Patent Publication Number: US-2013228394-A1

Title: Worker Safety Device and Method

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of worker safety, and in particular, the field of devices and methods for improving worker safety. 
     BACKGROUND OF THE INVENTION 
     In recent years, governments, businesses, and society at large have placed a progressively greater value on worker safety. Injuries to workers can be devastating to the injured workers themselves, their families, and their communities. The costs to businesses and governments associated with such injuries are also substantial. Such costs include the costs to businesses of insuring against the risk of liability for worker injuries. Meanwhile, it is usually government, and ultimately the taxpaying public, that bears the costs of caring for injured workers, particularly those that have suffered severe or catastrophic injury. For these and other reasons, businesses, governments and workers themselves striving to improve safety, including the optimization of work processes and methods, and the use of the most advanced safety-promoting equipment available. 
     Tractor-trailers (also known as truck-and-trailer, or semi-trailer trucks) are a common sight on North American highways. A tractor-trailer consists of a towing engine (“tractor”), and a trailer that carries freight. The trailer (also referred to as a “truck trailer” is attached to the tractor at the tractor&#39;s rear end, so that some fraction of the weight of the trailer is held up by the tractor, while the rest of the weight rests on the trailer&#39;s own wheels. 
     From time to time, it is necessary to perform repairs or routine maintenance on these trailers, requiring a repair person to climb onto the roof of the trailer. Climbing onto and working on the roof creates a safety hazard, namely, the risk that the worker will fall off of the roof and suffer injury or death. 
     SUMMARY OF THE INVENTION 
     Therefore, according to the present invention, there is provided a worker safety device for use with an object having a person support surface, the device comprising a length-adjustable device frame positionable on said object; a frame fastener coupled to the device frame configured to detachably fasten the device frame to the object; an attachment means, attached to the device frame, configured and positioned to attach a personal fall-prevention device to the device frame; whereby a person on said surface using the fall-prevention device can prevent a fall from said surface by attaching the fall-prevention device to the attachment means. 
     According to another aspect of the invention, there is provided a method of preventing a worker from falling off of a roof of a truck trailer, the trailer having first and second side rails, the method comprising the steps of: providing a worker safety device including a length-adjustable device frame, a first frame fastening element at a first end of the device frame, and a second frame fastening element at a second end of the device frame; fastening the frame to the trailer by (1) positioning the device frame in a pre-fastening position and (2) actuating a frame fastener to cause the frame fastening elements to fasten the device frame to the side rails; and attaching fall-preventing worker safety gear to the device to prevent a worker from falling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made, by way of example only, to preferred embodiments of the invention and in which: 
         FIG. 1  is a perspective view of a worker safety device according to the present invention. 
         FIG. 2  is a top view of a worker safety device according to the present invention. 
         FIG. 3  is a side view worker safety device according to the present invention, with the device fastened to an object. 
         FIG. 4  is a close-up perspective view of a fastening element according to the present invention. 
         FIG. 5  is a close-up cross-sectional view of a portion of the device, including a frame fastener according to the present invention. 
         FIG. 6  is a perspective view of an alternative worker safety device according to the present invention. 
         FIG. 7  is an end schematic view of a truck trailer. 
         FIG. 8  is a side view of an alternative lateral movement facilitating means. 
         FIG. 9  is a perspective view of an alternative worker safety device according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIGS. 1-3 , the worker safety device  8  is shown. As shown in  FIG. 3 , the device  8  is preferably positioned on an object, typically a truck trailer  10 . Trailer  10  comprises trailer body  12 , supported by trailer wheels (not shown). Trailer  10  further comprises roof  16 , and sides, preferably in the form of first and second side walls  18 ,  19 . At the intersection between roof  16  and each side wall  18 ,  19  is a side edge of roof  16 . Typically, at each of the two side edges of roof  16 , there is a roof rail ( 20 ,  21 ) running along substantially the entire length of the trailer body  12 , from the back of the trailer to the front. Also on the side walls of the typical trailer body  12 , adjacent to each rail  20 , is a rail indentation ( 22 ,  23 ), generally located immediately below rail  20 . Some trailers have no such indentation, but commonly, the rail  20  protrudes outward beyond the portion of the wall ( 18 ,  19 ) immediately adjacent to rail  20 , providing a geometry that facilitates the fastening of the device  8  to the rails  20 ,  21 . 
     It will be appreciated that the invention may be used on a variety of objects, including, without limitation straight trucks. 
     An embodiment of the worker safety device  8  is shown at  FIGS. 1-3 . The device  8  comprises a length adjustable device frame  26  positionable on the object, typically the trailer  10 . It will be appreciated, as elaborated below, that the worker safety device  8  is preferably configured for use with an object, such as trailer  10 , that has a person-support surface on which a worker might be located. In the case of truck trailer  10 , that person-support surface would typically comprise roof  16 , but it will be appreciated that a device in accordance with the present invention may be used with other objects where it is desired to protect worker safety. 
     As shown in  FIG. 3 , the device frame  26  is preferably positioned above the roof  16 , with the sides  22 ,  23  of the trailer  10  extending downward from the roof  16 . 
     In the embodiment shown in  FIGS. 1-3 , the frame  26  comprises a first elongate member  28  and a second elongate member  30 . The members  28 ,  30  are preferably attached to one another, and are slidably and axially moveable relative to one another. Most preferably, members  28 ,  30  are configured and positioned in telescopic relation to one another. Thus, the length of the frame  26  is increased by the first elongate member  28  and second elongate member  30  coming apart (preferably like lengthening a telescope), and decreased by their coming together (preferably like shortening a telescope). First elongate member  28  has a hollow central channel in which second elongate member  30  is positioned. It will be appreciated that other possible configurations for the device frame  26  are comprehended by the invention. For example, the frame  26  could comprise two pieces mounted side by side in axial sliding relation. Or, member  28  could be positioned in member  30 . What is important is that the device or frame, in the preferred embodiment, be length-adjustable to permit the device  8  to be fastened to the object as described below. 
     The device  8  further comprises a frame fastener, coupled to device frame  26 , and configured to detachably fasten the frame  26  to the trailer body  12 . 
     Referring to  FIG. 5 , the preferred frame fastener comprises a coil spring  64 , attached to a first spring attachment element  66  that is fixed to member  28 , and a second spring attachment element  67  that is fixed to member  30 . The preferred frame fastener works by means of spring  64  configured to pull members  28 ,  30  together. In the process of fastening the frame  26  to the trailer  10 , fastening elements  42 ,  44  (described in further detail below) are pulled against the side edges of the trailer, so as to grip rails  20 ,  21 , and preferably engage indentations  22 ,  23 . The frame  26  is thus fastened to trailer  10 . To detach the frame  26 , members  28 ,  30  and elements  42 ,  44  are pulled apart against the force of spring  64 , thus releasing the grip of one or both of elements  42 ,  44  on the corresponding rail  20 ,  21 . 
     In an alternate embodiment (see  FIG. 6 ), the frame fastener comprises a rotatable threaded shaft  32 , having handle  34  attached thereto and configured to turn the shaft  32 . The alternate frame fastener further comprises lock  36 , which is preferably positioned on shaft  32  to lock shaft  32 . When lock  36  is actuated, shaft  32  is locked from rotating relative to frame  26 . Thus, when shaft  32  is rotated, using handle  34  to fasten frame  26  to the trailer body  12 , lock  36  is then actuated to prevent frame  36  from becoming unfastened. In this alternate embodiment, the fastening is accomplished by the fastening elements  42 ,  44  gripping the rails  20 ,  21  and indentations  22 ,  23 , as explained elsewhere. 
     To adjust the length of frame  26  in this alternate embodiment, the threaded shaft  32  may be rotated. Preferably, the shaft  32  is threadably coupled to, and axially moveable relative to, the first frame element  28 , and attached to the second frame element  28 . Thus, when the shaft  32  is turned so as to move further into frame element  28 , second frame element  30  is pushed out of first frame element  28 , thus extending the length of frame  26 . By contrast, when shaft  32  is rotated so as to extend further out of first frame element  28 , second frame element  30  is pulled further into first frame element  28 , thus reducing the length of frame  26 . Thus, by coupling shaft  32  to frame elements  28 ,  30 , the length of frame  26  can be adjusted. 
     It will be appreciated that apart from the preferred and alternate embodiments described herein, the invention comprehends other modes of frame fastener. What is important is that the fastener be configured to fasten the device frame to the object. Thus, for example, anything that functions to hold the frame  26  in place on the object could be a frame fastener. Preferably, though not necessarily, the device frame will be detachably fastened to the object, meaning that the frame fastener is selectively operable to fasten the frame to the object and detach the frame from the object. A further example of such a frame fastener would be selectively engageable and disengageable suction cups attached to the frame, configured to fasten the frame to the object when engaged, and detach the frame when disengaged. 
     It will be appreciated that the fastening may be accomplished by means other than the gripping of rails  20 ,  21 . For example, other parts of trailer  10  may be gripped. Or, a mode of fastening other than gripping may be employed. What is important is that the frame fastener be configured to fasten frame  26  to the object. 
     The elongate frame  26  preferably includes two opposed ends, comprising first end  38  and second end  40 . Preferably, the frame fastener further includes a first fastening element  42  at end  38 , and a second fastening element  44  at end  40 . Preferably, each fastening element is shaped and positioned so as to define a chamber  46  sized, shaped and positioned to receive the rail ( 20 ,  21 ). The chamber  46  may be formed within each fastening element by means of bottom wall  48 , end wall  50 , and top wall  52 , which define the chamber  46 . The fastening elements  42 ,  44  are thus configured to cooperate with spring  64  to fasten frame  26  to trailer  10 . 
     Preferably, the device  8  includes two wheel means attached to the device frame  26  and positioned so as to bear on sides  18 ,  19 , so that the wheel means roll along the sides to facilitate movement of the device along the object. In the preferred embodiment, there is a wheel means associated with each of the fastening elements  42 ,  44 , with each wheel means consisting of two wheels  54 . Preferably, wheel means  54  are positioned in chamber  46 , and rotatably attached to bottom wall  48  of each fastening element ( 42 ,  44 ). As can be seen in  FIG. 3 , wheels  54  are positioned so as to bear on respective sides  18 ,  19 , and particularly, rails  20 ,  21 . 
     Further included in device  8  is a lateral movement lock means. In the preferred embodiment, the lateral movement lock means comprises lock bolts  56 . As shown in  FIG. 1 , there may be one lock bolt positioned on and rotatably attached to each top wall  52 . Each bolt  56  comprises a head  58  configured to facilitate the rotation, by hand, of lock bolt  56 . Each bolt  56  further preferably comprises a pressure lock pad  60 . It will be appreciated that when the bolts  56  are turned in a locking direction, pads  60  move downward and press against the top side of rails  20 ,  21 . When the lock bolts are in such locking position, they prevent the device  8  from being moved laterally along the length of the trailer, and along the length of rails  20 ,  21 . To allow for such lateral movement, bolts  56  are turned in an unlocking direction, such that pads  60  come away from rails  20 ,  21 , with the result that the device  8  can be pulled along the length of the trailer body  12 . 
     It will be appreciated by those skilled in the art that the invention comprehends two types of locking, or fastening. First, the invention comprehends the use of the frame fastener to fasten the device frame  26  to the trailer body  12 . The purpose of such fastening is to allow a person working on roof  16  to attach worker safety gear to the device  8  to prevent falling and injury. However, even with the frame  26  fastened to trailer body  12  by the frame fastener, it is still possible to move the device frame  26  along the length of trailer  12 . This lengthwise or lateral movement along trailer  12  is important because it may be necessary for a worker to perform maintenance on one portion of the trailer, and then move safely to a different portion of the trailer and perform more maintenance there. Thus, in accordance with the present invention, a worker may fasten the device frame to trailer body  12  and perform work in the vicinity of the trailer adjacent to device frame  26 . When it is desired to perform maintenance on a different portion of trailer body  12 , bolts  56  may be unlocked, and the worker can push or pull device frame  26  along the length of trailer body  12  while the device frame  26  remains fastened to trailer body  12 . This provides safety to the worker even as the worker moves the device frame  26 . Then, when the worker reaches the portion of the trailer where further maintenance is to be performed, he can lock lock bolts  56 , thus preventing lateral movement of device frame  26  along the length of trailer body  12  as he does his work. 
     It will be appreciated that the invention comprehends other means for facilitating lateral movement of the device frame  26  along trailer body  12  besides the wheel means referred to above. For example, as shown in  FIG. 8 , the lateral movement facilitating means may include low friction sliders, consisting of low friction pads  62 , positioned within chamber  46  of each fastening element  42 ,  44 . Pads  62  are preferably made of a low-friction material, and like the wheel means, are positioned so as to bear against sides  18 ,  19 , and in particular indentations  22 ,  23 . Whatever form the means for facilitating lateral movement may take, it will be appreciated that such means preferably include a low-friction interface between device frame  26  (preferably fastening elements  42 ,  44 ), and the trailer body  12 , to allow for easy lateral movement of the device frame  26  along the trailer body  12 . 
     On the other hand, it will be appreciated that while the capability for such lateral movement is preferred to permit movement for maintenance, repair, snow removal etc., and while having means for facilitating such lateral movement is preferred, the invention does not require the capability for such lateral movement. Rather, though not preferred, it is possible for a user to simply unfasten or detach the device  8  from the trailer body  12  when it is desired to move the device  8  along the length of the trailer body  12 . 
     The device  8  further preferably includes an attachment means, attached to the device frame  26 , configured and positioned to attach a personal fall-prevention device for the frame  26 . As a result, a person on roof  16  using the fall-prevention device can prevent a fall by attaching the fall-prevention device to the attachment means. 
     It will be appreciated that it is typical for fall-prevention safety equipment to include some kind of hook or carabiner which is meant to be attached to a fixed point to prevent a worker from falling. Therefore, the attachment means preferably comprises a hook-receiving element, most preferably in the form of ring  68 . Preferably, as can be seen in  FIGS. 1-3 , the ring  68  is attached to both element  28  and element  30  adjacent to opposed ends  38  and  40  of the frame  26 . This form of attachment is achieved, in the preferred embodiment, by means of cables  70 ,  72 , which both attach ring  68  to fixed U-bolts  74 ,  76 , which are fixed to elements  28  and  30  respectively by means of plates  73 ,  75 , adjacent opposed ends  38 ,  40  respectively. 
     It will be appreciated that the attachment means may take other forms. It may be curved, and may have an open or closed shape. What is important is to provide a means for attaching a fall prevention device. 
     To use the device  8 , a worker would fasten the device  8  to the trailer body  12 . In the preferred embodiment, the worker climbing up to the roof  16  is initially positioned at one side of trailer  10 . The worker positions device  8  in a pre-fastening position above roof  16 . Preferably, the worker extends it across roof  16  so that the opposite end of device  8  (the opposite fastening element) grips the opposite rail. Then, the worker pulls the near side of the device  8 , extending spring  64  and extending frame  26 , so that the near fastening element is positioned off roof  16 . The adjacent fastening element is then gently released and spring  64  contracts to cause the near fastening element to grip the near rail. The device  8  and frame  26  are thus fastened to the trailer  10  by actuating spring  64  to cause the fastening elements to fasten frame  26  to the side rails. Frame  26  can be removed or detached by pulling the near fastening element away from the opposite one against spring  64 , releasing the near fastening element from gripping the near rail and then removing the device  8  from roof  16 . 
     In the alternate embodiment of the frame fastener described above, the frame  26  would be lengthened so that fastening elements  42 ,  44  are wider apart that the width of roof  16  in the pre-fastening position. Shaft  32  is then rotated to bring elements  42 ,  44  together to fasten frame  26  to rails  20 ,  21 . 
     It will be appreciated that the invention comprehends other modes of actuating the frame fastener to cause the fastening elements to fasten frame  26  to the side rails. For example, a strap connecting the frame elements may be retracted to pull the fastening elements together to fasten the frame  26  to rails  20 ,  21 . 
     After fastening, the worker would attach a fall-prevention device or safety harness, to which he himself is attached, to ring  68 , which is fixed via cables  70 ,  72  and fix U-bolts  74 , 76  to frame  26 . Then, in the event that the worker were to be in danger of falling (e.g. the worker trips or stumbles, and is about to fall off of roof  16 ), his fall-prevention device would act as a brake. Meanwhile, the fall-prevention device is attached to device frame  26 , which is in turn fastened to trailer body  12 , with the result that the worker would be prevented from falling off of roof  16 , and would be saved from the attendant injury. 
     Preferably, the ring  68  is positioned approximately midway along the length of device frame  26 , and thus, approximately equidistant from the sides  18 ,  19  when the device frame  26  is fastened to the trailer body  12 . This positioning is preferred because it maximizes the area of roof  16  that a worker can reach while his fall-prevention gear is attached to ring  68 . 
     It will be appreciated that the attachment of the ring  68  to the frame  26  at opposed ends  38 ,  40 , though preferred, is not required. Other modes of attachment are comprehended by the invention. The above-described form of attachment is preferred because it has been found that having two widely distributed attachment points distributes the force on those attachment points, and on the device frame  26 , in a beneficial manner in the event that a worker is falling and is thus exerting a force on the device frame  26 . By having the ring  68  attached to the frame  26  at the opposed ends  38 ,  40 , the force on the frame  26  acts at points adjacent to the fastening points of the device frame  26  to the trailer body  12 . Thus, the amount of twisting force and torque applied to the device frame  26  is reduced, thus reducing the risk that the device would not operate properly. 
     Furthermore, distributing the points at which the attachment means is attached to the device frame  26  is beneficial, in that it is less likely that the attachment means will undesirably come off of the device frame  26 . For example, the invention comprehends the attachment means comprising a single eye-bolt at the center of device frame  26 . However, in such a configuration, there is a greater risk that, in the event of a worker fall, such an eye-bolt would simply break off of device frame  26 . Thus, in such a non-preferred configuration, it would be necessary to fix the eye-bolt to the center of device frame  26  very securely and carefully. 
     It will further be appreciated that the attachment means may take other forms besides the embodiments described above. What is important is that the attachment means be attached to the device frame and be configured and positioned to attach the fall-prevention device to the device frame. 
     While the preferred embodiments have been described in detail, it will be appreciated that the invention comprehends other embodiments as well. For example, as shown at  FIG. 9 , the frame fastener may comprise a strap  78  attached to both frame elements, with the strap being attached to a release-and-retraction means, preferably in the form of spindle  80  and release element  82  for releasing spindle  80  to permit extension of the strap.