Manhole cover

Abstract

 To improve the reliability and practicability of manholes, there is described a level adjusting device (10, 100, 200) for a removable or liftable cover (C) of a manhole (MH). It comprises a stand-alone base body (20; 120; 220), adapted to be placed under the cover and having a thread, and a counter-threaded element (40; 140; 240) that is adapted to support the cover and is couplable by screwing on the thread of the body to translate along an axis (X) and protrude in an adjustable manner from the body.
The device allows an independent adjustment for each support point.

Description

[0001] The invention relates to a height-compensating (i.e. level adjusting) device for covers of manholes, drains or the like.

[0002] To place and maintain leveled the covers or hatches of manholes, wells or drains onto the road surface is not easy. Unleveled covers or hatches are dangerous for road safety, especially for the safety of bicycle riders or the safeguard of tires. On the other hand, it is essential to allow inspection and maintenance of filled-up constructions.

[0003] To solve this problem several solutions have appeared in the art. DE102011001082 describes a height compensation element with an annular frame, and adjustment screws keep it against a pressure distribution plate. The structure, however, is complex, expensive and allows only one adjustment along an axis.

[0004] KR101125206 presents a manhole or hatch that should allow for easy adjustment and installation. The entire manhole is constructed with two cylindrical bodies to be screwed in one another. The structure is very complex, expensive, only allows adjustment along an axis and is not suitable when one has to cover a manhole or a pre-existing hole.

[0005] EP1357230 describes a height compensator formed by four adjustable feet, in particular connected with each other by a mechanical transmission adapted to actuate them together. Again, the structure is complex to be produced, and inherently precludes the adjustment of the cover according to an inclination relative to the road surface.

[0006] It is proposed a height regulator device of the aforesaid type as defined in claim 1, which is free from one or more of the problems described.

[0007] The device is self-contained (i.e. it is an autonomous and independent structural unit) and serves to adjust the height of a removable or liftable cover of a manhole (e.g. a hatch). It comprises:

a base body, adapted to be placed under the cover and having a thread, and

a counter-threaded element that is adapted to support, preferably by direct abutment, the cover and is couplable by screwing on the thread of the body to translate along an axis and to protrude from the body in an adjustable manner.

[0008] The device being the autonomous, the counter-threaded element can be adjusted independently from the counter-threaded elements of other adjacent devices, and therefore each support point of the cover has a regulation independent of the other points. This allows to adjust the spatial tilt of the cover and not only the height of its lying plane.

[0009] The device may comprise a second threaded element which is mountable by screwing on a thread of the counter-threaded first element to be movable along said axis. The second element is used to reduce stress generated by the weight of the cover, or by weights that it must support, localized on the thread between the base body and the first element. In particular, this construction is very effective if the screwing between the first and second elements is such that one end of the second element is able to translate and get flush with the end of the body opposite to that from which the first element can protrude.

[0010] To make the device compact the body can comprise a cylindrical cavity in which said thread is formed; therefore the first element can be a cylindrical body with zero or few voids, and/or with minimal protrusions.

[0011] To make it easy to adjust the first element and to increase the adjustment range thereof, said cavity of the body is preferably a pass-through cavity having a thread on its entire surface.

[0012] To make the device compact, the first element may comprise a cylindrical cavity in which there is made a thread on which the second element can be screwed, so the second element can be a cylindrical body with zero or few voids.

[0013] To make it easy to adjust the second element and to increase the adjustment range thereof, said cavity of the first element is preferably a pass-through cavity having a thread on its entire surface.

[0014] The structure of the device can be reinforced if it comprises a shell having a cavity within which the base body is completely insertable. It is very important to make sure that the threaded structures will not yield laterally because of the high loads transmitted to them e.g. by heavy vehicles passing over the cover.

[0015] Among the many possible materials, the shell is preferably made of concrete or brick (low cost and excellent resistance), and/or the body and/or one or each of the elements are made of polyethylene or Teflon (ease of obtaining by molding the threads and their self-lubrication).

[0016] The ease of installation can be increased if the shell is a block with a section, taken orthogonally to said axis, having at least one rounded edge. A sharp edge can make it complicated the installation of the device due to the irregularity of the well that hosts the manhole.

[0017] It is also proposed a manhole with removable cover comprising three or more devices as defined above arranged to support the perimeter of the cover. The manhole thus constructed allows the independent adjustment of the height in correspondence of each supported point of the cover, and/or an improved distribution of the loads in the supports of the cover.

[0018] It is also proposed a method for installing in a well devices which are independent, unconstrained among each other, and adapted to adjust the level of a removable or liftable cover of a manhole, and having a support base. The method comprises the step of inserting in fresh concrete, which forms and/or is placed above the walls of the manhole/well, the bases of the devices arranging them under the perimeter of the cover.

[0019] The embedding of the devices in the concrete lining the well greatly simplifies the laying operations (e.g. EP1357230 requires the installation of special laborious plates) and lowers the cost of assembly (e.g. by eliminating the fixing means).

[0020] The method can comprise the further step of cementing the walls of the well prior to the previous phase.

[0021] The method can be enriched of advantages if one or each device is made defined above, in particular with the advantages of an independent adjustment of the individual heights and better distributed weights.

[0022] The advantages of the device will be clearer from the following description of a preferred embodiment thereof, making reference to the attached drawing in which

• Fig 1 shows a vertical section of a manhole;
• Fig 2 shows a vertical section of the device (enlargement of fig. 1);
• Fig 3 and 4 show a scheme of variations of the device.

[0023] In a hole or well of a ground G with a surface S (fig. 1) is arranged a wall or structure made of concrete or the like, formed by a bottom WB and vertical walls WW, to delimit the opening or mouth of a manhole MH having a lid or closing cover C. Generally the cover C has e.g. square or circular form, and is supported on three or four or more points of the perimeter (as in EP1357230). As a support for each point of the cover C a device 10 is used, separated from the other devices and placed on top of a wall WW. In the following we describe only a device 10, for the sake of simplicity.

[0024] The device 10 is formed by a body 20, e.g. cylindrical, comprising a thread 22 obtained on the entire surface of a cylindrical pass-through cavity 24. Inside the cavity 24 is insertable by screwing a cylinder 40 which is counter-threaded on its outer lateral surface (see thread 42). The diameters of the cavity 24 and the cylinder 40 are sized appropriately, that is almost equal. Therefore one can move the cylinder 40 along an axis X, by screwing it, inside the cavity 24, to make it protrude from the body 20 (as in fig. 1). Optionally at the free end of the cylinder 40 there is a layer or disc 44 made of resistant and/or soft material, so as to facilitate the laying of the cover C.

[0025] A second cylinder 60 with a thread 62 on its lateral surface is mountable by screwing on a thread 46 made on the surface of an axial cavity 44 made along the X axis in the first cylinder 40. Therefore also the cylinder 60 is movable along the X axis, relative to the cylinder 40. The diameters of the cavity 42 and the cylinder 60 are sized appropriately, that is almost equal.

[0026] The body 20 can be contained in an outer shell 90, in order to strengthen the structure thereof and/or to keep it vertical enlarging its base. The section perpendicular to the axis X of the shell 90 can have any shape, preferably cylindrical or polygonal, e.g. square, and in general at least one edge is rounded and not sharp, so as to easily accommodate the device 10 at the corners of the hole dug.

[0027] As preferred materials:

for the body 20, the cylinder 40 and the cylinder 60: teflon or polyethylene, or plastic material in general, to ensure long duration, especially to water;

for the shell 90: concrete or terracotta, being low cost but having high mechanical strength.

INSTALLATION and OPERATION Method

[0028] Generally, the device 10 is laid as soon as the structure made of brick or concrete of the walls WW, WB is ready. In particular, the base of the device can be embedded in the fresh concrete, to secure the device permanently to the manhole.

[0029] As the three elements 20, 40, 60 are mounted into one another, and these three are mounted in the shell 90 if present, the device 10 thus composed is placed in position above a plane of the wall or wall WW. Generally there are placed three or four or more devices 10 along the perimeter of the cover C, arranged with central symmetry (as in EP1357230 fig. 2 or 4).

[0030] By manually rotating the cylinder 40, it is pushed away from a side of the body 20 until the cover C, that will stand leaning on it, arrives at the desired level. While holding the cylinder 40 one rotates the cylinder 60 so that its free end abuts on the wall WW below (on the side opposite to that from which the cylinder 40 protrudes). If the cavity 44 is of pass-through type, namely it crosses axially through the entire cylinder 40, it allows from the top the angular adjustment of the cylinder 60 via e.g. a screwdriver or other tool, which can e.g. grip on a notch 64 at the top of the cylinder 60. Otherwise by trial one finds the correct relative position between the cylinders 40, 60 before the laying on the wall WW.

[0031] By using a device 10 for each support point of the cover C one can have an independent adjustment for the height of that point. Not only the overall height of cover C is adjusted along the X axis, but - unlike EP1357230 - also its inclination with respect to the surface S.

[0032] The cylinder 60 unloads on the wall WW the weight of the cover C applied to the cylinder 40, avoiding that all the stress is concentrated on the threads 22, 42. Besides lengthening the operating life and reliability, this allows to make the cylinders 20 and/or 40 and/or 60 in plastic material, e.g. polyethylene (low cost and weight), and to avoid using metals which, when buried, eventually deteriorate.

[0033] Essentially the device 10 can consist of three cylinders or bushings placed one inside the other, two by two in rotatable coupling through a thread along the same axis. The concept of having three elements movable along a same axis X thanks to two by two mutual screwing gives life to many variants.

[0034] The variant 100 in Fig. 2 has a central cylinder 120, this time e.g. solid, with axis X. On its lateral surface there is a thread (not shown) on which can be screwed an internally counter-threaded sleeve 140 equipped, on the outer lateral surface, with a thread on which a second bushing 160 can be screwed. With respect to the cylinder 120, the two bushings 140, 160 are movable along the axis X to support the cover C, the first, and to rest on the wall W, the second.

[0035] The variant 200 in Fig. 3 has a central bushing 220 with axis X and an axial cavity. Such cavity has a thread (not shown) on the surface on which a cylinder 240, counter-threaded on the outer lateral surface, can be screwed. On the thread of cylinder 240 can be screwed a bushing or glass 260. With respect to the bushing 220, the elements 240, 260 are movable along the axis X to support the cover C, the first, and to rest on the wall W, the second.

[0036] In general, it is advantageous that the threads between the components are two by two with opposite directions (one clockwise and the other anticlockwise, or vice versa), so that the rotation of the second cylinder or bushing 60, 160, 260 does not move the height of the cover C regulated with the element 40, 140, 240.

Claims

1. Level adjusting device (10, 100, 200) for a removable or liftable cover (C) of a manhole (MH), comprising:

a stand-alone base body (20; 120; 220), adapted to be placed under the cover and having a thread, and

a counter-threaded element (40; 140; 240) that is adapted to support the cover and is couplable by screwing on the thread of the body to translate along an axis (X) and protrude in an adjustable manner from the body.

2. Device according to claim 1, comprising a second threaded element (60; 160; 260) that is mountable by screwing on a thread of the counter-threaded first element to be movable along said axis so that one end of the second element is able to translate and arrive flush with the end of the body opposite to that from which the first element can protrude.

3. Device (10) according to claim 2, wherein the body comprises a cylindrical cavity (24) in which said thread is formed, said cavity of the body preferably being a pass-through cavity having a thread (22) over its entire surface.

4. Device according to claim 2 or 3, wherein the first element comprises a cylindrical cavity (44) in which a there is formed thread (46) on which the second element can be screwed, the cavity of the first element preferably being a pass-through cavity having a thread over its entire surface.

5. Device (10) according to one of the preceding claims, comprising a shell (90) having a cavity within which the base body is completely insertable.

6. Device according to claim 5 and/or one of claims 1 to 4, wherein the shell is made of concrete or brick, and/or the body and/or one or each of the elements are made of polyethylene or teflon.

7. Device according to claim 6, wherein the shell is a block with a section, taken orthogonally to said axis, having at least one rounded edge.

8. Manhole (MH) with a removable cover (C) comprising:

three or more devices according to one of the preceding claims arranged in support of the perimeter of the cover.

9. Method for installing in a well devices (10, 100, 200) that are independent,
unconstrained among each other, and
adapted to adjust the level of a removable or liftable cover (C) of a manhole (MH),
and having a support base,
comprising the step of
inserting in fresh concrete, forming and/or placed on the walls of the manhole, the bases of the devices placing them under the perimeter of the cover.

10. Method according to claim 9, wherein one or each device is realized according to one of claims 1 to 7.

Drawing