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TECHNICAL FIELD  
       [0001]     The invention relates to a mobile building having a longitudinally extending mobile chassis mounted with a pair of foldable frames supporting a foldable roof and collapsible walls to create an enclosure in an extended position and to rapidly adopt a collapsed position for vehicular transport.  
       BACKGROUND OF THE ART  
       [0002]     The invention relates to transportable building structures in general and specifically to mobile buildings or shelters that utilize fluid powered extendable frames mounted on a wheeled chassis to enable rapid roadway transport.  
         [0003]     An example is described in U.S. Pat. No. 6,763,633, incorporated herein by reference, which relates to an extendable folded framework actuated by hydraulic cylinders between a folded position and a deployed position to support a flexible waterproof fabric covering the roof and walls.  
         [0004]     Such transportable building structures have uses in sheltering people and equipment during construction activities, during emergency or humanitarian operations, for military applications, at sporting events, or outdoor social events. Rapid deployment and re-deployment with minimal labour is a benefit of such structures. A single operator can drive a towing vehicle to tow the building structure over roads or terrain to the erection site. Due to the hydraulic powered actuation and control system used to fold and extend the frames to the extended position, the single operator can work alone to erect or collapse the support framework in minutes. Unfurling of the flexible fabric covering the roof and walls can also be performed by the single operator although handling large heavy sheets of covering material may be better performed by a crew of workers. The practical limits of this operation are determined by the amount of time and labour involved in securing various flexible fabric components in position to ensure that the completed tent-like structure resists weather conditions and load conditions such as wind, sand, snow and ice accumulation.  
         [0005]     Features of the present invention will be apparent from review of the disclosure, drawings and description of the invention presented below.  
       DISCLOSURE OF THE INVENTION  
       [0006]     The invention provides a mobile building having: a longitudinally extending mobile chassis; a pair of foldable frames mounted to the chassis and operable transversely between an extended and a collapsed position; a rigid roof structure longitudinally spanning the pair of frames; a pair of side walls suspended from the pair of frames; and a pair of end walls suspended from the rigid roof structure.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]     In order that the invention may be readily understood, one embodiment of the invention is illustrated by way of example in the accompanying drawings.  
         [0008]      FIG. 1  is an isometric simplified view of a mobile building in the extended position with rigid roof and flexible wall coverings removed to show the structure of the mobile chassis to the lower right and the centrally disposed pair of foldable frames which support: longitudinal roof purlins, eaves beams and wall girts; as well as the gables and flexible end curtains of the transverse end walls.  
         [0009]      FIG. 2  is an isometric simplified view of the mobile building of  FIG. 1  in the collapsed position with wheeled dollies rotated forward to tow the mobile building over a road.  
         [0010]      FIG. 3  is a sectional elevation view along line  3 - 3  of  FIG. 1  showing the detailed construction of one of the pair of foldable frames in the extended position.  
         [0011]      FIG. 4  is a sectional elevation view along line  4 - 4  of  FIG. 2  showing the detailed construction of one of the pair of foldable frames in the collapsed position.  
         [0012]      FIG. 5  is a half-sectional elevation view of a foldable frame in the extended position with rigid roof panels and flexible side wall curtain deployed.  
         [0013]      FIG. 6  is a half-sectional elevation view of a foldable frame in the collapsed position with rigid roof panels and flexible side wall curtain stowed.  
         [0014]      FIG. 7  is an elevation view of an end wall showing the overlapping gable panels and flexible end curtain deployed.  
         [0015]      FIG. 8  is an elevation view of an end wall showing the overlapping gable panels and flexible end curtain stowed.  
         [0016]      FIG. 9  is a sectional view along line  9 - 9  of  FIG. 3  through a column of the frame showing telescopically engaging coaxial portions with sheet bearings, of Teflon™ for example, between contact surfaces.  
         [0017]      FIG. 10  is an elevation view along line  10 - 10  of  FIG. 1  of a side wall at a corner showing a top corner post suspended from a bracket in the eaves beam with a roller rolling on the upper surface of a side wall girt in phantom outline towards the collapsed position, and showing a bottom corner post suspended from the side wall girt. 
     
    
       [0018]     Further details of the invention and its advantages will be apparent from the detailed description included below.  
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]      FIG. 1  shows the general layout of a mobile building example embodying the invention in a schematic manner. Many of the roof and wall covering components have not been shown in  FIG. 1  in order to illustrate the underlying structure of the chassis  1  and foldable frames  2 . To simplify the fluid power controls and actuating system, use of two frames  2  may be preferred in some applications however those skilled in the art will recognize that more than two frames can be accommodated without departing from the teaching of this invention.  
         [0020]     The mobile building as shown in  FIG. 1  has a longitudinally extending chassis  1  upon which are mounted on chassis hinges  3  ( FIGS. 3-4 ) a pair of foldable frames  2  that operate in a transverse plane between the extended operating position shown in  FIG. 1  and the collapsed transport position shown in  FIG. 2 .  
         [0021]     To move between the extended position of  FIG. 1  and the collapsed position of  FIG. 2 , the details of the frame  2  construction are explained below with reference to  FIGS. 3-4 . Each frame  2  in the embodiment illustrated is mounted on a chassis hinge  3  to the chassis  1  and includes a proximal column  4 , a proximal rafter  5 , a distal rafter  6  and a distal column  7 . A rafter hinge  8  pivotally connects the two rafters  5 ,  6  at the peak, and peak cylinder  21  articulates the rafters  5 ,  6  to extend and collapse. The chassis cylinder  9  rotates the proximal column  4 , and hence the entire collapsed frame  2 , about the chassis hinge  3 .  
         [0022]     The length of each column  4 ,  7  and each rafter  5 ,  6  is extended and collapsed in a telescoping manner. Proximal column  4  is of hollow square steel tubing with an upper and lower coaxial telescoping portions extended and retracted by an internally housed cylinder  10 . Proximal rafter  5  and distal rafter  6  are also of hollow square steel tubing with an upper and lower coaxial telescoping portions extended and retracted by an internally housed cylinders  11  and  12  respectively. Distal column  7  is of hollow square steel tubing with an upper, middle and lower coaxial telescoping portions  14 ,  15 ,  16  extended and retracted by an internally housed cylinder  12  and internally housed cylinder  17 . With reference to section  9 - 9  shown in  FIG. 9 , the engaging portions of the coaxial telescoping portions  14 ,  15 ,  16  are separated and lubricated with sheet bearings  18 , of Teflon™ for example. Preferably in a like manner, each coaxial telescoping portion of the rafters  5 ,  6  and columns  4 ,  7  are separated and lubricated with like sheet bearings  18  disposed between contacting surfaces.  
         [0023]     The eaves joints, i.e.: joining column  4  and rafter  5 , and joining column  7  and rafter  6 , are rigid and not articulated. Therefore the extended frame  2  shown in  FIG. 3  is rigidly fixed when all internal and external cylinders  10 ,  11 ,  12 ,  13 , and  17  are extended, the peak cylinder  21  is extended to eliminate rotation at the rafter hinge  8  and the chassis cylinder  9  is withdrawn to eliminate rotation at the chassis hinge  3 .  
         [0024]     Referring to  FIGS. 3 and 4 , the distal columns  7  may include an end wheel  19  to support the frame  2  and permit rolling on the ground surface as the frame  2  is extended. The end wheel  19  is preferably hinged to the distal column  7  at a wheel hinge  20  to increase ground clearance in the collapsed position of  FIG. 4 . An optional configuration is to mount motorized tractors powered by hydraulic motors at the bottom of the distal columns  7  and below the chassis  1  to move the building on chain link tracks engaging the ground surface in the extended position.  
         [0025]     Having described the basic operation of the frames  2 , the construction and operation of the roof and wall structures supported on the frames  2  and chassis  1  will be described below with reference to  FIGS. 5-6  showing the roof and side walls, with  FIGS. 7-8  showing the end walls.  
         [0026]      FIG. 1  shows how the roof and walls are supported on the pair of frames  2 . The chassis  1  includes two wheeled dollies  22  that rotate about a vertical axis between the transport position shown in  FIG. 2  and the stowed position shown in  FIG. 1 . The dollies  22  can be manually rotated after the chassis  1  is raised on telescoping trailer legs  23  providing secure ground bearing support to the chassis  1  and frames  2 . As noted above, the distal columns  7  of the frames  2  are supported on end wheels  19  or motorized tractors, and the proximal columns  4  of the frames  2  are secured to the chassis  1  with chassis hinge  3  braced with chassis cylinder  9 . Longitudinal roof purlins  24 , longitudinal eaves beams  25  and longitudinal wall girts  26  are secured to and span across the pair of frames  2 . To maintain the shape of the building, the movements of the frames  2  must be substantially synchronized.  
         [0027]     As seen in  FIGS. 5-6 , the roof purlins  24  and eaves beam  25  support rigid upper roof panels  27  and lower roof panels  28 . As the supporting rafter  6  moves from an extended position in  FIG. 6  to the collapsed position in  FIG. 5 , the upper roof panel remains fixed at an upper end and is flexibly connected at it&#39;s lower end with hinges  41  to the lower roof panel  28  causing the lower roof panel to slip over the eaves beam  25  and hang down vertically rotating about the hinges  41 . At the same time the end wheel  19  pivots about the wheel hinge  20  and acts as a stowing clamp to engage and hold the lower roof panel  28  in the collapsed position shown in  FIG. 5  and in  FIG. 2 . Spring loaded stowing clamps are provided on the proximal column to similar effect to clamp the lower roof panel on the other side of the building for transport. Of course the reverse process is followed when the building is extended as the columns  4 ,  7  extend, the lower roof panels  28  are released from the stowing clamps and slide over the eaves beam  25  to lay in the planar orientation shown in  FIG. 6 . The lower edge of the lower roof panel  28  includes pins which engage openings in the eaves beam  25  as the rafter  6  extends fully, to secure the lower edge of the lower roof panel  28  to the eaves beam  25 .  
         [0028]     Flexible side wall curtains  29  are suspended from the eaves beam  25  and wound upon a roller  30  for stowing away. The bottom portion of the curtain  29  is weighed down with a metal rod  31  and the curtain  29  is laterally supported by the girts  26 . Ultimately though the frames  2  support the wall curtains  29  since the eaves beam  25  is supported by the pair of frames  2 .  
         [0029]     Referring to  FIGS. 7 and 8 , the end walls of the mobile building are also ultimately supported on the frames  2  by suspending the end walls from the purlins  26  and eaves beams  27  of the rigid roof structure. The end wall includes a gable made of two inner gable panels  32  and two outer gable panels  33 . The outer gable panels  33  which are connected to the eaves beam  25  slide behind the inner gable panels  32 , as the frame rafters  5 ,  6  collapse, into the collapsed position shown in  FIG. 8 , while the inner gable panels  32 , which are suspended from purlins  24 , overlap in a scissor fashion (centered about the peak rafter hinge  8 ). The gable includes a foldable curtain rail  34  with a flexible end curtain  35  hung upon the curtain rail  34  with curtain rollers  36 . The end curtain  35  may be removed from the rail  34  for transport, or gathered and stowed in place. The four corners of the mobile building each include a flexible corner cover  37  that seals between the side wall curtain  29  and the flexible end curtain  35 .  
         [0030]     As seen in  FIG. 10 , the side walls at each corner include a suspended corner post for reinforcing the flexible corner cover  37  and providing support for the flexible end curtain  35  and side wall curtain  29 . In the embodiment illustrated, the corner post includes a top corner post  38  suspended from a bracket on the eaves beam  25  with a bottom roller  39  engaging an upper surface of a side wall girt  26  and a bottom corner post  40  suspended from the side wall girt  26 . The bottom corner post  40  is rotated manually and pinned in place. As the columns  4 ,  7  are collapsed, the eaves beam  25  and girt  26  approach each other and the top corner post  38  is folded as the roller  39  moves along the girt  26 .  
         [0031]     It will be understood that the cylinders described above are fluid powered i.e.: pneumatic or hydraulic, requiring a control system to coordinate the motions of the operation and prevent damage due to twisting or misalignment. Preferably the control system includes a radio controlled console  42  communicating with a receiver in a housing  43  with hydraulic pumps, manifolds and valves powering and controlling the movements of the cylinders. The complete hydraulic actuation system therefore includes column and rafter extension cylinders ( 10 - 13 ,  17 ), two in each of the rafters  5 ,  6  and three in each of the columns  4 ,  7 ; two tilting chassis cylinders  9  connecting the chassis  1  and each adjacent proximal column  4 ; and two rafter peak cylinders  21  engaging adjacent rafters  5 ,  6 . Seven control levers on the radio control console  42  each control two or more associated cylinders with fluid flow volume balancing to ensure that the building extends and collapses in a substantially parallel fashion. A first lever actuates the two chassis cylinders  9  simultaneously; a second lever actuates the two peak cylinders  21  simultaneously; a third and a fourth lever each actuate two of the four rafter extension cylinders  11 ,  12  simultaneously; a fifth and a sixth lever actuate four interior column extension cylinders  10 ,  13  simultaneously; and a seventh lever actuates two exterior column end cylinders  17  simultaneously.  
         [0032]     Although the above description relates to a specific preferred embodiment as presently contemplated by the inventor, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.

Summary:
The invention provides a mobile building having: a an elongate mobile chassis; a pair of foldable frames mounted to the chassis and operable transversely between an extended and a collapsed position; a rigid roof structure longitudinally spanning the pair of frames; a pair of side walls suspended from the pair of frames; and a pair of end walls suspended from the rigid roof structure.