Drop-Arm Barrier

A kit is formed from an elongate arm, a shaft, a column from which the shaft is supportable, and at least one shear-resistant structure. The shaft is extendable through the arm, in orthogonal relationship thereto, and is rotatable with the arm as a unit. The column has an internal chamber through which a portion of the shaft is extendable. The at least one shear-resistant structure is positionable within the internal chamber in shear-receiving relationship to the shaft.

A barrier, shown in, comprises an elongate armadapted to traverse a gapto be selectively opened and closed by the barrier. The armis supportable at one end by an actuator, and at the opposite end by a receiver. The actuatorand receiverare situated on opposite sides of the gap.

In the embodiment shown in, the actuatoris supported by a footingembedded within a terrain. The receiveris supported by a similar footing, spaced from the footingand embedded within the terrain. Preferably, the footingsandare of identical size, shape and construction.

Each of the footingsandis preferably formed from a ballast material, such as steel-reinforced concrete. Preferably, each footing is buried such that its upper surface coincides with the surface of the terrain. In one embodiment, each footing has the external shape of a rectangular prism with surface dimensions of 5 feet by 5 feet and a depth of 4 feet. However, other shapes, sizes and arrangements for the footings are possible.

In another embodiment, not shown in the Figures, the actuator and and receiver may be supported by the same single footing, which is a shallow structure, embedded within the terrain, that extends continuously between the actuator and the receiver.

The actuator, shown in detail in, comprises a rigid bodysupported by the footing. An axially rotatable rigid shaftis supported by the bodyat an elevated position above the terrain. As shown in, the armis joined to the shaft, and extends in orthogonal relationship thereto. The shaftand the armare rotatable as a unit around the longitudinal axis of the shaft.

The actuatormay further comprise a lift system, which causes the armto rotate from a lowered position, shown in, to a raised position that clears the gap. The lift systemis offset from the shaft, and is characterized by an output shaft that pivotally engages the underside of the arm. The lift system may be powered hydaulically or electrically. Alternately, the lift system could be gravity-powered, with the use of one or more counterweights.

The arm, shown in detail in, is an elongate and hollow structure having a restrained first endand a free second end. The armis preferably formed from a material that is relatively lightweight, but strong and durable as well. One suitable material for the armis aluminum.

A first pair of opposed openingsare formed in the armadjacent the first end, and a second pair of opposed openingsare formed in the armadjacent the second end. The first pair of openingsare sized and positioned to receive the shafttherethrough, while the second pair of openingsare sized and positioned to receive a rigid pintherethrough.

Preferably, the armis filled to near-capacity with an energy-absorbing material, such as a strong and flexible cable. Within the arm, the cable is arranged in multiple windings, each of which loops around both the shaftand the pin. The cable may be formed from metal, such as wire rope, or more preferably from non-metallic fibers.

In one embodiment, the armis formed from A6061 aluminum alloy. The armis configured to traverse a gap of 12 feet, and is 173.25 inches in length. The hollow interior of the armis filled with 12-strand HMPE rope having a 0.5 inch diameter. Within the arm, each winding of the rope has a length of about 165 inches.

The bodyof the actuatoris shown in detail in. It comprises a pair of spaced and vertical columns, specifically first columnand second column. The columns, which are preferably parallel, extend from the same single side of a flat base plate, in orthogonal relationship thereto. The base plate, which is preferably rectangular in shape, is perforated by a plurality of openings. The openingspermit the base plateto be joined by bolts to the footingunderlying the actuator.

The columnsare preferably of identical size, shape and construction, except that first columnis a mirror image of second column. Each columncomprises an elongate tubular structure having opposed upper and lower endsand. Preferably, each columnhas a square cross-sectional shape and is laterally bounded by four flat walls, including a first side walland an opposed second side wall, a forward walland an opposed rearward wall. The opposed wallsandextend in parallel relationship, as do the opposed wallsand.

At its lower end, each columnis permanently attached to the same single side of the base plate, preferably by welding. For strengthening of the body, one or more external gussetsmay join the exterior of a columnto its base plate. To further enhance column strength, a flat brace plateinternally bisects each columnadjacent its lower end, and is held in place by welds.

Adjacent its upper end, each columnis provided with a flat and internal chamber panel, which spans the column interior and blocks loose tools and hardware from falling into difficult-to-access areas near the lower endof the column. The chamber panelforms the lower boundary of an internal chamberthat extends within the columnto its upper end.

A pair of aligned openingsare formed in each columnand communicate with the internal chamberof that column. More specifically, a first access openingis formed in the first side wall, and a second access openingis formed in the second side wall. The first and second access openingsandare preferably circular in shape. Also preferably, the size of the first access openingexceeds the size of the second access opening.

A plurality of fastener openingsare formed in the first side wallof each column, and are arranged peripherally about the first access opening. In one embodiment, the number of fastener openingsis four, and they are arranged about the first access openingin a square pattern.

An elongate channel-shaped bracketis oriented vertically and attached externally to the rearward wallof each column. The brackets, which should be parallel, in turn support a control enclosure, shown in. The control enclosurehouses components of the lift system.

A plurality of L-shaped mounting elementsare internally installed on at least two opposed walls of each columnat its upper end. The mounting elementsprovide attachment surfaces for a cap, shown in, that closes the upper end. In one embodiment, two mounting elementsare installed on the forward and rearward wallsandof each column.

A pin storage elementis internally installed within each column, preferably by welding. The pin storage elementis preferably situated at a corner of the column, at a level reachably below the upper end. The pin storage elementfeatures a perforation within which a service pinmay be received, as shown in. The service pinis configured to hold the armin a raised position during maintenance operations. When in use, the service pinis held by a reinforced openingin the first side wallof a column.

The columnsforming the actuatorshould be arranged on the base platesuch that their respective first side wallsare adjacent and parallel. The pairs of aligned openingsin the columnsshould be aligned.

In one embodiment of the barrier, the base plateis shaped as a rectangle with sides of 16 inches and 36 inches. Each of the columnsis a square tube having sides of 8 inches and a length of 42.63 inches. The centers of the aligned pair of openingsare 8 inches from the upper endof their associated column. The first access openinghas a circular shape with a diameter of 4.75 inches, and the second access openinghas a circular shape with a diameter of 2.88 inches. The center-to-center separation between adjacent columnson the base plateis about 19 inches.

Components of the body, including the columnsand the base plate, are preferably formed from a strong and durable material, such as steel. To enhance resistance to corrosion, such components are preferably galvanized before assembly.

The shaft, shown in detail in, is preferably formed from a strong and durable material, such as steel. It is a rectilinear member comprising a central body. In one embodiment, the bodyis flanked at opposed ends by a pair of stub sections.

The bodyand stub sectionseach have a cylindrical shape, and are disposed in axially concentric relationship. The bodyis bisected into equal parts by an imaginary plane. Adjacent each of its opposed ends, the bodyis diametrically perforated by a rectilinear passage. Preferably, the passagesare coplanar. If present, the stub sectionsare identical, and of lesser length and diameter than the body.

In one embodiment, the shaftis formed from 17-4 PH stainless steel. The bodyis 23.514 inches long, while each stub sectionis 5.118 inches long. The diameter of the bodyis about 2 inches, while the diameter of each stub sectionis 0.787 inches. Each passagehas a circular cross-sectional shape, with a diameter of 0.906 inches.

When installed, the shaftextends through the pairs of aligned openingsof the columnsand. Between the columnsand, the shaftpasses through the armat its first pair of openings. The shaftis fixed to the armso that they rotate together as a unit around the longitudinal axis of the shaft. The armextends in orthogonal relationship to the shaft.

The shaftis rotatably supported by a pair of flat bearing plates, one of which is installed within the internal chamberof each column, as shown in. Each bearing platefeatures a central opening, within which an annular bearingis installed. The shaft bodyis sized to be closely but clearingly received through central opening of the annular bearing.

Each bearing platepermits the shaftto rotate axially, and is supported by the first side wallof the columnwithin which it is installed. A plurality of fastener openingspenetrate the bearing plate, and are arranged peripherally about around the central opening. The fastener openingsshould be are provided in the same number as the fastener openingsin the first side wall. The pattern of the fastener openingsshould register with that of the fastener openings.

At least one, and preferably a plurality of shear-resistant structures are situated within the internal chamberof each column, in shear-receiving relationship to the shaft. Such shear-resistant structures preferably comprise thick and substantially solid blocks of a strong and durable material, such as steel. The at least one shear-resistant structure preferably comprises a first shear plate, a second shear plateand a shear pin.

The first shear plateis shown in detail in. It is a flat and solid member having a central openingthrough which the shaftis clearingly receivable. The external cross-sectional shape of the first shear plateis preferably rectangular, and more preferably square. The external dimensions of the first shear plateshould exceed the diameter of the first access opening.

A plurality of peripheral fastener openingsperforate the first shear plate, and are arranged around the central opening. The fastener openingsare provided in the same number as the fastener openingsin the first side wall, and in the same number as the fastener openingsin the bearing plate. The pattern of the fastener openingsshould register with that of the fastener openings, and that of the fastener openings.

The first shear plateis interposed between the bearing plateand the first side wallof each column, and engages both such structures in face-to-face relationship. Within the internal chamberof a column, the first shear plateand bearing plateare installed by aligning their respective fastener openingsand, and further aligning these aligned openings with the fastener openingsof the first side wall. Fasteners, shown in, are inserted through the aligned openings and actuated to join the first shear plateand the bearing plateto each other, as well as to the first side wall.

In one embodiment, the first shear plateis a square member formed from plain carbon steel. It has sides of 5.63 inches and a thickness of 0.75 inches. The central openinghas a diameter of 3 inches.

The second shear plateis shown in detail in. It is a flat and solid member having a central openingthrough which the shaftis clearingly receivable. The external cross-sectional shape of the second shear plateis preferably circular. The external diameter of the second shear plateshould exceed the diameter of the first access opening.

As shown in, the second shear plateresides on the bodyof the shaft, which passes through the central opening. The second shear plateis situated on the opposite side of the bearing platefrom the first shear plate.

In one embodiment, the second shear plateis an annular member formed from plain carbon steel. It has an external diameter of 5.63 inches and a thickness of 0.75 inches. The central openinghas a diameter of 2 inches.

The shear pinis shown in detail in. It is an elongate solid member, preferably cylindrical in shape. The shear pinhas a length less than the side length of the columns, but greater than the diameter of the first access opening.

The cross-sectional shape and size of the shear pinshould closely match that of the passages, so that the shear pinis closely, but clearingly, receivable in the each of the passages. On opposite sides of its midpoint, the shear pinis perforated by a pair of diametrical passages, which are preferably parallel.

Within the internal chamberof each column, the shear pinis installed by pressing it through the passagethat perforates the shaft, as shown in. The shear pinextends in orthogonal relationship to the shaft, and is held in place by cotter pinsinstalled in the passages.

In one embodiment, the shear pinis a cylindrical member formed from 17-4 PH stainless steel. It has a length 5.74 inches and a diameter of 0.88 inches. The passagesare symmetrically disposed about the midpoint of the shear pin, with a separation distance of 2.375 inches.

The shaftis installed after the bearing plateand first shear platehave been installed in their respective columns. A free end of the shaftis passed into the internal chamberof the first columnthrough the second access opening. Within the internal chamber, the free end of the shaftis passed through the central openingof a second shear plate, through the central openingsandof the bearing plateand the first shear plate, and through the first access openingof the first side wall.

Outside the first column, the free end of the shaftis next passed through the arm, by way of the first pair of openings. Within the arm, the free end of the shaftpasses through the windings of the contained energy-absorbing cable. These steps are preferably carried out while the armis suspended by a crane or other lifting apparatus. The armshould thereafter remain in suspension until the shafthas been fully installed.

Once through the arm, the free end of the shaftis next passed into the second columnthrough its first access opening. Within the second column, the free end of the shaftpasses through the central openingsandof the first shear plateand the bearing plate. Within the internal chamber, the free end of the shaft is then passed through the central openingof a second shear plate, and then through the second access openingin the second side wall.

When the foregoing installation steps are complete, the shaftpasses through both columnsandand is situated such that the opposed stub sectionsproject outside these columns at opposite ends of the shaft. The armis moved into alignment with the plane, if necessary, and fixed into position on the shaft. After any necessary positioning adjustments are made, the fastenersare fully tightened, thereby completing installation of the shaft.

Optionally, the actuatormay be equipped with a torsion spring (not shown), which engages the shaftat a stub sectionand controls the force and heat associated with descent of the arm.

Like the actuator, the receiveris characterized by a body comprising a pair of spaced and vertical columns. The columns, which are preferably parallel, extend from the same single side of a flat base plate. The base plate is joined to the footingunderlying the receiver, preferably by bolts. When the armis lowered, it rests adjacent its free end on an elevated support structure, such as a bumper pad, that extends between the paired columns of the receiver.

When a moving vehicle strikes the arm, the energy from the collision is transmitted to the shaftand thence into the columns. That energy can be so great as to threaten destruction of any bearing within either column. If bearings are the only structures that engages the shaft within the internal chambers of the columns, destruction of those bearings could allow the shear forces associated with the collision to bend the shaft to its breaking point, pull the shaft out of the columns, and ultimately snap the shaft in two. Such a process would leave the arm without support, thereby causing it to fall, and the barrier to fail.

Loading the internal chamberwith shear-resistant materials reduces the susceptibility of the barrierto the foregoing scenario. The first shear plateabsorbs and dissipates a portion of the shear collision force that would otherwise be internalized within the shaft. The second shear plateand the shear pinabsorb and dissipate collision energy as well. In addition, the size of the first and second shear platesand, and the shear pin, serves to block the shaftfrom being withdrawn through the first access opening. The shaftis thereby able to better maintain its structural integrity after the armundergoes a vehicular collision.

Kits of components can be useful for building a barrier. A kit may comprise an arm 12, a shaft, at least one, and preferably at least two columns, and at least one, and preferably a plurality of shear-resistant structures. The columns may comprise the first and second columnsandof a body. The shear-resistant structures may comprise one of more of a first shear plate, a second shear plateand a shear pin. At least one, and preferably at least two, bearing platesmay also be included in the kit. Other components of the barrier, and the hardware needed to assemble it, may be included in the kit.