Abstract: The method of repairing a manhole begins with assembling concrete forms above ground to correspond to the shape of the manhole wall. Then, a plastic liner sheet is wrapped around the assembled forms and the seams are welded. The forming sections are then removed, and the liner is placed in the manhole. An annular space exists between the liner and the manhole wall. The forming sections are re-assembled inside the liner. Concrete is then poured into the annular space and allowed to cure. The forming sections are removed, leaving the liner anchored in a new monolithic concrete wall fully engaging the old manhole wall.

Abstract: A manhole rehabilitation system where in one example an existing cross-pipe is exposed and a manhole base and riser are cast around and above the existing cross pipe to form a manhole. In one example an FRP base liner and FRP riser liner are placed before casting in place. In one example casting is made of an aggregate. In one example, a collar and manhole cap rest upon the casting, and are supported thereby such that the liner need not be structural. In one example an existing pipe or manhole forms the outer surface of the casting. In one example shoring is placed and used as the outer surface of the casting.

Abstract: A manhole assembly including a base, riser, and cap. The base having an upper surface forming a bench, a bottom surface, and a radially outward surface with penetrations there through; and a radial spigot in the radially outward upper edge of the base. The base having a corrosive-resistant layer covering the channels, bench, and radial spigot. Also disclosed is a riser comprised of a corrosive-resistant polymer pipe having a radially outward surface, an inner surface and a bottom surface in contact with, supported by, and sealed to the radial spigot. The cap having a radial spigot, and access hole; the radial spigot in the radially outward bottom edge of the cap resting upon and sealed to an upper edge of the riser. The radially outward surface of the cap and base are aligned with the radially outward surface of the riser.

Abstract: A retractable step system for getting into and out of a vehicle has at least one step and a supporting element, which carries the step and is movable between a raised position and a lowered position; in the lowered position, the step projects from the supporting element along a first horizontal axis so as to allow a user to place a foot on it; the system has a control member, which can be manually operated, and a stop device, which holds the supporting element in the raised position, when the control member is arranged in a first position, and allows the supporting element to freely move to the lowered position, when the control member is arranged in a second position; the control member has a retention portion, which, in the second position, projects along a second horizontal axis, which is orthogonal to the first horizontal axis, so as to keep, in use, a vehicle door open.

Abstract: A manhole base assembly and a method for making the same employ a non-cylindrical, low-volume concrete base that is fully lined to protect the concrete against chemical and physical attack while in service. This lined concrete manhole base assembly may be readily produced using a modular manhole form assembly which can be configured for a wide variety of geometrical configurations compatible with, e.g., varying pipe angles, elevations and sizes. The form assembly is configurable to provide any desired angle and elevation for the pipe apertures to interface with various underground systems, and can be formed on-site to facilitate compatibility with existing structures. The assembly provides for flexible, modular construction of a wide variety of lined manhole base assemblies at minimal cost, reduced concrete consumption and reduced operational complexity. The modular nature of the production form assembly also facilitates reduced inventory requirements when various manhole base assembly geometries are needed.

Abstract: A skid plate assembly is provided for mounting to a vehicle front-end, proximate a vehicle bumper. The assembly includes a support frame that defines a bottom portion configured to extend forward from the vehicle and a front portion connected to the bottom portion and configured to extend upwardly from the bottom portion and a cross at least a portion of the vehicle front end. A skid plate defines a bottom portion extending along the support frame bottom portion, and a front portion extending upwardly to the support frame front portion. The skid plate extends about at least a portion of the support frame front portion to define a skid plate upper surface. A skid plate cover is detachably engaged to the skid plate and extends along the skid plate bottom portion and the skid plate front portion. Mounting brackets are provided to engage the skid plate to the vehicle.

Abstract: A tailgate assembly is provided for a vehicle having a cargo area disposed between first and second bedsides. A tailgate having at least one step is pivotally supported on the first and second besides. A tailgate latch assembly releasably retains the tailgate in a stowed position. First and second swing links are pivotally connected to first and second close faces of the tailgate. First and second swing link latch assemblies releasably retain the first and second swing links in a stored position. First and second support cables are connected to the first and second swing links to limit rotation of the tailgate between the stowed position and a first open position when the first and second swing links are in the stored position and to limit rotation between the first open position and a second open position when the first and second swing links are in a deployed position.

Abstract: A side bar and steps attached to the side attached to a vehicle or to the side of the vehicle by gears, ratcheting teeth or other movable engagement to the side bar or vehicle. A step is constructed by attaching a curved or flat member to the top of an L-shaped support bar that is in turn connected to the side bar or vehicle. The steps are movably affixed to the side bar or vehicle via ratcheting teeth or gearing. The L-shaped supports have a plurality of engagement points so that the step can be adjusted upward and downward using the different attachment points on the gear or ratchet. In this manner steps can be moved for different users depending on the height of the vehicle or user preference. The L-shaped support bars may be flared outward and provided with a plate for mounting the step thereon.

Abstract: The present invention is directed to a truck step that is typically used with a lifted truck. The steps on the truck step have additional space for receiving a user's foot, shoe, or boot. The additional space is created by compressing a main bar on its bottom surface thereby creating an indentation in the main bar just above the truck step. The utility of the present invention is related to improving access to the truck step while at the same time providing a low profile appearance that does not distract or diminish the appearance of a lifted truck with a low hanging step.

Abstract: A step bolt connector and bolt assembly creates steps on a structure for accommodating a worker's boot. A first threaded bore is formed in a cylindrical end of a step bolt connector and this first threaded bore is threaded onto an exposed bolt on a structure. A sight hole extends from the exterior of the connector to the inward end of the first threaded bore for visually checking to see if the bolt is adequately attached in the first bore. A recess is formed in the cylindrical end and the recess is dimensioned to fit over fastening nut on the exposed bolt on the structure. When the first threaded bore is screwed onto the exposed bolts on the structure, the recess at least partially surrounds shields and protects the fastening nut on the exposed end of the bolt. A second threaded bore is formed in a second end (a truncated conical end) of the connector, and a step bolt is secured in the second threaded bore.

Abstract: An end-gate that is moveable from a closed position to an access position to allow access to an interior or storage area of a vehicle, comprises an interior or storage area facing panel and an inwardly extending step feature, formed in the interior or storage area facing panel, defining a stepping surface that allows an operator to step up and through an interior or storage area opening and into the interior or storage area of the vehicle.

Abstract: A supplemental step assembly for a vehicle having a vehicle step includes a step which has a first end and an opposite second end. A first side member has a first step end which is connectable to the first end of the step, and an opposite first vehicle step end which is connectable to the vehicle step, the first step end being offset from the first vehicle step end. A second side member has a second step end which is connectable to the second end of the step, and an opposite second vehicle step end which is connectable to the vehicle step, the second step end being offset from the second vehicle step end. The supplemental step assembly can be connected to the step of the vehicle in either an upward projecting direction or a downward projection direction. The supplemental step assembly provides an additional step which reduces the vertical step height and facilitates entry of the vehicle.

Abstract: A dually pickup truck includes a rear axle having a dual-wheel assembly on an end of the axle and a fender positioned over a portion the dual-wheel assembly. A foot-step is in cooperation with the fender providing a user easier access to a cargo bed of the truck.

Abstract: An arrangement allowing a person to climb up and/or down an object, such as a high-voltage mast, the arrangement including an elongate, rail-type profiled element that is provided with at least one guiding part extending along the profiled element, and a part for absorbing force transmission. A climbing aid is also provided, comprising two climbing consoles with one respective foot supporting area and a guiding section that embraces or grips the guiding part and a holding section which at least partly rests against or on the profiled element opposite the guiding section.

Abstract: A tree climbing system, the system comprising a tree climbing apparatus, the tree climbing apparatus including a handle portion, the handle portion including a first end portion, a second end portion and a ring portion including a top member, a bottom member, a first side member and a second side member, the ring portion defining an open interior portion, a threaded support member secured adjacent the first side member and the top member and a step member secured adjacent the second side member and the bottom member an installation tool, the installation tool including a first end, a second end and a handle near the first end and a carrier, the carrier including a carrier body sized to correspond with the open interior portion of the tree climbing apparatus.

Abstract: A tree step includes (i) a metal or metal alloy core, the core including a threaded section, a first bend proximate the threaded section, an offset section extending from the first bend to a second bend, and a step section extending from the second bend; and (ii) a plastic coating covering at least the step section, the plastic coating including an outer surface portion that is textured and simulates a natural surface of a tree.

Abstract: A portable tree stand step providing assistance to hunters when entering and exiting hunting tree stands includes a rope fastened to a lower frame of the tree stand. The rope forms a pair of flexible stepping loops that hang downwardly and into which the hunter can step, thereby allowing the hunter to enter the tree stand. Additionally, each stepping loop of the portable tree stand step is supplied with a foot pad and a length adjustment mechanism, allowing the hunter to position and securely step upon the foot pad when entering the stand.

Abstract: A quick folding step stool is provided that folds compactly enough to fit in a cabinet toe-kick area while requiring no modifications to existing cabinets. The quick folding step stool can also be mounted on a track to move laterally along a bank of cabinets. The quick folding step stool or the track can also be mounted on a wall, behind a bar, in a work area, or in any other location where occasional access to higher shelves or other features is required.

Abstract: A step unit includes: a step member which is provided with a pair of lower rails extending in an opening and closing direction of a slide door of the vehicle; and a rail plate member which is provided to a cutout formed in a part of either of the lower rails and which continuously connects the lower rails in the opening and closing direction. The step member is molded using a resin material and is provided with an insertion hole which vertically penetrates through the step member at a position corresponding to the cutout; and a support extension section which is extended from a side end of the cutout of the lower rail. The rail plate member is mounted to the step member by being inserted so as to penetrate through the insertion hole from above the step member.

Abstract: An anchor system for a utility pole that temporarily prevents falls by a utility worker. The system has a bolt and a head formed on one end and a threaded shank that extends through a utility pole and exposed on one surface of the pole. A concave saddle washer is attached to the bolt that rests against the pole's outer curved surface. A concave saddle plate located on the end of the bolt opposite the saddle washer rests against the opposite surface of the pole. An optional nylon sleeve is disposed between the ring member and the hinge plate to reduce sounds and interference. In one embodiment, the ring member freely pivots on the hinge plate. In another embodiment, the ring member is held in a diagonal position of the hinge plate until a free-fall force is exerted thereto that causes the ring member to move to a longitudinal position.

Abstract: A step unit includes: a step member which is provided with a pair of lower rails extending in an opening and closing direction of a slide door of the vehicle; and a rail plate member which is provided to a cutout formed in a part of either of the lower rails and which continuously connects the lower rails in the opening and closing direction. The step member is molded using a resin material and is provided with an insertion hole which vertically penetrates through the step member at a position corresponding to the cutout; and a support extension section which is extended from a side end of the cutout of the lower rail. The rail plate member is mounted to the step member by being inserted so as to penetrate through the insertion hole from above the step member.

Abstract: A two piece climber includes an upper calf bracket portion and a lower “J” shaped stirrup bracket portion permanently or removably interchangeably connected together. The lower “J” shaped stirrup bracket portion includes an upper slotted portion for receiving the lower portion of the upper calf bracket portion. The lower “J” shaped stirrup bracket portion also includes a bottom grooved or knurled grip portion to provide traction for an arborist walking across branches.

Abstract: A rail vehicle step mounts to the sill step of a rail vehicle. The rail vehicle step comprises a support sized to support a rail worker. A coupling is supported in relation to an end of the support. The coupling is sized and configured to hold the support in fixed relation to the sill step. The support is sized to extend outward beyond the rail vehicle and support a rail worker.

Abstract: A railcar step mounts to the stirrup of a rail vehicle. The railcar step comprises a support sized to support a rail worker. A coupling is supported in relation to an end of the support. The coupling is sized and configured to hold the support in fixed relation to the stirrup. The support is sized to extend outward beyond the rail vehicle and support a rail worker.

Abstract: The purpose of the present invention is to provide access to some outside portions of a vehicle that is difficult to reach. The solution provided consist of two steps temporarily attached to a vehicle tire and supported with webbing material and pressure activated hangers.

Abstract: An apparatus that provides for a conveniently removable mounting stirrup that assists a rider in climbing into a riding saddle, and provides for compact storage. The removable mounting stirrup includes features for a convenient saddle attachment and removal while on top of the riding animal.

Abstract: A tree-climbing assembly includes at least one tree step and a tool for rotating the tree step relative to a tree such that the tree step is threadingly coupled to the tree. The tree step includes a threaded first portion, a foot peg, and a second portion that extends between the first portion and the foot peg. The tool includes a retaining sub-assembly and a handle that extends outwardly from the retaining sub-assembly. The retaining sub-assembly includes a first retainer and a second retainer. The second retainer is for engaging the tree step second portion during rotation of the tree step, and the tool first retainer is for engaging the tree step threaded first portion during rotation of the tree step such that the tool handle is substantially concentrically aligned with respect to the tree step first portion.

Abstract: Method and apparatus for forming cast members. Steps are provided in the cast member by sliding mounting flanges of hollow plastic step inserts into slots provided in the inner mold shell. The cast material is then poured into the mold. Once the cast material has set, the cast member is withdrawn from the mold assembly. The step insert mounting flanges are broken away, leaving hollow step inserts into which manhole steps are force-fittingly mounted. The inserts are provided with integral cover tabs which cover larger slots provided to facilitate insertion of the step inserts, preventing leakage of the cast material into the mold assembly. Integral cover tabs are similarly provided on enforcement ring support members mounted in a similar fashion to insertion slots provided on one of the mold members to cover larger width slot portions to prevent seepage of cast material. Similar seals are provided by cylindrical-shaped inserts for use in wetcast and drycast fabrication methods.

Abstract: An access system for a terminal or a yard type motor truck tractor includes three vertically and laterally spaced steps which are mountable on the tractor frame just aft of the tractor cab to provide access between ground level and a deck or platform of the tractor aft of the cab. First and second vertical and laterally spaced steps are mounted on a member supported by one of the tractor frame rails. A third step is separately mounted on the frame rail interposed the second step and the platform and includes handrails disposed adjacent thereto. The access system provides improved access between the tractor rear deck or platform and ground level and reduces user fatigue. A member supporting the first and second steps may form a storage compartment.

Abstract: A support device may be used by a technician when performing elevated line work, for example. The support device may include a shaft having a first end and a second end and threads disposed at the first end of the shaft for use in securing the device to a pole. The support device further may include at least one rigid support member disposed on the second end of the shaft for supporting an object from the device and a pusher attached to the second end of the shaft and adapted to drive the support device into the pole. The pusher may include a driving end adapted to receive force applied from a piston of a powder driven tool, an extension portion extending from the driving end and contacting the support device.

Abstract: A step apparatus (10) is provided for use on a vehicle tire and includes a first step assembly (12) which includes a first step portion and a pair of first struts extending upward from the first step portion. A second step assembly (18) includes a second step portion and a pair of end bracket members extending downward from the second step assembly. Each of the end bracket members includes a front bracket portion and a rear bracket portion. Hinge members (28) are connected between the first struts and the front bracket portions. A pair of pawl assemblies (30) are connected to the rear bracket portion. When the tire step apparatus is installed on a tire, a person can step up on the first step portion and the second step portion. Each of the first struts includes a stop member for contacting the tire when the apparatus is installed on the tire. Each of the pawl assemblies includes a pawl hinge connected to one of the rear bracket portions. A pawl plate is connected to the pawl hinge.

Abstract: A ladder which is particularly useful as a boat ladder is constructed with a pair of centrally located side-by-side elongated support members which are movable lengthwise, to a limited degree, with respect to one another. The ladder rungs are pivotally attached to the support members such that when one support member is moved lengthwise the rungs are swung to extend outward from the support members for use as a stepping ladder and swung inward to be in line with the support members to make the ladder compact for storage. The ladder is pivotably engageable with a storage compartment in a boat hull for swinging the ladder downward for use from an opening in the compartment and upward in line with the opening for insertion into the compartment for storage.

Abstract: An adjustable ladder with self-storing features and suitable for installation in the sleeping berth of an over-the-highway tractor. The ladder includes an upper and lower member. The upper member includes first and second side rails and at least one step rung rigidly disposed between the side rails. The first side rail includes a mounting end, an open end, and a center portion. One end of the first and second side rails are rotateably mounted to a mating surface. The lower member includes a first end, a second end, and a center portion extending between the first and second ends. The lower member first end is slideably engaged within the upper member open end to define a ladder length. The length is adjustable over a range by sliding the lower member with respect to the upper member. The range may be from an application length to a stored length.

Abstract: A step assembly is provided that can be easily slipped into a utility pole opening and locked in place, and then easily removed after use. The step assembly includes 1) a step member having first and second legs, which are connected at one end and open at the opposite end and 2) a lever member that is rotatably attached to the step member and that urges the first and second legs apart. The free end of the legs include tabs protruding upwardly. The step assembly is inserted into the utility pole opening by pressing the legs toward each other. The step assembly is then inserted into the opening. The legs are released such that the legs spread apart and press against the opening's sides. The lever member is then rotated, forcing the enlarged portion between the legs of the step assembly to lock the step assembly in place.

Abstract: A folding foot step of the type used on vehicles has an improved anti-skid, friction grip, stand-on surface with a clover-leaflet-shaped perimeter. The stand-on surface is interrupted by three elongate openings that are spaced inwardly from the perimeter and arrayed to extend about an uninterrupted central region of the stand-on surface. An upwardly-opening recess is defined by a narrow upstanding rim that runs along and defines the perimeter of the stand-on surface, and by narrow upstanding rims that encircle the three openings.

Abstract: A step apparatus is provided for use on a vehicle tire and includes a first step assembly which includes a first step portion and a pair of first struts extending upward from the first step portion. A second step assembly includes a second step portion and a pair of end bracket members extending downward from the second step assembly. Each of the end bracket members includes a front bracket portion and a rear bracket portion. Hinge members are connected between the first struts and the front bracket portions. A pair of pawl assemblies are connected to the rear bracket portions. When the tire step apparatus is installed on a tire, a person can step up on the first step portion and the second step portion. Each of the first struts includes a stop member for contacting the tire when the apparatus is installed on the tire. Each of the pawl assemblies includes a pawl hinge connected to one of the rear bracket portions. A pawl plate is connected to the pawl hinge.

Abstract: A portable step system for fastening to a member such as a tree includes a first rung having an integral first arm, a plate connected to the first arm, a second arm integral with a second rung connected to the plate, and a fastener for securing the step to the member. At least two weldments connect the plate to the first and second arms. The fastener is preferably a screw having a uniquely shaped head. The plate has a hole for receiving the screw. A tool having a hole shaped for receiving the head of the screw is used to tighten the screw. The rungs are preferably covered with an irradiative material to increase visibility during darkness and may also have an anti-slip surface. A method of using the step is also described.

Abstract: A step assembly for securing a step to hollow poles and like. The step assembly includes a lock bushing and a mounting base that have cooperating flats to prevent relative rotational movement between the pole-like structure and the step. More particularly, the step includes a first end portion with an arm and a flat. The first end portion extends through a hole in the pole-like structure to position the arm in the pole-like structure. The lock bushing also includes a flat that defines, in part, an interior hole that receives the first end portion of the step so that the flat can engage the flat on the step. The lock bushing also includes an exterior flat and can be received by a hole defined by the base such that a flat surface or edge on the base engages the exterior flat on the lock bushing. The flats prevent relative rotational motion between the pole-like structure and the step.

Abstract: A frangible insert that is inserted in a pre-positioned bushing in the wall of a manhole form from the convex, easily reached side of the inner form wall. A key in the insert is received in a keyway in the bushing in the form wall so that the insert is properly oriented in the form. Concrete is then poured into the form, enveloping and affixing the insert within the man hole wall. A weakened, frangible region is provided on the insert in a position immediately adjacent to the form wall so that after the concrete is cured, the manhole and form can simply be separated, causing the portion of the insert embedded in the concrete to separate from the insert portion in the form bushing.

Abstract: The foothold of the manhole, the quay, and the like comprises the tread and side portions continued from and positioned at both sides of the tread, wherein at least the upper surface of the tread is inclined upward from a central portion of the tread toward the side portions at an angle ranging from 1 to 5 degrees.

Abstract: An adjustable running board comprising an elongated deck having an integrated first end-cap and an underlying support frame in which clamping bolts may be slideably positioned. The elongated deck may be cut to the length required for installation on a particular vehicle. A mounting shoulder on a second end-cap is bolted to the underlying support frame forming the running board assembly.

Abstract: There is provided a foothold comprising a tread, side portions positioned at both sides of the tread, legs to be inserted into a concrete wall, said tread, side portions and legs being formed of a core and first and second synthetic resins for covering the core, said second synthetic resins for covering the core of the legs having a substantially circular shape in cross section, and the first and second synthetic resins being integrated with each other, a plurality of fins provided axially on outer peripheries of the synthetic resins in a plurality of stages in the direction from the legs toward the side portions, and contact support pieces protruded from boundaries between the side portions and legs so as to bring into contact with the concrete wall.

Abstract: A foothold including a tread, side portions positioned at both sides of the tread, and legs to be inserted into a concrete wall. The tread, side portions and legs are formed of a core covered by synthetic resins. A plurality of fins are provided axially on outer peripheries of the synthetic resins which cover the legs, and pins are provided on the side portions so as to extend radially therefrom at portions adjacent boundaries between the side portions and legs. Universal washers are provided and are pressed against the concrete wall by the respective pins which are engaged in the side portions. The universal washers have substantially elliptical holes through which the side portions extend, and recessed grooves are provided along the short axis of the elliptical holes for accommodating the pins. With this arrangement, the legs can be easily and reliably fitted into the holes defined in the wall surface so that the foothold can be reliably fixed to a manhole wall.

Abstract: A tree step for climbing a vertical structure such as a tree and a pole in a relatively enlightened environment and then descending the vertical structure in a relatively darkened environment. The tree step comprising an attaching structure. A surface engageable portion connected to the attaching structure. A step connected to the surface engageable portion. The step having an outer end with an upwardly facing surface. A luminescent member for radiating light upwardly from the upwardly facing surface only in a substantially vertical direction. A semi-rigid, semi-transparent cover structure protecting the luminescent member from an outside environment.

Abstract: A foothold provided with reflectors capable of preventing reflectors having different colors from being erroneously attached to the foothold, of securing unity of the positions of the footholds in respect of right and left colors thereof without fixing the foothold again to the body, of sufficiently serving as a channel mark, and of being used for a long period of time since given colors are provided at given positions even if the foothold is fixed to the body while the front and back thereof are turned upside down.

Abstract: A scaffold step including an elongated platform and a number of clamps disposed at spaced-apart positions along the length of the elongated platform. The elongated platform has an openwork construction which sheds dirt and moisture and provides a non-slip surface for standing. Each of said clamps, however, includes hinged, upper and lower members which may be clamped around a tubular scaffold member by means of a simple, nut and bolt arrangement.

Abstract: A fire escape ladder which includes recessed steps which are mounted into an interior or exterior wall of a house, or the concrete walls of a basement, to provide an escape route to a window. When the ladder is used, the lock to the window is automatically released, and springs in the window frame cause the window to partially open. An associated smoke detector or a connection to the household smoke detector activates lights in the recessed steps and an audible alarm which aids in egress from a dark or smoke-filled building.

Abstract: The device includes a step and a handle as separate units. The step is made of two steel rods welded together, and having a threaded screw at one end to be driven into a tree. The user detachably attaches the handle to the step, and by swinging the handle, thrusts or throws the step against the tree, starting the screw into the tree, and then turns the handle to drive the step entirely into fully secured position into the tree. The user then detaches the handle from the step and repeats the maneuver with additional steps.

Abstract: A vehicle having a horizontal transport platform or bed with steps mounted within the horizontal platform. The vehicle comprises a horizontal platform supported three to four feet above ground by wheels. The platform is reinforced by longitudinal I-beams. In accordance with the present invention, a rectangular opening is provided at the rear of the platform. The opening is positioned between adjacent longitudinal I-beams. The opening contains one or more steps that descend from the level of the horizontal platform to just above ground level. The steps are within the perimeter of the platform. To maximize transport area on the horizontal platform, a cover is provided for the platform opening. The cover is attached by a hinge along one side of the rectangular opening in the horizontal platform.

Abstract: A folding ladder includes a vertical supporting strap formed from fabric material. The supporting strap has top and bottom ends. The top end of the strap has means, e.g., a fastener, rope or opening, for securing it to a fixed object for holding the ladder upright. At least one loop formed from strap material is provided below the top of the strap and is held in place by the supporting strap. The strap loop depends from the supporting strap and has two upper portions that are connected to each other at the top of the loop. The connected upper portions of the loop lie in lapped face-to-face relationship. Each such loop includes a downwardly depending, generally U-shaped intermediate bend between the connected portions. The U-shaped bend defines a step or hand grip with an opening above it to facilitate the entry of a hand or foot. In a preferred form of the invention, the strap material of each loop is provided with one or more half-twists.