Abstract:
A fall restraint anchor is disclosed which has an anchorage connector with a rail that can be secured to and pass about the anchor to allow a full 360° movement. A carriage is secured to the rail and a cable secured between the carriage and a worker. The device is particularly suitable for use on a tank with a vent to provide the anchor.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a fall restraint anchor and particularly to a fall restraint anchor which can easily be retrofitted for use on large cylindrical structures.  
         BACKGROUND OF THE INVENTION  
         [0002]    Fall restraints are used in construction and maintenance to provide security for workers operating at elevated locations. Typically they are in the form of a cable secured to some form of anchor at one end and to a harness worn by the worker at the opposite end. This provides a form of security to prevent the worker from inadvertently falling from the elevated location and being severely injured or killed.  
           [0003]    Typically the fall restraint is anchored to a fixed point such as the ridge of a building or anchor points provided around the periphery of a building for attachment of a lifeline. Such an arrangement is typically used during construction of a structure or where frequent maintenance is anticipated thereby justifying a permanent installation. However, in certain environments, maintenance is much less frequent such that the provision of a permanent installation for a fall restraint is not justified or, has not been provided for in the design of the structure.  
           [0004]    One such environment is found in storage tanks which generally are large cylindrical structures having a low pitched sloping or domed roof. These structures are carefully designed for structural integrity and do not lend themselves to retrofitting or subsequent adaptation for fall restraints. It would be desirable, therefore, to have a fall protection restraint for such structures which was easily retrofittable and which provided a full  360 ° of movement.  
         SUMMARY OF THE INVENTION  
         [0005]    According to one aspect of the present invention, there is provided a fall restraint anchor comprising an anchorage connector aving a rail circumnavigating the anchor, a carriage slidably mounted on the rail for 360° movement about the anchor, and a cable secured to the carriage. The cable is attachable to a worker to inhibit movement of the worker beyond a predetermined distance from the anchor.  
           [0006]    According to a further aspect of the present invention, there is provided a fall restraint anchor for use on a large storage tank having a tubular vent structure upstanding from a roof of the tank. The fall restraint anchor includes a collar extending about the vent and secured thereto, an annular rail attached to the collar and circumnavigating the vent, a carriage mounted on the rail and a cable secured to the carriage and attachable to a worker to inhibit movement of the worker beyond the periphery of the roof of the tank.  
           [0007]    Other details, objects and advantages of the present invention will become apparent as the following description of a presently preferred embodiment of practicing the invention proceeds. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings wherein:  
         [0009]    [0009]FIG. 1 is a side view partly in section of a representation of a storage tank;  
         [0010]    [0010]FIG. 2 is an enlarged view of a portion of the storage tank shown in FIG. 1 on an enlarged scale.  
         [0011]    [0011]FIG. 3 is a view on the line III-III of FIG. 2.  
         [0012]    [0012]FIG. 4 is a plan view in the direction of arrow IV of the portion shown in FIG. 2; and  
         [0013]    [0013]FIG. 5 is a side view of the portion shown in FIG. 4.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    Referring to FIG. 1, a storage tank  10  has a side wall  12  and roof  14 . The tank  10  is of circular cross-section and the roof  14  is elevated at its center to provide a conical surface. The roof  14  is supported at intervals at internal columns  16  and has a central vent  18  to accommodate expansion and alleviate pressure build-up within the tank  10 . The construction of the tank  10  as described above is by way of example only and can follow any of a number of well-known designs utilized in the tank storage industry.  
         [0015]    To provide security for a worker on the roof  14 , a fall restraint system having a cable  20  is provided. As can be seen from FIG. 1, the cable  20  is secured at one end by a fall restraint anchor to the vent  18  and at the opposite end to a harness worn by the worker  22 .  
         [0016]    The fall restraint anchor is shown in more detail in FIGS.  2 - 5 . Referring firstly to FIG. 2, the vent  18  typically includes a tubular body  24  with a radial flange  26  to which is secured a domed cap  28 . A collar  30  is secured to the tubular body and comprises a band  32  formed into two semi-circular parts  34 ,  36  with radial tongues  38 . The two parts  34 ,  36  are joined together by bolts  40  so that the band  32  can be snuggly secured against the outer surface of tubular body  24 .  
         [0017]    A plurality of radial spokes  42  extend from the band  32  to support an annular rail  44 . The rail  44  is suspended below the spokes  42  on bolts  46  and is formed in two parts joined by splice plates  48 . The plates  48  are received within recesses in the end of the rail to provide a smooth rail of substantially uniform thickness.  
         [0018]    The rail  46  supports a carriage  50  that has a reentrant opening  52  to receive the rail  46 . A pair of rollers  54  are located in the opening  52  and are positioned on opposite edges of the rail  46  to rotate on bolts  56 . The rollers  54  have flanges  58  that overlay the peripheral edges of the rail  46  to hold the carriage snuggly on the rail.  
         [0019]    A resilient coiling device  60  is secured to the carriage  50  through a universal joint formed by a wire loop  62 . The coiling device  60  is of conventional construction and retracts cable  20  when tension is removed from the cable.  
         [0020]    The coiling device  60  is maintained in a radial horizontal orientation by means of a pair of lost motion devices  66 . Each of those devices includes a pair of abutments  68 ,  70  secured respectively to the carriage  50  and the restraint  60 . A coil spring  72  is positioned between the abutments  68  and  70  and opposes downward movement of the restraint  60  toward the roof  14  of the tank  10 .  
         [0021]    In operation, the restraint can be secured to the vent  18  by assembly of the two parts  34 ,  36  around the wall and securing them to one another through bolts  40 . The rail  46  may then be similarly placed about the wall  24  and the spliced plates  48  secured to provide the unitary annular rail.  
         [0022]    The carriage  50  is free to move along the rail through 360° about the vent  18  and with the cable  20  secured to the worker  22  provides a restraint against inadvertent falling from the roof  14 . As the worker  22  moves about the roof  14 , the coiling device  60  retracts or plays out the cable  20  to maintain a minimum tension in the cable. Movement of the worker  22  circumferentially about the roof  14  is accommodated by the carriage  50  moving along the rail and maintaining the cable  20  directed radially toward the worker  22 . The lost motion devices  66  maintain the restraint in a generally horizontal plane and accommodate vertical movements of the cable  20 , depending upon the position of the worker. The restraint therefor ensures that the cable  20  is always positioned to provide a direct line of action to the worker and not encumber movement on the roof  14 .  
         [0023]    Upon completion of the maintenance, the cable may be removed and either stored within the coiling device secured to the restraint or, alternatively, the coiling device may be removed from the cradle. It will be noted that domed top  28  of the vent provides some protection for the rail from inclement weather thereby prolonging the service life of the fall restraint.  
         [0024]    While a presently preferred embodiment of practicing the invention has been shown and described with particularity in connection with the accompanying drawing, the invention may otherwise be embodied within the scope of the following claims.