetermined path, an applicator (16,20,22) along the path for receiving the ribbon and applying the same to the article, a resolver (176) connected to the applicator for providing a signal representative of the rate of application of the ribbon to the article, and a control (FIG. 5) for controlling the speed of the article drive including a circuit for receiving the signals and adjusting the speed of the drive to match a desired proportion between the rate of extrusion and the rate of application.

Abstract: The invention relates to the formation of a tire tread profile by the application of rubber tread material upon a tire casing by employing a micro-computer programmer in conjunction with a tread material applicator apparatus. The control system employed during tread formation uses a programmer having a micro-computer unit, a floppy disk and a keyboard, interfaced with a tread material application apparatus.In operation, the programmer is connected to a drive motor of the tire tread application assembly and operates under the control of a tire profile program stored in the floppy disk. Proper tread profile shape is arrived at as a function of the digital ratio between the actual position of the tire rotation and the transverse position of the tire tread applicator assembly. The latter is digitally controlled within the parameters of a preprogrammed set of commands, as a direct and sole function of the position of the tire casing about its spin axis.

Abstract: The invention relates to an apparatus and method for producing an elastomeric extrudate having a constant cross section area. The extrudate is shaped in to a ribbon through a roller die and applied to a tire surface mounted on a rotating spindle. Digital electronic circuitry is employed to provide precise shaft synchronization at a pre-selected rotational velocity ratio between the rotating shafts. The synchronization assures repeatable velocity synchronization between the source of elastomeric material and a take-up device at the axis of rotation of the two components. The elastomeric material is extruded in a manner permitting control over the wrap operation and the amount of elastomeric material employed for a given cycle.

Abstract: Herein disclosed are pneumatic tire building method and apparatus for applying a continuous rubber strip on a tire carcass preliminarily wrapped around a tire building drum to produce a pneumatic tire having a tread rubber portion and one or more side rubber portions both of which or any one of which consists of different rubber materials. A pair of calender rollers are positioned in opposing and spaced relation with each other and each having a rotational axis parallel to that of said tire building drum, and at least one comparment plate is vertically disposed on and between said calender rollers in perpendicular relation with said rotational axes of said calender rollers and having a lower edge contoured in sliding contact with said calender rollers. At least one separator relatively movably mounted on said compartment plate and having a lower edge contoured in sliding contact with said calender rollers to separate and joint said calendered rubber materials.

Abstract: Method and apparatus for building a cord or wire wound carcass for a closed torus tire. An endless flattened inflatable tube providing a liner for the carcass and coaxially spaced bead rings are placed on a support comprising a cylindrical array of rolls. The bead rings are spaced axially to control the length of each turn of cord or wire wound in the flattened oval path around them. A single wire or cord is wound in a flat oval orbit about the liner and bead rings by orbiting a spool along a track having two straight parallel portions, one inside, the other outside the bead rings and liner. The parallel track portions are connected at their ends by semi-circular track portions. No rigid core is required. After winding the cord or wire about the liner and bead rings, the liner is inflated and the bead rings are shifted axially toward each other to the axial spacing appropriate for the inflated tire in use.

Abstract: A programming apparatus for use with a machine applying successive wraps of rubber on a tire surface during a retreading operation. The contour of the layers to be deposited is translated upon a template device by positioning of select metallic contacts. In turn, the number of wraps for a given arcuate distance are more finely defined upon a second template device. The second template being indexed with a series of metallic contacts. The entire operation is controlled electrically such that successive movement of the tire surface is correlated to arcuate distance.

Abstract: Apparatus for forming a tire reinforcing belt by positioning continuous cord on a movable support surface in a zigzag pattern including a traversing guide member, drive means for moving the support surface and for traversing the guide member, cam means operatively connecting the drive means and the guide member, and moving means for changing the position of the guide member and the cam means with respect to the support surface.

Abstract: Method and apparatus for wrapping a cord or wire in a toroidal helix about a liner to form a closed torus carcass. An extruder, die, and diehead provide means for extruding a liner having a horseshoe-shaped profile. Circumferential edges of the liner are joined with a preformed assembly of bead rings and a spacer ring. Cord or wire is wound snugly about an array of control fingers and then slipped off the fingers as successive tensionless turns about the liner and rings as the latter rotate through a winding plane in which a spool supplying cord or wire orbits. No rigid core is required. An endless inflatable tube can be used in lieu of the extruded liner.

Abstract: An endless reinforcement comprising a unitary strip positioned across the width of the reinforcement from one side to the other at an angle to the edges of the reinforcement, the unitary strip including a multiplicity of continuous filaments surrounded and separated by rubber disposed in a contiguous undulating relationship throughout the length of the strip. Also, apparatus for forming a unitary strip including interdigitating gripper means arranged in an oval path, means for advancing the gripper means around the oval path, and means for increasing the degree of interdigitation of the gripper means during a portion of their advancement around the oval path.

Abstract: Method and apparatus for use in building a closed torus tire. An expandable sleeve having an inflatable portion expands to wrap a sheet of tire building material partially about a disintegratable generally toroidal core. A bladder beneath the sleeve is then inflated to roll the sleeve toward the core causing the edges of the sheet to flip or snap from the sleeve surface to the core surface. The apparatus includes a drum expandable to either of two fully supported and different building diameters enabling stable support first of the core with at least one sheet of material engaged with the internal circumference of the core, and then the core with added thickness of tire components engaged with the internal diameter of the core.

Abstract: The instant invention involves the production of articles exhibiting an internal microstructure and physical characteristics like those of glass-ceramic bodies but which can be formed spontaneously from a molten glass. Hence, in contrast to the production of conventional glass-ceramic articles, no heat treatment of a parent or precursor glass body is required to cause crystallization in situ to occur. More particularly, the instant invention is concerned with the manufacture of highly crystalline glass-ceramic articles, having compositions within the Li.sub.2 O-Na.sub.2 O-Al.sub.2 O.sub.3 -MgO-SiO.sub.2 -F system, wherein a fluormica constitutes the predominant crystal phase, which can be formed spontaneously from a molten glass batch.

Abstract: A tire breaker is formed from a cord on a gum base supported on a work belt. A rotor member is mounted above the work belt, and includes inner and outer cord engaging and laying means. Upon intermittent rotation of the rotor member, the cord engaging and laying means engage the cord, fold the same into successive side-by-side loops, and lay the loops on the gum base.

Abstract: Disclosed herein is a method of forming a tire carcass on a porous sand core in the shape of the toroidal member, such method comprising the steps of helically wrapping rubber material about the body of the toroidal member, applying a vacuum through the porous toroidal member to the inner surface of the helically wrapped rubber material, applying force to the outer surface of the rubber material, helically winding wire about the body of the toroidal member over the outer surface of the already-wrapped rubber material, and helically wrapping additional rubber material about and over the wire and first-mentioned rubber material. A vacuum probe is introduced into the area of the helically wound wire, and force is applied to the additional, outer rubber material to urge it against the wire and against the first-mentioned rubber material.

Abstract: Apparatus for positioning a continuous strip on a movable support surface in a zigzag pattern including a traversing guide member having a slot passage disposed longitudinally of the movement of the support surface, means for reducing friction in the slot passage of the guide member, and positioning means between the guide member and the support surface movable into the path of the strip at the ends of each traverse to form the reversals of the zigzag pattern.