US 3142234 A
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Description (OCR text may contain errors)
July 22;, 1964 F. v. MALOON 3,142,234
MANHOLE SHIELD Filed Dec. 21, 1959 F IG .--|9 6 tl9 o INVENTOR.
FRED M MALOO/V ATTORNEYS United States Patent 3,142,234 MANHOLE SHIELD Fred V. Maloon, 3117 Withers Ave, Lafayette, Calif. Filed Dec. 21, 1959, Ser. No. 861,082 6 Claims. (Cl. 94-48) This invention relates to a manhole shield adapted to be supported on a manhole frame when the manhole cover is removed to prevent water, dirt, tools and other material from falling into the open manhole.
Heretofore, when a manhole cover for a manhole that opens into an underground passageway, or an underground service chamber for servicing or repairing electrical, gas or water conduits etc., is removed, it is customary to position a shield around the frame opening to prevent tools and foreign material above the surface of the ground from falling into the opening and onto the workmen below the opening. These are caulked around the opening to prevent water, snow etc. on the street or above the surface of the area around the opening from passing through the latter. This is a time consuming operation that is quite expensive, particularly where those installing the shield are skilled workmen who may also do the repair or servicing work Within the underground chamber or passageway.
One of the objects of the present invention is the provision of a manhole shield that is economical to make and that may be installed and removed in a matter of sev* eral minutes, and which shield, when installed, effectively seals off the manhole against any leakage of water, sleet, snow, etc. between the shield and the frame.
Other objects and advantages will appear in the drawings and description.
In the drawings, FIG. 1, is a fragmentary, vertical sec tional view of slightly more than half of the shield secured in place on a manhole frame, said view being taken along line 1-1 of FIG. 2.
FIG. 2 is a reduced size top plan view of the shield on a frame.
FIG. 3 is an enlarged fragmentary sectional View through one side of the shield and the manhole frame and an extension on said frame.
FIG. 4 is a slightly modified form of clamp adapted to be used on a shield.
FIG. 5 is a top plan view of a rectangular manhole frame with a shield thereon.
FIG. 6 is an enlarged sectional view taken along line 66 of FIG. 5.
In detail a conventional circular manhole frame is indicated at 1, in which the upper inner corner of the frame is rabbeted to form a recess providing a radially inwardly directed surface 2 and an axially upwardly directed surface 3. An axially downwardly facing surface 4 is below the portion having the upwardly directed surface 3. Normally, the manhole cover is formed with a rabbet complementary to the aforesaid rabbet in the frame, so that a radially projecting portion on the cover rests in the rabbet in the frame with the uppermost sur face of the cover flush with the uppermost surface 5 of the frame. Where the frame is in a paved street, the upper surface of the street is normally substantially flush with the upper surface of the cover and frame.
The manhole shield that is shown in the drawings comprises a cylindrical, vertically disposed wall 6 the outside diameter of which is slightly smaller than the inside diameter of the frame and this wall has a radially outwardly directed annular flange 7 rigid therewith that is adapted to extend over the upper surface 5 of the frame for supporting the wall on said frame in an upright position.
The wall 6 has a downwardly extending lower portion 8 below flange 7 that may terminate at its lower edge approximately flush with the shoulder or axially downwardly facing surface 4 of the frame.
This lower portion 8 may be tapered inwardly along its lower terminating edge to facilitate guiding the portion 8 into the manhole in setting up the shield.
From the foregoing it will be seen that a generally rectangular space will be left between the shield and the frame defined by the lower surfaces of the flange 7, the upper surface 3, the radially inwardly facing surface 2, and the outer surface of the portion of wall 6 that is below flange 7. The radially inwardly facing surface 2 of the frame is usually slightly inclined laterally outwardly in an upward direction.
Around the lower portion 8 of the wall 1 that is opposed to surface 2 on the frame, is an expansible, fluid inflatable tube 9, which tube is carried by the portion 8 in yieldable frictional engagement therewith, or it may be vulcanized or otherwise connected to the portion 8, if de sired.
When inflated by any suitable source of fluid under presure through a conventional valve stem 10 having a conventional check valve, such as in an automobile or bicycle inner tube or tire, the tube 9 will expand radially outwardly and axially to form a tight fit in the space formed by the rabbet in the frame. Tube 9 is preferably molded to generally conform to the cross sectional contour of the space formed by the rabbet, although it may be cylindrical.
When the valve 10 is opened to permit escape of the air or whatever fluid is in the tube, the latter will collapse and will move away from the surface 5. Thus, in its collapsed position the tube will offer no obstruction to entering the rabbet in the frame, and will not become chafed. In this connection, it should be mentioned that the lower portion 8 of the wall 6, fits the inside of the frame below the rabbet thereon with suflicient accuracy to center the portion 8 in a manner that will prevent the tube 9 from sliding against the surface 2 when the shield is installed and removed.
The valve stem 10 may extend radially of the portion 8 to the inside of the shield, but preferably it is outside wall 6 and extends upwardly through the flange 7 so as not to interfere with a person entering the manhole or leaving it, and also, in the position extending through flange 7 the latter will protect it against possible injury.
Projecting inwardly inside wall 6 are several pairs of vertically aligned and vertically spaced bearings 13. Supported for vertical reciprocable movement by each pair of bearings is a vertically elongated rod 14 carrying a jaw or clamping member 15 at its lower end and a head 12 at its upper end.
The jaw or clamping member 15 on each rod 14 may be of the conventional type that is adapted to be moved upwardly at any time by the hand of an operator, but which will be releasably locked against return or downward movement by a spring urged toothed cam 16 that is adapted to engage the rod. The cam has a releasing lever 17 projecting therefrom. Upon pressing said lever away from rod 14 jaw 15 will be released to slide downwardly but the cam will automatically engage the rod again upon release of the lever.
This clamping jaw 15 is only one suitable example of a structure that may be used.
Each rod 14 is cylindrical and may be rotated in the bearings so that the jaw thereon may be swung to a position projecting radially outwardly of the wall 6 below its lower end position. When not in use the jaw may be swung inwardly, and the lower portion of wall 6 is formed with a downwardly opening recess 18 (FIG. 1) in which the rod-mounted portion of jaw 15 is adapted to move 3 when the jaw is swung to radially inwardly projecting position and the shield is stored or carried. Thus the clamping means may vertically be positioned wholly within the laterally projected confines of the structure of the shield. It is obvious, of course, that the recess 18 may partially receive jaw 15 when the latter is in operative position should the manhole frame dimensions be such that the jaw must move into the recess in order to be operative.
Preferably the rod 14 is formed with vertically spaced openings 19 each adapted to removably receive a pin 20 therein.
In certain instances where streets are repaved, the manhole frame would be positioned below the upper surface of the added layer of paving, unless some means were provided to bring the cover supporting portion to the level of the pavement. The usual structure for doing this is the provision of a ring 21 (FIG. 3) that fits in the rabbeted portion of frame 1, and this ring, in turn, is formed with a rabbet that is identical to that in the frame. This ring is of a thickness that equals the added paving on the old street.
Ring 21 has an upper surface 23 that corresponds to surface 3 of frame 1, and a radially inwardly facing surface 24 that corresponds to surface 2 of said frame.
In operation, where no ring is used (FIG. 1) the initial step in positioning the shield, after the manhole cover is removed, is to insert the lower portion 8 of the wall 6 in the opening in the frame so that the flange 7 will support the wall upright on the frame. The flange 7 will, of course, rest on the uppermost surface of the frame.
The pin 20 in each rod 14 will be in the middle one of the three openings 19 shown in FIG. 1, in which position the clamping jaw, when at the lower end of each rod, will be adapted to be swung to a position below the downwardly facing shoulder 4 of the frame, which shoulder is the lower surface of the portion 22 of the frame.
The clamping jaws are then moved upwardly until they engage said surface 4, and thereafter the tube 9 is inflated.
When tube 9 is inflated, it will positively seal the space between the wall and the frame and will also form a seal between the flange 7 and the frame. The flange 7 will cover the tube and will protect it, and assures a uniform pressure against the frame and will shield it at all points around the latter.
In the event the ring 21 is used, as seen in FIG. 3, the tube 9 will be positioned within the rabbet that corresponds to that of the frame, and the flange 7 will be supported on the uppermost surface of the ring outwardly of said rabbet.
The pin 20, in the above instance, will be positioned in the uppermost of openings 19 in each rod, which will allow rod 14 to be lowered a suflicient distance to bring the jaw thereon below the surface 4 of the ring. Each of the jaws may then be moved upwardly to engage surface 4, and the tube is inflated.
When the shield is collapsed for transport or carrying,
the pin 20 on each rod may be inserted in the lower of the openings, in which position the rods will be held within the shield.
As seen in FIG. 1 the pins 20, in each position of the rods, engage the upper bearings 13 of each pair thereof to limit the downward movement of the rods, pins 20 may be cotter pins or any other suitable pins adapted to be releasably held in the openings 20.
The modification shown in FIG. 4 is one in which the shield itself, including its lower end portion, is identical with the shield of FIGS. 1-3, hence the cylindrical wall 6 and its lower portion 8 will bear the same numbers. Bearings 13 are also the same as in FIG. 1.
Bearings 13 have rods 25 reciprocably supplied thereon which rods may be substantially the same as rods 14 except that they do not require openings 19 and in the modified form each rod is provided with a laterally projecting jaw 26 rigid therewith.
A helical spring 27 reacts between the upper bearing 13 and the head 28 at the upper end of the rod to yieldably hold each rod in collapsed position within the shield, when the jaws 26 are turned so they project into the shield.
In actual practice, after the shield is positioned on a manhole frame 1, as described for the shield of FIG. 1, the jaws 26 are drawn downwardly against the resistance of springs 27 and are swung outwardly to positions below the portions 21 of the frame 1, and are released. The jaws will then guidably hold the shield in position.
To remove the shield it is merely necessary to swing the jaws inwardly and they will automatically be drawn into collapsed positions.
Recently certain municipalities have adopted rectangular manhole structures. FIG 5 is a top plan view of a manhole frame 30 that is rectangular, with corner recesses to receive corresponding extensions on a rectangular cover.
In this form of manhole frame the four sides are straight but each corner recess is formed with a ledge 31 thereon spaced a substantial distance below the upper side of the frame that is adapted to have its underside engaged by a clamping jaw similar to that shown in FIG. 3 or 4.
In this form of invention, the shield itself will have flat rectangular walls 32 having a flange 33 (FIG. 6) adapted to overlie the uppermost surface of the frame. The lower portion of the shield will be an integral extension of walls 32 projecting into the rectangular space enclosed by the latter providing a laterally outwardly opening channel 34 in which an expansible tube 35 is positioned. This tube will be in opposed relation to the inner surfaces of the sides of the shield along the uppermost edge of the frame. When it is inflated it will form a tight seal between the frame and the shield.
Rods 36 are mounted for vertical reciprocation in bearings 37 mounted on the vertically designed bottom of channel 34. Springs 38 are interposed between the heads 39 of the rods and the bearings to yieldably urge the rods upwardly. Jaws 40 respectively on the lower ends of rods 36 are adapted to engage the under sides of the ledges 31 in each corner recess. The tube 35 will accommodate itself to any irregularities in contour at the corners of the frame.
From the foregoing description, it will be apparent that only a few minutes time will be required to install a shield or to remove it.
It is not intended that the detailed description shall constitute limitations on the invention. The claims appended hereto are intended to cover such modifications as may be made within the scope of the invention.
1. A shield for use on a horizontally disposed, centrally open manhole frame that defines the outline of a manhole comprising: an open ended vertically disposed rigid tube having an upper portion and a lower portion and a horizontally disposed flange rigid with said tube adapted to extend over and directly engage the upper surface of such frame for supporting said upper portion directly on said frame coaxial with the latter and projecting upwardly thereon and for supporting said lower portion within such frame, an air inflatable tube below said flange and around said lower portion expansible upon inflation with air from a collapsed position out of sealing engagement with said frame when said flange is on and in engagement with the latter whereby said rigid tube may be removed from said frame without injury to said inflatable tube, to an expanded position in sealing engagement with said flange, lower portion and such frame, and means on said rigid tube adapted to positively but releasably lock said rigid tube rigid with such frame and to hold said flange against the upper side of said frame when said inflatable tube is inflated.
2. A shield for use on a horizontally disposed, centrally open manhole frame that defines the outline of a manhole comprising: an open ended vertically disposed rigid tube having an upper portion and a lower portion and a horizontally disposed flange rigid with said tube adapted to extend over and directly engage the upper surface of such frame for supporting said upper portion directly on said frame coaxial with the latter and projecting upwardly thereon and for supporting said lower portion within such frame, an air inflatable tube below said flange and around said lower portions expansible upon inflation with air from a collapsed position out of sealing engagement with said frame when said flange is on and in engagement with the latter whereby said rigid tube may be removed from said frame without injury to said inflatable tube, to an expanded position in sealing engagement with said flange, lower portion and such frame, and means on said rigid tube adapted to positively but releasably lock said rigid tube rigid with such frame and to hold said flange against the upper side of said frame when said inflatable tube is inflated, said flange terminating at its outer peripheral edge a distance from said lower portion to fully extend over said inflatable tube and the upper surface of said frame only whereby said flange will be adapted to seat against the upper surface only of said frame to thereby be free from the influence of irregularities in pavement that may be around and extend to said frame.
3. In combination with a horizontally disposed manhole frame having a horizontally disposed upper surface; a central manhole opening formed in said frame having vertical sides defining the outline of said opening; said frame being rabbeted to provide a recess in said frame around said opening at the upper end thereof having an axially upwardly facing surface and an adjoining radially inwardly facing surface respectively adjoining said upper surface and said vertically extending sides; a tubular open ended shield coaxial with said opening having a lower portion extending into said opening downwardly past said recess and an upper portion projecting upwardly from said opening; a horizontally disposed rigid flange rigid with said shield at the upper end of said lower portion extending horizontally over said recess and in engagement with said upper surface supporting said shield on said frame; an inflatable expandable tube of elastic, rubber-like material around the upper end of said lower portion and below said flange disposed in said recess, said tube being inflatable with air from a collapsed position within said recess out of sealing relation with said radially inwardly facing surface of said recess to an expanded position in sealing relation with said lower portion, said flange and said radially inwardly and axially upwardly facing surfaces of said recess, means for inflating and deflating said tube, and locking means carried by said shield in locking engagement with said frame for holding said flange against said upper surface when said inflatable means is inflated.
4. In combination with a horizontally disposed manhole frame having a horizontally disposed upper surface; a central manhole opening formed in said frame having vertical sides defining the outline of said opening; said frame being rabbeted to provide a recess in said frame around said opening at the upper end thereof having an axially upwardly facing surface and an adjoining radially inwardly facing surface respectively adjoining said upper surface and said vertically extending sides; a tubular open ended shield coaxial with said opening having a lower portion extending into said opening downwardly past said recess and an upper portion projecting upwardly from said opening; a horizontally disposed rigid flange rigid with said shield at the upper end of said lower portion extending horizontally over said recess and in engagement with said upper surface supporting said shield on said frame; an inflatable expandable tube of elastic, rubberlike material around the upper end of said lower portion and below said flange disposed in said recess, said tube being inflatable with air from a collapsed position within said recess out of sealing relation with said radially inwardly facing surface of said recess to an expanded position in sealing relation with said lower portion, said flange and said radially inwardly and axially upwardly facing surfaces of said recess, means for inflating and deflating said tube, and locking means carried by said shield in locking engagement with said frame for holding said flange against said upper surface when said inflatable means is inflated, said frame being imbedded in pavement extending to said upper surface of said frame and said flange terminating at its outer peripheral edges short of said pavement as to be supported solely by said frame and independently of said pavement whereby said flange will seat against said upper surface free from the influence of irregularities in contour of the pavement adjoining said frame.
5. In combination with a horizontally disposed annular manhole frame having a central opening for passage of a man therethrough, said frame being rabbeted circumferentially thereof along its upper and radially inwardly facing sides to provide an annular recess coaxial with the frame having adjoining axially upwardly and radially inwardly facing surfaces; a tubular, cylindrical, vertically disposed shield in a position coaxial with said frame removably extending at its lower end portion into said opening and past said recess and having an upper portion projecting a substantial distance above said frame, a radially outwardly extending flange rigid with said shield extending over said recess and the uppermost surface of said frame adjoining the latter supporting said shield on said frame in said position whereby said flange, said axially upwardly facing and radially inwardly facing surfaces of said recess and the radially outwardly facing surface of said lower portion of said shield coact to provide the walls of an annular passageway around said shield below said flange; an annular, air inflatable tube of flexible, elastic material within said passageway expansible upon inflation thereof with air to tightly engage said walls of said passageway for forming a seal between said shield and said frame to prevent water outside said shield and above the level of said frame from entering said central opening in said frame, and quick releasable locking means carried by said shield within the latter including spaced frame engaging members separately and releasably engaging said frame at spaced points around said frame and spaced below said recess for holding said shield rigidly in said position with said flange over said recess.
6. In a construction as defined in claim 5, said quick releasable locking means comprising rods extending vertically along the radially inwardly facing surfaces of said shield, means for supporting said rods on said shield for rotation about their vertical axis, said frame engaging members projecting laterally from the said rods and being movable from frame engaging positions projecting radially outwardly relative to the axis of said shield and across the lower edge of the latter to a shield releasing position in which they project radially inwardly relative to said last mentioned axis and to positions within the downwardly projected confines of the outline of said shield to enable upward removal of said shield from said frame.
References Cited in the file of this patent UNITED STATES PATENTS 1,908,909 Manz May 16, 1933 1,957,162 Erickson May 1, 1934 2,281,633 Stitzer May 5, 1942 2,559,564 Sperling July 3, 1951 2,757,225 Dunn July 31, 1956 3,007,600 Horner Nov. 7, 1961 FOREIGN PATENTS 547,072 Great Britain Aug. 12, 1942