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FIELD OF THE INVENTION 
     The present invention relates to a safety gate and, in particular, to a safety gate for use at the loading bay entrance of a mezzanine floor. 
     BACKGROUND ART 
     Generally, a mezzanine floor loading bay means any floor, having a loading bay which loading bay is accessible from a lower floor by a suitable load evaluating equipment such as a fork lift truck. Such loading bays are common to gain access to mezzanine floors which are frequently used for additional storage. Generally, to prevent operators on the mezzanine floor from falling onto the floor below, a safety gate is provided along the edge of the loading bay. Unfortunately, during repeat loading exercise the safety gate is inevitably left permanently open, increasing the risk to operators working on the mezzanine floor and in and around the loading bay area. Furthermore, the use of the gate is inconvenient for the operator of the fork lift truck who must wait until the gate is opened, either by an operator or by suitable electronic equipment before delivering the load to the loading bay. Furthermore, in the former case, the operator opening the gate is also at further risk as it is necessary for the operator to approach the vicinity of the drop whilst opening the gate. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a safety gate for a mezzanine loading bay operable to have an open and a closed position, wherein the safety gate is upright and includes barrier means providing an upright barrier and which prevents access to the mezzanine loading bay edge when the gate is in the open position and wherein the ends of the barrier means are spaced apart to provide, in use, a barrier area opening into the loading bay area. 
     Preferably, the barrier remains upright during movement from the open to the closed position. 
     Preferably, the barrier remains upright during movement from the closed to the open position. 
     Advantageously, unlike prior art devices the upright barrier does not include any overhead restriction or barrier so that no limit on the vertical height of the load that may be received in the loading bay area is imposed by the safety gate. 
     Preferably, the barrier means also prevents access to the mezzanine floor edge when the gate is in the closed position. 
     Preferably, the barrier means are shaped to partially enclose the loading bay. 
     Preferably, the barrier means take a substantially arcuate form. 
     Preferably, the upright safety gate includes rotating means to rotate the barrier means and the barrier area opening between the loading and unloading positions. 
     In accordance with the above invention, the barrier area opening is generally positioned at the mezzanine opening for off-mezzanine load delivery into the area defined by the barrier means. Thereafter, the barrier is rotated so that the opening is positioned for access for on-mezzanine level unloading and, simultaneously, the upright barrier means is rotated across the mezzanine opening to prevent access thereto by personnel. Once on-mezzanine level unloading is complete, the barrier means may be rotated back ready to receive an off-mezzanine load. 
     The term mezzanine should be understood in a broad sense to define a split level where loads may be received from a lower level, or possibly, an upper level and, accordingly, the invention may be utilised in any loading area where operator access to the edge of the loading area is to be restricted to prevent personnel falling. 
     Commonly, however, the invention will have utility where fork lift trucks are used to deliver loads, via a loading bay, to higher level storage areas and where there is a risk of personnel falling off the edge of the loading bay onto the lower level. For instance, the invention is particularly suited to use at the edge of the loading platform of a steel scaffold structure, such as would be used during construction or refurbishment of a building and where it is necessary to lift pallets of material to various levels, as the construction progresses, using a telescopic jib fork truck or similar device. 
     Preferably, the rotating means comprises a suitable mechanism to rotate the upright gate between the closed and open position. Preferably, when the barrier means is in arcuate form, the safety gate rotates about a central vertical axis of symmetry. Preferably, to maximise the available loading bay area, the said suitable mechanism does not impinge upon the loading bay. 
     Accordingly, in one embodiment of the invention, the mechanism is located off to one side of the loading bay, wherein the upright barrier means rotates through an arrangement of fixed bearings which define the path through which the barrier travels. Preferably, the barrier means is mounted on a pair of wheels, preferably, castor wheels, to assist the rotary movement. Preferably, the arrangement of bearings is housed in a framework which may also provide an additional barrier perpendicular to the loading bay edge. A complimentary barrier may also be present on the opposite side of the loading bay so that operator access is restricted to the side facing the loading bay edge but spaced therefrom by the safety gate. In this manner, the operator may only gain access to the loading bay area after the gate has been rotated into the closed position so that the opening between the ends of the barrier means is accessible to the operator on the mezzanine level. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: 
     FIG. 1 a  shows a plan view of a safety gate in accordance with the present invention; 
     FIG. 1 b  shows a side view of a rotating mechanism in accordance with the present invention; and 
     FIG. 2 is a schematic diagram of a method of use of a safety gate in accordance with the present invention wherein the safety gate is shown with the open side of the arcuate safety gate coincident with the mezzanine edge; 
     FIG. 3 is a schematic diagram of the method of use of a safety gate in accordance with the present invention wherein a pallet is loaded onto the loading bay; 
     FIG. 4 is a schematic diagram of the method of use of a safety gate in accordance with the present invention wherein the safety gate is rotating toward the operator zone after loading the pallet; 
     FIG. 5 is a schematic diagram of the method of use of a safety gate in accordance with the present invention wherein the safety gate is rotated through 180° until the opening resides adjacent to the operator zone after loading the pallet; and 
     FIG. 6 is a schematic diagram of the method of use of a safety gate in accordance with the present invention wherein the safety gate is rotated through 180° until the opening of the safety gate resides adjacent to the mezzanine edge. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1 a,  a safety gate  2  extends in an arc through approximately 260° to partially enclose a loading bay area and to simultaneously provide an opening into the area defined by the arc. The opening  4  is defined by the spaced ends  6 ,  8  of the arcuate gate  2  and, in the position shown in FIG. 1 a,  accommodates access to the mezzanine loading bay area  10  from the lower level  12 . In this manner, a loading device (not shown) such as a fork lift truck may deliver a load  14  onto the mezzanine loading area  10  from the lower level  12 . 
     The gate  2  is mounted on a pair of castors  16 ,  18  each located at the respective spaced ends  6 ,  8  of the safety gate  2 . Additionally, the safety gate  2  is supported by a series of bearing castors  20 ,  22 ,  24 ,  28 ,  30 ,  34 ,  36 . Generally, the bearing arrangement is designed to guide and support the arcuate form of the gate barriers  40 ,  42 . The castor bearings are separated into three complimentary support areas  44 ,  46  and  48  and this is more clearly seen in the end section shown in FIG. 1 b  which shows the first support area incorporating castors  20 - 24 . 
     Referring to FIG. 1 b,  a support frame  50  has a base member  52 , two spaced parallel upright members  54 ,  56  and a cross member  58  welded across the top of the upright members,  54 ,  56 . The base member  52 , upright members  54 ,  56  and the cross member  58  define a rectilinear opening through which the gate  2  passes. A base castor  20  is journalled in a spaced pair of brackets  60 ,  62  which are mounted on the base member  52  so that the castor provides base support for the gate  2  as it rolls thereover. The gate is guided in its arcuate path by a pair of vertically spaced opposed castors  22 ,  24  which are journalled in brackets mounted on respective side members  56 ,  54  so that lateral movement of the barrier with respect to the side members is prevented. The arrangement of bearings is mirrored in support area  48  and partially mirrored in support area  46  save that the base bearing is substituted by a top bearing (not shown) which depends from the cross member  72  by a suitable bracket so that the castor abuts against the top of the barrier  42  and together with base support bearing  20  and a corresponding bearing in area  48  (not shown) provides three point vertical support for the safety gate  2 . 
     Additional support is provided by the track shaped cross-section of the barriers  40 ,  42  which provide a stable track for the lateral support castors  22 ,  28 ,  34  which extend into the track during arcuate movement of the gate  2 . 
     Referring to FIGS. 2-6, a schematic view of a mezzanine  80  and ground floor  82  is shown. The edge  84  of the mezzanine level  80  is fitted with hand rails  86 ,  88  which respectively terminate on either side of the loading bay  90 . Complimentary hand rails  92 ,  94  each extend from the ends  96 ,  98  of the edge hand rails  86 ,  88  at either side of the loading bay  90 , to terminate at the operator zone  100  at the opposite side to the loading bay mezzanine edge. 
     An arcuate safety gate  102  according to the present invention is fitted in the loading bay  90  and extends through approximately 260°. In FIG. 2, the gate is shown with the open side  104  of the arcuate safety gate  102  coincident with the mezzanine edge  84 . 
     The pallet  106  supported on the forks of a fork lift truck (not shown) may be elevated by the forks of the truck and loaded onto the loading bay  90  after passing through the opening  104  in the safety gate  102  as shown in FIG.  3 . 
     Referring to FIG. 4, after the pallet has been loaded into the loading bay  90 , safety gate  102  may be rotated through 180° until the opening  104  resides adjacent to the operator zone  100  so that the load  106  may be removed in the direction of the arrow  108  by appropriate lifting equipment located on the mezzanine floor  80 . Thereafter, the gate may be rotated back through 180° so that the opening  104  is once more adjacent to the mezzanine edge  84 . 
     By virtue of the invention, it is not possible for the operator to approach the mezzanine edge of the loading bay area. Furthermore, by leaving the gate in the position shown in FIG. 6 it is possible for a load to be safely received when an operator is not present on the mezzanine floor, thus, improving the efficiency of the loading operation for the operator of the loading device on the ground floor whilst maintaining safety and denying access to the mezzanine floor edge of the loading bay by a mezzanine floor operator. 
     It is envisaged that alternative embodiment to the invention may have barriers which are other than arcuate but which nevertheless describe a loading area. Generally, the mechanisms for opening, closing and rotating the gate may be suitably automated. 
     All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. 
     Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
     The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Summary:
A mezzanine safety gate for a mezzanine loading bay having a rotatable barrier which is movable between an unloading position and a loading position. The barrier prevents access to the mezzanine loading bay edge when the barrier is in either the unloading or loading position and does not include any overhead restriction or barrier so that loads having a height greater than the height of the barrier can be placed within an interior space of the gate.