Abstract:
A load bearing device for supporting ceilings during repair, said load bearing device including: a base having at least one support; a lifting means connected to said base, said lifting means including an operating mechanism used to operate said lifting means and an elongate extension means having a lower end and a upper end; a pressure plate mounted on said upper end of said elongate extension means to apply a load to and raise a portion of said ceiling when said lifting means is operated; said lifting means being arranged to move through a predetermined distance, the distance being substantially equivalent to a typical sagging distance, the lifting means being arranged to indicate to a user when it has moved through the predetermined distance.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is related to a mechanical load bearing device, in particular a mechanical load bearing device for the vertical hoisting of ceilings by a single person. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are many designs available for vertical lifting equipment, however much of the equipment available is not readily manoeuvrable with a load in place and many require the operator to use both hands to lift and manoeuvre the device, whereby the load being lifted is either unattended or additional people are required to complete the operation. 
         [0003]    In the construction industry, by way of example, it is often required to repair ceilings which over time have sagged. When such a ceiling sags over time, the plasterboard ceiling will typically set (goes hard) in the position to which it has sagged. If the plasterboard and ceiling are not repaired the ceiling will eventually fall down causing major damage to other sections of the ceiling and the contents below. To lift the ceiling back to the desired horizontal position and hold it in place while the ceiling is repaired would require several workers. It is firstly apparent that such workers are not effectively used. Secondly it takes several workers to place props in position to hold the ceiling in place and this requires substantial physical effort to push a sagged ceiling back into place. The props are normally used to hold the ceiling once it is in the required position to be repaired so further substantial physical effort is required to lift and hold a ceiling prior to placement of the props. 
         [0004]    There are also several devices known which allow the overhead installation of plasterboard panels and cornices. In the construction of a ceiling, a plasterboard panel is lifted into place and supported by a panel hoisting and positioning device. The device allows the panel to be held effectively and positively in place while the panel is fixed to the rafters in the ceiling. These devices are designed to place and support a sheet of plasterboard in a position to be fixed to the ceiling rafters, they do not require the device to be able to apply substantial force to the plasterboard as it is only required to support the plasterboard while it is fixed to the ceiling. 
         [0005]    With the installation of cornices it is generally recognised that the process requires the use of at least two operators in order to install a standard ceiling cornice. However, it is possible to install a lightweight cornice using only one person. This installation is carried out by means of driving a large 4 inch nail into the wall at the opposite end of the cornice which would have normally been held by the other operator to hold the cornice in place. This method of installing lightweight cornices is not acceptable for solid plaster walls as it causes extensive damage to wall and requires the wall to be repaired once the cornice has been installed. There is also the problem that the nail which is holding the cornice may come out before the cornice is properly installed and thereby damage the cornice. As stated above this method of installation is only appropriate for lightweight (gyprock) cornice, it cannot be used for heavier (plasterglass) cornice. 
         [0006]    Also known in the construction industry are vertical lifting devices which allow materials such as kitchen cabinets to be installed along vertical walls. The devices are used to lift and support the materials while the materials are fixed in place to the wall, they are not required to apply a substantial force to the materials as they are only required to support and hold the materials. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of admission that the prior art forms part of the common general knowledge in Australia. 
         [0007]    Any discussion of documents, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a load bearing device for supporting ceilings during repair, said load bearing device including: 
         [0009]    a base having at least one support; 
         [0010]    a lifting means connected to said base, said lifting means including an operating mechanism used to operate said lifting means and an elongate extension means having a lower end and a upper end; 
         [0011]    a pressure plate mounted on said upper end of said elongate extension means to apply a load to and raise a portion of said ceiling when said lifting means is operated; 
         [0012]    said lifting means being arranged to move through a predetermined distance, the distance being substantially equivalent to a typical sagging distance, the lifting means being arranged to indicate to a user when it has moved through the predetermined distance. 
         [0013]    In another embodiment the present invention provides a load bearing device for supporting ceilings during repair, said load bearing device including: 
         [0014]    a tripod base having a plurality of legs each having an upper end and a lower end, a wheel connected to the lower end of each leg to allow the device to be manoeuvrable; 
         [0015]    a support having a top end and a bottom end, said plurality of legs attached to said support; 
         [0016]    a lifting means including an operating mechanism used to operate said lifting means and said lifting means is connected to said top end of said support, said lifting means including:
       a release mechanism to allow the lifting means to retract after use;   an elongate extension means having a lower end and a upper end, said lower end connected to said lifting means;       
 
         [0019]    a pressure plate attached to said upper end of said elongate extension means to apply a load to and raise a portion of said ceiling when said lifting means is operated; 
         [0020]    wherein said lifting means being arranged to move through a predetermined distance, the distance being substantially equivalent to a typical sagging distance, the lifting means being arranged to indicate to a user when it has moved through the predetermined distance. 
         [0021]    The present invention overcomes the problems of the prior art by providing a mechanical load bearing device which is easily operated by a single person. The device allows a single operator to repair a sagging ceiling without the requirement of an assistant. For example, once a ceiling has been re-positioned by the mechanical load bearing device the single operator is then easily able to use such devices as an auto-collating screw gun to fix the ceiling back to its original position. The device also allows the repair to be carried out using less physical effort as the device is used to hoist the sagging ceiling and also hold the ceiling while the repair is carried out. Finally the device allows the operator to perform the repair in substantially less time than had previously been required to repair a ceiling. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The present invention will be understood more fully from the detailed description given hereinafter and from the accompanying drawings of the preferred embodiment of the present invention, which, however, should not be taken to be limitative to the invention, but are for explanation and understanding only. 
           [0023]      FIG. 1  is an isometric view of a mechanical load bearing device according to one embodiment of the present invention. 
           [0024]      FIG. 2  is an exploded isometric view showing the separated main components of a mechanical load bearing device according to one embodiment of the present invention. 
           [0025]      FIG. 3  shows a mechanical load bearing device positioned in preparation for use in repairing a sagging ceiling according to one embodiment of the present invention. 
           [0026]      FIG. 4  shows a mechanical load bearing device positioned in preparation to hoist the ceiling according to one embodiment of the present invention. 
           [0027]      FIG. 5  shows a mechanical load bearing device after having hoisted the sagging ceiling and holding the ceiling in place so as the operator may repair the ceiling according to one embodiment of the present invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
       [0028]    The present invention will be discussed hereinafter in detail in terms of the preferred embodiment of a mechanical load bearing device according to the present invention with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to those skilled in the art that the present invention may be practiced without these specific details. 
         [0029]      FIG. 1  shows the mechanical load bearing device  10  assembled in preparation for use. The mechanical load bearing device  10  provides an improved method of repairing sagging ceilings  50 . When a ceiling  50  sags over time, the plasterboard ceiling will typically set (goes hard) in the position to which it has sagged. For example a typical distance which a ceiling would sag to would be a distance in the range of 2 cm to 8 cm. It therefore requires a significant amount of force to re-position a sagged and set ceiling back to its original position. The device  10  allows the operator to repair a ceiling  50  without the need for another person who would normally be required to push up the sagging ceiling  50  manually with a wooden or similar type prop. It can be seen that the use of the mechanical load bearing device  10  will simplify the ease in which the task of repositioning a ceiling panel which has sagged is accomplished. 
         [0030]      FIGS. 1 and 2  shows a mechanical load bearing device  10  including three main components, a base  20 , a lifting means  30  and a pressure plate assembly  40 .  FIG. 2  shows an exploded view of the three components. The base  20  includes three identical supports  27  welded onto shaft  22 . In this preferred arrangement the base  20  includes three supports  27  arranged in a tripod configuration, however the device  10  is not limited to this number and configuration of supports  27 , it may for example have four supports  27  to define a shape of a square. 
         [0031]    Each support  27  ideally has a wheel  21  attached to the bottom of each leg  27  to allow the mechanical load bearing device  10  to be moved. The wheels  21  also include a lock  28  to prevent the wheels  21  and subsequently the device  10  from moving when the locks  28  are engaged. 
         [0032]    A lifting means  30  is mounted on the top end of the shaft  22  to a flat metal plate  23 . The lifting means  30  may include a bottle jack  25  and an elongate extension means  31 . The lifting means  30  provides the higher pressure required to repair a sagged ceiling. The high pressure required is significantly more than what known panel lifters and other similar devices used in the industry are capable of producing and therefore does not allow for the substitution of known panel lifters or other similar known devices to repair sagged ceilings. A further requirement for the lifting means  30  is that it must only have a short lift in order to lift a ceiling  50  which requires repositioning and repairing. The short lift is required as a ceiling will generally only sag a distance of 8 cm, once the plasterboard has set in this position it requires a short lift and a high pressure lift in order to repair the sagged ceiling. There is also the added advantage that by having only a short lift the load bearing device  10  and the lifting means  30  can be quickly retracted to enable the user to move on to further repairs and also provides the time saving factor for the overall job. Alternatively the bottle jack  25  may include a screw jack or a combination hydraulic/air jack to lift and repair the ceiling  50 . 
         [0033]    The bottle jack  25  is secured to the plate  23  by bolts (not shown) or similar securing devices. The bottle jack  25  has been modified so as to extend the operating mechanism  26 , for example a handle to allow for one-handed operation. The bottle jack  25  also includes a pressure release valve (not shown) which is operated by mechanism  24 . The mechanism  24  is in the shape of a t-bar, however, alternatively it could form any shape which allows the user to easily release the pressure in the bottle jack  25 . 
         [0034]    To mount the elongate extension means  31  to the bottle jack  25  a short housing spigot  60  is welded to the hydraulic shaft  29  of the bottle jack  25 . It should also be noted that other methods of attaching the short housing spigot  60  to the bottle jack  25  and the hydraulic shaft  29  may be used such as a simple screw thread on the bottle jack  25  and a mating screw thread on the short housing spigot  60 . The housing spigot  60  has an aperture  61 , when the lower end of the elongate extension means  31  is placed over the spigot  60  the aperture  61  lines up with aperture  33  in the elongate extension means  31  and a bolt  34  is passed through both apertures  61 ,  33  to secure the elongate extension means  31  to the spigot  60 . This allows the elongate extension means  31  to be easily disassembled from the bottle jack  25  for transport and storage. 
         [0035]    At the upper end of the elongate extension means  31  a bolt hole  35  and fixing pin  32  enable the pressure plate assembly  40  to be inserted into the upper end of the elongate extension means  31  and secured by use of the fixing pin  32 . The T-bar  41  has several height adjustment holes  42  which enable the user to vary the overall height of the mechanical load bearing device  10  for the repair of different ceiling  50  heights. It is also possible to incorporate different length T-bar assemblies  41  to vary the overall height of the mechanical load bearing device  10 . 
         [0036]    On the T-bar cross-member  43  a flat rectangular aluminium plate  44  is mounted to the T-bar cross member  43  by screws (not shown) which are countersunk into the aluminium plate  44  so that they do not appear above the surface of the aluminium plate  44 . Alternatively the rectangular aluminium plate  44  can be attached to the T-bar cross-member  43  by any other suitable means, for example it may be welded. To reinforce the aluminium plate  44  the T-bar cross member  43  is preferably constructed from a open box channel which is fixed to the underside of the aluminium plate  44 . The open box channel is used to strengthen the plate and provide for the distribution of weight over a greater cross-sectional area when the mechanical load bearing device  10  is used to push up a sagging ceiling  50 . 
         [0037]    The four corners of the aluminium plate  44  are rounded. The aluminium plate  44  is the flat member which comes into contact with the ceiling  50 . The contacting portion of the plate  44  which comes into contact with the ceiling  50  is substantially planar so as it easily distributes the pressure across the portion of the ceiling  50  to be lifted and repaired. The aluminium plate  44  is sized so as to span three rafters which are 450 cm apart from the centre of each rafter to the centre of the next rafter. 
         [0038]    To repair a sagging ceiling  50  the operator of the mechanical load bearing device  10  must first make an estimation of the height of the ceiling  50  to be repaired. The estimation is carried out by lifting the pressure plate assembly  40  manually until it is located just below the centre of the concave part  51  of the ceiling  50  to be repaired (see  FIG. 3 ). Then using the adjustment holes  42  on the pressure plate assembly  40  of the mechanical load bearing device  10 , the operator then inserts the fixing pin  32  in the required position. The operator then positions the whole device in place under the ceiling to be repaired (see  FIG. 4 ) and locks the wheels  21  by engaging the wheel locks  28 . The ceiling  50  is then hoisted by pushing up and down on the operating mechanism  26  of the bottle jack  25  in the usual manner. The operator continues up and down pumping action on the operating mechanism  26  until the ceiling  50  is back in place against the rafters  52  (see  FIG. 5 ). The operator can tell when the ceiling  50  is firmly positioned against the rafters  52  due to the resistance which will be felt in the operating mechanism  26  of the bottle jack  25 . For an operator to determine when the ceiling  50  is in the correct position against the rafters  52 , a combination of feeling the resistance in the operating mechanism  26  which is used to indicate to the user that the ceiling is in the correct position and also the very short lift in the lifting means  30 , for example the bottle jack  25  has a very short lift, and high pressure to enable the operator to repair a ceiling  50 , especially when the ceiling has sagged and set in the sagged position. For example a typical distance which a ceiling would sag, would be a distance in the range of 2 cm to 8 cm. The operator makes the required repair and once this is achieved the pressure releasing valve is released by turning mechanism  24  on the bottle jack  25 . When the pressure is released the elongate extension means  31  and pressure plate assembly  40  are lowered and the whole mechanical load bearing device  10  can be relocated to the next position requiring repair. 
         [0039]    A mechanical load bearing device  10  according to the present invention may also be used to repair or replace damaged cornices or install a new cornice to a ceiling  50  in a similar manner as described above. The device  10  allows the operator to repair and install long and heavy lengths of cornice without the need for another operator who would normally be required to install a standard ceiling cornice. It can be seen that the use of a mechanical load bearing device  10  according to the present invention will simplify the ease in which the task of repositioning a ceiling cornice is accomplished. 
         [0040]    A mechanical load bearing device  10  according to the present invention may also be used to repair steel rafter ceilings were the distance between steel trusses is usually between 1.5 to 1.8 metres. To repair this type of ceiling more than one mechanical load bearing device  10  can be used with the two pressure plate assemblies  40  placed side by side to cover the span of the steel trusses. 
         [0041]    Although the present invention has been illustrated and described with respect to exemplary embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omission and additions may be made therein and thereto, without departing from the spirit and scope of the present invention. Therefore, the present invention should not be understood as limited to the specific embodiment set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalent thereof with respect to the feature set out in the appended claims.