BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which are intended to illustrate embodiments of the invention and which are not intended to limit the scope of the invention:
FIG. 1 is a perspective view of a fall protection apparatus in accordance with an embodiment of the invention, with the apparatus installed on an overhead structure and in use with two workers attached to the apparatus;
FIG. 2 is an end view of a fall protection apparatus in accordance with another embodiment of the invention;
FIG. 3 is a partially exploded view of a trolley of FIG. 2, with the lower trolley wheels removed for clarity;
FIG. 4 is a partial sectional view of the fall protection apparatus taken along lines IV-IV of FIG. 2, and also showing a partial view of a self retracting lanyard attached to the double pivot;
FIG. 5 is an end view of a fall protection apparatus in accordance with yet another embodiment of the invention with the apparatus having a sliding lanyard anchorage;
FIG. 6 is a partial top plan view of a rigid rail for a fall protection apparatus in accordance with yet another embodiment of the present invention, with the rail including an end stop;
FIG. 7 is an end view of FIG. 6; and
FIG. 8 is an end view of a fall protection apparatus in accordance with another embodiment of the invention, with the apparatus attached to a support member positioned below the apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIG. 1, an embodiment of a fall protection apparatus 10 is shown installed on an overhead structure and in use with two workers 12, each attached to the fall protection apparatus 10 by a lanyard 14, with a self retracting lanyard being shown. With further reference to FIG. 2, the fall protection apparatus 10 generally comprises a substantially horizontally and longitudinally extending rigid rail 16 having a generally H-shaped cross-section and first and second moveable anchorages 18a, 18b attached to each of the rail 16 and a lanyard 14. More particularly, the rigid rail 16 comprises opposing substantially vertically oriented first and second longitudinally extending flanges or tracks 20a, 20b and a horizontally oriented web or connecting member 22 extending between the tracks 20a, 20b and attached thereto. The moveable anchorages 18a, 18b are mounted on the first and second tracks 20a, 20b, respectively. Each moveable anchorage 18a, 18b is adapted to be independently movable along the length of the respective track 20a, 20b, with the anchorages 18a, 18b being permitted to freely bypass one another.
The rail 16 is suspended in place by at least one overhead support member 24 secured to an attachment point 26 on an upper surface 28 of the connecting member 22. Preferably, the support members 24 are substantially vertically extending support members. In an alternative embodiment and as shown in FIG. 8, the rail 16 can be supported by a support member 24 attached to an attachment point 26 on a lower surface 29 of the connecting member 22. In any case, the tracks 20a, 20b are sufficiently spaced apart to permit attachment of the support members 24 without interfering with movement of the moveable anchorages 18a, 18b.
Overall, the fall protection apparatus 10 is constructed and used in accordance with local safety regulations, as would be appreciated by one skilled in the art.
The connecting member 22 extends substantially continuously along the length of the tracks 20a, 20b. The transverse stiffness of the rail 16 thereby exceeds the vertical stiffness such that the rail 16 does not exhibit lateral-torsional buckling in the gross cross section. The substantially continuous connecting member 22 also supports the tracks 20a, 20b to reduce or eliminate the propensity of lateral torsional buckling of the tracks 20a, 20b themselves, particularly if the connecting member is of sufficient stiffness. Consequently, the connecting member permits the tracks 20a, 20b to participate in carrying main-span loading. Consequently, the structural advantage of a substantially continuous connecting member 22 thereby permits the number of support members 24 to be reduced, thereby reducing manufacturing costs associated with the use of the fall protection apparatus 10.
The rail 16 can be of any suitable construction and fabrication which provides sufficient strength to support the forces from arresting two simultaneous falls, with the tracks 20a, 20b and the connecting member 22 being of sufficient stiffness to prevent lateral torsional bucking, as would be apparent to one skilled in the art. Preferably, the tracks 20a, 20b and the connecting member 22 are integrally formed, such as from a rolled or extruded beam, but can also be formed by welding or joining of each track to the connecting member 22. Conveniently, the rail 16 is an H-oriented flanged structural beam in which the opposing vertical flanges form the first and second tracks 20a, 20b and the web forms the connecting member 22. Despite an H-oriented flanged beam being less structurally efficient than an I-oriented flanged beam, the H-oriented flanged beam can be designed to provide the same moment of inertia or bending strength as an I-oriented flanged beam, as would be apparent to one skilled in the art. Further, while the rail 16 can be a single rail, the rail 16 can also be constructed of one or more rails attached end-to-end to form a single contiguous rail, such as by using a splice plate attached across connecting members 22 of adjacent rails (not shown).
With reference to FIGS. 2-4, in one embodiment, the moveable anchorages 18a, 18b are wheeled trolleys 34a, 34b and the first and second tracks 20a, 20b each form an upper edge 36 and a lower edge 38. Each trolley 34a, 34b includes at least one pair of upper and lower wheels 40, 42 positioned to engage the upper and lower edges 36, 38 respectively, of one of the tracks 20a, 20b for rolling movement therealong. While each trolley 34a, 34b is supported on the respective track 20a, 20b by engagement of at least one of the upper wheels 40 with the upper edge 36, it is generally not necessary that any lower wheels 42 be engaged with the lower edge 38 at all times.
In more detail, each trolley 34a, 34b comprises a body 44 to which the upper and lower wheels 40, 42 are rotatably mounted. Preferably, there are two pairs of longitudinally spaced apart upper and lower wheels 40, 42. A lanyard attachment point 46, extends below the body 44 to attach a worker below the fall protection apparatus 10 to one of the trolleys 34a, 34b. As best seen in FIG. 4, the lanyard attachment point 46 is preferably a double pivot assembly, which permits a self-retracting lanyard 14 to be properly oriented about each of an axial pivot 50 and lateral pivot 52 during use. Consequently, the self-retracting lanyard 14 is maintained above the head of the worker.
As best seen in FIGS. 2 and 3, the trolley wheels 40, 42 are each flanged to have an annular peripheral groove 54, the base 56 of each of which can engage the associated upper or lower edge 36, 38 of the tracks 20a, 20b while the sides 58 of which can engage the opposite surfaces of the tracks 20a, 20b for the purpose of lateral guidance.
The wheels 40, 42 can be fabricated from any suitable material, such as suitable plastic or metal. The wheels 40, 42 are mounted on the trolley body 44 in any suitable manner. For example, as best seen in FIG. 5, the wheels 40, 42 are mounted using a bolt 62, nut 64 and washer 66 arrangement, with each wheel 40, 42 having an internal annular sealed bearing surface 68 through which the bolt 62 extends.
Preferably, each trolley 34a, 34b also includes upper and lower safety hooks 70, 72 to prevent the trolley 34a, 34b from falling off the rail 16 should one or more of the trolley wheels 40, 42 fall off or break. The upper hook 70 extends laterally inwardly and downwardly from the trolley body 44 while the lower safety hook 72 extends laterally inwardly and upwardly from the trolley body 44, with each hook 70, 72 having a portion 74 adjacent an inner side 76 of the track 20a, 20b on which the trolley 34a, 34b is respectively mounted. Preferably, the upper safety hook 70 is integrally formed with the trolley body 44 while the lower safety hook 72 may be removably attached to permit installation and removal of the trolley 34a, 34b on the rail 16 if the ends of the tracks 20a, 20b are blocked.
While the moveable anchorage 18a, 18b has thus far been described as a wheeled trolley 34a, 34b, other suitable varieties of moveable anchorages 18a, 18b are contemplated, as would be apparent to one skilled in the art. For example, with reference to FIG. 7, the moveable anchorage 18a, 18b can be a sliding anchorage 78a, 78b having a C-shaped profile that slidably engages one of the tracks 20a, 20b for longitudinal movement therealong. The sliding anchorage 78a, 78b can have low friction pads 80 or the like to aid in sliding movement. Also shown in FIG. 7, the connecting member 22 can be offset from the midpoint of the tracks 20a, 20b.
With reference to FIGS. 1, 6 and 7, fall protection apparatus 10 can also include stops 82 positioned at each end 84 of the rail 16 to prevent the moveable anchorages 18a, 18b from moving off the rail ends 84. For example, as shown, the stops 82 can be attached to the outer sides 86 of the each of the tracks 20a, 20b, with the stops 82 having a stop surface 88 against which the respective moveable anchorage 18a, 18b abuts.
Although preferred embodiments of the invention have been described in some detail herein above, those skilled in the art will recognize that various substitutions and modifications of the invention may be made without departing from the scope of the invention as defined by the claims as defined herein.