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Title : A Protection Device of Manhole Covers.
Prior Art:
Still today manhole covers are fitted as prevailing practice. Nothing new or extra ordinary systems are observed in the existing manhole covers. We think that the existing practice can be developed further. Frequently here and there coverless manholes are seen on the roads. Accidents are inevitable for the coverless manhole. In the past it caused loss of life. Who knows how many such incidents will occur in future? Vehicles may face accidents at any time. But in our newly invented system we can overcome it.
Our objection :
In the existing practice the manhole covers are fitted in a casing / frame. Which can be easily taken out by any miscreant. Some dishonest and antisocial elements steal those manhole covers for a little earning which causes heavy damage to the society. It is a matter of great anxiety. This causes heavy loss of money on the part of corporation / Municipality to fill up the manhole cover. In order to stop such antisocial activities no positive action or remedial measure has yet been taken from any corner for stopping of such type of activities. It has not yet been possible to stop theft of manhole covers and it is really too difficult to stop the same in the existing process. As it is a National problem and carries great significant, we want its remedial measure so that no body can steal manhole covers easily in future.
Our object:
Now we have already overcome this problem after so many observation and research. We claim it boldly that it will be very difficult to take out the manhole covers in future if our newly invented technology is applied resulting to no loss of life or any accident due to theft of manhole covers. This will arrest heavy drainage of money on the part of corporation on account of theft of the manhole covers which in turn will attract a great relief to our social life.

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Description of the device :
In our new device/ project in order to lock a manhole cover in a frame coupled with maintaining the norms of ISI standard some additions and alterations of the device has been blue printed which has been marked in fig. 1 Sheet no. 1
The manhole cover is itself locked inside the frame if its cover is properly placed over the frame. Without the application of a special type of key ( K ) the same cannot be unlocked or opened, as in fig - 3 the design of the key has been exhibited in diagram (f-1 ) sheet no. 2 the keyhole ( Kw ) on manhole cover has also be exhibited.
In the new device two special designed of same size and same shaped solid metallic cylindrical roads (R1 and R2) whose length is a little less than the radius of manhole cover and one end of each rod is tapered in one side. A little ahead from this tapered end a 0.5" thick 0.5" high cylindrical shaped bit (B, & B2) has been made in each rod.
Two same type of special springs (S1 & S2) through which the rods can move freely are placed between the bits (B1, B2) and the casted (0.5" thick 2" length 3" height) walls (W1 & W2) which is fixed with the inside surface of the manhole cover are used for keeping the rods towards the outside walls of the Manhole cover.
There is a hole in the centre of each wall (W1 and W2), and the diametre of the hole is a little larger than the diameter of the rods.
There are another two holes (H1, H2) in oposite direction on the cylindrical wall of manhole cover. Both the axis of casted wall's hole and cover wall's hole is on same line and the rods are placed between two holes and only the tapered end of the rods are extended (for locking purpose) towards the inside wall of the frame of the manhole cover. By pressing the tapered end, the rods will move inside, on the other hand by pulling the another end of the rods then it will also move in side the cover and after removal of the pushing or pulling pressure, the rods will return to its previous position.
Two same type rectangular shaped first category levers (L1 & L2) whose fulcrum has divided the arms of the levers into 2:3 ratio, the end of big arm of the lever has been loosely fitted with the other end of the rods ie opposite side of tapered end and the shape of the end of the rods is squared shaped and there is a small hole on the square flat surface of each end of the roads for riveting.
The end of small arm of the levers are L-type shaped on which the wings of the key will create pressure to unlock the manhole cover from the frame. Inspite of that two casted pins (P1 & P2) are fixed on inside surface of the cover to hold the levers in different height and act as fulcrum point of the leavers.
All these rods, springs, levers, which are integrated and fixed with the inside of manhole cover are made of stainless steel to avoid the rust.

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A special key ( K ) which has two metallic wings in one end of a cylindrical shape (3'/4') long stick and in other end a T-type handle to move clockwise or anti-clockwise of the key. The wings are square type (3" x 3") aprox. and ½" thick metallic plates and fixed in different height and also fixed in opposite side on the other end of the stick according with the levers height respectively.
With a specific distance apart from the wings end two (3" to 4"diameter) metallic discs (D1 & D2)with a spring (S) between two discs are fixed on the stick as a manner that lower round plate will stop absolute moving of the key into the keyhole as the wings touch the lever end which has been fixed in diferent hight. The spring is used to move the key freely and easily on the top surface of manhole cover.
In this device there is a little alteration in the frame in which a (1.5" to 2" approx). groove/ channel has been made (in the time of casting) inside of cylindrical wall of the frame and parallel with the same hight and maintains same axis of the tapered rods and the height of the groove/channel must be a little larger than the diameter of the rods and the depth of the groove is also a little larger from the extended tapered portion of the rods ie the tapered end of (R1 & R2) easily stay and move into the groove/ channel of the frame.
The rods (R1 & R2)will be placed between the holes (H1, H2) and the wall (W1 & W2) respectively as a manner that the extended portion of the tapered end remains near to the top of the manhole cover.

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Working Procedure :
When the manhole cover is placed on a frame in proper measurement, the cover will go inside the frame easily because the inside edge as well as the body of the wall of the frame will press the tapered portion / end, and the rods will move into the wall of the cover without any trouble and whenever the cover will take its proper position the pressure on the tapered end will be removed because in that time the tapered end will take its position for the springs (S1, S2) into the channel/groove and for this reason this tapered end of the rods are spring loaded and shifted in the frame wall in a way that it can move either forward or backward direction as per the tapered end will hold the cover with its frame,that means manhole cover has been locked.
When it is necessary to open the cover from its frame with the help of key then at first, the key will be placed into the keyhole on the cover and by pressing a little on the handle of key down wards (the round plate will help misplacing of the key) after that by moving the key handle clockwise, the cover can be unlocked because the wings of the key will press the levers' end and it will move forward and other end of the lever will pull the rod in backward so tapered end will move in side as well as it is taken out from the groove / channel and there will have no obstruction as the cover will go out after pulling up the cover by lifter in fig-4. To make easy this operation two L-type lifters will help, by placing the lifter in the opposite to any of two holes out of four holes which had been made in four different places over the manhole cover and has been shown in fig —1, sheet no.2

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Title : A Protection Device of Manhole Cover We Claim :
Claim 1. A Protection device of Manhole cover comprising of two complementary parts, one part being a setup of a locking device consisting of two same type steel rods (R1 & R2), two steel springs (S1 & S2) and two same type levers (L1 &L2) which are integrated in a specially designed manhole cover (C) that is compacted inside a specially designed Frame (F) and another part is a specially designed Key (K) by which the manhole cover can only be unlocked.
2. A Protection Device of Manhole Cover as claimed in claim 1, wherein
mentioned manhole cover which is specially designed and consists of two holes
(H, & H2) on the wall of the cover in opposite direction and two casted
partition walls (W1, & W2) (Size aprox 3" X 3" Xl/2") inside with the cover
and two casted pins (P1 & P2) in different height and fixed on both side of the
keyhole inside with the cover to hold the Livers (L1 & L2) are placed inside the
Frame (F) and shown in fig-f-1 sheet no. 2.
3. A Protection Device of Manhole cover as claimed in claim 1 and 2 wherein
two steel rods (R1 & R2) are mentioned of which one end is one side tapered
and other end is square type flat in shape with a hole in its center and there is
also at a little heigh and thick bit (0.5" X 0.5") approx like a ring arround the
rods is situated aprox 2" apart from the tapered end which are drawn in fig f-1
sheet no. 2.
4. A Protection device of manhole cover as claimed in claim 1 & 2 wherein the
said steel springs (S1 & S2 ) are placed in between the bits (B1 & B2) and the
partition walls (W1 & W2) respectively inside surface of the manhole cover to
press the rods (R1 & R2) towards out side the wall of the cover continuously
and have been shown in fig-1 sheet no. 2.
5. A Protection Device of Manhole Cover as claimed in claim 1 & 2 wherein
the said levers (L1 & L2) are placed on the pins (P1 &P2) respectively that
worked as fulcrum point which divided the levers in 3:4 ratio, whose long end
are fixed with two flat end of Rods (R1 & R2) respectively and the small arm
whose ends are 'L' type in which wings of the key use to press for unlocking of
the manhole cover and these lever are drawn in fig -1 sheet no. 2

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6. A protection Device of Manhole Cover as claimed in claim 1 & 2 wherein
the said Frame (F) in which the Cover is inserted has a chanel/groove cutting
with a little over size of the diameter of the rod along with the same axis A1B1
and A2B2 of the cover holes and Rods (R1, & R2) is shown in fig -1 and 2 sheet
no. 2
7. A protection Device of manhole cover as claimed in the preceeding claims
where in the key which is a specially designed, placed into the key whole ( Kw)
of manhole cover for unlocking of the cover from the frame with a 3' or 4' long
1" to 1.5" diameter stick of solid wooden roller or cylindrical hollow iron pipe
with a T-type handle in one end and two wings at different heights are fixed in
the other end in opposite direction and two discs with a spring in between those
metallic discs (3 to 4" diameter approx.) and are placed in a specific distance
apart from the wings to keep the key in the right position in the hole inside of
the manhole cover and are shown in fig-3 sheet no. 2
8. A protection Device of Manhole Cover substantially as herein before
described with reference to the accompanying drawings attached with this
complete specification, sheet no. 1 & 2