Reciprocating barrier assembly

The assembly includes a pair of parallel guide rails, each shaped generally as an inverted U; a first gate segment having at least one pair of rollers positioned on opposite lateral sides thereof, where each roller is received within a respective one of the guide rails so that the first gate segment is guided by the pair of guide rails; a second gate segment having at least one pair of rollers positioned on opposite lateral sides thereof, where each roller is received within a respective one of the guide rails so that the second gate segment is guided by the pair of guide rails; and at least one substantially rigid cross-bar pivotally connected between the first and second gate segments. The first gate segment is guided by the guide rails from a first barrier position in which it is positioned entirely within the front vertical portions of the guide rails to an open position in which it is positioned at least partially in the horizontal portion of the guide rails; and the second gate segment is guided by the guide rails from a second barrier position in which it is positioned entirely within the back vertical portions of the guide rails to an open position in which it is positioned at least partially in the horizontal portion of the guide rails. The cross-bar has a length which requires that when the first gate segment is in its barrier position the second gate segment will be in its open position, and vice-versa. Therefore, because the cross-bar is substantially rigid, it will restrict the first and second gate segments from being lifted simultaneously to their open positions.

BACKGROUND
 The present invention is a barrier assembly protecting the edge of an
 elevated loading platform or mezzanine, where the loading platform is
 adapted to receive pallets of articles from an elevated load-in side of
 the loading platform, and where workers/handlers will remove the articles
 from a handling side of the loading platform. In particular, the present
 invention is a barrier assembly that provides a protective barrier on the
 load-in side of the loading platform when workers are removing articles
 from the handling side of the platform and also provides a protective
 barrier on the handling side of the loading platform when the articles are
 being loaded onto the platform by forklift trucks through the load-in side
 of the platform.
 A typical distribution center or warehouse may include a plurality of
 elevated loading platforms or mezzanines that have openings on the load-in
 side of the loading platforms for receiving pallets of articles from
 forklift trucks, and that also have openings on the handling side of the
 loading platforms for facilitating removal of the loaded articles by
 workers. Even though the workers will typically remain clear from the
 load-in side of the loading platform while removing the articles
 therefrom, the openings from the load-in side of the loading platforms for
 receiving the pallets from the forklift trucks present a potential fall
 hazard for the workers. Furthermore, even though workers will typically
 remain clear from the loading platform while pallets are being loaded onto
 the platform by forklift trucks, openings into the loading platform during
 this operation present a potential fall hazard for the workers as well as
 a potential for injuries caused by the loading articles.
 U.S. Pat. No. 4,422,264 discloses a safety gate assembly that includes
 first and second safety gates, each of which have rollers that are
 received within a pair of parallel, inverted U-shaped tracks. The safety
 gates are coupled together by cables, which are guided between the gates
 by pulleys positioned above the gates. When one of the safety gates is
 lifted (providing access to one side of the preselected area) the pulley
 assembly will operate so as to allow the second safety gate to be lowered
 into a position blocking entrance to the opposite side of the preselected
 area. Likewise, when the second safety gate is lifted so as to allow
 entrance to the preselected area, the cable and pulley assembly will
 operate so as to allow the first safety gate to be lowered again, thereby
 restricting entrance to the preselected area from its opposite position. A
 disadvantage with this assembly is that the cable and pulley system allows
 both the first and second safety gates to be lifted simultaneously,
 thereby facilitating easy circumvention of the protections provided by the
 barrier assembly. Another disadvantage with this apparatus is that the
 cable and pulley systems add unnecessary complexity and expense to the
 apparatus.
 Accordingly, there is a need for a barrier assembly which provides a
 barrier on a handling side of an elevated loading platform when articles
 are being loaded onto the platform, through a load-in side of the
 platform, by lift trucks, and provides a barrier on the load-in side of
 the elevated platform when articles are being removed from the loading
 platform through the handling side of the platform by workers. There is
 also a need for such a barrier assembly which restricts the load-in side
 barrier and handling side barrier from being opened at the same time, and
 which is relatively uncomplicated in design and relatively inexpensive to
 build.
 SUMMARY
 The present invention provides a reciprocating barrier assembly that
 provides a barrier on a handling side of an elevated loading platform when
 articles are being loaded onto the platform, through a load-in side of the
 platform, and provides a barrier on the load-in side of the elevated
 platform when articles are being removed from the loading platform through
 the handling side of the platform by workers.
 The barrier assembly includes a pair of parallel guide rails, each shaped
 generally as an inverted U, and having a first substantially vertical
 portion, a second substantially vertical portion opposite the first
 substantially vertical portion and a substantially horizontal portion
 interconnecting the first and second substantially vertical portions; a
 first gate segment having at least one pair of rollers positioned on
 opposite lateral sides thereof, where each roller is received within a
 respective one of the guide rails so that the first gate segment is guided
 by the pair of guide rails; a second gate segment having at least one pair
 of rollers positioned on opposite lateral sides thereof, where each roller
 is received within a respective one of the guide rails so that the second
 gate segment is guided by the pair of guide rails; and at least one
 substantially rigid cross-bar pivotally connected between the first and
 second gate segments. The first gate segment is guided by the pair of
 guide rails from a first barrier position in which the first gate segment
 is positioned entirely within the first substantially vertical portions of
 the pair of guide rails to an open position in which the first gate
 segment is positioned at least partially in the substantially horizontal
 portion of the pair of guide rails. The second gate segment is guided by
 the pair of guide rails from a second barrier position in which the second
 gate segment is positioned entirely within the second substantially
 vertical portions of the pair of guide rails to an open position in which
 the second gate segment is positioned at least partially in the
 substantially horizontal portion of the pair of guide rails. Finally, the
 cross-bar has a length which requires that when the first gate segment is
 in its barrier position the second gate segment will be in its open
 position, and vice-versa. Therefore, because this cross-bar is
 substantially rigid, it will restrict the first and second gate segments
 from being lifted simultaneously to their open positions.
 Preferably, the cross-bar is pivotally coupled to each of the first and
 second gate segments, approximate a first lateral edge of the first and
 second gate segments, and the barrier assembly further includes a second
 cross-bar pivotally coupled between the first and second gate segments
 adjacent to an opposite lateral edge of the first and second gate
 segments. Furthermore, it is preferred that the barrier assembly also
 includes stops coupled to guide rails for restricting downward movement of
 the first or second gate segments when the first or second gate segments
 are in their respective barrier positions. It is also preferred that the
 barrier assembly includes a stationary support elevated above the
 horizontal portions of the pair of guide rails and a spring mounted
 between the stationary support and the cross-bar, where the spring acts to
 reduce the amount of force needed to lift the first or second gate
 segments from their respective barrier positions to their respective open
 positions.
 Accordingly, it is an object of the present invention to provide a
 reciprocating barrier assembly which provides a barrier on the handling
 side of an elevated loading platform when articles are being loaded onto
 the platform by lift trucks, and provides a barrier on the load-in side of
 the elevated platform when articles are being removed from the loading
 platform through the handling side of the platform by workers. It is also
 an object of the present invention to provide a reciprocating barrier
 assembly which restricts the load-in side barrier and handling side
 barrier from being opened or lifted at the same time. It is also an object
 of the present invention to provide a reciprocating barrier assembly that
 is relatively uncomplicated in design and relatively inexpensive to build.
 These and other objects of the present invention will be apparent from the
 following description, the attached drawings and the appended claims.

DETAILED DESCRIPTION
 As shown in FIG. 1, the reciprocating barrier assembly 10 of the present
 invention is positioned upon a loading area 11 of an elevated loading
 platform or mezzanine. The reciprocating barrier assembly 10 includes a
 pair of parallel guide rails 12 that are shaped generally as an inverted-U
 and have a first substantially vertical portion 14 approximate a load-in
 side 16 of the elevated loading platform or mezzanine, a second
 substantially vertical portion 18 approximate handling entrance side 20 of
 the elevated loading platform or mezzanine and a substantially horizontal
 portion 22 interconnecting the first and second substantially vertical
 portions. Preferably the vertical portions 18, 20 are connected to the
 horizontal portions 22 by curved sections of the guide rails. The guide
 rails are preferably constructed from conventional 3" C-channel track
 commonly used in overhead or garage door systems. Although not shown in
 FIG. 1, entrance into the loading area 11 from the lateral sides 23 of the
 loading area is preferably restricted by permanent barriers, which may be
 part of the barrier assembly 10 or part of the mezzanine construction, for
 example.
 As shown in FIGS. 1, 2A and 2B, a multi-segmented barrier gate 24 is
 received within and guided by the guide rails 12. The multi-segmented
 barrier gate 24 includes a load-in side gate segment 26 having two
 opposing lateral pairs of guide rollers/wheels 28 received within and
 guided by the guide rails 12; a handling side gate segment 30 having two
 opposing lateral pairs of guide rollers/wheels 32 received within and
 guided by the guide rails 12; and a pair of cross bars, pivotally
 interconnecting the load-in side gate segment 26 and the handling side
 gate segment 30.
 In FIG. 1, the load-in side gate segment 26 is in a barrier position in
 which it is positioned entirely within the vertical portions 14 of the
 rails 12, approximate the load-in side 16 of the elevated loading platform
 or mezzanine, and provides a barrier for protecting workers from the
 load-in side edge of the elevated loading platform or mezzanine. The
 handling side gate segment 30 is positioned in an open position in which
 it is positioned in the substantially horizontal portions 22 of the guide
 rails 12, thus providing access to the loading area 11 from the handling
 side 20 of the loading platform or mezzanine. The handling side gate
 segment may be guided along the guide rails 12 to a barrier positions, in
 which it will be positioned entirely within the vertical portions 18 of
 the rails 12, approximate the handling side 20 of the elevated loading
 platform or mezzanine, and providing a barrier for preventing access into
 the loading area 11 by workers. Likewise, the load-in side gate segment 26
 may be guided along the rails 12 to an open position, in which it will be
 positioned in the substantially horizontal portions 22 of the guide rails
 12, thus providing access to the loading area 11 for lift trucks on the
 load-in side 16 of the loading platform or mezzanine. The cross-bars 34
 operate to push the handling side gate segment 30 from its open position
 to its barrier position when the load-in side gate segment 26 is lifted
 from its barrier position to its open position. Likewise the cross-bars 34
 operate to push the load-in side gate segment 26 from its open position to
 its barrier position when the handling side gate segment 30 is lifted from
 its barrier position to its open position.
 While the open position of the load-in side and handling side gate segments
 26, 30 is shown in FIG. 1 as being positioned completely within the
 horizontal portions 22 of the guide rails 12, it is within the scope of
 the invention that the open positions of the gate segments can include
 positioning at least a portion of the gate segments within the horizontal
 portions 22 of the guide rails or in the curved portions of the guide
 rails between the horizontal and vertical portions of the guide rails.
 Furthermore, while each of the guide rails 12 are shown as being shaped as
 an inverted U, it is within the scope of the invention to remove a small
 middle section of the horizontal portion 22 that is not necessary for use
 with the present invention, leaving two inverted L-shaped rails for each
 of the guide rails 12.
 Preferably, the vertical portions 14, 18 of the guide rails include rubber
 stops mounted within the c-channels of the guide rails that act to
 maintain the gate segments 26, 30 at a desired height above the floor of
 the elevated loading platform or mezzanine when in their respective
 barrier positions. The dimensions of the gate segments 26, 30 and the
 height above the floor of the elevated loading platform or mezzanine of
 the gate segments 26, 30 when in their barrier positions may depend upon
 the local safety codes. Typically, when in their respective barrier
 positions, the upper edges of the gate segments 26, 30 will be positioned
 40-50 inches from the floor of the elevated loading platform or mezzanine
 and the lower edges of the gate segments will be positioned 20-25 inches
 from the floor of the elevated loading platform or mezzanine.
 Nevertheless, it is within the scope of the invention to modify such
 dimensions and heights depending upon the particular application.
 Alternately, the stops may be positioned in the horizontal portions 22 of
 the guide rails to perform the same function. Furthermore, it is within
 the scope of the invention to use other types and positions of stops
 available to those of ordinary skill in the art.
 It is preferred that a spring 36 is connected between the center portion of
 a cross-bar 34 and a stationary object 38, such as a mezzanine support
 beam or post positioned substantially above the reciprocating barrier
 assembly. Accordingly, the spring 36 acts as a counter balance to assist
 in the lifting of the gate segments 26, 30 from their respective barrier
 positions to their respective open positions.
 As shown in FIGS. 2A and 2B, in the preferred embodiment, the load-in side
 and handling side gate segments 26, 30 are preferably rectangular in shape
 and are constructed from 13/4" 14 and 20 gauge steel tubing. Each gate
 segment 26, 30 preferably includes a pair of horizontal tubes 40 welded to
 a pair of vertical tubes 42 at the longitudinal ends of the horizontal
 tubes to substantially form a triangle. For additional rigidity, each of
 the gate segments also include a third vertical tube 44 welded between
 each of the horizontal tubes 40, midway along the longitudinal length of
 the horizontal tubing segments. Each of the horizontal tubes adjacent to
 the cross-bars 34 include a pair of metal tabs 46 extending therefrom for
 receiving a pin 48 extending through the tab and cross-bar, for pivotally
 connecting the respective gate segments 26, 30 to the cross-bar segments
 34. In the preferred embodiment the cross-bar segments 34 are preferably
 one inch by one-quarter inch flat steel bars. The rollers/wheels 28, 32
 are mounted for free rotation on shafts 50, which are in turn freely
 slidably within protecting sleeves or bushings 52 extending through the
 vertical tubes 42 of the gates 26, 30. In the preferred embodiment, the
 wheels/rollers are 3" rollers.
 As shown in FIGS. 3A and 3B, the vertical portions of the guide rails 12
 are preferably connected to a protective support plate 54 on the closed
 side of the guide rails (by flathead screws, for example). The protective
 support plates 54 are in turn preferably bolted to the frame 56 (such as a
 post) of the mezzanine or loading platform. The protective support plates
 54 include a contact plate 58 extending at a right angle from the support
 plate 54 in front of the C-channel guide rail 12, thereby preventing
 damage to the guide rails caused by the tines of the forklift truck, for
 example.
 As shown in FIG. 4, an alternate embodiment of the of the multi-segmented
 barrier gate 24' includes a pair of segmented cross-bars 34'. Each of the
 segmented cross-bars 34' include a pair of rigid cross-bar segments 60,
 62, where the first cross-bar segment 60 is pivotally coupled to the
 load-in side gate segment 26, where the second cross-bar segment 62 is
 pivotally coupled to the handling side gate segment 30 and where the two
 cross-bar segments are pivotally coupled to each other between the load-in
 side and handling side gate segments. Preferably, the pivot point 64,
 where the two cross bar segments 60, 62 are pivotally coupled together,
 includes a guide roller/wheel that is received within the guide rails (not
 shown). This embodiment is designed for longer loading areas 11 of the
 elevated loading platform or mezzanine, where the horizontal portions 22
 of the guide rails will be lengthened to correspond with the length of the
 loading area. Of course, it is within the scope of the invention to add
 more segments to the segmented cross-bars to accommodate even longer
 loading platforms. For example, as shown in FIG. 5, yet another alternate
 embodiment of the multi-segmented barrier gate 24" includes a pair of
 segmented cross-bars 34", where each of the segmented cross-bars 34"
 include three rigid cross-bar segments 66, 68 & 70, and where the pivotal
 connections between the cross-bar segments include guide rollers/wheels 72
 that are received within the guide rails (not shown).
 While the forms of apparatus herein described constitute preferred
 embodiments of the invention, it is to be understood that the invention is
 not limited to these precise forms of apparatus, and that changes may be
 made therein without departing from the scope of the invention as defined
 by the following claims.