EP1486622B1 - Height adjustable street cover - Google Patents

Abstract

Access to a sub-road utility valve or switch is provided via a narrow shaft (4) which terminates in a two-part (2, 3) plastic collar and cap at street level. The collar has a first cylindrical section (3) with an inner wall having the same approximate diameter, though not perfectly circular, as the upper part sleeve insert (2). The sleeve insert may be raised and lowered to the correct height and self-locked in this position by a twist action and interference fit.

Description

The invention relates to a height-adjustable plastic street cap, consisting of an upper part and a lower part, wherein the upper part in an opening of the lower part by a pressing pressure is infinitely fixed to a certain height adjustment within the lower part.

Road caps are installed in roads and serve to access fittings of utility lines laid under the roads. You will be asked about the corresponding fitting. Then they will be e.g. Covered with asphalt so that its surface is level with the street level. The lid is removable to get to the fitting, and is usually secured by a bolt against removal. Originally, cast iron street caps were made, but they are rust susceptible and difficult to handle because of their weight. Therefore, one has begun to make them from plastic.

In most cases, road surfaces are applied in multiple layers, and there is often a need to temporarily put a road into service after application of the base, even if it is only for site traffic. Therefore, the height adjustment of the road cap must be designed to be flexible, so as not to endanger traffic passing through outstanding tops. The same situation can also arise when repairing roads when old tiles are removed to replace them with new ones. The problem with a stepless adjustability, which is expedient for an exact level adjustment, was the fixation of the height adjustment.

A first solution was to fix the height adjustment manually by holding the top during the application of the topcoat. This had the disadvantage that two persons were employed at the same time and that the person holding it was at risk of being burned by the deposit, which can reach temperatures of up to 200 ° C. Hand holding of the upper part practically precluded mechanical deposit application in the area of the toe cap because of the aforementioned risk.

At a height adjustment before application of the topping such a street cap had to be held by one person and by another person, for example, with tar, a wedge or otherwise, fixed. But then there was the danger that the height adjustment was wrong.

Another solution sees the DE 196 35 648 A1 respectively. CH 692 708 A5 before, are introduced at the spacers between the upper part and an inwardly projecting edge projection of the lower part. This has the disadvantage that the handling requires several handles, since first the upper part must be pulled out of the lower part, so that the spacers can be introduced. Also, no continuous adjustment is possible because the adjustment options are given by the existing spacer dimensions. Exact level equality was difficult to achieve in this way.

The same disadvantages would arise from the use of spacers, which are variously referred to in connection with adjustable road caps. This also applies to the in the AT 408 106 B proposed supports, which are mounted between the protruding upper edge of the upper part and the upper edge of the lower part.

The same applies to the street cap of the WO 099/36633 , of the FR 1 592 110 A and the DE 72 04 914 U in which locking positions are provided at different heights, in which the upper part can be locked by relative rotation relative to the lower part. In such road caps, the top can not yield if one Road roller for smoothing an applied layer moves over it. If such a road cap is set too high, it will be destroyed.

For a stepless adjustment see the DE 196 18 431 . DE 296 23 845 and the CH 692 709 A5 before that the upper part can be screwed by threads in upper and lower part in the lower part. However, such a thread is expensive to manufacture, since the upper part must be made by longitudinally split mold halves and removed at the bottom of the injection molding core by a screwing or the thread has to be machined. Furthermore, the height adjustment can only be changed by rotation. If such a road cap is set too high, so it comes when driving over with a road roller to destruction, since the thread does not yield.

The EP 0 462 036 A1 discloses a road cap of the type mentioned. In this road cap, the upper part is free in the lower part and slidably mounted with play. It is located on the upper part of a stretchable ring with a diameter-expanding bias, such that it is rollable for adjusting its vertical position. Thus, the height of the road cap is specified and only then the upper part is inserted into the lower part, To achieve the pressing pressure of this ring acts together at the insertion with a groove at the upper end of the lower part, said groove has an outer diameter, which the ring from the outside compressed against the wall of the shell. This guarantees the locking of the upper part relative to the lower part in the preset vertical position. Since the ring is wedged between the upper part and the groove, an adjustment of the upper part down is not possible or only with considerable expenditure of force. By contrast, it is not possible to bring the shell by pulling it into a different height adjustment to the lower part, since the ring would leave the groove while performing a rolling motion between the upper part and groove and no pressing pressure and thus no height adjustment would be available.

This means that when the upper part is to be brought to a higher position relative to the lower part, the upper part not only has to be pulled up, but has to be removed in order to reposition the ring by means of a rolling movement and then to bring about again the clamping described above. This is cumbersome and time-consuming, especially when this process is required several times by the application of several coating layers on the road surface. However, under certain circumstances, this may not even be possible if the applied paving blocked the ring when pulling up or if the pavement yields, the ring leaves its position in the groove and may be stripped on further withdrawal of the upper part of the road slip. Then you would have to remove a part of the road surface and clean the groove to the top with the new applied and set ring can not use without this is displaced by remnants of the road surface. In particular, when applied with a first height adjustment of the base of a road surface and the road caps were set to this level, a further increase for the reasons mentioned above is possible only with considerable effort. This does not do justice to the practice of road construction, since roads are usually already put into operation after application of the base layer, which presupposes a provisional height adjustment of a road cap, in order to then apply the top deck covering, which requires a subsequent Höherstellung the road caps.

The invention is therefore based on the object, a plastic-road cap of the type mentioned in such a way that it is easy to manufacture and install and adjust effortlessly on exact street level in particular for a lower setting for a provisional use of not yet completely finished road for an application of another deck covering can be set even higher.

This is achieved by the features of claim 1.

The invention has the advantage that upper parts that protrude from the road surface or are to be set up according to the height of a future road surface, most easily by a person by a relative movement, which is composed of a combination of movement in the horizontal and vertical directions on the predetermined height can be brought. It is essential that the hold of the upper part is achieved in the lower part of a pressing pressure, which generates a surmountable fixation of the upper part to the lower part. This causes a corresponding pressure on the upper part always lifting the fixation before it comes to a destruction of the road cap.

Most conveniently, the height is set slightly above the desired street level, and the road roller then pushes the shell at the completion of the topmost pavement exactly at street level. This is possible because the height adjustment is fixed only by the pressing pressure of surface areas of the upper and lower part and this pressing pressure is selected such that the height adjustment can be reduced by a road roller in any case by means of a downward pushing of the upper part, but this downward movement stops immediately when the road roller has passed over the rolled surface, ie the final road level has been reached. This allows an absolutely exact level adjustment without any additional work required. Also, a road roller can not cause any damage to protruding caps. The upper and lower parts according to the invention are easy to produce, since they can be removed from the injection mold in a slightly conical configuration or removed from the mold core.

One possibility provides that the relative movement is a combination of a horizontal movement as a rotational movement and a vertical movement. For this purpose, it is provided that the outer surface of the upper part and the corresponding inserted in the inserted state surface of the opening of the lower part are formed such that in at least one achievable by a relative rotation assignment of upper and lower part in at least two areas of the surfaces a pressing pressure prevails, the height adjustment fixed in other achievable by a relative rotation assignments, the height adjustment by the adjusting movement is easily adjustable.

This road cap has the advantage that its height can be adjusted even more easily by hand. In contrast to a road cap, which always has the same pressing pressure regardless of the assignment of upper part and lower part, it is now provided that there is at least one adjustment without this pressing pressure depending on the relative rotation of the upper part in the lower part. This adjustment range is used so that a simple adjustment of the height can be done by hand, with both a game, as well as a reduced pressing pressure are possible. Thereafter, the person handling turns the upper part into a position in which a pressing pressure for secure fixation of the upper part relative to the lower part is established. This has over the aforementioned option with always the same pressure on the one hand the advantage of a lighter height adjustment, which must not be done by overcoming a pressing pressure or the full pressing pressure for fixation, since this is generated only after the height adjustment by the relative movement. On the other hand, in this way, the areas for achieving the pressing pressure may be formed so that it is higher, since it is no longer in the rotational movement as in the Height adjustment arrives at the achievement of an exact position. Therefore, you can adjust the height in a smooth area easier and more accurate and subsequently, a much safer fixation of the upper part is achieved by the rotational movement than in the above-mentioned road cap with allocation-independent pressing pressure. Of course, however, such an increased pressing pressure must also allow a lowering of the upper part in the above-mentioned manner.

In this embodiment, the height is most conveniently set slightly above the desired road level, and the road roller then presses the top exactly at street level upon completion of the topmost pavement. This allows an absolutely exact level adjustment without any additional work required. Again, a road roller, as described above, cause no damage to protruding caps.

The areas of the surfaces in which the pressing pressure prevails can be formed in various ways. Thus, elevations, for example as humps, can be arranged on the surfaces, ie on the outer surface of the upper part and the corresponding surface of the opening of the lower part, which slide on one another by the relative rotation and thereby exert the pressing pressure in their region. Preferably, however, it is provided that the two surfaces at least partially have an out-of-roundness, the meeting of small radii of the lower part with large radii of the upper part generates the pressing pressure and the coincidence of the respective small radii and the respective large radii of the lower part and the upper part of a smooth adjusting movement allows for height adjustment. Essentially, a columnar shape of the upper part and the opening of the lower part should be maintained over the entire corresponding surfaces in order always to achieve pressing pressure and ease in the same angular positions. If this column shape is optionally equipped with a slight conicity, the production is easier, as this allows easy removal of the injection mold or the injection core. Of course, despite this Konzizität sufficient pressure for fixation in all possible height settings to be guaranteed. At the same time is achieved by the column shape that a height adjustment in a range is possible, ranging from the complete insertion of the upper part in the lower part up to a pulling out, which just enough surfaces correspond to ensure the fixation.

Preferably, the transitions from smaller to larger radii or vice versa are designed to be fluent. Such flowing transitions create during the relative rotation of a wedge effect, by which a particularly high compression pressure without too much effort is generated. It is then not necessary that the smallest radius of the lower part are brought exactly to coincide with the largest radius of the upper part. The relative rotation can also be completed a little earlier, if the pressing pressure is sufficiently large or, if it is so strong that a further rotation by hand or by means of a tool is no longer possible. Due to this effect, no great demands are placed on the tolerances. The tolerance must only ensure that an easy insertion and the achievement of a sufficient pressing pressure by the relative rotation are possible.

The runout can be configured in various ways. For example, the surfaces may be formed such that, in each of the surfaces, the small and the large radii face each other with respect to the center line. Thus, the cross section of the upper part, or the cross section of the opening of the lower part of an oval, elliptical or similar shape. Preferably, however, it is provided that the surfaces are formed such that in each of the surfaces, the smaller and the larger radii are evenly distributed on the circumference three times. This arrangement guarantees a secure fit of the upper part in the lower part and prevents instability by a tilting movement, as is possible with two opposing contact surfaces. In combination with the smooth transitions from small to large radii, there is a rotation of 60 ° between the position of maximum ease of movement and the position of greatest pressure. Within this rotational movement of 60 °, a clearance fit may be present first. After a short rotational movement, the pressing pressure begins, which then finally increases to its maximum at 60 °. Instead of the three-way arrangement of the small and of course, it is also possible to arrange them four times or more with large radii on the circumference.

The handling can be further facilitated by the fact that the relative positions of the upper part and lower part for the height adjustment and for the fixation are indicated by markings. Thus, a mark may be provided on the upper part, which is assigned for insertion and for height adjustment of a first mark on the lower part, and then to be moved to reach the height to a further mark by the rotational movement indicating the position of maximum fixation. Of course, these markers could also be arranged vice versa.

Since road surfaces are usually inclined to provide drainage or to make a Kurvenerhöhung, it is useful if the areas for a pressing pressure are designed such that they allow a slight inclination of the upper part relative to the lower part. This is possible regardless of which of the two above-mentioned basic embodiments is selected, that is, regardless of whether the relative movement is a pure vertical movement or a combined rotational and vertical movement. In this way, the lower part can be placed on a straight ground and it is possible to bring the upper side with an inclined road surface by the slight inclination of the upper part in accordance. Such an inclination of the upper part relative to the lower part can be achieved, for example, by shortening the regions for a pressing pressure in relation to the areas of the corresponding surface in such a shortened manner that the slight inclination is possible. Another possibility would be to make this area slightly convex in the vertical direction, or you could combine both measures. An even better fixation can be achieved if the areas in which the pressing pressure prevails in the fixing position have a roughened surface. Since the adjustment of an inclination by overcoming a holding force, which is determined by the pressing pressure and surface friction, takes place, can Adjust inclination as well as the final height adjustment to the final road level by rolling over with the road roller.

In the embodiment, it is possible that the areas for the pressing pressure on the surface of the opening of the lower part have a slightly more concave shape than the remaining parts of this surface in the direction of the horizontal. Wherein this concave shape is configured such that the corresponding areas of the outer surface of the upper part can apply with uniform surface pressure to the more concave shape of the opening of the lower part. In this way, the areas acted upon by the pressing pressure are increased, which also serves for a better fixation. Such a configuration also leads to the fact that it comes at the transition of the concave surface to the rest of the surface to a slight grandeur in the surface. Their overcoming takes the relative rotation between the upper and lower part executive person by a slight snap true, which signals the achievement of the fixing position. Thereafter, the convex surfaces of the upper part with the larger radii are at the slightly concave shape of the corresponding surfaces of the lower part.

Of course, there are other ways to improve the fixation, for example, the areas for the pressing pressure of at least one of the surfaces may be formed as resilient elements. This leads in both embodiments to a better smoothness, which in the first embodiment, the vertical movement and in the second embodiment, the rotational movement relates. A further possibility for both embodiments is that one of the surfaces in the regions for the pressing pressure has slight projections which press into the corresponding surface upon application of the pressing pressure. The protrusions may be, for example, a slight knobby structure of one of the surfaces.

It may also be expedient that a height scale is mounted on the outer surface of the upper part, so that it is possible to bring the upper part to a height corresponding to an applied road surface or in the aforementioned manner and Way slightly above it to bring the surface of the shell then with the road roller to the exact height, which also transfers a possible inclination of the road by itself on the upper side of the upper part.

Fig. 1

eine Darstellung der Erfindung in Schnitt,

Fig. 2

eine Prinzipskizze der Ausführungsform mit einer Ausgestaltungsmöglichkeit der korrespondierenden Flächen von Oberteil und Unterteil,

Fig. 3

eine Prinzipskizze der Ausführungsform mit einer weiteren Ausgestaltungsmöglichkeit der korrespondierenden Flächen von Oberteil und Unterteil,

Fig. 4

ein für die Ausführungsform mögliches Ausführungsbeispiel einer Neigbarkeit des Oberteils im Schnitt,

Fig. 5

eine für die Ausführungsform mögliche Ausgestaltung korrespondierender Bereiche für den Pressdruck,

Fig. 6

die Anordnung einer Höhenskala und

Fig. 7

eine Ausgestaltungsmöglichkeit eines Bereiches für den Pressdruck.

The invention will be explained with reference to embodiments shown in the drawing. Show it

Fig. 1

a representation of the invention in section,

Fig. 2

a schematic diagram of the embodiment with a possibility of designing the corresponding surfaces of the upper part and lower part,

Fig. 3

a schematic diagram of the embodiment with a further embodiment possibility of the corresponding surfaces of the upper part and lower part,

Fig. 4

a possible embodiment of the embodiment of a tiltability of the upper part in section,

Fig. 5

a possible embodiment of the embodiment of corresponding areas for the pressing pressure,

Fig. 6

the arrangement of a height scale and

Fig. 7

a possible embodiment of an area for the pressing pressure.

Fig. 1 shows an embodiment of the road cap 1 according to the invention in section. This has an upper part 2, which is inserted into the opening 4 of a lower part 3. The lower part 3 is made in road construction in the field of a threaded fitting on a base, usually the ballast bed, then by an actuating movement 11 the Adjusted height 8 of the upper part 2, so that this upper part 2 closes with the road surface, when the still applied coverings are applied. It is also possible, if the last deck covering has not yet been applied, to first lower the upper part 2 in order to obtain a provisionally usable road level and then set the upper part 2 even higher before applying the last layer. Thus, the adjustment of the upper part 2 in the lower part 3 is possible, must prevail between the outer surface 12 of the upper part 2 and the corresponding surface 13 of the opening 4 of the lower part 3 illustrated by the double arrows 9 pressing pressure 9.

According to one embodiment of the invention, the adjusting movement 11 for adjusting the height 8 is characterized in that by a relative rotation 6 'a range of smooth adjusting movement 11 is adjustable and that after finding the correct height adjustment 8 by the adjusting movement 11 by means of a relative rotation 6, a fixation of the upper part 2 in the lower part 3 can be brought about. For this purpose, an embodiment of the upper part 2 and the lower part 3 is required, as exemplified by the Fig. 2 or 3 is illustrated.

Fig. 2 shows a schematic diagram of a possible embodiment of upper part 2 and lower part 3, wherein only the outer surface 12 of the upper part 2 and the corresponding surface 13 of the opening 4 of the lower part 3 are shown. Here, these surfaces 12 and 13 are formed as a slightly larger and slightly smaller ellipse in such a way that the same orientation of the ellipses, the surface 12 of the upper part 2 with the surface 13 of the lower part 3 a clearance fit for Height adjustment 8 forms and in a relative rotation 6 by about 90 °, a press fit is achieved. This state is shown here, wherein the large radius 7 'of the lower part 3 and the small radius 7 "of the upper part 2 correspond to each other as well as the small radius 7 of the lower part 3 and the large radius 7''' of the upper part 2. With respect to the latter is the large radius 7 '''of the upper part 2 is slightly larger than the small radius 7 of the lower part 3, so that sets in the areas 5 and 5', a pressing pressure 9. This pressing pressure 9 allows fixing the height adjustment 8. It is characterized by the respective transitions 14 of small to large radii or vice versa ensured that when making a relative rotation 6, which takes place when the radii 7 and 7 "'brought on, a wedge effect occurs, by which a high pressing pressure 9 is easily achievable. Since the drawn position shows the fixation, the indicated relative rotations 6 'lead in both directions to a solution of the fixation.

Fig. 3 shows a schematic diagram of a further embodiment possibility of the corresponding surfaces 12 and 13 of the upper part 2 and the opening 4 of the lower part 3. Here are provided for the two surfaces 12 and 13 forms in which large 7 ', 7''' and small 7, 7 '' Radii are arranged evenly distributed on the circumference. As a result, small radii 7, 7 "and large radii 7 ', 7'" each alternate in a 60 ° sequence, resulting in three regions 5, 5 ', 5 "for generating a pressing pressure 9. The differences between the radii 7, 7 "and 7 ', 7''' are exaggerated here for better visibility.

In the position shown this pressing pressure 9 is already achieved, but can be increased by a relative rotation 6 until the large radii 7 '''of the upper part 2 with the small radii 7 of the opening 4 of the lower part 3 correspond. If, on the other hand, the large radii 7 '''of the upper part 2 are brought into coincidence with the large radii 7' of the lower part 3, and of course the small radii 7 and 7 ", then a clearance fit is also created here, which allows a height adjustment 8 to be smooth could the upper part 2 and the opening 4 of the lower part 3 are also designed such that in place of this clearance fit a smooth interference fit occurs and can be set to fix a comparison with the latter significantly increased pressing pressure 9.

Also in this embodiment, the transitions 14 of small radii 7, 7 "to large radii 7 ', 7' '' - and vice versa - designed so that these transitions 14 are gradual and thereby the wedge effect already described above is achieved.

In the embodiments acc. Fig. 2 and 3 the final height adjustment 8 described above takes place by means of the road roller in the fixing setting, that is, overcoming the surface friction by the pressing pressure 9.

Fig. 4 shows a second embodiment of the road cap 1 according to the invention in section, with respect to the identical reference numerals to the Fig. 1 is referenced. This embodiment, which serves to achieve a tiltability of the upper part 2 relative to the lower part 3, can be realized for both embodiments. In the first embodiment, the two surfaces 12 and 13 are round and form a press fit. In the second embodiment, the outer surface 12 of the upper part 2 and the corresponding surface 13 of the opening 4 of the lower part 3 are configured in a manner as well Fig. 2 or 3 has been described or in a corresponding other way.

In contrast to Fig. 1 is here provided that the areas 5, 5 ', 5 "for the pressing pressure 9 on one of the surfaces 12 or 13 - here on the surface 13 of the lower part 3 - is reduced in height such that a slight inclination 10 of the upper part of the second in the direction of the arrows 10, in order to be able to adjust in this way an inclination of the upper side of the upper part 2 with respect to the standing surface of the lower part 3. As a result, it is not necessary for the standing surface of the lower part 3 and the road surface to be parallel, but instead For example, during the application of the road surface layers, an inclination of the road surface may still be built up which does not exist on the ground on which the lower part 3 stands, which is also the rule since the exact modeling of the road surface, in particular for the water drainage, in usually occurs when applying the outer layers.

Fig. 5 shows for the second embodiment, a possible embodiment of the areas 5, 5 'or 5 "of the outer surface 12 of the upper part 2 and the corresponding surface 13 of the opening 4 of the lower part 3. This configuration of the areas 5, 5', 5 '' for the pressing pressure 9 is that a surface 15 of the opening 4 of the lower part 3 has a slightly more concave shape relative to the remaining surface 13. This also creates a slight sublimation 17 at the boundaries of these regions 5, 5 ', 5 "in relation to further course of the surface 13. In this way, for a relatively large areas for the areas 5, 5 ', 5 "( Fig. 3 ) or 5, 5 '( Fig. 2 ) or otherwise made available on surfaces 12 and 13 in areas 5, 5 ', 5 "with equally high pressing pressure 9. In addition, the slight elevation 17 at both boundaries of these areas 5, 5', 5 "when making a relative rotation 6 for fixing a slight engagement of the upper part 2 during the rotational movement 6 in the opening 4 of the lower part 3 is achieved, so that the person handling knows when the fixing position is reached.

Fig. 6 shows a schematic diagram with the arrangement of a height scale 16 on the outer surface 12 of the upper part 2, so that a presetting of the height adjustment 8 of the upper part 2 before application of a road surface layer is possible without having to use a meter stick.

Fig. 7 shows in the form of a section of an embodiment of the areas 5, 5 ', 5''for the pressing pressure 9 of one of the surfaces 12, 13 as a resilient element 18. The spring action is achieved here by an undercut 19. Length, thickness, angle and elasticity of the nose-like projection of the resilient member 18 determine the specific spring force. These parameters are therefore to be adapted to the specific requirements in the concrete production, as they result from the desired adjustability and fixing effect. In order to achieve a spring effect, the resilient elements 18 can of course be designed differently, for example, by a bridge-like shape.

The illustrations are of course only exemplary nature. Further embodiments, in particular of the corresponding surfaces 12 and 13 are possible. Thus, it could also be provided that these surfaces 12, 13 are designed with their regions 5, 5 ', 5 "in such a way that a stop is achieved during a relative rotation 6 for fixation and a relative rotation 6' away from this stop to release the fixation For this purpose, rising areas with respective end stops for the areas would have to be provided.

Height adjustable road cap LIST OF REFERENCE NUMBERS

1

Surface box

2

top

3

lower part

4

Opening of the lower part

5, 5 ', 5 "

Areas for pressing pressure

6

Arrow: relative rotation - fixation

6 '

Arrow: relative rotation - release fixation

7

small radius of the base

7 '

large radius of the base

7 ''

small radius of the shell

7 '' '

large radius of the shell

8th

height adjustment

9

Double arrows: pressing pressure

10

Arrows: inclination directions / inclination

11

Arrows: Adjustment movement for height adjustment

12

Outer surface of the upper part

13

corresponding surface of the opening of the lower part

14

Transitions from small to large radii

15

slightly more concave shape of areas for pressing pressure

16

height scale

17

slight grandeur in relation to the course of the surface 13

18

resilient element

19

undercut

Claims (12)

1. A vertically adjustable plastic road manhole cover (1) comprising a top part (2) and a bottom part (3), said top part (2) being adapted to move into and out of an opening (4) in said bottom part (3) and to be locked in a defined vertical position (8) within said bottom part (3), and a force-fit pressure (9) can be achieved between said top part (2) and said bottom part (3) such that said vertical position (8) can be overcomably set by relative movement between said top part (2) and said bottom part (3),
   characterized in that
   an outer surface (12) of said top part (2) and a surface (13) of said opening (4) in said bottom part (3), which surface (13) faces said outer surface (12) in the inserted state thereof, are formed in such a manner that in at least one arrangement of said top part (2) in said bottom part (3), obtainable by relative rotation (6), a force-fit pressure (9) is achieved in at least two regions (5, 5', 5") of said outer surface (12) of said top part (2) and said surface (13) of said bottom part (3), which force-fit pressure locks said vertical position (8), and in other arrangements, obtainable by relative rotation (6'), said vertical position (8) can be set by a low-effort adjustment movement (11), which surfaces (12, 13) are at least partially non-circular in cross-section such that the force-fit pressure (9) is produced when small radii (7) of the bottom part (3) coincide with large radii (7"') of the top part (2) and a low-effort adjustment movement (11) can be carried out to adjust said vertical position (8) when the respective small radii (7, 7") coincide with the respective large radii (7', 7"') of said bottom part (3) and said top part (2) respectively.
2. The road manhole cover as defined in claim 1,
   characterized in that
   the transitions (14) from said small radii (7, 7") to said large radii (7', 7"') are smooth.
3. The road manhole cover as defined in claim 1 or claim 2,
   characterized in that
   said surfaces (12, 13) are arranged in such a manner that the small radii (7, 7") of each of said surfaces (12, 13) are opposite the large radii (7', 7"').
4. The road manhole cover as defined in claim 1 or claim 2,
   characterized in that
   said surfaces (12, 13) are designed in such a manner that said small radii (7, 7") and said large radii (7', 7"') are each present three times on each of said surfaces (12, 13) and are regularly distributed over the periphery thereof.
5. The road manhole cover as defined in any one of claims 1 to 5,
   characterized in that
   the relative positions of said top part (2) and said bottom part (3) are distinguished by marks for said adjustment movement (11) and for locking by said force-fit pressure (9).
6. The road manhole cover as defined in any one of claims 1 to 5,
   characterized in that
   said regions (5, 5', 5") for a force-fit pressure (9) are designed in such a manner that they allow for slight inclination (10) of said top part (2) relatively to said bottom part (3).
7. The road manhole cover as defined in claim 6,
   characterized in that
   on one of said surfaces (12 or 13) said regions (5, 5', 5") for a force-fit pressure (9) relatively to the corresponding regions (5, 5', 5"') of said corresponding surface (13 or 12) are vertically discontinued in such a manner that said slight inclination (10) of said top part (2) relatively to said bottom part (3) is made possible.
8. The road manhole cover as defined in any one of claims 1 to 7,
   characterized in that
   said regions (5, 5', 5") have a roughened surface.
9. The road manhole cover as defined in any one of claims 1 to 8,
   characterized in that
   said regions (5, 5', 5") on said surface (13) of said opening (4) of said bottom part (3) have a slightly more concave form (15) than the rest of said surface (13), as regarded in the horizontal direction, such that said regions (5, 5', 5") of said outer surface (12) of said top part (2) can bear against said slightly more concave form (15) with a uniform surface pressure.
10. The road manhole cover as defined in any one of claims 1 to 9,
    characterized in that
    said regions (5, 5, 5") for said force-fit pressure (9) are formed as resilient elements (18) on at least one of said surfaces (12, 13).
11. The road manhole cover as defined in any one of claims 1 to 10,
    characterized in that
    one of said surfaces (12 or 13) in said regions (5, 5', 5") exhibits small protrusions, which are pressed against said corresponding surface (13 or 12) on the occurrence of said force-fit pressure (9).
12. The road manhole cover as defined in any one of claims 1 to 11,
    characterized in that
    a vertical scale (16) is provided on said outer surface (12) of said top part (2).

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