WO2005032978A2

WO2005032978A2 - Work platform for an overhead crane

Info

Publication number: WO2005032978A2
Application number: PCT/US2003/027887
Authority: WO
Inventors: Steve K. Waisanen; Fred J. D'amico; Neal Charles Eriksson; Henry Jacob Conrady, Iii
Original assignee: Mhe Technologies, Inc.
Priority date: 2003-09-05
Filing date: 2003-09-05
Publication date: 2005-04-14
Also published as: CA2537014A1; CA2777793C; WO2005026035A3; CA2537014C; WO2005032978A3; CA2777793A1; WO2005026035A2

Abstract

A work platform (10) for use in performing maintenance while supported on an overhead crane (14). The work platform is particularly useful for performing maintenance on overhead cranes located in areas where normal lifting equipment and/or scaffolding cannot easily access the overhead crane. However, the work platform is also useful for performing maintenance on equipment and/or structures in the vicinity of overhead cranes, and on overhead cranes located in areas without accessibility problems. The work platform is hoisted for placement on support structure of the overhead crane by hoist apparatus (18) of the overhead crane. When positioned, the work platform may be fully supported on the support structure of the overhead crane.

Description

WORK PLATFORM FOR AN OVERHEAD CRANE

BACKGROUND OF THE INVENTION

[0001] The invention relates to overhead cranes, and more particularly, to the performance of maintenance on overhead cranes.

[0002] It is often necessary to erect scaffolding and/or utilize lifting equipment when performing maintenance (e.g., repair, inspection, cleaning, modernization, and the like) on overhead cranes, and equipment and/or structures in the vicinity of overhead cranes. Erection of scaffolding and/or placement of lifting equipment can be time consuming and dangerous for maintenance personnel. This is especially prevalent in areas with limited access, such as containment buildings for atomic reactor power generating plants.

SUMMARY OF THE INVENTION

[0003] The invention provides work platforms for use in performing maintenance while supported on an overhead crane. The work platforms are particularly useful for performing maintenance on cranes located in areas where normal lifting equipment and/or scaffolding cannot easily access the crane. However, work platforms according to the invention are also useful for performing maintenance on equipment and/or structures in the vicinity of overhead cranes, and on overhead cranes located in areas without accessibility problems.

[0004] The work platform is hoisted for placement on the support structure of the overhead crane by at least one hoist apparatus of the overhead crane. When positioned, the work platform may be fully supported on the support structure of the overhead crane so the work platform can be utilized to perform an array of tasks, including, among others, the replacement or repair of portions of the overhead cranes's hoist apparatus.

[0005] In one embodiment, the invention provides an overhead crane apparatus including an overhead crane and a work platform. The overhead crane includes a hoist apparatus operable to raise and lower a load, and a support structure that supports the hoist apparatus above the ground. The work platform is usable to perform maintenance while supported on the support structure. The work platform is capable of being lifted above the ground by the hoist apparatus. The work platform has a work surface sized to support at least one maintenance personnel for the performance of maintenance, and at least one support member that is connectable to the support structure when the work platform is supported by the hoist apparatus. The at least one support member is capable of supporting the work platform on the support structure independent of the hoist apparatus.

[0006] In another embodiment, the invention provides a method of performing maintenance while supported on an overhead crane. The overhead crane includes a hoist apparatus operable to raise and lower a load, and a support structure that supports the hoist apparatus above the ground. The method includes providing a work platform, lifting the work platform above the ground using the hoist apparatus, and connecting the work platform to the support structure when the work platform is supported by the hoist apparatus, such that the support structure supports the work platform above the ground for the performance of maintenance. The work platform has a work surface sized to support at least one maintenance personnel for the performance of maintenance. The work platform is capable of being supported on the support structure independent of the hoist apparatus.

[0007] In yet another embodiment, the invention provides a method of performing maintenance while supported on a polar reactor overhead crane positioned in a containment building. The containment building includes an equipment hatch for moving equipment in to and out of the containment building. The polar reactor overhead crane includes a hoist apparatus operable to raise and lower a load, and a support structure that supports the hoist apparatus above the ground. The support structure includes a pair of spaced apart, generally parallel girders, and a generally circular rail that supports the girders. The method includes providing a work platform, moving the work platform through the equipment hatch and into the containment building, lifting the work platform above the ground using the hoist apparatus, and connecting the work platform to the girders when the work platform is supported by the hoist apparatus, such that the support structure supports the work platform above the ground for the performance of maintenance. The work platform has a work surface sized to support at least one maintenance personnel for the performance of maintenance. The work platform is capable of being supported on the support structure independent of the hoist apparatus.

[0008] Further obj ects of the present invention together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings wherein like elements have like numerals throughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention is further described with reference to the accompanying drawings, which show an embodiment of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in embodiments which are still within the spirit and scope of the present invention. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of" including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0010] FIG.1 illustrates a perspective view of a work platform for use in performing maintenance while supported by an overhead crane.

[0011] FIG. 2 illustrates an elevation view of the work platform of FIG. 1 moving through an equipment hatch of a containment building.

[0012] FIG. 3 illustrates a sectional view of the work platform of FIG. 1 showing the work platform positioned in a hoisted position.

[0013] FIG. 4 illustrates a view similar to FIG. 3 showing the work platform positioned in a maintenance performing position.

[0014] FIG. 5 illustrates a top view of the work platform of FIG. 1 positioned in a maintenance performing position. •

[0015] FIG. 6 illustrates a side view of a suspension support of the work platform of FIG. 1. [0016] FIG. 7 illustrates a rear view of the suspension support of FIG. 6.

[0017] FIG. 8 illustrates side view of the work platform of FIG. 1 with a jib crane attachment installed.

[0018] FIG. 9 illustrates a drum cradle attachment that can be installed on the work platform of FIG. 1.

DETAILED DESCRIPTION

[0019] The figures illustrate a work platform 10 according to one embodiment of the invention. The work platform 10 is illustrated and described as being utilized to perform maintenance while supported on a polar reactor overhead crane 14 (FIG. 3). A polar reactor overhead crane is disclosed in each of U.S. Patent Nos. 3,960,242 and 5,706,736. It should be understood that the work platform 10 of the present invention is capable of use in performing maintenance while supported on other overhead cranes, and the overhead crane 14 is merely shown and described as one such example.

[0020] The overhead crane 14 includes hoist apparatus 18 (FIG. 8), and a pair of spaced apart, generally parallel girders or bridge cross-members 22 (FIGS. 3-5). With reference to FIG. 3, trucks 23 mounted at opposite ends of the girders 22 include drive wheels 24 rotatably mounted for engagement with a circular rail 25. The trucks 23 may also include non-driven or idler wheels 27 rotatably mounted for engagement with the rail 25. The rail 25 is mounted on suitable foundation means. The trucks 23, drive wheels 24, rail 25, and idler wheels 27 are schematically illustrated in FIG. 3 and may be sized differently and/or positioned alternatively with respect to the girders 22 in actual constructions. Engagement of the drive and idler wheels 24 and 27 with the rail 25 supports the crane 14 and permits travel of the crane 14 along the rail 25. Movement of the hoist apparatus 18 relative to the girders 22 in combination with movement of the girders 22 along the rail 25 allows the hoist apparatus 18 to access all areas within the containment building in which the crane 14 is operating. In other embodiments, the hoist apparatus 18 may be fixed relative to the girders 22 and/or the girders 22 may be fixed relative to the rail 25.

[0021] With reference to FIG. 8, each hoist apparatus 18 is adapted to be supported on the girders 22 for movement relative to the girders 22. More specifically, each hoist apparatus 18 includes a trolley or frame 26 that is supported for travel on tracks or rails 30 by wheel assemblies 34. The rails 30 are mounted on the girders 22 of the crane 14. The hoist apparatus 18 also includes a hoist drum 38 mounted on the frame 26 for rotation about a drum axis. A hoist rope 42 (FIGS. 3 and 4) is wound around the drum 38 such that the rope 42 winds on to and off of the drum 38 in response to rotation of the drum 38 in opposite wind-on and wind-off directions, respectively.

[0022] The hoist apparatus 18 also includes a load engaging mechanism 46 connected to the rope 42. The load engaging mechanism 46 includes a bottom block through which the rope 42 is reeved, and a hook depending from the bottom block. As is known in the art, the load engaging mechanism 46 moves upward when the rope 42 winds on to the drum 38, and moves downward when the rope 42 winds off of the drum 38. The hoist apparatus 18 also include a motor 50 that is mounted on the frame 26. The motor 50 is connected to the drum 38 for selectively rotating the drum 38 in the opposite wind-on and wind-off directions. The hoist apparatus 18 as thus far described are conventional and need not be described in greater detail. The crane 14 is illustrated as including two hoist apparatus 18. In other embodiments, the crane 14 may include fewer or more hoist apparatus 18.

[0023] The work platform 10 is a structure that is temporarily attached to the girders 22 of the crane 14. The work platform 10 functions as a work area for maintenance personnel that are performing maintenance on the crane 14 and/or on other equipment and/or structure in the vicinity of the crane 14. The work platform 10 also functions as an installation tool in the performance of such maintenance. The work platform 10 is particularly useful for performing maintenance on the crane 14 because it is located in an area (i.e., a containment building) where normal lifting equipment and/or scaffolding cannot easily access the crane 14. In other embodiments, work platforms according to the invention are also useful in performing maintenance in areas without accessibility problems.

[0024] The work platform 10 includes a generally horizontal work surface 54 (FIG. 5) sized to support at least one maintenance personnel for performing maintenance. The illustrated work surface 54 is sized to support up to four maintenance personnel. In other constructions, the work surface 54 may be smaller or larger. The illustrated work surface 54 is coated with an anti-skid paint. [0025] With reference to FIG. 5, a mast 58 extends through the center of the work surface 54. Guide rollers 60 allow the mast 58 to move vertically relative to the work surface 54. The illustrated mast 58 is constructed in two portions to ease transport of the work platform 10. The upper portion of the mast 58 (FIG. 8) includes a rotating assembly 58a. A number of different attachments are connectable to the mast 58 for use in performing maintenance.

[0026] FIGS. 1 and 9 illustrate a drum cradle attachment 62. The drum cradle attachment 62 is sized to handle hoist drum assemblies 64 (e.g., the drum 38, the rope 42 wrapped on the drum 38, gearing of the drum 38, and the like). The drum cradle attachment 62 is fully rotatable when positioned on the rotating assembly 58a. In one construction, the rotating assembly 58a includes two sets of thrust bearings to provide such rotation. The drum cradle attachment 62 also includes a longitudinal adjustment feature to ease placement of the drum cradle attachment 62 with respect to a hoist drum assembly 64, and to allow movement of the hoist drum assembly 64 relative to the mast 58 when the hoist drum assembly 64 is supported on the drum cradle attachment 62. The drum cradle attachment 62 may be alternatively constructed in other embodiments.

[0027] FIG. 8 illustrates a jib crane attachment 66. The jib crane attachment 66 is movable between a locked position, as shown in dotted lines on FIG. 8, and a fully extended position, as shown in solid lines on FIG. 8. The jib crane attachment 66 includes a two-beam design that eases movement of the jib crane attachment 66 relative to the crane 14. The lower beam 66a includes a two-ton capacity hook 66b mounted on rollers. The upper beam 66c includes a one-ton capacity chain hoist 66d mounted on rollers. The illustrated jib crane attachment 66 can extend up to approximately eighteen feet from the mast 58. The jib crane attachment 66 may be alternatively constructed in other embodiments.

[0028] In other embodiments, a worker basket attachment that supports movement of maintenance personnel relative to the work surface 54 may be connected to the mast 58. The worker basket attachment may include both vertical and horizontal movement relative to the mast 58. In constructions where the worker basket attachment is utilized to perform maintenance on equipment and/or structure in the vicinity of the crane 14 (e.g., sprayers located on the ceiling of the containment building), the crane 14 may be moved to reposition the worker basket attachment relative to the equipment and/or structure. In yet other embodiments, other types of attachments may be attached to the mast 58 to perform or assist in the performance of maintenance.

[0029] With reference to FIGS. 1 and 8, the lower portion of the mast 58 includes a sheave assembly 58b. Rope 70 extending from a hoist unit 74 is reeved around redirection sheaves 76, through the sheave assembly 58b, and to a dead ended assembly 78 mounted on the underside of the work platform 10. The illustrated dead end assembly 78 includes two dead ends mounted to a load bar. The hoist unit 74 is mounted below the work surface 54 in a hoist unit compartment 82. The hoist unit 74 includes a hoist drum 86 having the rope 70 wound there around in a double reeved configuration such that the rope 70 winds on to and off of the drum 86 in response to rotation of the drum 86 in opposite wind-on and wind-off directions, respectively. The hoist unit 74 also includes a motor 90 that selectively rotates the drum 86 in the opposite wind-on and wind-off directions. The mast 58 moves upward when the rope 42 winds on to the drum 38, and moves downward when the rope 42 winds off of the drum 38. The illustrated mast 58 provides fourteen feet of vertical travel at ten feet-per- minute, and includes eleven tons of lift capacity. The mast 58 may be alternatively constructed in other embodiments.

[0030] With reference to FIG. 1, the work platform 10 is equipped with lift-off handrails 94. The hand rails 94 may include multiple removable segments to allow equipment or other objects to pass. In other embodiments, the handrail 94 may include a chain gate to allow equipment or other objects to pass. Further, the hand rail 94 may include a removable barrier to prevent objects from falling from the work platform 10. In some constructions, the removable barrier is see-through (e.g., acrylic).

[0031] With reference to FIGS. 1 and 3-4, the work platform 10 includes wing plates 98 extending outward from the sides of the work surface 54. A wing plate 102 is also positioned on a portion of the handrail 94. The wing plates 102 prevent objects from falling from the work platfonn 10. The illustrated wing plates 98 are pivotable, and the wing plate 102 is fixed. In other embodiments, the work platform 10 may include fewer or more wing plates 98, 102, or other types of object deflectors.

[0032] With reference to FIGS. 3-5, the work platform 10 includes hook linkages 106. Each hook linkage 106 is mounted below the work surface 54 in a hook linkage compartment 110. The hook linkages 106 fold away into respective hook linkage compartments 110 when not in use, and extend from the hook linkage compartments 110 for engagement by the load engaging device 46 of a respective hoist apparatus 18. The work platform 10 includes two sets of hook linkages 106. In other embodiments, the work platform 10 may include fewer or more sets of hook linkages 106, or other types of hook attachments.

[0033] The work surface 54 includes a plurality of trap doors to compartments (e.g., the hoist unit compartment 82, the hook linkage compartments 110) located below the work surface 54. The compartments are utilized to provide access to equipment (e.g., the hoist unit 74), and to stow equipment, tools, and the like. With reference to FIGS. 3-5, the work platform 10 also includes load engaging device compartments 114. The load engaging device compartments 114 are each sized to receive the load engaging device 46 of a respective hoist apparatus 18. Each load engaging device compartment 114 can be utilized to support the load engaging device 46 for reeving and unreeving. Utilization of the compartments provides an unobstructed work surface 54 for the maintenance personnel that includes an optimized amount of floor space.

[0034] With reference to FIGS. 1 and 6-7, the work platform 10 includes four suspension supports 118. Each suspension support 1 18 is secured to a bracket 122 mounted on the work surface 54 using two pins. Each suspension support 118 is movable between a folded position, as shown in FIG. 2 and as shown in dotted lines on FIG. 5, a hoisting position, as shown in FIG. 3 and as shown in dotted lines on FIG. 6, and a maintenance performing position, as shown in solid lines on FIGS. 1 and 4-8. A top portion 118a of each suspension support 118 includes a pivotable head having a profile that allows the hoist apparatus 18 to pass over the top (i.e., the suspension supports 118 do not interfere with the interaction between the hoist apparatus 18 and the rails 30). Each suspension support 118 includes a horizontal stabilizer 118b, a vertical stabilizer 118c, and a biasing member 118d. The vertical stabilizer 118c pivots the top portion 118a relative to the remainder of the suspension support 118. The biasing member 118d includes a spring that biases the top portion 118a against the vertical stabilizer 118c. Contact pads 118e on the top portion 118a and the horizontal stabilizer 118b may include an elastomer or other non-abrasive material to prevent metal-to-metal contact and paint scraping on the girders 22. As best shown in FIG. 7, each suspension support 118 also includes a set of hand grips 118f. In other embodiments, the work platform 10 may include other types of support members that connect the work platform 10 to the girders 22. In one such embodiment, the support member(s) may be mounted on the rails 30 for movement of the work platform 10 relative to the girders 10. A come-along or other suitable means may be utilized to move the work platform 10 relative to the crane 14.

[0035] h some embodiments, the work platform 10 may include bottom support members such as retractable outrigger supports that extend from the work platform 10 to contact the bottom side of the girders 22. The bottom support members act as a positive stop when hoisting the work platform 10 to the girders 22. Bottom support members are particularly useful when hoisting a work platform 10 using a single hoist apparatus 18. The hoist apparatus 18 can hoist the work platform 10 until the bottom support members are tight against the underside of the girders 22, thereby providing a stable work surface 54 until the suspension supports 118 are in place.

[0036] The work platform 10 is designed as a fluid tight structure to prevent fluids (e.g., water, oil, lubricants, and the like) utilized while performing maintenance from falling through the work platform 10 and to the floor below. The work platform 10 is also designed to prevent objects (e.g., tools, equipment, and the like) utilized while performing maintenance from falling through the work platform 10 and to the floor below. Further, the work platfonn 10 is designed to utilize removable pins and quick connections for ease of the assembly of removable and/or collapsible components (e.g., handrails 94, suspensions supports 118) of the work platform 10. The pins may include grab handles for ease of removal, and tie chains secured to the work platform 10 to prevent dropping of the pins from the work platform 10. The removable pins may be stowed in a compartment under the work surface 54 when not being used.

[0037] The work platform 10 includes electrical service to allow for utilization of power tools and welding equipment. In one construction, power is connected to the work platform 10 by means of a cable reel, tag line festoon, or the like. A circuit breaker may be located on the work platform 10 that includes control of all power to the hoist unit 74 and the receptacles located on the work platform 10. [0038] The work platform 10 includes a control for the hoist unit 74 that allows the maintenance personnel to raise and lower the mast 58 relative to the work surface 54. In one construction, the hoist unit control includes an isolation transformer and is located in a compartment under the work surface 54 near the mast 58. A mast control pushbutton station

123 (schematically illustrated in FIG. 4), with mast on/off and mast raise/lower controls, is electrically connected to the hoist unit control. The mast control pushbutton station 123 may include a cord or wireless connection that allows for operation of the mast 58 from any location on the work surface 54. The mast control pushbutton station 123 may also include attachment controls (e.g., jib crane attachment controls, drum cradle attachment controls, worker basket attachment controls). In other constructions, the attachments may be alternatively controlled.

[0039] The work platform 10 also includes a crane control pushbutton station 124 (schematically illustrated in FIG. 4) that allows for remote operation of the crane 14. The crane control pushbutton station 124 is electrically connected to the crane controls. The crane control pushbutton station 124 includes crane on/off, hoist-one raise/lower and forward/reverse, hoist-two raise/lower and forward/reverse, hoist-auxiliary raise/lower and forward/reverse, and girders forward/reverse controls. The crane control pushbutton station

124 may include a cord or wireless connection that allows for operation of the crane 14 from any location on the work surface 54. In one embodiment, the normal crane controls are locked-out to only allow operation of the crane 14 using the crane control pushbutton station 124 while the work platform 10 is being utilized to perfonn maintenance.

[0040] With reference to FIG. 2, the work platform 10 is designed to fit through an equipment hatch 126 of a containment building 130. The illustrated work platform 10 is approximately twelve feet wide, twenty- four feet long, four feet deep, and weights approximately twenty-one tons. The equipment hatch 126 is approximately fourteen feet, six inches in diameter. The work platform 10 is brought into the containment building 130 in a collapsed state on an equipment hatch transfer car 134. The transfer car 134 is supported on a pair of temporary rails 138 that extend into the containment building 130.

[0041] When the work platform 10 is inside the containment building 130, the removable and/or collapsible components (e.g., handrails 94, suspensions supports 118) of the work platform 10 are assembled to configure the work platform 10 in an uncollapsed state. Configuration of the work platform 10 in the uncollapsed state may occur before and/or after the work platform is connected to the girders 22.

[0042] In the illustrated embodiment, a respective hoist apparatus 18 (e.g., an auxiliary hoist apparatus of the crane 14) is utilized to lift the suspension supports 118 from the folded position to the hoisting position. The illustrated suspension supports 118 weight approximately 4O0 pounds. The suspension supports 118 may be locked in the hoisting position using the pins. As illustrated in FIG. 6, the hoisting position is approximately eighty percent of the maintenance performing position. Placement of the suspension supports 118 in the hoisting position allows a maintenance personnel to moved the suspension supports 118 the remainder of the way to the maintenance performing position using the hand grips 118f. The suspension supports 118 are moved to the maintenance performing position when the work platform 10 is positioned in a hoisted position, as illustrated in FIG. 3.

[0043] Once the work platform 10 is ready to be hoisted, the load engaging devices 46 of the hoist apparatus 18 are lowered and connected to the hook linkages 106. When each load engaging device 46 is securely connected, the motors 50 are driven to turn the drums 38 in the wind-on direction. The work platform 10 is hoisted up to the girders 22 (i.e., to the hoisted position). Hoisting the work platform 10 for placement on the crane 14 using the crane 14 eliminates the need for other lifting equipment. In other constructions, the work platform 10 may be hoisted to the girders 22 using fewer or more hoist apparatus 18.

[0044] While the work platform 10 is still supported by the hoist apparatus 18, the suspension supports 118 are comiected to the girders 22 (i.e., moved to the maintenance performing position). The horizontal stabilizers 118b are adjusted to center the work surface 54 between the girders 22. The vertical stabilizers 118c are adjusted to level the work surface 54. The suspension supports 118 may be utilized to fully support the work platform 10. In other embodiments, the load engaging devices 46 may remain connected to the hook linkages 106 to provide additional support. Once the work platform 10 is stabilized, the wing plates 98 are pivoted into position against the girders 22 (FIG. 3-5) to prevent objects from falling between the work platform 10 and the girders 22. [0045] When the work platform 10 is in the maintenance performing position, as illustrated in FIG. 4, the maintenance personnel ca begin to perform the necessary maintenance.

[0046] In one embodiment, maintenance may include the replacement of the hoist drum assembly 64. The drum cradle attachment 62 is connected to the mast 58 and moved into position under the hoist drum assembly 64. The crane control pushbutton station may be utilized to position the hoist apparatus 18 above the mast 58. Further, the longitudinal adjustment feature of the drum cradle attachment 62 may be utilized to position the drum cradle attachment 62 directly below the hoist drum assembly 64. The mast 58 is then raised vertically and the hoist drum assembly 64 is lifted from its bearing seats. When the hoist drum assembly 64 is clear of the remaining components of the hoist apparatus 18, the crane control pushbutton station 124 is utilized to move the remaining components of the hoist apparatus 18. The drum cradle attachment 62 is then rotated ninety degrees so the drum axis is parallel to the girders 22. The mast 58 is lowered to bring the drum cradle attachment 62 near the work surface 54. The hoist drum assembly 64 can then be lowered off the work platform 10 using an existing hoist apparatus 18 or, alternatively, a lifting devices that is temporarily supported by the crane 14 or structure adjacent to the crane 14.

[0047] In another embodiment, maintenance may include the replacement of the motor 50 or other components on the hoist apparatus 18. The jib crane attachment 66 is connected to the mast 58 and moved into position above the hoist apparatus 18. Either the hook 66b or the chain hoist 66d may be utilized to lift the motor 50 from the frame 26 to the work surface 54. Once the motor 54 is positioned on the work surface 54, the motor 50 can then be lowered off the work platform 54 using an existing hoist apparatus 18 or, alternatively, a lifting devices that is temporarily supported by the crane 14 or structure adjacent to the crane 14. In some embodiments, the jib crane attachment 66 maybe designed to lower objects to the ground. In yet other embodiments, the work platform 10 may include other lifting devices capable of moving objects from the work surface 54 to the ground.

[0048] The work platform 10 provides a convenient means to work high in the air, while virtually eliminating the possibility of objects and/or fluids falling to the ground. The work platform 10 includes the ability to lift heavy pieces on to and off of the crane 14. The work platform 10 also allows for the operation of power tools and welding equipment. Additionally, the crane 14 can be remotely operated from the work platform 10, and the work platform 10 does not interfere with operation of the crane 14.

[0049] The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.

Claims

CLAIMSWhat is claimed is:

1. An overhead crane apparatus comprising: a hoist apparatus operable to raise and lower a load; a support structure that supports the hoist apparatus above the ground; and a work platform usable to perform maintenance while supported on the support structure, the work platform capable of being lifted above the ground by the hoist apparatus, the work platform having a work surface sized to support at least one maintenance personnel for the performance of maintenance and at least one support member that is connectable to the support structure when the work platform is supported by the hoist apparatus, the at least one support member capable of supporting the work platform on the support structure independent of the hoist apparatus.

2. An overhead crane apparatus according to claim 1 wherein the work platfonn includes a mast extending vertically from the work surface and a hoist unit adapted to raise and lower the mast relative to the work surface.

3. An overhead crane apparatus according to claim 2 wherein the work platform includes a jib crane attachment connected to the mast, wherein the jib crane attachment is operable to lift objects on to and off of the hoist apparatus.

4. An overhead crane apparatus according to claim 2 wherein the work platform includes a drum cradle attachment connected to the mast, wherein the hoist apparatus includes a hoist drum assembly, and wherein the mast and the drum cradle attachment are operable to lift the hoist drum assembly on to and off of the hoist apparatus.

5. An overhead crane apparatus according to claim 1 wherein the at least one support member is pivotable between a folded position and a maintenance performing position, and wherein the at least one support member includes four suspension supports that hang from the support structure when positioned in the maintenance performing position.

6. An overhead crane apparatus according to claim 1 wherein the work platform includes wing plates extending upwardly and outwardly from the work surface to prevent objects from falling from the work surface.

7. An overhead crane apparatus according to claim 1 wherein the work platform includes a load engaging device compartment located under the work surface, wherein the load engaging device compartment is accessible using a trap door, wherein the hoist apparatus includes a frame, a drum mounted on the frame for rotation about a drum axis, a motor connected to the drum for selectively rotating the drum in opposite wind-on and wind-off directions about the drum axis, a rope wound around the drum such that the rope winds on to and off of the drum in response to rotation of the drum in the wind-on and wind-off directions, respectively, and a load engaging mechanism connected to the rope such that the load engaging mechanism moves upward when the rope winds on to the drum and moves downward when the rope winds off of the drum, and wherein the load engaging device is supportable in the load engaging device compartment for reeving the rope on to the drum and the load engaging device.

8. An overhead crane apparatus according to claim 1 wherein the work platform is substantially fluid tight to prevent fluids utilized when performing maintenance from falling through the work platform.

9. An overhead crane apparatus according to claim 1 wherein the support structure includes a pair of spaced apart, generally parallel girders, and wherein the at least one support member is connectable to the girders when the work platform is supported by the hoist apparatus.

10. An overhead crane apparatus according to claim 9 wherein the at least one support member includes four suspension supports that hang from the girders to support the work platform on the girders independent of the hoist apparatus.

11. An overhead crane apparatus according to claim 1 wherein the work platform includes at least one hook attachment, wherein the hoist apparatus engages the at least one hook attachment to lift the work platform above the ground, and wherein the at least one hook attachment is stored under the work surface when not engaged by the hoist apparatus.

12. A method of performing maintenance while supported on an overhead crane, the overhead crane including a hoist apparatus operable to raise and lower a load and a support structure that supports the hoist apparatus above the ground, the method comprising: providing a work platform having a work surface sized to support at least one maintenance personnel for the performance of maintenance; lifting the work platfonn above the ground using the hoist apparatus; and connecting the work platform to the support structure when the work platform is supported by the hoist apparatus such that the support structure supports the work platform above the ground for the performance of maintenance, the work platform capable of being supported on the support structure independent of the hoist apparatus.

13. A method of performing maintenance according to claim 12 and further comprising disconnecting the work platform from the hoist apparatus so the work platform is fully supported on the support structure during the performance of maintenance.

14. A method of performing maintenance according to claim 12 and further comprising controlling the overhead crane remotely from the work platform.

15. A method of performing maintenance according to claim 12 wherein the work platform includes at least one support member that is connectable to the support structure when the hoist apparatus is supported by the hoist apparatus, and wherein the at least one support member is capable of supporting the work platform on the support structure independent of the hoist apparatus.

16. A method of performing maintenance according to claim 12 wherein the work platform includes a mast extending vertically from the work surface, a hoist unit adapted to raise and lower the mast relative to the work surface, and an attachment rotatably connected to the mast, and wherein the attachment is utilized to perform maintenance.

17. A method of performing maintenance according to claim 12 and further comprising performing maintenance on the overhead crane.

18. A method of performing maintenance according to claim 12 and further comprising performing maintenance on equipment or structure in the vicinity of the overhead crane.

19. A method of performing maintenance while supported on a polar reactor overhead crane positioned in a containment building, the containment building having an equipment hatch for moving equipment in to and out of the containment building, the polar reactor overhead crane including a hoist apparatus operable to raise and lower a load and a support structure that supports the hoist apparatus above the ground, the support structure including a pair of spaced apart, generally parallel girders and a generally circular rail that supports the girders, the method comprising: providing a work platform having a work surface sized to support at least one maintenance personnel for the performance of maintenance; moving the work platfonn through the equipment hatch and into the containment building; lifting the work platform above the ground using the hoist apparatus; and connecting the work platform to the girders when the work platform is supported by the hoist apparatus such that the support structure supports the work platform above the ground for the performance of maintenance, the work platform capable of being supported on the support structure independent of the hoist apparatus.

20. A method of performing maintenance according to claim 19 and further comprising configuring the work platform in a collapsed stated prior to moving the work platform through the equipment hatch, and reconfiguring the work platform in an uncollapsed state after moving the work platform through the equipment hatch, wherein the work platform includes a profile when in the uncollapsed state that does not fit through the equipment hatch.