Abstract:
The tool for handling a cover, in particular covers for sewers or vents, or for manholes, relates to the covers of sewers or vents or manholes, having a substantially planar top surface. The tool includes a holder defining a surface for engaging with the top surface of a cover, a lifting fulcrum, and a handle. The handle has one end spaced apart from the lifting fulcrum. The holder, fulcrum and handle are arranged such that a force exerted by an operator on the one end is transmitted as a force on the holder by the lifting fulcrum. The holder includes a leg connected to the handle and is rigidly configured such that, in the position for lifting a cover, the assembly formed of the cover- and the holder with the leg is rigid. The invention further relates to a method for removing or re-placing such a cover.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (1) Field of the Invention 
         [0002]    The invention is related to the handling of covers, namely of sewer or road-manhole covers, or the like. It relates in particular to a tool for handling such covers, which can be referred to as a cover lifter, which should enable an operator to remove such a cover, in order to have access to the manhole or to the sewer, then to re-place it after the inspection. 
         [0003]    The invention also relates to a method for removing and re-placing a sewer or road-manhole cover using the cover lifter according to the invention. 
         [0004]    (2) Description of the Prior Art 
         [0005]    In the field of the tools for handling such covers, tools with hooks have since long been developed, which permit to take hold of the cover at a point of the cover in order to take hold of it with such hooks. Nevertheless, the covers are heavy, up to 70 kg, and their lifting is difficult, even if it is carried out by two persons. Furthermore, the covers are often jammed in their recess, by small stones or tar, which have been introduced into the gaps between the cover and its recess. 
         [0006]    EPO 484 285 discloses a tool for handling covers including such a hook, a fulcrum, and a handle, thus permitting to gear down the force for separating the cover. Nevertheless, this tool provides no solution for an efficient removal of the cover, nor for its displacement to one side. 
         [0007]    EP2 702 753 discloses a tool for handling covers, also with a hook, a fulcrum and a handle. The tool disclosed in this document permits in a first phase the separation of the cover from its recess ( FIGS. 2 and 3 ), then the effective removal, with the displacement of the cover by means of two tools handled by two operators. Nevertheless, besides the necessity of causing two operators to intervene, the work remains difficult, since the whole weight of the cover has to be carried, then displaced and laid down. 
         [0008]    U.S. Pat. No. 7,544,035 discloses a tool for handling covers with a hook and with a magnet. Two magnets are placed on the cover, then a bar with hooks is arranged so as to take hold of the two magnets, and the hook of the tool takes hold of the bar, in order to lift it. Nevertheless, if the magnets are not placed accurately on both sides of the center of gravity of the cover, it is highly likely that the latter tilts during the lifting. 
         [0009]    There is thus a need for finding a solution permitting to facilitate the handling of such covers. With the tools of the state of the art, it could indeed be observed that about 20% of the operators have suffered from work accidents, namely with back troubles, or entrapment of fingers. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention pretends to cope at least partially with the cited drawbacks and namely to make possible the removal and re-placing of a cover by one single operator, without requiring any accuracy in the positioning of the tool. 
         [0011]    To this end, the invention relates to a tool for handling a cover including a substantially planar upper face, namely sewer or vent or road-manhole covers, including a means for holding a cover defining a plane aimed at cooperating with the upper face of said cover, a lifting fulcrum, and a handle provided with an end spaced apart from said lifting fulcrum, said holding means, fulcrum and handle being arranged so that a force exerted by an operator at the level of said end is transmitted as a force at the level of the holding means by means of said lifting fulcrum. 
         [0012]    Said holding means is rigid in the vicinity of said plane, in order to impede any rotation of the cover about an axis included in said plane. 
         [0013]    By impeding any rotation of the cover about an axis included in said plane, the tool permits, on itself, to lift the cover, while guaranteeing that the cover remains substantially horizontal. In this way is avoided the tilting of the cover, which could cause an impact on the tool, and which would in addition oblige to lift the cover much higher, in order to permit its displacement to a side of the opening in order to lay it down and to permit the access to the manhole or to the sewer. Since the cover remains horizontal, it is enough to lift it by some ten centimeters, then to displace it, and to lay it down next to the manhole. 
         [0014]    Such rigid holding means in the vicinity of said plane can be a substantially vertical rod, and a substantially horizontal board rigidly fixed to said rod; the fastening of the cover to the board can occur by any means available for the specialist: glue, clamps, hooks, and yet other means. 
         [0015]    According to further features:
       said holding means includes a permanent magnet   a box for protecting the magnet is arranged around the permanent magnet   a separation fulcrum ( 28 ) and a separation means ( 21 ) are arranged in the immediate vicinity of said permanent magnet   said tool includes a substantially rectilinear framework, said permanent magnet including a ridge in the vicinity of said plane, in which said separation fulcrum is formed of a ridge of said permanent magnet, and said separation means comprises a rod passing through said permanent magnet by one of its ends, and is arranged in abutment against said framework by the other one of its ends, so that, through a force applied by said framework on said rod, the latter protrudes with respect to said permanent magnet and, by pushing on said cover while forming a lever with said ridge, permits to separate the permanent magnet with respect to said cover   said tool includes, at one of the ends of said framework, an extension extending away from said framework in order to serve as a lifting fulcrum on the ground, and including a tool leg hung from said movable framework rotating about the point of hanging from the framework, and extending away from the framework in the same plane and on the same side as said extension, said permanent magnet being rigidly fastened to its end away from the framework, said tool leg and said framework being arranged so that, in the position of the framework, in which the tool leg is placed on said cover and the extension is lifted up from the ground, said rod protrudes with respect to the permanent magnet and pushes on the cover, so that it moves the permanent magnet away from the cover   the position of the tool leg is adjustable along said framework thanks to a plurality of drilled holes arranged along said framework, and in which a pin attaches said tool leg movably in rotation about said pin   said leg and drilled holes are configured so as to permit blocking the cover raised in such a position that the force applied on the framework by the cover contributes through this position to reducing the load to be applied by the operator at the level of the handle   said tool comprises a rear grip arranged on the framework, in front of the extension   said extension is provided with at least one wheel, in order to facilitate the displacement of the tool loaded with the cover   said extension is provided with two wheels, which can be spaced away from each other, so as to permit the tool to pass over a cover or an opening caused by the removal of a cover, both wheels passing on both sides of said cover or said opening   said handle is arranged in a telescopic way, so as to permit to move the end of said handle away from said fulcrum   a removable grip is arranged at the end of said handle, in order to facilitate the taking hold of said end by the operator, a receptacle being arranged in said protective box for receiving said grip when it is removed from said handle       
 
         [0028]    The invention also relates to a method for removing a cover, as well as to a method for re-placing a cover. 
         [0029]    The advantage resulting from the present invention resides in that the removal and the re-placing are largely facilitated, and become possible with one single tool and one single operator. 
         [0030]    Further features and advantages of the invention will become clear from the following detailed description, which refers to an exemplary embodiment given as an indication and in a non-restrictive way. 
         [0031]    This description will be more easily understood when referring to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0032]      FIG. 1  represents a perspective view of a tool according to the invention in a resting situation; 
           [0033]      FIG. 2  represents a perspective view of the tool of  FIG. 1  in a second situation; 
           [0034]      FIG. 3  represents a side view of the tool of  FIG. 1  in the situation of  FIG. 2  and in a third situation; 
           [0035]      FIG. 4  represents a side view of the tool of  FIG. 1  in a fourth situation; 
           [0036]      FIG. 5  represents a side view of the tool of  FIG. 1  in a fifth situation; 
           [0037]      FIG. 6  represents a side view of the tool of  FIG. 1  in a sixth situation; 
           [0038]      FIG. 7  represents an exploded view of an embodiment of an essential detail of the invention; 
           [0039]      FIG. 8  represents a schematic and exploded view of a variant of the tool according to the invention; 
           [0040]      FIG. 9  represents the tool of  FIG. 1  in closed and open situation of a hinged cover. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0041]    As shown in  FIGS. 1 to 6  and  8  of the attached drawing, the present invention relates to a tool  1 , including a substantially rectilinear framework  2 . A tool leg  3  is fixed to the framework  2  by means of a pin  4  passing through one of several drilled holes  5  provided for along the framework  2 . 
         [0042]    At the end of the tool leg  3  is arranged a permanent magnet  6  accommodated, in resting position, in a protective box  7 . The latter serves, on the one hand, for protecting the permanent magnet  6  from scratches it might be subjected to during the displacements of the tool  1 , on the other hand, for avoiding the permanent magnet  6  from being caught on metallic objects such as trucks or loading buckets that may be in the vicinity of the covers to be removed or re-placed. Furthermore, the protective box  7  avoids the magnet  6  from drawing small metallic objects that may be present on the road, such as nails, screws or clips. 
         [0043]    At an end of the framework  2  is arranged an extension  8 , at the end of which an axis  9  provided with two wheels  10  permits a fulcrum for the tool  1 , easily movable in translation thanks to the wheels  10 . The tool  1  may also be carried out without such wheels, the extension  8  resting directly on the ground, in order to form a fulcrum  8 . In this case, the horizontal displacement shall occur either by causing the fulcrum  8  to slide or by causing the tool  1  to rotate about this fulcrum  8 , in order to be able to place the cover  22  next to the manhole to be opened. With the wheels  10 , both the translation and the rotation are largely facilitated. On a tool  1  according to the invention can be provided an extensible axis  9  that permits to move the two wheels  10  apart from each other, so that the two wheels  10  pass, one of them on one side, the other one on the other side of the cover  22 . This way they do not roll on the cover  22  at all, which permits to pass over the opening even when the cover  22  is removed. 
         [0044]    At the opposite end of the framework  2  with respect to the extension  8  is arranged a handle  11 , at the end of which a traverse bar  12  and two grips  13  permit a good manual grip of the handle  11 . The handle  11  may also be provided with only one grip  13  at the end  11   b  of the handle  11 . This can be a round, square, polygonal, hollow or not, tube, or a tube of any other shape. According to an alternative, not shown, the handle  11  of the tool  1  may be reinforced, for example by inserting a bar having a rhombic cross-section into the hollow tube. 
         [0045]    This handle  11  is fastened to the framework  2  in a telescopic way: it can slide along the framework  2  (see  FIG. 2 ), maintained upwards by a plurality of hoops  14  connecting the two side plates  15  of the framework  2 , and downwards by a sheet  16  arranged between the two side plates  15  of the framework  2 , and provided with side keys that insert into slots  17  in the two side plates  15 . This arrangement of the handle  11  permits to increase the total length of the tool  1 . This permits to increase the lever arm at the location where the force for lifting the cover  22  is applied with the operator&#39;s hands, and thus to increase the force applied at the level of the cover  22 . 
         [0046]    When a lifting force is applied by the operator&#39;s hands at the level of the grips  13 , this force results, at the level of the framework  2 , into a torque, to which the framework  2  reacts by a resistance to an upward force at the level of the end hoop  14   a , and a resistance to a downward force at the level of the end  11   a  of the handle  11  opposite the grips  13 . In order to avoid said downward force at the level of the end  11   a  from prematurely damaging the sheet  16  at this location, a pin  18  is arranged in a drilled hole provided to this end at various positions along the framework  2 , on which the end  11   a  of the handle  11  then rests. Said end  11   a  can also be provided with an appropriate shape that matches the shape of the pin  18  and partially surrounds it. Thus, this pin  18  accomplishes a second function, which is that of impeding the handle  11  from protruding fully out of the framework  2  in working position, or at least from going beyond the limit for which the forces received by the framework  2  and the handle  11  remain acceptable. 
         [0047]    At the level of the extension  8 , a rear grip  19  is arranged on the framework  2 , the function of which will be specified below. 
         [0048]    The operation of the tool  1  is then as follows: 
         [0049]    The handle  11  is then first of all used alone, extracted from the framework  2  (see  FIG. 7 ), in order to separate the cover  22 , by using the handle  11  as a chisel for beating with the mass side  26 , or as a miner&#39;s bar for locally lifting the cover  22  by means of the hook  25 . 
         [0050]    The handle  11  is then brought into a stretched position, the more stretched as a large lever arm is thought to be needed. The grips  13  can be mounted removably on the handle  11 , in this case on the traverse bar  12 , by means of a threaded rod arranged on the grips  13 , which inserts into a tapped hole provided for in said traverse bar  12 , washers  24  being inserted between said grips  13  and said traverse bar  12 . When the grips  13  are not used, for example while the handle  11  is used alone, the grips  13  can be stored in two receptacles  27  provided to this end in the protective box  7  of the magnet  6 . 
         [0051]    The tool leg  3  is arranged on the framework  2  by means of a drilled hole  5  that is located the closer to the extension  8  forming a fulcrum  10  as the force to be applied seems more important. The closer this tool leg  3  is fixed to the fulcrum  10 , the higher will be the force applied on the cover  22  for a given force applied at the level of the grips  13 , but the shorter will be the lifting distance for a lifting distance conferred at the level of the grips  13 . Thus, when a light, but thick cover  22  must be removed (for example a vent grid), it will be convenient to choose a position farther away from the fulcrum  10 . While, when the cover  22  is heavier, a position closer to the fulcrum  10  should be chosen. 
         [0052]    The magnet  6  is then extracted from its box  7  (see  FIG. 3 ) by lifting the tool  1  by its grips  13 , while placing its leg on a protrusion  20  arranged to this end on the box  7 . 
         [0053]    The tool  1  is then positioned above the cover  22  to be removed, and the magnet  6  is brought into contact with said cover  22  (see  FIG. 4 ), preferably in a position close to the center of said cover  22 . 
         [0054]    This position close to the center needs not be reached accurately. It is indeed obvious that, when the magnet  6  is positioned at the edge of the cover  22 , there will be an unbalance, and the cover  22  will be lifted only at the side where the magnet  6  will be positioned. On the other hand, it is enough to be positioned very approximately in the center of the cover  22  for the balance of the cover  22  to occur naturally. 
         [0055]    Indeed, in the state-of-the-art solutions, when the cover  22  is hooked by means of a hook, it rotates freely about this hook, and the horizontal position of the cover  22  represents a very instable point of balance. By contrast, with a holding means  3  according to the invention, configured for impeding any rotation of the cover  22  about an axis included in a plane corresponding to the plane of the cover  22 , the latter cannot tilt. 
         [0056]    This is shown in particular in  FIG. 5  with a tool leg  3  provided with a permanent magnet  6 , like in the exemplary embodiment of the figures. The assembly consisting of the cover  22 , the magnet  6  and the tool leg  3  is rigid. This aggregate can rotate, but about the axis located at the level of the pint  4 , which is located at several tens of centimeters above the cover  22 . Thus, if the cover  22  were inclined to tilt, it would be about this axis. This would oblige its center of gravity to raise, which it would not do spontaneously. The balance of the cover  22  in horizontal position is thus stable. 
         [0057]    When the magnet  6  is positioned somewhat away from the center of the cover  22 , the balance will be found in a position in which the cover  22  is not perfectly horizontal, but it will still be a stable balance close to the horizontal position. A perfectly satisfactory operation of the tool has been observed with the magnet located at one third of the radius of the cover  22 , with at least twice as much cover weight on one side of the magnet as on the other side. 
         [0058]    The fastening of the tool leg  3  to the framework  2  could also be made rigid; this would provide the cover  22  with a forced position, which would also be close to the horizontal line. 
         [0059]    The advantage of letting this fastening freely rotate about the point of hooking to the framework  2  is that, while preserving the advantage of a stable balance without accurate positioning, it avoids, on the one hand, inducing additional stresses on the framework  2 , and thus increases its lifetime and, on the other hand, it avoids increasing the force the operator must maintain in order to hold the cover  22  in raised position. 
         [0060]    The next step consists in displacing the cover  22 , in order to place it next to the opening, in order to make it free and to be able to have access to it. In the embodiment shown, the wheels  10  largely facilitate this displacement. 
         [0061]    The operator can then lower the tool  1  until the plate  22  rests on the ground. 
         [0062]    The tool  1  can then be separated from the cover  22  according to the method explained below, or remain united with the cover  22  until the moment at which the cover  22  must be re-placed. 
         [0063]    When the cover  22  must be re-placed, the operator lifts the cover  22 , like during the removal, positions it above the opening, then lowers it until it is in place. 
         [0064]    Now remains to separate the magnet  6  from the cover  22 . Now, the force applied by the magnet  6  is high, in order to guarantee its capacity of lifting the cover  22 , despite the frictions in the opening at the moment of the removal. This force is therefore considerably higher than the weight of the cover  22 . The lever arm between the grips  13  and the lifting fulcrum  10 , which is in the range of twice that between the force of the magnet  6  on the cover  22  and the lifting fulcrum  10  in the example shown, is then not sufficient to separate the magnet  6  from the cover  22 . 
         [0065]    A rod  21  has been inserted into the tool leg  3 . This rod  21  extends downwards until through the magnet  6 , and upwards until the sheet  16 , when the tool  1  is in the position of  FIG. 4 . Since the point of hanging of the tool leg  3  from the framework  2  is sidewise shifted rearwards (towards the lifting fulcrum  10 ), in raised position ( FIG. 5 ) the sheet  16  moves apart from the upper end of the rod  21 , which does not produce any particular effect. In contrast, when the tool  1  is caused to tilt in the opposite direction, by lifting the side of the wheels  10 , the sheet  16  pushes on the end of the rod  21 , which then pushes with its other end on the cover  22 . When continuing to lift the tool  1  with the side of its wheels  10 , for example with the rear grip  19 , a lever effect is created between a ridge  28  of the magnet  6  and the end of the rod  21 . The lever effect is then much greater, since it is related to the ratio between the distance between the rear grip  19  and the tool leg  3  and the distance between the rod  21  and the ridge  28  of the magnet  6 , which can provide, according to the exemplary embodiments, a ratio in the range from 1 to 10, compared to a range of for example 1 to 2 in normal operation of the tool  1 . Such a lever ratio permits without any difficulty to separate the magnet  6  from the cover  22 . Then, when continuing the movement, the tool  1  rests on the ground with the end  11   b  of the handle  11  (see  FIG. 6 ), and the tool leg  3  moves away from the cover  22 , which ends the operation. Said rod  21  is arranged so as to pass through the magnet  6 , in the example shown. It could however also be arranged immediately next to the magnet  6 . What is important is that the distance between the end of this rod  21  resting on the cover  22  and the ridge  28  of the magnet  6  farthest away from the lifting fulcrum  10  is small compared to the distance between the magnet  6  and the lifting fulcrum  10 , at least 3 times smaller, and preferably at least 5 times smaller. This is met for example when the rod  21  is arranged next to the magnet  6  on the side farthest away from the lifting fulcrum  10 . 
         [0066]    According to another embodiment, the tool leg  3  and the drilled holes  5  in the framework  2  for its fastening can be arranged so that, in &lt;&lt;normal&gt;&gt; raised position of the cover  22  (see  FIG. 5 ), the neighboring drilled hole  5  farthest away from the lifting fulcrum  10  is &lt;&lt;hidden&gt;&gt; by the tool leg  3 ; but, when further lifting the tool  1 , this drilled hole  5  gets free, and an additional pin  23  can be inserted into same, thus impeding the tool leg  3  from adopting again its initial position. Thus, when lowering the tool  1  into its &lt;&lt;normal&gt;&gt; raised position, the tool leg  3  will remain more inclined than its balance position, the cover  22  being slightly inclined upwards on the side of the lifting fulcrum  10 . The cover  22  will then exert, through the tool leg  3  and the additional pin  23 , a torque on the framework  2  that tends to cause the latter to rotate in the same direction as the forces applied on the grips  13  by the operator. Thus, the forced unbalance of the cover  22  will reduce the force to be applied by the operator, by transmitting the force onto the fulcrum, and namely onto the wheels  10 . The displacement of the cover  22  is then made easier for the operator. 
         [0067]    When referring to  FIG. 8 , one can see that, according to a variant of the invention, it is possible to widen the track of the wheels  10 , so that they pass on both sides of the large-size cover, this transformation being achieved through two extenders  29 , each one intercalated between a wheel  10  and the framework  2 . 
         [0068]    When referring to  FIG. 9 , the tool according to the invention can advantageously be used to open a so-called hinged cover  30 . Such covers  30  are not aimed at being removed, but merely opened like a window, an end of the cover being mounted on a hinge  31 . 
         [0069]    To open such a cover, the tool is arranged above the cover  30 , the magnet  6  being positioned in the area opposite the hinge  31 ; then the position of the leg  3  is adjusted so as to be able to position the wheels  10  close to the hinge  31 , preferably placed on the cover  30 . It is then enough to lift the handle  11 , which opens the hinged cover  31 . In this case, the handle is lifted up to the vertical line, until the tool  1  rests on the ground with its rear grip  19 . In this position, the hinged cover  30  has performed a rotation of more than 90° about its hinge  31 , and is stable in open position. The closing occurs by means of the reverse movement. Here too, the exact position of the magnet  6  on the area of the cover  30  far away from the hinge  30  does not matter. It will easily be understood that the farthest this position is away from the axis of the hinge  31 , the lesser the tool  1  will be stressed, but the force to be applied will be similar. Furthermore, the closer the wheels are positioned to the hinge, the smaller will be the stresses induced into the tool, but here too the force to be applied by the operator will be similar. 
         [0070]    According to an alternative shown in  FIG. 10 , the tool  1  according to the invention permits to open a hinged cover  30  the hinge of which  31  permits an open position stable on itself. The position of the wheels is then advanced towards the center of the cover, so that in open position the tool can easily be removed from the cover, by taking hold of it at the rear grip  19 , as described above. 
         [0071]    Said rear grip  19  can also be designed movable in rotation about an axis, as shown in  FIG. 10 , which permits a more pleasant esthetical appearance of the tool. For the application shown in  FIG. 9 , it is enough to provide a stop in rotation of the grip (not shown).