US 446151 A
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R. MUNROE. MAN HOLE COVER.
No. 446,151. Patented Feb. 10, 1891.
UNITED STATES ATENT FFICE.
ROBERT MUNROE, OF ALLEGHENY, PENNSYLVANIA.
SPECIFICATION forming part of Letters Patent No. 446,151, dated February 10, 1891.
Application filed October 16, 1890, fierial No. 368,312. (No model.)
Tdall whom, it may concern} Be it known that I, ROBERT MUNROE, a citizen of the United States, residing at Allegheny, in the county of Allegheny and State of Pennsylvania, have invented or discovered a certain new and useful Improvement in Man-Hole Covers, of which improvement the following is aspecification.
My invention relates to covers for manholes on steam-boilers, tanks, &c., and is an improvement upon that for which Letters Patent of the United States No. 339,998 were granted and issued to me under date of April 13, 1886.
The object of myinvent-ion is to providea man-hole cover by the use of which a perfect and absolutely steam-tight joint may be attained and there-enforcement and strengthening of the metal around the man-hole effected.
The improvement claimed is hereinafter fully set forth.
In the accompanying drawings, Figure 1 is a face View of a man-hole plate in accordance with my invention; Figs. 2 and 3, transverse sections through the same when connected to a boiler-head at the linesoc 0c and y y, respectively, of Fig. 1; and Fig. 4, a perspective View, partly in section, of a portion of a steamboiler with my improvement applied.
In the practice of my invention I form the man-hole 2 in the head 1 of a boiler or tank or in the shell thereof, as the case may be, similarly to the man-hole of my Letters Patent No. 339,998 aforesaid-that is to say, by
cutting an opening in the Sheet 1 of smaller dimensions than the man-holedesired and turning the metal of the sheet inwardly around said opening, so as to increase it to the desired size and form afiange 3 around it. The sheet is properly annealed after flanging the opening, and the face of the flange 3 is planed off truly, so as to insure a uniform bearing for the cover and a correspondingly tight joint therewith. The man-hole plate or cover 4 is of corresponding form with, but slightly larger than, the contour of the flange 3 ofthe head, and is provided near its periphery with a circumferential groove 5, in which said flange fits when the cover is put in place on the man-hole, a gasket or packing ring 8 of rubber, lead, asbestus, or other suitable mateouter faces of the lugs 7. slipped laterally into the recesses, which are 5 rial being interposed between the face of tlres flange 3 and the cover. In order that mutual bracing and support of the metal of the head 1 5 5 around the man-hole and .of the cover may be provided, a deep flange 5 is formed on the cover 4 on the inner side of the groove 5, said flange being adapted to fit against the flange 3 of the head up to or near the turn of said flange, thus acting effectively to resist lateral strains and re-enforoing and strengthening the flange 3.
The function for which the flange 5 is specially provided is to afford a continuous lateral bearing for the flange 3 of the head on its inner side, such function being wholly independent of and additional to that of forming the wall of a recess for the reception of packing, as in my patent, No. 339,998, before referred to. The rigidity thereby imparted to the flange 3 greatly promotes its maintenance in normal form under strain, and has been found in practice to make a materially better and tighter joint than under the former practice Without involving any objectionable increase in the weight or cost of the cover 4.
The clamping-bolts by which man-h'ole covers are secured in place have ordinarily been lugs to receive and provide bearings for the 90 heads of the clamping-bolts 10,from which recesses narrower recesses 11, adapted to admit the bodies of the bolts, extend to the The bolts 10 are open at one side, the boltheads bearing against the shoulders at the bottoms of the recesses'll, and the cover is drawn up to the requisite bearing on the gasket 8 and headflange 3 by nuts 12, engaging threads on the IOC clamping-bolts and bearing on arch-bars 13, fitting freely around the bolts and having their ends abutting against the head 1 on opposite sides of the man-hole. A handle 6 is In order to admit fixed to the man-hole cover to facilitate its connection to and removal from the head, as from time to time required.
The laterally-recessed lugs and the clamping-bolts having ordinary heads fitting therein, While desirably and preferably applicable in connection with my improvement, do not form an essential part thereof and are not claimed as of my invention.
Iclaim as my invention and desire to secure by Letters Patent- 1. A man-hole cover having a circumferential groove adapted to receive a flange surrounding a man-hole opening, and provided with a flange at the inner side of said groove of contour similar thereto and of suflicient depth to fit against the man-hole opening flange from its face to or near its turn, substantially as set forth.
2. The combination of a metal sheet having a flange turned upon it around a manhole opening, and a cover provided with a circumferential groove receiving the flange of the sheet, and a flange at the inner side of said groove fitting against the flange of the sheet to or near the turn thereof, substantially as set forth.
In testimony whereof I have hereunto set my hand.
Witnesses J. SNoWDEN BELL, R. H. WHITTLESEY.