Abstract:
A manhole cover tool useful in unsealing and moving a manhole cover over a predetermined distance along a surface, including: i) A handle end; accommodating an operator; ii) A fulcrum end distant the handle end; suitable for engagement and stabilizing the tool on the surface; iii) A rod of a predetermined length for connecting the handle end t o the fulcrum end; iv) A manhole cover engagement rod of a predetermined length having a first end and a second end; the first end connected to the rod, and said second end being a manhole cover engagement tool.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    A chamber lid tool for removing, moving and replacing a chamber lid, is provided which reduces the need for heavy pulling and/or lifting of a chamber lid when cracking the seal of the chamber lid and removing the lid by an operator to allow access to underground electrical chambers. The chamber lid tool uses the principle of a first class counter lever. 
       BACKGROUND 
       [0002]    Across many industries, services sector workers are most prone to experiencing high impact injuries. Amongst them, electrical powerline workers are often subject to physically demanding work, typically involving exerting high forces in awkward postures. Often times these workers handle routine tasks in servicing underground power lines ranging from removing 300 lb manhole covers to bending power cables 2-3 inch in diameter in tight working spaces. These working conditions are often exacerbated by emergencies requiring performance of tasks in an urgent manner in order to reduce the impact of down time for services delivered to customers. Working under such conditions may result in unnecessary strain and may increase the chance of injury due to improper handling of tasks. 
         [0003]    Lifting and removal of underground chamber lids has been identified as a physically challenging work task. Tools and devices available in the market purportedly address this physically challenging work task, but are not popular options for utility workers given the tools and devices are cumbersome to handle and time consuming to use. Ultimately, a simple pole with a hook remains the preferred choice for utility workers due to ease of storage in a service vehicle and effectiveness in performing the needed task.
   The use of the hooked pole however, still requires lifting activities involving high joint moments of the worker to remove the heavy chamber lids increasing the risk of personal injury.   
 
         [0005]    U.S. Pat. No. 4,512,554 discusses a levering tool for lifting up a manhole cover. The levering tool disclosed therein requires the operator to pull the handle engaging the arm shoulder and back muscles in an unstable position risking injury to the operator. Similarly, U.S. Patent Application Publication 20120027559 discusses a levering tool for lifting up a manhole cover. The levering tool disclosed therein also requires the operator to pull the handle while keeping the forearms substantially horizontal and the back substantially vertical to the ground. The pulling action again places the operator in a position of potential muscle or joint strain and/or injury. 
         [0006]    U.S. Pat. No. 4,978,103 discusses a levering tool for lifting and moving a manhole cover. The manhole cover must first be unsealed by a separate tool and then the levering tool is engaged with the manhole cover and pulled backwards and rolled to another position by the constant pulling of the manhole cover with its weight supported on the levering tool and requiring control of the weight of the manhole cover by the operator at all times. 
         [0007]    There is a need for a manhole cover tool which may crack or unseal the manhole cover and move the manhole cover with a single tool. There is also a need for a manhole cover tool which does not require pulling both the tool and manhole cover simultaneously under the weight of the manhole cover. There is also a need for a manhole cover tool with improved ergonomics for the operator during use, reducing the risk of injury. There is also a need for a manhole cover tool that is readily easy to handle and to be accommodating in storage spaces of trucks typically used by operators. 
         [0008]    When used herein, the term manhole cover encompasses chamber lid and the like. 
       SUMMARY 
       [0009]    According to one aspect, there is provided a manhole cover tool useful in unsealing and moving a manhole cover over a predetermined distance along a surface, comprising:
       i) A handle end; preferably a handle accommodating at least one hand of an operator, more preferably accommodating two hands of an operator;   ii) A fulcrum end distant said handle end; preferably an elongated arcuate ski shape with the bottom of said elongated arcuate ski shape suitable for engagement and stabilizing said tool on said surface; preferably further for assisting the operator to orient said tool with said chamber lid to allow for optimal use of said tool,   iii) A rod of a predetermined length for connecting said handle end to said fulcrum end;       
 
         [0013]    iv) A manhole cover engagement rod of a predetermined length having a first end and a second end; said first end connected to said rod, preferably distant said handle end, and said second end being a manhole cover engagement tool, preferably a hook, or the like; preferably said engagement rod is flexible.
   Wherein when said manhole cover tool is in a resting position, said handle end is proximate waist level of said operator, and said handle end and fulcrum end form an angle with said surface such that the operator is in a neutral standing position; preferably said angle is substantially a 45 degree angle with said surface; more preferably, said angle is one which brings said handle of said tool (at rest) proximate waist level of said operator.   Wherein when a line drawn from said handle end to said fulcrum end and from said fulcrum end to said first end of said engagement rod and from said first end of said engagement rod to said handle end, form a triangle.   
 
         [0016]    According to another aspect, when said manhole cover tool is in use and said manhole cover engagement tool is engaged with and under the load of said manhole cover, an operator pushing said handle end down towards said surface results in said manhole cover to move towards the fulcrum end of said manhole cover tool a first predetermined distance. When said manhole cover tool is in use and said manhole cover engagement tool is engaged with and not under the load of said manhole cover, an operator pulling said handle, preferably without the weight of the manhole cover but only the weight of said tool, causes said fulcrum end to move along said surface away from said manhole cover to a second predetermined distance allowing the operator to move the manhole cover along said surface by pushing down on said handle causing the tool to drag the manhole cover along the surface. 
         [0017]    According to another aspect, the manhole cover tool is of a height that facilitates the operator to push down on the handle by:
       1. maintaining the arms substantially vertical with said surface; and   2. bend at the waist while maintaining an ergonomic stance and avoiding pulling the weight of the manhole cover; or   3. bend at the knees while maintaining an ergonomic stance and avoiding pulling the weight of the manhole cover; and   4. combinations thereof.       
 
         [0022]    For example, for an operator of about 1.8 metres height, the tool would preferably be about 0.75 metres tall when said tool is in the resting position. The height of said tool may vary depending on the arm and leg length of the operator, as well as the overall height of the operator 
         [0023]    According to another aspect, the manhole cover tool is adjustable in length, preferably to allow for height variation of the operator. In one embodiment, the tool may be adjusted in height by adjusting the angle the tool makes with the surface by raising or lowering the handle as well as adjusting the distance the fulcrum is from the chamber lid. In another embodiment, the connecting rod may be telescopic in nature to allow for adjustment of length and height of the tool.
   In yet another embodiment, said manhole cover tool is made of a lightweight strong material, preferably aluminum, light formed steel, fiberglass, polypropylene, and combinations thereof. In one embodiment, said engagement rod is flexible, preferably a chain or steel cable, or the like. In another embodiment, said engagement rod runs along a portion of said connecting rod. Preferably said connecting rod further comprises an engagement rod channel for receiving said engagement rod and assisting in maintaining alignment of said engagement rod with said connecting rod when said tool is in use.   
 
         [0025]    In another embodiment one of said connecting rod and/or engagement rod channel is substantially arcuate, half a tear drop or “D” shape with one end of the arc or “D” being proximate the handle end and the other end of the arc or “D” being proximate the fulcrum end. In another embodiment said fulcrum end, handle end and first end of said engagement rod, when connected, form a triangle. Preferably the line joining the fulcrum end and handle end forms a base of the triangle, and the first end of said engagement rod forms an apex of the triangle. More preferably, the distance from the base to the apex of the triangle is greater than the radius of the manhole cover to be engaged, more preferably at least twice the radius of the manhole cover to be engaged. 
         [0026]    In another embodiment, said manhole cover tool is substantially triangular in shape. 
         [0027]    In another embodiment, said engagement rod channel comprises a plurality of engagement rod connectors along said length to allow for the adjustment of the angle of said engagement rod to said connecting rod. 
         [0028]    In another embodiment, said connecting rod comprises a plurality of engagement rod connectors along said length to allow for the adjustment of the angle of said engagement rod to said connecting rod. 
         [0029]    In another embodiment, said manhole cover engagement tool comprises a hook having a hook end and a hook handle end, said hook end and hook handle end connected to each other via a connector. Said hook handle end weighing more than said hook end, such that when said hook is engaged with a manhole cover, said hook end is urged to remain engaged with said manhole cover until the operator disengages said hook from said manhole cover.
   In another embodiment, there is provided a hook having a handle end and a hook end distant said handle end, said hook end connected to said handle end via a connector, preferably an elongated connector, wherein said handle end is heavier than said hook end.   
 
         [0031]    In another embodiment, said hook when not in use is releasably fastened to said tool, preferably releasably fastened to at least one of said connecting rod or engagement rod, more preferably said hook is magnetically fastenable to at least one of said connecting rod or engagement rod, or both. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0032]      FIG. 1  is a side view of the manhole cover tool in the resting position 
           [0033]      FIG. 2  is a perspective view of the manhole cover tool in the resting position 
           [0034]      FIG. 3  is a side view of the manhole cover tool engaged with a manhole cover in the resting position 
           [0035]      FIG. 4  is a side view of the manhole cover tool engaged with a manhole cover and cracking the seal of the cover 
           [0036]      FIG. 5  is a side view of the manhole cover tool engaged with a manhole cover and dragging the cover along the surface 
           [0037]      FIG. 6  is a side view of a manhole cover tool engaged with a manhole cover and the manhole cover dragged off the manhole 
           [0038]      FIG. 7  is a side view of the manhole cover tool (at rest) engaged with a manhole cover showing the manhole cover engagement tool remaining engaged with said manhole cover until the operator disengages same 
           [0039]      FIG. 8  is a perspective view of the manhole cover tool (at rest) of another preferred embodiment 
           [0040]      FIG. 9  is a perspective view of the manhole cover tool of  FIG. 8  with the connecting rod with handle in an extended position 
           [0041]      FIG. 10  is a perspective view of the manhole cover tool of  FIG. 9  with an extendable connector 
           [0042]      FIG. 11  is a perspective view of the manhole cover tool of  FIG. 10  with a fixed extended connector 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    Referring now to the Figures, there is provided a preferred embodiment of a manhole cover tool  10  and a manhole cover  20 . The manhole cover tool  10  has a handle  30  and a fulcrum  40  connected to each other by a connecting rod  50 . The tool  10  further includes a manhole engagement rod  60  connected to an engagement rod channel  70  of arcuate or “D” shape. The radius formed between the connecting rod  50  and the engagement rod channel  70 , in one instance, is greater than the radius of the manhole cover  20 . This provides a mechanical advantage when moving said manhole cover  20 . When the tool  10  is at rest, the connecting rod  50  forms a 45 degree angle with the surface  80  or the ground. This angle may be any angle which maintains the handle  30  proximate waist level of the operator  90 , when said tool is at rest. The handle  30 , in this instance, extends along the engagement rod channel  70  and beyond the connecting rod  50  and is made up of a left handle portion  31  and a right handle portion  32 , each handle portion being substantially normal to and equidistant from said rod channel  70 . Although not shown, the handle portions  31  and  32  may further include grip material to assist the operator in gripping the tool. 
         [0044]    The fulcrum  40  is essentially ski shaped and is an extension of the engagement rod channel  70 , extending beyond the fulcrum end  40  of the connecting rod  50 . The fulcrum has a left ski portion  41  and a right ski portion  42  extending equidistant from said rod channel  70  and connecting rod  50 , allowing for the lateral stabilization of the tool  10  when being used by an operator  90 . The centre of the fulcrum  40  is at the terminus of the connecting rod  50  fulcrum end. Optional brace  43  further rigidifies fulcrum  40  with connecting rod  50 , and in particular, when the tool  10  is in use. The engagement rod  60  is a steel chain connected at one end to the rod channel  70  and the other end having a hook  61  for engagement with an aperture  21  of the manhole cover  20 . 
         [0045]    In use, the operator  90  moves the tool  10  proximate the manhole cover and engages the hook  61  to an aperture  21  of the manhole cover  20 . The operator  90  positions the tool  10  in the direction of choice to move the manhole cover  20 , and pushes the handle  30  towards the surface  80  causing the tool to rotate along the ski portions  41  and  42  of the fulcrum  40 , which in turn cracks the seal of the manhole cover. At this point, when the operator pulls the tool  10  away from the manhole cover  20  by dragging the fulcrum  40  along the surface  80 , the operator  90  only experiences the weight of the tool  10  and not the weight of the manhole cover  20 , and sets the tool  10  to its resting position where it forms a 45 degree angle with the surface  80 . The operator pushes down on the handle  30  keeping the arms  91  substantially vertical to the surface  90  and back substantially straight while bending at the waist causing the tool  10  to pivot on the fulcrum  40  and in turn causing the engagement rod  60  to pull the manhole cover  20  and be dragged along the surface  80 . In another embodiment, when pushing down on the handle  30 , the operator  90  may also maintain the back substantially normal to the surface  80  while bending at the knees. The operator  90  continues these steps until the desired location for the manhole cover  20  is reached. 
         [0046]    When the operator  90  wants to return the manhole cover  20  to its original position or to the manhole  22 , the same actions are repeated as above except the direction will be towards the manhole  22  and the tool  10  is placed on the surface  80  proximate the side of the manhole  22  distant the manhole cover  20  (i.e. the open manhole  20  is between the tool  10  and the manhole cover  20 ). 
         [0047]    As best seen in  FIGS. 2 and 7 , in one embodiment, the hook  61  is constructed such that the hook end  62  is lighter that the hook handle end  63 . This configuration allows the hook  61  to remain engaged with the manhole cover  20 , when there is no tension between the hook  61  and the engagement rod  60 , until the operator disengages the hook  61  from the cover  20  via the handle  63 . In yet another embodiment, the engagement rod  60  is further connected to the hook  61  such that when there is tension between the hook  61  and engagement rod  60 , the hook  61  is urged to remain engaged with the cover  20  when the operator  90  is moving the handle  30  downwards towards the surface  80 . The configuration of the present hook  61  reduces the likelihood of injury to the operator  90  due to the hook  61  coming away from the cover  20  while in operation. 
         [0048]    As best seen in  FIG. 3 , the fulcrum end  40 , the handle  30  and the first end of the engagement rod  60 , when connected to each other with a line, form a triangle. Also, in one embodiment, the distance rT is greater than the distance rM, preferably rT is at least twice rM 
         [0049]    As best seen in  FIG. 8 , in this embodiment, the tool  10  is substantially triangular in shape (as opposed to the “D” shaped discussed above) with the handle engagement rod  71  connected directly to the connecting rod  50  at the handle end  30 , and the handle engagement rod  71  connected to the connecting rod  50  via a connector  72  proximate the fulcrum end  40 , such that the handle engagement rod  71 , connecting rod  50  and connector  72  form a triangle. In this instance, the first end of the engagement rod  60  is connected at the joint formed by the handle engagement rod  71  and connector  72 . 
         [0050]    As best seen in  FIG. 9 , the handle  30  is extended via extender  73  in said handle engagement rod  71 . In this instance, extender  73  fits in said handle engagement rod  71  allowing for the extension of the length of the handle engagement rod  71  facilitating users of various heights. Although not depicted, the extender  73  could fit in the engagement rod  60 . 
         [0051]    As best seen in  FIG. 10 , in this embodiment, the connector  72  is extended beyond the end of the handle engagement rod  71  allowing for accommodating longer engagement rods  60 , in this instance a steel chain and for manhole covers of significant weight and size. The connector  72  may be fixed at the extended length or may be extendable via a telescopic manner for example such as that seen with the handle engagement rod  71 . When extendable, a locking mechanism is preferred to lock the connector at the desired position when in use. 
         [0052]    As best seen in  FIG. 11 , when the connector  72  length is fixed and is extended beyond the end of the handle engagement rod  71 , the tool may further comprise and corner brace  74  to reinforce the strength of the connector  72  when extended beyond the end of the handle engagement rod  71 . 
         [0053]    The hook  61  is releasably attachable to said tool  10  via a magnetic area on at least one of said engagement rod  71 , connecting rod  50 , connector  72  or a combination thereof. 
       EXAMPLES 
       [0054]    The following are examples of the forces applied to the joints of the operator when using the tool as described herein and the tools of the prior art. 
       Example 1 
     Comparison of Moments Between Prior Art Tools and Present Tool 
       [0055]    Initial comparison of the present tool and prior art tools was performed using 3DSSPP (3D static strength prediction program). This program estimates joint loading based on body position and forces applied. 3DSSPP combines force data with the posture and predicts the percent of the population who have the strength to do the job. In biomechanics research, increased joint moments often indicate increased risk of injury due to increased strain on the musculoskeletal system.
   A comparison of the present tool with other available tools with respect to initial analysis with 3DSSPP and ergonomic and biomechanic factors is provided below. All moment data is given for the saggital plane (i.e. flexion/extension of the spine) as this is the plane where most movement occurs during the lid lift.   
 
         [0057]    The tool currently used by most of hydro electronic services for removal of chamber lids is the pickaxe. Initial examination of the use of the pickaxe with a force meter indicates a requirement of 130-220 lbs of lifting force when using the pickaxe to lift a chamber lid. As shown in the graph below, this force results in a moment production in the spine of approximately 400N*m at L5/S1 and 360N*m at L4/L5. The moment produced at the shoulder is approximately 30N*m. Moments produced when using the pickaxe are much higher than moments produced using the present tool, which are approximately 20N* for both L5/S1 and L4/L5, and approximately 15N*m for the shoulder. In addition to decreased moments when using the present tool, the present tool allows the operator to push in a downwardly direction, recruiting the core muscles and allowing use of their body weight to apply the force, rather than using the back extensor muscles, as is done with the pickaxe. 
         [0058]    Another prior art tool includes the tools found in U.S. Pat. No. 4,512,554 and U.S. patent publication 20120027559. Both of these prior art tools include a straight bar between the fulcrum and the handle as well as the handle orientation being horizontal. The straight bar of these prior art tools forces the operator to pull backwards using the shoulder and back extensor muscles, causing the pectoral muscles to contract and form a tight angle between the pectoral muscles and the arm muscles, along with the upper back muscles causing significant strain, wherein the muscle strain increases as the vertical handle gets closer to the operator. The present tool allows the operator to push down using the body core and body weight for assistance during operation. As shown in the graph below, the prior art tool of U.S. Pat. No. 4,512,554 and U.S. 20120027559 (T-lift) produces larger moments at L4/L5 (315N*m for T-lift; 20N*m for present tool) and L5/S1 (360N*m for T-lift, 20N*m for present tool). Large production of force by the back extensor muscles (as is the case for the T-lift and pickaxe) results in large compression and shear forces in the spine, which may increase the risk of musculoskeletal injury, such as a dislocated disc, or the like. 
         [0059]    The tool of U.S. Pat. No. 4,978,103 (magnetic dolly) or similar systems requires the application of multiple chains and the complete lifting of the entire weight of the chamber lid above the surface, whereas the present tool slides the chamber lid out of place with the chamber lid maintaining contact with the surface throughout the procedure. In this instance, the full weight of the chamber lid never needs to be supported by the operator. The requirement to lift the full weight of the chamber lid when using the prior art dolly systems results in moment production of over 700N*m at L4/L5 and L5/S1 (see the graph below). In addition, the use of the dolly system requires much more space than the present tool, making it less feasible in urban areas where streets cannot be completely shut down for removal of chamber lids. Dolly systems are also larger and heavier than the present tool when in storage, making transportation on a packed utility van more difficult. Further the dolly systems are not as stable as the present tool in moving a heavy load such as a chamber lid. The wheels make the dolly system extremely unstable in comparison to the present tool. The instability of the dolly system, in particular, when the operator walks with the load, increases the chance of low back injury. The present tool movements however, are completed intermittently and as mentioned earlier the load is slid on the ground by the operator and the fulcrum ski aligns the operator with the load facilitating the optimal operation of the present tool. 

 
       Example 1 
     Comparison of Shoulder and Low Back Moments Among Different Chamber Tools 
     Example 2 
     Comparison of Prior Art and Present Tool 
       [0060]    The present tool was compared to the prior art in use with two chamber lids of different mass. One chamber lid (CL) has a mass of 300-320 lbs. A second chamber lid (NL) has a mass of approximately 150 lbs. 
         [0061]    The force required to remove each of the two lids with prior art tools and the present tool was recorded with a handheld force meter (Chatillon E-DFE, Ametek, Berwyn, Pa., USA). 
         [0062]    13 male utility workers were outfitted with an inertial motion capture system (IGS-180 Animazoo, Synertial, Brighton, UK). 
         [0063]    4 conditions were tested (3 trials each):
   CL with Pickaxe (PICK)=CL+PICK;   CL with present tool (CLRT)=CL+CLRT;   NL with J-hook (JH)=NL+JH; and   NL with present tool (CLRT)=NL+CLRT.   
 
         [0068]    Kinetic and kinematic data collected were combined in a modelling program (MatLab) which calculates 3D joint moments via inverse dynamics. 
         [0069]    Spine L4/L5 and shoulders were selected for analysis. The resultant moment was calculated using the equation RM=√{square root over ((x{circumflex over (-)}         v{circumflex over (-)}          z{circumflex over (-)}))} where RM=resultant moment; x=x-axis co-ordinate; y=y-axis co-ordinate and z=z-axis co-ordinate, where peak force was applied during the procedure or lid removal. Mean values were compared using a one-way repeated measures ANOVA. 

 
         [0070]    The above chart depicts the force required to remove a chamber lid (CL or NL) with various tools. The Force (N) is significantly lower (p&lt; 0 . 05 ) with the present tool (CLRT) versus PICK and JH. 

 
         [0071]    The above L4/L5 Resultant Moment Charts 1 and 2 depict that the resultant moment is significantly lower with the present tool when compared to the prior art (PICK and JH). 

 
         [0072]    The Shoulder Resultant Moment Charts 1 and 2 depict that the shoulder resultant moments were significantly (p&lt;0.0001) lower with the present tool (CLRT) when compared to the prior art (PICK and JH). 

 
         [0073]    The L4/L5 Kinematic chart 1 depicts there is significantly more flexion at Sagittal with PICK when compared to all other tools (p&lt;0.05)* and significantly more lateral bend at Frontal with PICK compared to the present tool (CLRT) when removing CL (p=0.048)**. 
         [0074]    As many changes can be made to the preferred embodiment of the invention without departing from the scope thereof; it is intended that all matter contained herein be considered illustrative of the invention and not in a limiting sense.