JP2001172999A - Locking device of manhole cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the locking device of a manhole cover capable of unlocking the manhole cover without using a key, dispensing with the carrying and management of a key bundle and securing the maintenance of the facility of the manhole inside. SOLUTION: The lever shaft 4 of a dial lock provided integrally on the manhole cover 1 is engaged with an engaging member 7 provided on a cover receiving frame 2 to lock the manhole cover 1 on the cover receiving frame 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a locking device for a manhole cover (including a handhole cover) provided in a manhole (including a handhole).

[0002]

2. Description of the Related Art In recent years, with the advancement of road functions, the number of road occupation properties such as water and sewage, electric power, telephone, telecommunications, gas, and management-related facilities has increased, and management information has been diversified. The information gathering and work when performing construction work is complicated, complicated, and inefficient. For this reason, at present, construction and the like cannot be performed unless a plurality of maps, records, and the like of each road private property manager are collected and decoded.

In recent years, a road management system using computer mapping has been promoted, and an IC chip storing management data of roads, management facilities for the roads, and buried and housed articles for road occupation has been attached to a manhole cover, and the road has been constructed. In management work, managers and on-site installers read the information with a non-contact or contact type reader, so that quick and accurate patrols and on-site inspections, construction,
Techniques for realizing efficiency such as attendance have been proposed.

On the other hand, a conventional manhole cover locking device is:
A relatively simple locking mechanism, such as locking / unlocking by inserting a tool from outside into a keyhole provided in the manhole cover, stores management data stored buried and stored in roads and their management-related facilities and road-exclusive properties. The preservation of the IC chip was not sufficient.

A technique disclosed in Japanese Patent Application Laid-Open No. 6-41998 (known example 1) as an example of a locking device for preventing the manhole cover from being easily opened is disclosed in FIG. 6 (a). A locking member 52 rotatably provided on a lid 51 serving as a lid engages with an engaging portion 54 of the receiving frame 53 to lock the lid 51, and an upper portion provided on the lid 51 is provided. A tool (not shown) is inserted from the insertion hole 55 to be inserted into and engaged with the lower insertion hole 56 of the locking member 52, and by pulling the tool, the locking member 52 is detached from the engaging portion 54 of the receiving frame 53, and the lid body is removed. 51 can be opened.

[0006] In a receiving shelf 57 provided below the upper insertion hole 55 of the lid 51, a lid (not shown) is inserted to prevent insertion of a tool (not shown).
A lock body 58 shown in FIG. A lock seat 59 having a head-shaped lock portion 59a is fixed to the receiving shelf 57, and a locking body 58 is inserted from an upper insertion hole 55 of the lid 51 to form a fitting formed on the lower surface of the locking body 58. The lock portion 59a of the lock seat 59 is placed on the receiving shelf 57 so as to be accommodated inside the chamber 58a, and the key 60 is inserted into the lock body 58 and turned to lock the lock piece 58b provided on the lock body 58. The lock body 58 is engaged with the lock portion 59 a of the lock seat 59 to lock the lock body 58 to the lid body 51.
A key cover 58c is provided on the upper part of the lock body 58 so as to be openable and closable.
Has been tightened against.

When opening the lid 51, first,
Release the key cover 58c with a square wrench, etc.
After opening 58c on the lid 51 from the upper insertion hole 55 of the lid 51,
The key 60 is inserted into the lock member 58 and rotated to retract the lock piece 58b from the lock portion 59a of the lock seat 59 to unlock the lock member 58.

After the locking member 58 is removed from the upper insertion hole 55 of the lid 51, a tool (not shown) is inserted from the upper insertion hole 55 of the lid 51 and inserted into the lower insertion hole 56 of the locking member 52 for engagement. Then, the locking member 52 is pulled by the tool so that the locking member 52
And the lid 51 is opened.

According to the above configuration, in the closed and locked state, the inside of the upper insertion hole 55 is substantially filled with the key cover 58c of the locking body 58. Unless the locking body 58 is removed, tools, rods and the like are used. Cannot be inserted.
Further, a key hole for inserting the key 60 into the lock body 58 is concealed by the key cover 58c, and the key cover 58c is locked by a square wrench or the like.
The manhole cover cannot be removed without special tools such as a square wrench and a key 60, so that the manhole cover can be prevented from being easily opened.

Further, Japanese Patent Publication No. 3-33857 (known example 2)
As disclosed in the above, the locking piece of the manhole cover is provided so as to be slidable in the horizontal direction with respect to the box, and the locking piece is fixed to the locking rod at the bottom of the box with a padlock. Some are locked.

[0011]

However, in the prior arts 1 and 2 in the above-mentioned prior art, however, a plurality of unlocking operators are required because the key 60 for unlocking the locking body 58 and the key (key) for unlocking the padlock are used. The user has to carry a key bundle in which the keys (keys) are bundled, and there is a problem that management of the key bundle is troublesome.

Further, the conventional key is not sufficient in security because a plurality of groups are grouped and unlocked by the same key. Further, if the user is familiar with the lock, the locked body 58 or the like can be locked using a wire or the like. Since the padlock could be opened relatively easily, there was concern about the maintenance of the equipment inside the manhole.

The present invention has been made to solve the above problems, and
The purpose is to unlock the manhole cover without using a key (key), eliminating the need to carry and manage the key bundle and ensuring the maintenance of the equipment inside the manhole. It will not be provided.

[0014]

According to the present invention, there is provided a locking device for a manhole cover, wherein the manhole cover is locked to a cover receiving frame by a dial lock integrally provided on the manhole cover. Or locked to a fixing member fixed to the ground.

Another configuration of the locking device for a manhole cover according to the present invention is a dial lock integrally provided on a cover receiving frame or a dial lock integrally provided on a fixing member fixed to the ground. A manhole cover is locked to the cover receiving frame or the fixing member.

According to each of the above-described configurations, the manhole cover can be locked by the dial lock, so that the key is unlocked by dialing an unlock code such as a memorized or listed number or symbol. This eliminates the need for carrying and managing a key ring, and prevents terrorism and other incidents from occurring, thereby ensuring the maintenance of equipment inside the manhole.

Further, the dial lock has a projection formed on a predetermined circumferential surface, is supported so as to be slidable in the axial direction with respect to the manhole cover, and has one end attached to the cover receiving frame or the fixing member. A lever shaft that can be engaged;
A through hole formed in the center portion is inserted into the lever shaft and is rotatably supported, and a plurality of different numbers and / or symbols are displayed on the outer peripheral surface. When the lever shaft slides, the lever shaft slides. A locking portion that abuts the protrusion formed on the locking member to prevent sliding movement of the lever shaft, and a portion of the locking portion is cut away at a position facing a predetermined number and / or symbol. And a notch continuous with a through hole formed in the central portion through which the protrusion formed on the lever shaft can pass.

According to the above configuration, the code such as the number or symbol displayed on the outer peripheral surface of the annular rotator by rotating the annular rotator matches the unlock code such as the memorized or listed number or symbol. By doing so, the notch of the annular rotating body matches the position of the protrusion formed on the lever shaft, so that the lever shaft can be slid in the axial direction, and the lid receiving frame or the fixing member at one end of the lever shaft is provided. Can be released to unlock the manhole cover.

Further, the dial lock has a projection formed on a predetermined circumferential surface, is supported so as to be slidable in the axial direction with respect to the lid receiving frame or the fixing member, and has one end attached to the manhole lid. A lever shaft that can be engaged;
A through hole formed in the center portion is inserted into the lever shaft and is rotatably supported, and a plurality of different numbers and / or symbols are displayed on the outer peripheral surface. When the lever shaft slides, the lever shaft slides. A locking portion that abuts the protrusion formed on the locking member to prevent sliding movement of the lever shaft, and a portion of the locking portion is cut away at a position facing a predetermined number and / or symbol. And a notch continuous with a through hole formed in the central portion through which the protrusion formed on the lever shaft can pass.

According to the above construction, the code such as the number or symbol displayed on the outer peripheral surface of the annular rotator is rotated by rotating the annular rotator so as to match the unlock code such as the memorized or listed number or symbol. By doing so, the notch of the annular rotating body matches the position of the projection formed on the lever shaft, so that the lever shaft can be slid in the axial direction, and the one end of the lever shaft is engaged with the manhole cover. The lock can be released to unlock the manhole cover.

In the case where the plurality of annular rotating bodies are rotatably supported coaxially on the lever shaft and the plurality of protrusions are formed at a predetermined pitch in the axial direction of the lever shaft, It is possible to increase the number of digits of the unlocking code such as a symbol and a symbol, and to assign individual unlocking codes to a plurality of manhole covers, thereby improving security.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a locking device for a manhole cover according to the present invention. FIG. 1 is a perspective explanatory view showing the structure of a locking device for a manhole cover according to the present invention, FIG. 2 is a partially enlarged explanatory view showing the structure of a dial lock provided integrally with the manhole cover, and FIG. It is sectional explanatory drawing which shows the structure of the engagement member movably provided and which can engage with the lever shaft of the dial lock integrally provided in the manhole cover.

FIG. 4 is an explanatory sectional view showing a state where the dial lock is locked, and FIG. 5 is an explanatory sectional view showing a state where the dial lock is unlocked.

In FIG. 1, reference numeral 1 denotes a manhole cover (including a handhole cover) provided in a manhole (including a handhole) serving as an opening through an underground object, an underground structure facility, etc. and the ground. The manhole cover 1 is supported by a cover receiving frame 2 laid almost flush with the ground surface of the ground.

The manhole cover 1 includes a large iron cover, a sewage basin cover that can open and close an opening through an underground object in a sewer, an underground structure facility, etc. and the ground, an underground facility device and wiring in electric power and communication. Fire hydrant with a function as an openable / closable iron cover for joints, power transmission iron cover, power distribution iron cover, underground pipes for water supply and gas pipes, and its auxiliary equipment to protect the ground It can be applied as a lid, a water control valve lid, a partition valve lid, an air valve lid, a lid for gas piping, a water meter lid, and the like.

The manhole cover 1 is integrally provided with a dial lock 3, which locks the manhole cover 1 with respect to the lid receiving frame 2. A hinge mechanism (not shown) is provided on the outer peripheral side of the manhole cover 1 facing the dial lock 3, and the manhole cover 1 is rotated around the hinge mechanism to be opened.

As shown in FIGS. 4 and 5, the dial lock 3 is slidably supported in the axial direction (left and right directions in FIGS. 4 and 5) by bearings 1a and 1b provided on the manhole cover 1. A lever shaft 4 is provided, and one end of the lever shaft 4 has a lever 4a standing upright.
Are formed.

The lever shaft 4 has a guide groove 5 in which both side surfaces of the lever 4 a are formed in the axial direction of the lever shaft 4.
4 and 5 so that the lever shaft 4 can slide along the guide groove 5 without rotating.

Projections 4b ₁ , 4b ₂ , 4 are provided on a predetermined circumferential surface of the lever shaft 4 at a predetermined pitch in the axial direction.
b ₃ , 4b ₄ , 4b ₅ , 4b ₆ , 4b ₇ (hereinafter, simply referred to as “projections 4b”) are erected in the same direction. Dials 6a ₁ , 6a ₂ , 6a ₃ , 6a ₄ , 6a ₅ , 6a ₆ , 6a
₇ (hereinafter simply referred to as “dial 6 a”) is rotatably inserted into the lever shaft 4.

At the center of each dial 6a, through holes 6b ₁ , 6b ₂ , 6 having a diameter corresponding to the outer diameter of the lever shaft 4 are provided.
b ₃ , 6b ₄ , 6b ₅ , 6b ₆ , 6b ₇ (hereinafter simply referred to as “through holes 6b”), through which the lever shaft 4 is inserted, and each dial 6a centering on the lever shaft 4 Are rotatably supported.

The inner diameter of each dial 6a comes into contact with each projection 4b formed on the lever shaft 4 when the lever shaft 4 moves rightward in FIG. Locking portions 6c ₁ and 6 for preventing movement
c ₂ , 6c ₃ , 6c ₄ , 6c ₅ , 6c ₆ , 6c ₇ (hereinafter simply referred to as “locking portion 6c”) are formed.

Between the dials 6a and between the dials 6a ₁
A spacer (not shown) having a slidable surface is interposed between the dial 6a and the bearing portion 1b, and between the dial 6a ₇ and the bearing portion 1a. It is held rotatably.

In this embodiment, ten different numbers 0 to 9 are displayed on the outer peripheral surface of each dial 6a as shown in FIG. In addition to the numbers, English characters such as A, B, and C and various other symbols may be displayed, or a combination of these characters may be displayed. Further, a code such as two or more other numbers or symbols may be displayed on the surface of each dial 6a.

In this embodiment, seven dials 6
a, but may be configured using one or a plurality of other dials 6a. As a means for displaying a code such as a number or a symbol on the outer peripheral surface of each dial 6a, the code such as a number or a symbol may be displayed in an embossed manner, or may be engraved and displayed in reverse. Or a code such as a symbol may be printed, or a printed seal may be attached and displayed on the outer peripheral surface of each dial 6a.

Further, a portion of the locking portion 6c of each dial 6a is cut at the inner diameter portion of each dial 6a at a position facing a predetermined number to be unlocked formed on the outer peripheral surface of each dial 6a. Notches 6d ₁ , 6d ₂ , 6d ₃ , 6 which are continuous with the through holes 6b through which the protrusions 4b of the lever shaft 4 can pass when the lever shaft 4 moves rightward in FIG.
d ₄ , 6d ₅ , 6d ₆ , 6d ₇ (hereinafter simply “notch 6d”
Is formed.

Also, a projection 4b of the lever shaft 4 of the bearing 1a for slidably supporting the lever shaft 4 is provided.
Notch 1a ₁ capable of passing through the projections 4b of the lever shaft 4 is formed in a position corresponding to.

On the other hand, as shown in FIGS. 2 and 3, the cover receiving frame 2 for receiving the manhole cover 1 is turned around the rotation shaft 7a in the direction shown by the arrow in FIG. A movable engagement member 7 is provided.
Is configured to be rotatable while exerting a predetermined frictional force by a friction member (not shown) provided on the rotating shaft 7a.

In the drawing, reference numeral 8 denotes a waterproof cover made of rubber, synthetic resin or the like which is detachably provided on the manhole cover 1 and covers the dial lock 3, the lever 4a and the engaging member 7 over the whole. It covers to prevent infiltration of rainwater, dirt, dust, sandstone and the like.

Reference numeral 9 denotes an outer cover made of stainless steel or the like having rigidity to withstand a traffic load, and is configured to be rotatable about a rotation shaft 9a and openable and closable with respect to the manhole cover 1.

In the above configuration, when locking the manhole cover 1, first, as shown in FIGS. 1 and 2, the outer cover 9 is opened and the waterproof cover 8 is detached, and as shown in FIGS. As described above, the engagement member 7 is rotated about the rotation shaft 7a to stand up as shown by the solid lines in FIGS.

Then, all the dials 6a of the dial lock 3 are set to the unlocking number positions, and the notches 6d of the all dials 6a are set.
Is aligned with the position of the projection 4b of the lever shaft 4, the lever 4a is gripped, the lever shaft 4 is slid to the left in FIG. 4, and the lever shaft 4 is inserted into the engagement hole 7b of the engagement member 7. Thereafter, the end 4c of the lever shaft 4 is inserted into the engagement hole 1c of the manhole cover 1.

At this time, as shown in FIG. 4, each projection 4b of the lever shaft 4 is located on the left side of FIG. 4 with respect to the locking portion 6c of each dial 6a, and each dial 6a is centered on the lever shaft 4. It is arranged rotatably.

Then, each dial 6a is set at a position other than the unlocking number, and the locking portions 6c of all the dials 6a are matched with the positions of the projections 4b of the lever shaft 4, so that the manhole cover 1 is connected to the dial lock 3. Can be locked.

Thereafter, the waterproof cover 8 is attached to the manhole cover 1 to cover the dial lock 3, the lever 4a and the engaging member 7 entirely, and the outer cover 9 is closed. The outer cover 9 may be locked as necessary, not shown.

On the other hand, when unlocking the manhole cover 1,
The outer cover 9 is opened, the waterproof cover 8 is detached, all the dials 6a of the dial lock 3 are set to the unlocking number positions, and the notches 6d of the all dials 6a are set in the projections 4 of the lever shaft 4.
5b, the lever 4a is gripped and the lever shaft 4 is slid rightward in FIG. 5 so that the end 4c of the lever shaft 4 is engaged with the engaging hole 1c of the manhole cover 1 and the engaging member 7. The manhole cover 1 can be unlocked by pulling it out of the hole 7b.

When the engaging member 7 hinders the elevating operation in the manhole, it is suspended as shown by a broken line in FIGS. 2 and 3, and when the manhole cover 1 is locked, the solid line in FIGS. 2 and 3 is used. Use standing up as shown by.

In the present embodiment, the engaging member 7 is
Although an example in which it is configured to be rotatable about a has been described, a fixed type engagement member may be used. Although the case where the engaging member 7 is provided on the lid receiving frame 2 has been described, the engaging member 7 may be provided on a fixing member other than the lid receiving frame 2 fixed to the ground near the manhole.

According to the above configuration, since the manhole cover 1 can be locked by the dial lock 3, the unlock code such as a memorized or listed number or symbol is dialed to unlock the keyhole without using a key. This eliminates the need for carrying and managing a key ring, and prevents terrorism and the like from occurring, thereby ensuring the maintenance of equipment inside the manhole.

That is, the dial 6a, which is an annular rotating body, is rotated so that the code such as the number or symbol displayed on the outer peripheral surface of the dial 6a matches the unlock code such as the memorized or listed number or symbol. As a result, the notch 6d of the dial 6a coincides with the position of the projection 4b formed on the lever shaft 4, so that the lever shaft 4 can be slid in the axial direction, and the end 4c of the lever shaft 4 The manhole cover 1 can be unlocked by releasing the engagement with the cover receiving frame 2 (or a fixing member fixed to the ground around the manhole).

When a plurality of dials 6a are rotatably supported coaxially on the lever shaft 4 and a plurality of the protrusions 4b are formed at a predetermined pitch in the axial direction of the lever shaft 4, the number By increasing the number of digits of the unlocking code such as a symbol and a symbol, each unlocking code can be assigned to a plurality of manhole covers 1. That is, it is possible to construct a locking system in which a large number of manhole covers 1 are individually changed in the unlocking code and each one is different, and security can be improved.

In the above embodiment, the case where the dial lock 3 is provided integrally with the manhole cover 1 has been described.
As another configuration, the dial lock 3 is provided integrally with the lid receiving frame 2, or the dial lock 3 is provided integrally with a fixing member other than the lid receiving frame 2 fixed to the surrounding ground where the manhole is provided. 7 may be provided on the manhole cover 1 side.

According to the above construction, the dial 6a is rotated in the same manner as described above, and the code such as the number or symbol displayed on the outer peripheral surface of the dial 6a is memorized or the unlock code such as the listed number or symbol. And the dial 6a
Notch 6d is formed in the protrusion 4 formed on the lever shaft 4.
The lever shaft 4 can be slid in the axial direction in accordance with the position b, and the engagement of the one end of the lever shaft 4 with the manhole cover 1 can be released to unlock the manhole cover 1.

In the above embodiment, the dial lock 3 is an example of the configuration of a rotary dial lock that unlocks the dial 6a by aligning the position of the notch 6d of each dial 6a with the position of the projection 4b of the lever shaft 4. However, as another rotary dial lock, a plurality of codes such as different numbers and symbols are displayed around the rotating body or the rotating body, and the rotating body is alternately rotated left and right by a predetermined angle. It may be an unlocking type dial lock or a push button dial type dial lock in which a plurality of codes such as different numbers or symbols are displayed on a plurality of push buttons.

[0054]

According to the present invention, the manhole cover can be locked by the dial lock, since the present invention has the above-described structure and operation, the dial lock can lock the manhole cover.
By dialing an unlock code such as a memorized or listed number or symbol, it can be unlocked without using a key (key), making it unnecessary to carry and manage key bundles and preventing terrorism. And the maintenance of the equipment inside the manhole can be secured.

Further, according to the third aspect of the present invention, the number or symbol which is obtained by rotating or rotating the annular rotator and memorizing or listing the number or symbol displayed on the outer peripheral surface of the annular rotator. And the like, so that the notch of the annular rotating body coincides with the position of the protrusion formed on the lever shaft, so that the lever shaft can be slid in the axial direction. The manhole cover can be unlocked by releasing the engagement of the portion with the cover receiving frame or the fixing member.

According to the fourth aspect of the present invention, the numbers and symbols are displayed by memorizing or listing codes such as numbers and symbols displayed on the outer peripheral surface of the annular rotating body by rotating the annular rotating body. And the like, so that the notch of the annular rotating body coincides with the position of the protrusion formed on the lever shaft, so that the lever shaft can be slid in the axial direction. The engagement of the part with the manhole cover can be released to unlock the manhole cover.

In the case where a plurality of the annular rotating bodies are rotatably supported coaxially on a lever shaft and a plurality of projections are formed at a predetermined pitch in the axial direction of the lever shaft, a number or a symbol is used. , Etc., the number of digits of the unlock code can be increased to give each unlock code to a plurality of manhole covers.

That is, it is possible to construct a locking system in which a large number of manhole covers are individually changed in the unlocking code and each one is different.
Security can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view showing a configuration of a locking device for a manhole cover according to the present invention.

FIG. 2 is a partially enlarged explanatory view showing a configuration of a dial lock integrally provided on a manhole cover.

FIG. 3 is a sectional explanatory view showing a configuration of an engaging member rotatably provided on a lid receiving frame and capable of engaging with a lever shaft of a dial lock integrally provided on a manhole cover.

FIG. 4 is an explanatory sectional view showing a state in which the dial lock is locked.

FIG. 5 is an explanatory sectional view showing a state where the dial lock is unlocked.

FIG. 6 is a diagram illustrating a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Manhole cover, 1a ... Bearing part, 1a1 _... Notch part, 1
b: bearing portion, 1c: engagement hole, 2: lid receiving frame, 3: dial lock, 4: lever shaft, 4a: lever, 4b, 4
b ₁ , 4b ₂ , 4b ₃ , 4b ₄ , 4b ₅ , 4b ₆ , 4b ₇ ... projections, 4c ... ends, 5 ... guide grooves, 6a, 6a ₁ , 6
_{a 2, 6a 3, 6a 4} , 6a 5, 6a 6, 6a 7 ... dial,
_{6b, 6b 1, 6b 2,} 6b 3, 6b 4, 6b 5, 6b 6, 6
b ₇ ... through _{hole, 6c, 6c 1, 6c 2} , 6c 3, 6c 4, 6
_{c 5, 6c 6, 6c 7} ... locking _{portion, 6d, 6d 1, 6d 2} , 6
_{d 3, 6d 4, 6d 5} , 6d 6, 6d 7 ... notch, 7 ... engaging member, 7a ... pivot shaft, 7b ... engaging hole, 8 ... waterproof cover,
9 ... Outer cover, 9a ... Rotating shaft

Continuation of the front page (72) Inventor Masafumi Mizutani F-term (reference) 2D047 BB03 2D063 DA12 in 1-22-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo

Claims (5)

[Claims] 1. The manhole cover is locked to a cover receiving frame by a dial lock provided integrally with the manhole cover, or is locked to a fixing member fixed to the ground. Locking device for manhole cover. 2. A manhole cover is locked to the cover receiving frame or the fixing member by a dial lock integrally provided on the cover receiving frame or a dial lock integrally provided on a fixing member fixed to the ground. A locking device for a manhole cover. 3. The dial lock, wherein a projection is formed on a predetermined circumferential surface, is supported so as to be slidable in the axial direction with respect to the manhole cover, and has one end attached to the cover receiving frame or the fixing member. A lever shaft that can be engaged, a through-hole formed in the center portion is inserted into the lever shaft and rotatably supported, and a plurality of different numbers and / or symbols are displayed on an outer peripheral surface of the lever shaft; An abutting portion that abuts on the protrusion formed on the lever shaft when the lever slides to prevent sliding movement of the lever shaft; and an engaging portion at a position facing a predetermined number and / or symbol. An annular rotating body having a notch continuous with a through-hole formed in the central portion, which can cut through a part of the lever shaft and allow the projection formed on the lever shaft to pass therethrough. The locking device for a manhole cover according to claim 1, wherein: 4. The dial lock, wherein a protrusion is formed on a predetermined radial peripheral surface, is supported slidably in the axial direction with respect to the lid receiving frame or the fixing member, and has one end attached to the manhole lid. A lever shaft that can be engaged, a through-hole formed in the center portion is inserted into the lever shaft and rotatably supported, and a plurality of different numbers and / or symbols are displayed on an outer peripheral surface of the lever shaft; An abutting portion that abuts on the protrusion formed on the lever shaft when the lever slides to prevent sliding movement of the lever shaft; and an engaging portion at a position facing a predetermined number and / or symbol. An annular rotating body having a notch continuous with a through-hole formed in the central portion, which can cut through a part of the lever shaft and allow the projection formed on the lever shaft to pass therethrough. The locking device for a manhole cover according to claim 2, wherein 5. A plurality of annular rotating bodies are rotatably supported coaxially on the lever shaft and a plurality of the protrusions are formed at a predetermined pitch in an axial direction of the lever shaft. The locking device for a manhole cover according to claim 3 or 4.