US 2009132 A
Description (OCR text may contain errors)
y 3, 1935- J. L. GEHRIS 2,009,132
MANHOLE CONSTRUCTION ori inal Filed Nov. 10', 19:52. 2 Sheets-Sheet 1 wuiiminm Jul 23, 1935. J, L, EHRls 2,009,132 7 MANHOLE CONSTRUCTION I Original Filed Nov. 10, 1932 2 Sheets-Sheet 2 5 20 mm" 5 51.2445 i4 J 50 A HHHWHII a Z5 0 24 26 ojflj 21 Z l a1 26 10 i4 29 Patented July 23, 1935 PATENT OFFIQE 2,009,132 MANHOLE GQNSTRUCTION Jeaeplr L. Gehrls, Reading, Pa.
Application November 10, 1932, Renewed lune 6,
My invention relates to inlet devices for sewers or the like and has particular reference to manhole cover structures that usually include metallic casings or housings permanently built into 5 the paving structure of the street and a detachable cover plate.
A purpose of the invention is to provide a device of the character indicated easy and inexpensive to manufacture and well suited to the needs of service.
A further purpose isto provide a manhole cover device that will not rattle under automobile traffic.
A further purpose is to provide a cover plate with virtually a three-leg support upon its casing, the legs preferably to comprise arcuately spaced downwardly directed arcuate pads integral with the cover and to rest upon spaced portions of a cooperating inward flange of the casing.
A further purpose is to reinovably downwardly wedge the cover to its seat at opposite sides thereof, preferably strongly spring pressing relatively movable wedge portions of the cover apart into wedge recesses of the casing on opposite sides thereof, one of the said relatively movable portions comprising preferably a spring latch and the other the main body of the cover.
A further purpose is to locate a spring latch in a radial perforation through one of the three legs or pads, spring wedging the cover down to its seat at the one arcuate leg or pad and on the other side to provide a wedge extension from the cover at a part thereof midway between the two other pads whereby at the said other side the downward pressure upon the cover, efiected by the cooperating wedge surfaces, is supported equally upon the said two other arcuately spaced legs or pads.
A further purpose is to provide a cover of the character indicated with a novel and particularly simple and convenient form of latch mechanism.
A further purpose is to provide a cover with a relief valve to permit automatic relief of any pressure within the sewer incident to the accumulation or explosion of sewer gases or the like.
A further purpose is to combine a casing, a
cover and a lock holding the cover rigidly to itscasing with a pressure relief valve, thereby avoiding danger of the casing and whole structure being blown out of its setting in the event of a gas explosion within the sewer closed by the structure.
Further purposes will appear in the specification and in the claims.
Serial No. 641,988 1935 I have elected to show one form only of my invention, selecting a form however that is practical and eflicient in operation and which well illustrates the principles involved.
Figure 1 is a top plan view of structure embodying a desirable form of my invention.
Figure 2 is a vertical section of Figure 1 taken upon the line 2-2 thereof and illustrating the latching mechanism with a. fragmentary dotand-dash showing of the point of a pick adapted to release the latch.
Figure 3 is a fragmentary portion of Figure 2, the latch being closed in Figure 2 and being pushed back by the inserted pick in Figure 3.
Figure 4 is a view corresponding generally to Figure 2, but with the parts together in Figure 2, separated in order to show both members more clearly and with the pressure relief valve closed in Figure 2 shown raised or open in Figure 4.
Figure 5 is a bottom plan view of the cover member and corresponds to a view taken upon the line 5-5 of Figure 4.
Like numerals refer to like parts in all figures.
Describing in illustration and not in limitation and referring to the drawings:
One of the aims of the present invention is to provide a manhole cover and casing structure that will not rattle when subjected to the heavy traflic of rapidly moving automobiles.
In the past the manhole covers have very generally or very frequently failed to seat sufficiently uniformly to prevent them from heavy knocking and rattling when traversed by rapidly moving cars, the plates striking perhaps first on one side, then on the other, being supported at indefinite portions of their circumferences, sometimes at one portion and sometimes at one or more other portions thereof.
I provide a manhole cover with virtually a three-leg support and strongly wedge the cover down to its seat at opposite points on the periphery, respectively in the middle of the engaging portion of one of the legs and midway between the other two legs.
I provide each leg with a very considerable peripheral extension along its line of engagement with the casing, an extension suitably nearly sixty degrees, and as a result of this and. of the downward wedging of the cover at the middle of one leg and at a portion midway between the other two legs, the cover maintains its seat without rocking even when subjected to heavy traffic. v The three-leg support of the manhole cover is very important because the cover and casing are ordinarily both rough castings, which cannot economically be machined. A full peripheral support, or a four-leg support, five-leg support, etc., is therefore likely to rock, due to irregularities in the cast surfaces, or due to rust or dirt between the cover and the casing.
While the manhole cover and easing may be of any suitable shape, they are frequently round, and I am accordingly illustrating an annular structure. It will be understood however, that by using language aptly describing a circular manhole, I do not intend to exclude manholes of other shapes.
The illustrated embodiment of my invention comprises a manhole casing 5 and a cover 6, the casing to be built permanently about a street inlet to a sewer or the like, the top of the casing being usually even with the surface of the street.
The casing circumferentially surrounds the cover and carries the cover upon three arcuately spaced portions of an inward flange 1, the bottom of the cover being suitably provided with three arcuate pads or legs 8 which seat on the corresponding spaced portions of inward flange 1 of the casing.
The flange 1 is spaced downwardy from the top of the casing a sumcient distance for even registry of the tops of the casing and cover and may desirably have greater inward extension under the arcuate pad or legs portions 8 of the cover than intermediate these portions.
The cover is suitably ribbed on bottom and top as at 9 and I0 respectively and when used to close an opening into a sewer in which there may be danger of sewer gas explosions, it is desirably provided with a central opening II to be normally closed by a pressure relief valve l2.
The need for a pressure relief valve is principally incident to my rigid fastening of the cover down to the casing. A vertically loose cover can itself act as a pressure relief member, lifting to permit escape of the gaseous products of any explosion within the sever, but with my cover rigidly fastened to the casing, the whole casing might with a severe explosion be blown from its setting without my safe-guarding relief valve.
The stem of the valve I2 is shown supported and guided by a hub l3 that is connected by radial ribs M to the body of the cover.
The valve I2 is preferably spring pressed downwardly, as by a spring l5 surrounding the stem and compressed between the hub and a suitable key l6 through the lower end of the stem. The key I6 is held in place by the edges of a flanged washer l6.
The valve seat is suitably relieved at three arcuately spaced portions I! of its circumferential length. This clearance along spaced portions of the valve avoids or lessens any danger of the valve either sticking or rattling in its seat, the support being along three preferably uniformly spaced portions of the circumference.
The cover 6 in closed position has a spring pressed wedge interlocking with downwardly directed abutments l8 and I! at diametrally op posite sides of the casing, the interior of the casing being diagonally downwardly, recessed to provide these abutments and to receive radially projecting wedge tighteners 20 and 2| carried by the cover.
The wedge tightener 2| isi rigid extension from the body of the cover and preferably integral therewith and the other wedge tightener 20 the outer end of a spring-pressed plunger 22 herein called a latch and has the double function of latching and wedging the cover into close connection with its supporting seat.
The latch 22 is mounted in an upward recess 23 in preferably the middle of one of the pad or leg portions 8 of the cover, the pad being extended radially inward at 24 to case the rearward portion of the latch and provided with downward lugs 25 to receive a retaining pin 26. A seat 21 is provided on the bottom of the cover for the inner end of a strong spring 28, the forward end 'of the spring seating in a. suitably formed recess at the inner end 21, of the latch member.
The pin 26, put in after the insertion of the latch member, has the double function of holding the body of the latch and of limiting the forward movement of the latch after the cover has been removed or lifted from the casing (Figure 4).
The spring 28 is compressed between inwardly and outwardly directed abutments of the latch and cover body and strongly presses the latch outwardly from the body and thereby strongly presses the wedge tighteners apart to engage the casing at diametrally opposite sides, one of these wedge surfaces being merely an extension suitably in tegral with the main body of thecover and the other the outer end of the latch 22.
The latch tightens under the heavy pressure of its spring whenever the cover plate is subjected to vibration, e. g. vibration incident to traific over the cover, and my combination of three-leg support and strong downward wedging of the cover at its opposite sides secures a continuous tight seating and an avoidance of rattle even under heavy traffic.
For more easy angular registry between the cover and its casing, I provide one of the members, suitably the cover, with a small angular projection 29 to fit a registry recess 30 in the other member. The registry projection (or recess) of the cover should be located directly above the middle of the wedge projection 2| and the corresponding recess (or projection) of the casing at the middle of the casing recess that receives the wedge member 2! of the cover. This registry projection on the cover or on the casing is preferably dimensioned to keep the cover from seating except when in proper registry with the casing.
In replacing a cover, a workman positions the cover so that the projection 29 is opposite the recess 30, drops this side of the cover to its seat, then pulls the cover until the projection 29 and recess 30 register, when the other side of the cover drops and latches to place, the spring latch automatically locking the cover down to its seat.
The wedge surfaces at the end ofv the latch are such that the latch does not reach its full outward movement except when the cover has been removed (Figure 4). The cover is thus wedged downwardly at the latch and the cover is spring pressed to firm engagement with the casing on the side of the cover opposite the latch.
The latch and cover are perforated at 3| and 32, these perforations being relatively offset as clearly shown in Figure 2 for retracting the latch with the point of a pick or the like.
To remove the cover, the point of a pick may be inserted through the perforations 3| and 32, as, for example, to the position shown in Figure 3. This insertion pulls back the latch with or without leverage of the pick and permits the workman to lift off the cover by means of the pick,
the insertion of the pick having pushed back the latch. a
It will be evident that the three-leg support or my invention may be obtained by placing projections on the cover as illustrated, by placing projections on the casing or by placing cooperating projections on both the cover and casing.
The three-leg support is desirable, even without latching down of the cover, but is much more desirable where the cover is latched and preferably continuously wedged down. With three-area support of the cover, and with resilient wedging down of the cover, an initially stable structure is more firmly held each time it yields under vibration or wear.
My relief valve permits ready escape of pressure, so that dangerous pressures are not likely to build up and damage due to explosions is minimized.
In view of my invention and disclosure variations and modifications to meet individual need or particular whim will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I therefore claim all such in so far as they fall within the reasonable spirit and scope of my invention.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:
1. In a manhole construction, a casing adapted to surround a cover and having an inwardly projecting flange to support the cover, there being a pair of peripherally spaced downwardly directed abutments in the casing and a cover resting upon the flange within the casing, there being a projection from the cover cooperating with one of the abutments and there being a spring-urged wedge, movable with respect to the cover and cooperating with the other abutment to urge the cover downward, the wedge being accessible from above to withdraw the wedge from operative position.
2. A manhole construction comprising a casing which surrounds and is flush at the top with a cover, the casing having an inwardly projecting flange, and a cover which rests upon the flange, the casing having diametrally spaced downwardly directed abutments of wedge form, there being a wedge projection from the cover rigid with respect to the cover, cooperating with one of the abutments, a movable wedge slidable radially of the cover and, in operative position, cooperating with the opposite abutment, there being an opening in the cover so that the movable wedge is slidable by a worker above the cover, and a stiff spring urging the movable wedge against its abut ment, whereby the wedge projection and the movable wedge cooperate to hold the cover tight in the casing.
3. A manhole construction comprising a casing which surrounds and is flush at the top with a cover, the casing having an inwardly projecting flange and a pair of peripherally spaced downwardly directed abutments 01 wedge form, and a cover which has three spaced legs resting upon the flange within the casing, there being a rigid wedge on one side or the cover cooperating with one abutment, a movable wedge peripherally spaced from therigid wedge, slidable in a radial direction and cooperating with the other abutment, rigid guides upon the cover to hold the movable wedge against lateral movement. and a spring urging the movable wedge to its position of cooperation with its abutment, an opening being provided in the movable wedge through which a tool can be inserted to move the movable wedge and another opening being provided in the cover to cooperate with the opening in the movable wedge.
4. In a manhole construction, a casing adapted to surround a cover, which is flush at the top with the cover, the casing having a horizontal flange projecting inwardly from the casing at a point intermediate between the top and the bottom of the casing, there being a pair of opposite downwardly directed abutments in the casing above the flange, and a cover resting upon the flange, having a rigid projection oi wedge formation cooperating with one of the abutments and having a movable projection of wedge formationcooperating with the other abutment, the movable projection being guided by walls on the lower part of the cover so as to move radially and being spring urged towards its radially outermost position, the movable projection being accessible from above the cover to operate it.
5. In a manhole construction, a relatively cooperating casing and cover, the casing having a recess and the cover having a projection to secure proper annular registry, the cover having three points of engagement with thecasing for maximum stability and having a pair of cooperating wedges which engage abutments upon the casing, one of said wedges being spring urged outwardly with respect to the other, whereby change in the position of the cover with respect to the casing due to wear on one of the three points of support of the cover will not render the cover unsteady due to the action of the wedges in continuously maintaining the cover firmly seated in the casing.
JOSEPH L. GEHRIS.