Abstract
A manhole frame includes one or more handholds near the entrance to the manhole so that the ladder rungs can be made lower and the access space at the entrance to the manhole thereby increased. The handhold can be cast into the cover-supporting lip, or can be a movable handle which is below the level of the manhole when not in use or extended above ground level when in use.
Claims
1. A manhole frame for a manhole, said manhole frame comprising a vertically extending hollow cylinder open at its top and bottom ends, said manhole comprising a plurality of vertically spaced ladder rungs, said manhole frame comprising an annular lip having an upper manhole cover-supporting surface and extending inwardly from said vertically extending cylinder adjacent the upper edge of said vertically extending cylinder, wherein said manhole frame comprises a handhold to facilitate a person to enter or exit the manhole, said handhold being located in the manhole frame above the uppermost of said ladder rungs close to the upper opening of the manhole, being smaller in width than one of said ladder rungs and protruding a radial distance into the manhole opening less than the inward radial protrusion of said ladder rungs.
2. The manhole frame of claim 1 wherein said handhold is provided in said annular lip of said manhole frame.
3. The manhole frame of claim 1 wherein said handhold extends through said annular lip of said manhole frame.
4. The manhole frame of claim 1 wherein said handhold protrudes less than about 2 inches into the manhole opening from the edge of said annular lip.
5. The manhole frame of claim 1 wherein said handhold comprises an opening cast into said annular lip of said manhole frame.
6. The manhole frame of claim 5 wherein the upper surface of said handhold is set flush with or lower than the upper surface of said annular lip.
7. The manhole frame of claim 1 wherein the inner surface said manhole frame in an area radially outwardly of said handhold is recessed so as to reduce the protrusion of the handhold radially inwardly into the manhole opening while permitting sufficient space for a hand.
8. The manhole frame of claim 2 wherein said handhold is horizontally oriented.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.
(2) FIG. 1 is a perspective view of a manhole casting cemented in place on a manhole using the inventor's apparatus as disclosed in U.S. Pat. No. 4,666,333.
(3) FIG. 2 is a cross-section taken along lines 2-2 of FIG. 1.
(4) FIG. 3 is a top view of a first embodiment of the invention.
(5) FIG. 4 is a top view of a second embodiment of the invention.
(6) FIG. 5 is a top view of a third embodiment of the invention.
(7) FIG. 6 is a cross-section taken along lines 6-6 of FIG. 5 illustrating the third embodiment of the invention.
(8) FIG. 7 is a top view of a fourth embodiment of the invention.
(9) FIG. 8 is a front view of the handhold shown in FIG. 7.
(10) FIG. 9 is a front view of a fifth embodiment of the invention, with the handhold shown extending horizontally.
(11) FIG. 10 is a cross-section view of the handhold shown in FIG. 9 taken along lines 10-10, with the handhold extending vertically downwardly.
(12) FIG. 11 is a front view of a sixth embodiment of the invention.
(13) FIG. 12 is a cross-section view of the handhold shown in FIG. 11 taken along lines 12-12 when placed in the upper position.
DESCRIPTION
(14) Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
(15) FIGS. 1 and 2 illustrate a manhole 10 with the upper end 40 of the manhole having outer side 46 and upper surface 44. Manhole frame 50, also referred to as a manhole casting, is secured to manhole upper end 40 by concrete casing 72, such as by using the inventor's manhole casting positioning apparatus as disclosed in U.S. Pat. No. 4,666,333, formed using inner sleeve 54 and outer surface 52 formed by the outer sleeve (not shown). Frame 50 has an upper annular lip 60 for receiving a manhole cover, vertical wall 51 and frame base 58. Ladder rungs of existing configuration and location are shown at 70.
(16) Referring to FIG. 3, handhold 20 is cast into the annular lip 60 of manhole frame 50 at the time of production of manhole frame 50, or welded to the annular lip 60 of manhole frame 50. The handhold 20 may be either oriented horizontally as shown in FIG. 3 or vertically. It is formed by providing an opening 22 having a radial dimension of about 2½ inches and a circumferential dimension of about 5 inches, on the interior side of which is handle 23 which is about ¾ inches wide. Preferably the upper edge of handle 23 is set slightly lower than or flush with the upper surface of annular lip 60 so that the bottom of the manhole cover does not rest on handle 23. Handle 23 can be made to protrude radially inwardly from the manhole frame so as to be convex, but the shape of handle 23 can also be straight across, or curved radially outwardly towards frame 50 so as to be concave. In the latter case, the area of the manhole frame behind the handle would be concave, proportional to the handle, to provide adequate clearance for a worker's hand.
(17) Alternately as shown in FIG. 4 a handhold 25 is mechanically attached to a pre-manufactured manhole frame 50. The handhold 25 is mechanically attached to a pre-manufactured manhole frame by drilling holes 55 into the manhole frame 50 a few inches below annular lip 60 and securing a handhold 25 to the manhole frame, for example by making ends 26 of handhold 25 threaded and using nuts 27 to secure the handhold to the frame 50. Alternatively handhold 25 can be provided with holes to receive threaded bolts which extend through frame 50. The handhold 25 can be oriented horizontally or vertically. FIGS. 5 and 6 illustrate handhold 28 in vertical orientation. The handhold may be made of rigid steel, or of loose link chain or wire rope to provide flexibility and resilience. The handhold may be manufactured to be straight, concave or convex as required, with the inner surface 53 of the frame 50 behind handhold 28, shown in front view as a separate detail view 56 in FIG. 4 and FIG. 6, recessed at 56 as necessary for clearance. Where bolts are used, the same handhold can provide either a concave or convex shape by reversing the handhold. Preferably the width A of the space formed between the handhold 23/25/28 and frame 50 is about 5 inches.
(18) FIGS. 7 and 8 illustrates a handhold which moves vertically to extend above ground level. T-shaped handhold 30 has a horizontal bar 31, vertical bar 32 which has threaded end 33 which threads into threaded hole 36 in annular lip 60 of frame 50. The diameter of vertical bar 32 is slightly less than the diameter of threaded end 33. A horizontal recess 38 in annular lip 60 receives bar 31 when the T-handle is threaded completely through the threaded hole 36 and vertical bar 32 then drops through hole 36. This latter handhold may also serve as an easily accessible attachment point for life lines attached to a worker in a manhole when the handhold is extended above the manhole frame. A locking nut (not shown) may then be threaded onto threaded end 33 to make the T-shaped handhold 30 an integral part of the frame 50. The handhold 30 may be made flexible and resilient by forming part of vertical bar 32 from wire rope. This can be done by welding one end of a wire rope to a shortened vertical bar 32 a couple of inches below horizontal bar 31, and welding the threaded end 33 to the other end of the wire rope. In this way the handhold 30 is resilient and flexible so a worker grasping the handhold can draw it away from frame 50 providing extra clearance for the worker's hand. Loose link chain mat also be substituted for the wire rope.
(19) FIGS. 9 and 10 illustrate a handhold 62 which can be rotated to a position above ground when the manhole cover is removed for workers. Handhold 62 rotates freely 180 degrees on axle 64 from a vertical orientation extending downwardly as shown in FIG. 10, to a position where handhold 62 extends vertically above ground level. Axle 64 is mounted on support element 67 which is secured to manhole frame 50 by bolts 69. Two pins 66 removably extend through holes 68 in support element 67 and handhold 62 to releasably hold handhold 62 in the up or down position depending on whether the manhole is in use.
(20) FIGS. 11 and 12 illustrate a handhold 80 which can be extended vertically and supported by hooks 82 in a position above ground when the manhole cover is removed for workers. Handhold 80 has horizontal upper bar 88, vertical shanks 81 and lower horizontal bar 85 which sits on hooks 82 when in the upper position shown in FIG. 12. Vertical shanks 81 extend through holes 83 in annular lip 60. Holes 83 are wide enough to allow shanks 81 to tilt to allow lower end 85 to pass around hooks 82. The upper surface of annular lip 60 can be recessed to receive upper bar 88 so that the surface is flush to receive a manhole cover when the handhold 80 is in the lower position shown in FIG. 11. When extended upwardly the handholds shown in FIG. 7-12 may also serve as an easily accessible attachment point for life lines attached to a worker in a manhole.
(21) Two piece manhole frames, comprising the manhole casting 50 and an inner support sleeve or riser 54 may have these methods applied to either or both of the manhole frames and base 50 and/or riser (inner sleeve) 54 sections. In the latter case holes for the extended arms of the handhold 23/25/28/30/62/80 are provided in the inner sleeve 54 higher up toward the base of the manhole frame. As noted above, the handhold is not required to be set in a continuous even spacing as required for a step rung placement. The handhold need not protrude as far from the frame 50 or inner sleeve 54 at the point of embedment as a step rung, allowing for a greater access area in the entrance to the manhole than the step rung placement procedure.
(22) With regard to the various methods described above, once the handhold has been incorporated into the manhole casting, the casting 50 is imbedded into the concrete support structure 72. Modifications to the design and placement of the handholds may be made to accommodate different sizes and styles of manholes. A handhold can be placed in a horizontal orientation while a vertical orientation would clearly distinguish it from a step rung as a handhold.
(23) The manhole thus in this way may have one or more handholds attached to the manhole frame to facilitate a person to enter or exit the manhole. The handhold is located close to the upper opening of the manhole. The handhold is smaller than a ladder rung and protrudes preferably about 2 inches or less radially inwardly into the manhole opening from the inner edge of the annular lip 60. The handhold can be vertically or horizontally oriented. In some embodiments, the area behind the handhold may be recessed so as to reduce the protrusion of the handhold into the manhole opening. According to one variation the handhold is movable between a first position wherein the handhold extends above ground in use and a second position wherein the handhold is stored below ground when the manhole cover is closed.
(24) While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the invention be interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
