US1618678A - Manhole frame and cover - Google Patents

Description

MANHOLE FRAME AND COVER Filed Q t, 18, 1922 Patented Feb. 22, 1927.

UNITED STATES JOHN ROOT, OF CHICAGO, ILLINOIS.

MANHOLE FRAME AIID COVER.

Application filed October 18, 1922. Serial No. 595,313.

This invention relates to manhole frames and covers used principally at street or road levels to afford access to'undcrground constructions.

The objects of this invention are ride a construction of manhole frame and cover, with an improved locking and center ing device for the cover, which also renders the construction free fromobjectional rattle when passed over by traffic.

The objects of the invention are accomplished by the devices shown in the accompanying drawing in which- Figure 1 is a plan view of themanhole frame and cover constructed according to this invention.

Figure 2 is a sectional view taken on line 2-2 of Figure 1.

Figure 3 is an enlargeddetail of one of the locking recesses in the inside of the frame.

Figure 4 is a plan view showing one of the recesses.

Figure 5 is an elevation of a portion of the edge of the lid showing one of the knobs.

The present invention is intended to provide a construction which will result in the cover becoming wedged in a central position in the frame, and which will be safer than the usual designs of manhole frames and covers, in that it is not subject to wear by the'cover vibrating in the frame upon the passage of traffic. The wearing of the covers and their supporting flanges in some designs, results in a liability of the cover tilting in the frame, when the cover is subjected to an eccentric load.

It is also the purpose of the invention to provide a construction wherein the cover cannot be easily removed from the frame except by the use of a crow-bar or some other special wedged-shaped tool.-

The construction jillustrated is the circular type of manhole frame and cover, although the invention may be applied to rectangular frames. The drawing shows a frame 1, the annular wall 2 of which carries on its inner surface an annular flange or seat 3 for cover 4.. Above the flange 3 on the inner surface of the frame are a plurality of bayonet-slot shaped recesses 5, which extend downwardly from the upper surface of the frame and then transversely at the lower portion. These recesses receive hemispherical knobs 6 on the periphery of the cover. As may be seen from Figure to pro- 3 and Figure 4, the recesses 5 arewedgeshaped horizontally, 'i. e., of thcirlower ends '7 than at the enlarged entering end 8 of the recesses with respect to the radius of the manhole; but in the vertical plane the slots o are of the same width, but slope downwardly in the. transverse oxtension. Thus, when the cover is placed in the frame and forced to turn slightlyv in rightshand, direction, the knobs 6 become wedged at the outer ends in the recesses. This causes the cover to properly center in the frame and to become locked thereto. When the cover is rotatedinto place, the lugs 6 jam at the outer ends. The resulting restraining forces therefrom are exercised horizontally at right angles to the vertical disturbing forces of the traffic. The horizontal wedging surfaces are less effective than the vertical wedging surfaces, which alone were depended upon heretofore. When a wheel strikes the cover, the load is suddenly applied downwardly and then suddenly released. This causes a rebound upwardly which reacts directly upon the upper wedging surfaces commonly used, and the force of rebound is resolved by the angularity of the wedging surface into a force which tends to unwind or unlock the cover. The covers become loose and the .upperjand lower surfaces of the lugs become battered and worn, so that the cover cannot lock, and even becomes tilted and thrown out of the manhole.

'VVhen, as in this invention, the lugs wedge at the outer ends. these wedging surfaces are not in line with the battering forces of the traffic and, of course, wear considerably longer than the vertical surfaces, and also effectually prevent the cover from becoming loosened. 7

With this arrangement the cover does not rattle in its frame when passed over by .a vehicle and has no tendency to become released from the frame, but rather to be more firmly wedged therein by thepassage of trafiic over the cover. The cover is provided with an opening 9 at one side and within which extends a shoulder 10 on the inner side of the frame. This shoulder serves as an abutment for a tool used in wedging the cover into the frame or for releasing it therefrom. The opening 9 also serves as a drain for water which collects in the cover.

I claim less depth at said slots being similarly inclined downwardly, peripheral lugs on said cover for engaging in said slots and adapted to jam at the outer ends against the radial Walls of the slots when the cover is rotated intoplace.

2. In a manhole closure, :1 frame having an opening, a cover loosely fitting and seating in saii'l opening having' a plnmlity' of hayonet slots tapering in depth in a horizontal plane, the transverse extensions of said slots being; similarly inclined downwardly, peripheral knobs on the said cover {or engaging in said slots and adapted to jam at the ends in the radial. walls of? the slots, said cover having a peripl'ieral recess, an inwardly projecting lng on said frame, said 111 cooperating with said recess to enahle rotating the cover.

8. In a manhole closure, a frame having a recessed opening, a cover loosely fitting in said recess, the side walls of said recess having a plurality of downwardly sloping slots, said slots being tapered inwardly in the horizontal plane, a plurality of peripheral lugs on said cover for engaging in said slots, said lugs being adapted to jam at the outer ends in said slots.

Signed at Chicago this 10th day of October, 1922. l

JOHN ROOT.

Ill)

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