Abstract:
A ladder system is provided for facilitating access through a confined opening. The system includes a support arrangement having a first bar. The first bar may be positioned on a surface adjacent an opening. A removable ladder support cradle, including a pair of ladder supports, is coupled to the first bar. A ladder is removably coupled to the support cradle within the opening.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to a ladder system for allowing a user to ascend or descend vertical distances, and in particular to a ladder system configured to gain access through a confined space, such as into an underground structure through as a manhole. 
         [0002]    Ladders are commonly used to assist users in reaching locations that are not accessible due to their vertical location relative to the user. These locations may be vertically above the user, such in a tree or a utility pole for example. Ladders may also be used when the location is below the user, such as a hole in the ground. Ladders are commonly used by service personnel with manholes to access underground chambers that house infrastructure components, such as but not limited to electrical distribution equipment, telecommunications equipment, natural gas conduits, water conduits and sewers for example. A manhole is generally a circular hole formed in the roadway, sidewalk or ground that is sized to allow service personnel to enter and exit the underground chambers. Generally, manholes are 22 inches (559 millimeters) to 60 inches (1524 millimeters) in diameter and may weigh up to 250 pounds (113 kilograms). 
         [0003]    While some manholes may have features such as steps or built in ladders, commonly there are no provisions for assisting the service personnel in reaching the floor of the underground chamber. In these circumstances, the service personnel will lower a ladder to facilitate the ingress and egress from the chamber. When a ladder is inserted within a manhole, the ladders are usually positioned against one side of the manhole opening and arranged on an angle prevent the ladder from slipping or moving during use. It should be appreciated that this angling of the ladder reduces the amount of available clearance space between the ladder and the sides of the manhole hindering access to the underground chamber. To provide greater access, the ladder may be arranged on a steeper angle, making the ladder more difficult to use. 
         [0004]    Accordingly, while existing ladders are suitable for their intended purposes, there remains a need for improvement in providing a ladder that may be easily deployed for use in entering and exiting underground structures. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    According to one aspect of the invention, a ladder system for entry into an opening for an underground structure is provided. The ladder system includes a first bar. A support cradle having a member is adapted to receive a first ladder rung on the ladder. The support cradle is arranged for attachment to the first bar. 
         [0006]    According to another aspect of the invention, a method of supporting a ladder within an opening is provided. The method includes the step of arranging a first bar on a sidewalk adjacent the opening. A support cradle is coupled on the first bar. A first rung is captured on the ladder within a top portion of the support cradle. 
         [0007]    According to yet another aspect of the invention, a ladder system is provided having a ladder having a first rung. A first bar is operably coupled to the ladder and arranged substantially perpendicular to a longitudinal length of the ladder. A second bar is rotatably coupled to a first end of the first bar, the second bar being rotatable between a first position and a second position. A first member is removably coupled between the first bar and the first rung. 
         [0008]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0009]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0010]      FIG. 1  is a top perspective view of the manhole ladder support within a manhole opening in accordance with the invention; 
           [0011]      FIG. 2  is a top perspective view of the manhole ladder support of  FIG. 1  with a ladder attached thereto; 
           [0012]      FIG. 3  is a top perspectives view the manhole ladder support in accordance with the invention prior to assembly of the manhole ladder support components; 
           [0013]      FIG. 4  is a top perspective view of the manhole ladder support in accordance with the invention after assembly of the components; and, 
           [0014]      FIG. 5  is a top perspective view of a further ladder cradle for use with the manhole ladder support in accordance with the invention. 
       
    
    
       [0015]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Embodiments of the present invention provide a method and device for entering and exiting underground structures, such as underground utility chambers. Embodiments of the invention may be discussed in relation to an electrical utility service and equipment, but the claimed invention is not so limited. The method and device discussed herein may be used with any underground structure having an entrance that provides for a vertical entrance or exit. These underground structures may include but are not limited to electrical utility service and equipment, telecommunications utility service and equipment, water and natural gas utility service and equipment, sanitation service and equipment, and television utility service and equipment for example. In accordance with one embodiment of the invention, a simple removable assembly is provided to which the top of a ladder may be attached or supported without involving complex connectors and the like to prevent ladder slippage. In accordance with another embodiment of the invention, a simple, convenient arrangement is provided for removable attachment to a ladder assembly that is arranged within a manhole to facilitate use of the ladder by service personnel. In accordance with yet another embodiment of the invention, a simple, convenient means of egress from a manhole provided in the event fast egress or exit is desired. 
         [0017]    Referring now to  FIGS. 1 and 2  a ladder support  10 , according to one embodiment of the invention is provided. The ladder support  10  is arranged on a sidewalk  7  surrounding a manhole opening  11 . A ladder cradle  8  is coupled to the ladder support  10  and is arranged for receiving a ladder  12 . The ladder  12  includes a plurality of rungs that are used by the service personnel to ascend or descend the ladder  12 . One of the ladder rungs  12 A, which is located above ladder rung  12 B, is captured within a cradle U-shaped supports  18 ,  19  in the manner to be described below. 
         [0018]      FIG. 3  illustrated an exploded view of the components of the ladder support  10 . The ladder support  10  includes an elongated center bar  13 , a first side bar  14  and an opposing side bar  15  at the opposite end thereof. In the exemplary embodiment, the side bars  14 ,  15  are substantially perpendicular to the center bar  13 . In one embodiment, the bars  13 ,  14 ,  15  have a rectangular cross-section and are fabricated from a metal, such as aluminum for example. 
         [0019]    The ladder cradle  8  includes a pair of supports  16 ,  17  joined at the bottom via a rod  9  which is coupled at to the supports  16 ,  17  at each end thereof. In the exemplary embodiment, the coupled to the supports  16 ,  17  by welding and have a rectangular cross-section. The supports  16 ,  17  include U-shaped supports  18 ,  19  at the top thereof for receiving the ladder  12  ( FIG. 2 ) and L-shaped extensions  20 ,  21  that contact a surface or wall  44  on the inside of the manhole opening  11 . The hooks  16 A,  17 A, extend from the U-shaped supports  18 ,  19  and are positioned over the center bar  13  as illustrated in  FIG. 1 . 
         [0020]    A pair of angular plates  22 A,  22 B, are positioned on opposite sides of the center bar  13  and side bar  14  and are attached to the center bar  13  and side bar  14  via openings  22 C,  22 D in the plates  22 A,  22 B and openings  13 A,  14 A in the elongate bar and the side bar by means of fasteners  23 ,  24 . In one embodiment, the center bar  13  and side bar  14  are coupled by welding. 
         [0021]    A pair of angular plates  25 A,  25 B, are positioned on opposite sides of the center bar  13  and side bar  15  and are attached to the center bar  13  and side bar  15  via openings  25 C,  25 D in the angular plates  25 A,  25 B and openings  13 B,  15 A in the center bar and the side bar by means of fasteners  26 ,  24 . In one embodiment, the center bar  13  and the side bar  15  are coupled by welding. 
         [0022]    Anti-skid plates  28 A,  28 B are attached at opposite ends of the side bar  14 . In the exemplary embodiment, the plates  28 A,  28 B are coupled via fasteners  29 ,  30  via openings  14 B,  14 C. Anti-skid plates  31 A,  31 B are attached at opposite ends of the side bar  15 . In the exemplary embodiment, the plates  31 A,  31 B are attached via fasteners  32 ,  33  through openings  15 B,  15 C. In one embodiment, the plates  28 A,  28 B and  31 A,  31 B are fabricated from a solid rubber compound to provide a desired anti-slip/anti-skid property. 
         [0023]    One embodiment of an assembled ladder support  10  is illustrated in  FIG. 4 . In this embodiment, the center bar  13  has the side bars  14 ,  15  attached via plates  22 A,  25 A and with the anti-skid plates  28 A,  28 B and  31 A,  31 B attached to the ends thereof. The ladder cradle  8  is positioned on the center bar  13  by arranging hooks  16 A,  17 A on the tops of the supports  16 ,  17  over center bar  13 . 
         [0024]    When the ladder support  10  is positioned relative to a manhole  8  ( FIG. 1 ), and the ladder  12  is positioned on the ladder support  10  by coupling one of the ladder rungs  12 A within the U-shaped supports  18 , 19  ( FIG. 2 ), the L-shaped extensions  20 ,  21  on the supports  16 ,  17  will abut against the manhole sidewalls (not shown). It should be appreciated that this arrangement provides advantages in maintaining a desired clearance between the ladder  12  and the manhole sidewalls. 
         [0025]    Referring now to  FIG. 5 , another embodiment of a ladder cradle  8 ′ is illustrated. The ladder cradle  8 ′ includes first and second supports  16 ′,  17 ′ with hooks  16 A′,  17 A′ arranged opposite thereto. An L-shaped extensions  20 ′,  21 ′ extend from one side of the ladder cradle  8 ′ and J-shaped extensions  35 ,  36  are subjacent the U-shaped supports  18 ′,  19 ′. A pair of J-shaped extensions  35 ,  36  are arranged on the supports  16 ′,  17 ′ subjacent the U-shaped supports  18 ′,  19 ′. 
         [0026]    The spacing distance “d” between the U-shaped supports  18 ′,  19 ′ and J-shaped extensions  35 ,  36  is adapted to be substantially the same distance as between two successive ladder rungs  12 A,  12 B, on the ladder  12  ( FIG. 2 ). With this configuration, the ladder rung  12 A, may be captured within the U-shaped supports  18 ′,  19 ′ and the ladder rung  12 B may be captured within the J-shaped extensions  35 ,  36  when the ladder cradle  8 ′ is used in place of the ladder cradle  8  described earlier. The provision of the J-shaped extensions  35 ,  36  in combination with the U-shaped supports  18 ′,  19 ′ inhibits the ladder  12  from swinging away from the manhole opening  11  ( FIG. 2 ) during operation. 
         [0027]    When the service personnel complete the desired tasks within the manhole opening  11 , the ladder  12  may be removed from the ladder cradle  8  by lifting the ladder rung  12 A out from the U-shaped supports  18 ,  19 . With the ladder  12  decoupled, the ladder cradle  8  may be removed from center bar  13  by moving the cradle in the direction of arrow  40  as shown in  FIG. 4 . To facilitate storage and transportation of the center bar  13 , the fasteners  23 ,  26  on the angular plates  22 A,  25 A are loosened and the side bars  14 ,  15  are rotated in the counterclockwise in the direction indicated by arrow  42  to form a linear arrangement where the side bars  14 ,  15  are substantially parallel to the center bar. The rotated (linear) position is illustrated in  FIG. 4  in phantom. It should be appreciated that while the embodiments illustrated herein show the side bars  14 ,  15  as being arranged substantially perpendicular when in the deployed position, the side bars  14 ,  15  may also be arranged on an angle relative to the center bar  13  to accommodate obstructions or other surface irregularities. 
         [0028]    A ladder support arrangement is provided whereby a ladder can be inserted within a manhole with part of the support extending from the manhole to the adjoining sidewalk or other adjacent surface. The ladder is held in contact with the support by capturing a ladder rung within a pair of U-shaped supports formed in the top of the support. Embodiments of the invention provide advantages in increasing the amount of space available for service personnel to enter and exit the entrance to an underground structure. Embodiments of the invention further provide advantages in increasing the stability of the ladder during use to facilitate the entry and exit of service personnel from underground chambers. Embodiments of the invention provide yet further advantages in being easily configured for transportation and deployment. 
         [0029]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.