Manhole cover receiving frame

A manhole cover receiving frame includes an outer tube and a cover receiving frame. The cover receiving frame may be axially moved relative to the outer tube so that an upper surface of the manhole cover receiving frame matches the level of the surrounding road surface. The cover receiving frame is moved by a plurality of bolts threaded in the outer tube.

BACKGROUND OF THE INVENTION AND PRIOR ART 
The present invention relates to a manhole cover receiving frame for 
underground structures such as manholes for water supply and sewage 
systems, and manhole structures for fire hydrants, etc. 
A conventional underground structure, for example, a cover receiving frame 
of a manhole for water supply and sewage systems is provided in a manhole 
tube. Therefore, when the road surface is not level with the upper surface 
of the manhole cover receiving frame, a level adjusting ring must be 
inserted between the manhole tube and the manhole cover receiving frame or 
a ring must be removed therefrom. However, this operation is not only 
cumbersome but also is time consuming. 
In the case where the level of the manhole cover receiving frame must be 
adjusted to match the level of the surrounding road surface, the traffic 
must first be stopped, after which the following tasks must be are carried 
out sequentially: 
(A) cutting an existing pavement 
(B) lowering the existing pavement 
(C) digging operation 
(D) removal of a cover receiving frame 
(E) installation of an adjusting ring 
(F) installation of a cover receiving frame 
(G) adjustment of the level of roadbed 
(H) transfer of the pressure of roadbed 
(I) temporary pavement 
(J) final pavement 
These tasks are troublesome and are time consuming, thus increasing costs. 
So, with roads having heavy traffic, a traffic jam is created due to the 
level adjustment work. Development of a method for simply finishing the 
level adjustment work has been desired. 
Further, it takes a large amount of time to adjust an angle of inclination 
for matching the upper surface of the manhole cover with the inclination 
of the road surface. Therefore, development of measures capable of 
carrying out the adjusting operation in a short period of time have been 
desired. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a manhole cover 
receiving frame in which the level adjusting operation can be carried out 
easily, the area around the manhole cover receiving frame need not be 
disturbed as much as with the prior art, the level adjusting operation can 
be finished in a short period of time, and adjusting an angle of 
inclination of a manhole cover can be carried out easily. 
The present invention has been accomplished in order to achieve the 
aforementioned objects. According to a first embodiment, an outer tube and 
a cover receiving frame which moves up and down therein constitutes a 
manhole cover receiving frame. The cover receiving frame is moved up and 
down by a suitable number of bolts threaded in the outer tube. 
That is, in the first embodiment, a cover receiving frame, provided with 
through-holes into which the bolts are inserted, is mounted vertically 
movably in the outer tube. The outer tube is provided at an internal lower 
part thereof with a receiving seat and a mounting portion. The mounting 
portion has a suitable number of bolts threaded therein. Upper portions of 
the bolts, inserted into the through-holes, are stopped by a stopper so 
that even when the bolts are rotated, the bolts are not moved axially with 
respect to the cover receiving frame. 
According to a second embodiment, a device is made to facilitate mounting 
and assembly of the bolts, in which an internal lower part of the device 
is provided with a receiving seat. In addition, the device has an outer 
tube provided with a suitable number of non-threaded holes for receiving 
the bolts. Nuts are inserted into lateral hole receiving portions of the 
outer tube. A cover receiving body having an outside diameter is 
internally provided on the receiving seat within the outer tube. The outer 
diameter of the outer tube is smaller than an inside diameter of an upper 
edge of the outer tube. The cover receiving body is provided with 
fork-like head engaging portions at suitable positions internally thereof. 
The bolts are provided threaded in the nuts and extend through the head 
engaging portions and through the non-threaded holes. The stoppers are, in 
turn, engaged with the lower surface of the head engaging portions. 
According to a third embodiment, there is provided a cover receiving frame 
which is nicely stabilized after it is adjusted to an inclination of the 
road surface. This embodiment provides a manhole cover receiving frame in 
which a cover receiving frame body having an outside diameter smaller than 
an inside diameter of an upper edge of an outer tube is internally 
provided in the outer tube. The outer tube is provided with a receiving 
seat at an internal lower part thereof. The cover receiving frame body is 
moved up and down by bolts provided on the receiving seat. Two spacers 
have non-parallel top and bottom surfaces or, in other words, two variable 
slope spacers, in contact with one another at curved surfaces or spherical 
joining portion are arranged between the receiving frame body and the 
receiving seat. 
According to a fourth embodiment, a scale showing an adjusted height is 
provided on the outer surface of the cover receiving frame body in order 
to facilitate the level adjusting operation of the cover receiving frame 
body.

DETAILED DESCRIPTION OF THE INVENTION 
FIRST EMBODIMENT 
FIG. 1 shows a first embodiment of the present invention. Reference numeral 
1 designates an outer tube in which a flange 2 for positioning the 
invention is provided externally thereof. Further, a receiving seat 3 and 
a bolt mounting portion 5 having bolts 4 threaded at three locations are 
provided at an inner lower part of the outer tube. The outer tube also has 
an upper edge 6 which is projected inward. Reference numeral 7 designates 
a cover receiving frame internally provided on the receiving seat 3 within 
the outer tube 1. The cover receiving frame has an outside diameter 
slightly smaller than an inside diameter of the upper edge 6 of the outer 
tube 1. Reference numerals 8, 8' designate level adjusting spacers 
inserted between the receiving seat 3 of the outer tube 1 and the cover 
receiving frame 7. The level adjusting spacers have a shape as shown in 
FIG. 2. 
The first embodiment has a constitution in which the bolt 4 is inserted 
into a non-threaded hole 9 provided in a projection 7a of the cover 
receiving frame 7. The bolt 4 is threaded through the bolt mounting 
portion 5. A stopper or nut 10 is stopped by stop rings 11 so that the 
former may not move on bolt 4. A clearance is formed between the bolt 
mounting portion 5 and the stopper 10 so that the cover receiving frame 7 
can be inclined as shown by the imaginary lines. The bolt 4 is rotated so 
that the cover receiving frame 7 is moved up and down within the outer 
tube 1. 
Next, the procedure for the level adjusting operation for the manhole cover 
receiving frame and the operation for adjusting an angle of inclination of 
a manhole cover (not shown) will be explained. 
First, the procedure for the level adjusting operation will be explained. 
In the case of raising the level, the bolts 4 provided at the three 
positions are rotated to raise the upper surface of the cover receiving 
frame 7 to coincide with the road surface. Then, an adjusting spacer 
having a desired height or thickness is inserted into a gap formed below 
the lower surface of the cover receiving frame 7. 
Several spacers different in thickness and spacers without taper as well as 
tapered spacers, similar to conventional spacers, are prepared for 
selective use. After insertion of the spacer or spacers, the bolts 4 are 
tightened to fasten the cover receiving frame 7. 
On the other hand, in the case of lowering the level, the bolts 4 are 
rotated to raise the cover receiving frame 7. After this, the adjusting 
spacer or spacers 8, 8' is/are removed. Then, the bolts are tightened to 
lower the cover receiving frame 7. When the cover receiving frame 7 
coincides with the road surface, an adjusting spacer or spacers having a 
desired thickness is/are inserted below the cover receiving frame 7, and 
the bolts 4 are tightened to fasten the cover receiving frame 7. 
With the prior art devices, it had been necessary to remove portions of the 
adjacent asphalt road surface before performing the level adjusting 
bulk-up operation. However, in the present invention, such action is not 
necessary. The cover receiving frame 7 can be simply moved up and down by 
rotating the bolts 4. Work is completed by a simple operation in which a 
calking material is filled in a clearance formed between the cover 
receiving frame 7 and the asphalt road surface. Work can be finished in a 
short period of time, for example, scores of minutes or a few hours. 
With the above embodiment, the nut 10 is used as a stopper, upper and lower 
portions of which are held fast by the stop rings 11. It is also to be 
noted that the nut 10 may be replaced with a stop pin such as a split pin. 
Next, the procedure for adjusting an angle of inclination will be 
explained. This procedure is similar to the level adjustment described 
above. The bolts 4 may be manipulated so that the upper surface of the 
cover receiving frame 7, that is the upper surface of the manhole cover, 
coincides with the inclination of the road surface. 
According to the present embodiment, in the case of a normal 650 mm 
manhole, assuming that the height of the outer tube is 110 mm, that the 
gap between the upper edge 6 of the outer tube 1 and the cover receiving 
frame 7 is 8 mm, and that the gap between the inner surface of the body of 
the outer tube 1 and the outer peripheral surface of the cover receiving 
frame 7 is 3 mm, then, the inclination can be changed from 0.degree. to 
about 5.degree.. It is also noted that the angle of inclination can be 
inclined more than that of the above noted angle by increasing the gap. 
SECOND EMBODIMENT 
FIG. 3 is a plan view of a second embodiment and FIG. 4 is a front view 
thereof. FIG. 5 is a plan view of a cover receiving frame and FIG. 6 is a 
sectional view taken on line VI--VI of FIG. 4. FIG. 7 is an enlarged 
sectional view taken on line VII--VII of FIG. 3. Reference numeral 1' 
designates an outer tube. Reference number 20 designates a cover receiving 
frame. 
The outer tube 1' is constituted such that a flange 2' for positioning the 
tube is provided externally thereof. Further, a receiving seat 13 and a 
bolt mounting portion 15 provided with non-threaded holes 14 at three 
locations are provided at an inner lower part of the outer tube 1'. Bolts 
18 are threaded to nuts 17 inserted into lateral hole receiving portions 
16 through the non-threaded holes 14. An upper edge 19 of the outer tube 
1' is projected inward, and scales M indicating the adjusted height are 
located at three positions around an outer surface of the outer tube 1'. 
Cover receiving frame 20 is internally provided on the receiving seat 13 
within the outer tube 1'. The cover receiving frame has an outer diameter 
slightly smaller than an inside diameter of an upper edge 19 of the outer 
tube 1'. Fork-like head engaging portions 21 in engagement with the bolts 
18 at the three positions and a base portion 21' are provided as shown in 
FIG. 7. The base portion 21' is not always necessary in terms of function, 
and may be omitted. 
Reference numeral 22 designates a stopper comprising washers 23, 24 and a 
nut 25. The washer 23 and the nut 25 are firmly fastened to the bolt 18 so 
that they are not moved axially even if the bolt 18 is rotated. These 
stoppers 22 are provided between the head engaging portions 21 and the 
base portions 21'. Reference numeral 26 designates a washer provided below 
a bolt head. 
Reference numerals 27 designate level adjusting spacers inserted between 
the receiving seat 13 of the outer tube 1' and the cover receiving frame 
20, and have a shape as shown in FIG. 8A. Spacers 27 are provided with 
hook-like portions 27a in engagement with bolts 18. 
Reference numeral 28 designates a fine adjusting spacer, which is made of a 
plate material as shown in FIG. 9A, and which resembles spacer 27 without 
arms 27b. 
Reference numeral 29 designates a spacer having non-parallel top and bottom 
surfaces or in other words is a variable slope spacer provided below the 
lower base portion 21'. The variable slope spacer is composed of two 
C-shaped seat bodies 29a, 29b which taper as shown in FIGS. 10A and 10B. 
In addition, one variable slope spacer is provided with a convex portion 
30 and the other is provided with a concave portion 31 fitted in the 
convex portion 30 so that the two are interlocked. An angle .theta. (a 
slope) formed between the upper surface and the lower surface may be 
changed as shown in FIG. 10D by rotating one of the spacers. 
The assembling procedure in the present embodiment will be explained. 
First, the washers 26 and the bolts 18 with the stoppers 22 are brought 
into engagement with the head engaging portions 21 at three positions of 
the cover receiving frame 20 and the base portion 21'. After this, the 
cover receiving frame 20 is moved down into the outer tube 1', and the 
bolts 18 are threaded to the nuts 17. A suitable number of the level 
adjusting spacers 27, the fine adjusting spacers 28 and the variable slop 
spacers 29 are mounted according to the difference in level between the 
surface of the cover and the adjacent roadway. 
Next, the procedure for the level adjusting operation and the operation for 
adjusting an angle of inclination of the manhole cover (not shown) will be 
described. 
First, the procedure for the level adjusting operation will be described. 
In the case of raising the level, in FIG. 3 and FIG. 7, the bolts 18 are 
rotated to raise the upper surface of the cover receiving frame 20 to 
coincide with the road surface, and the aforementioned spacers are 
inserted into the gaps formed below the lower surface of the cover 
receiving frame 20. After completion of the level adjustment, the bolts 18 
are fastened to the cover receiving frame 20. 
On the other hand, in the case of lowering the level, the bolts 18 are 
rotated to raise the cover receiving frame 20. After this, any unnecessary 
spacers are removed. Then, the bolts are rotated to lower the cover 
receiving frame 20. When the cover receiving frame 20 coincides with the 
road surface, necessary spacers are inserted below the cover receiving 
frame 20, and the bolts 18 are fastened. 
With the conventional prior art devices construction, it has been necessary 
to remove the adjacent asphalt road surface before the level adjusting 
operation. However, in the case of the present embodiment, such action is 
not necessary. The cover receiving frame 20 can be simply moved up and 
down by rotating the bolts 18. Work is completed by a simple operation in 
which a calking material is filled in a clearance formed between the cover 
receiving frame 20 and the asphalt road surface. Work can be finished in a 
short period of time, for example, scores of minutes or a few hours. 
Next, the procedure for adjusting an angle of inclination will be 
explained. This procedure is similar to the level adjusting operation 
described above. The bolts 18 may be manipulated so that the upper surface 
of the cover receiving frame 20, that is the upper surface of the manhole 
cover, coincides with the inclination of the road surface. 
In the illustrated embodiment, the bolts 18 and the nuts 17 are adjusted 
according to the desired inclination. The cover receiving frame 20 can be 
firmly locked to the inclined position by adding or removing variable 
slope spacers 29. The scales M are effective to facilitate these adjusting 
operations. 
In this embodiment, nut 17 is inserted into the lateral hole 16 thereby 
avoiding troubles associated with forming internal threads in the outer 
tube 1'. Hence, a construction can be employed in which the bolt 18 is 
inclined. Also, in the case where a stainless steel material is used, the 
stainless steel material overcomes problems caused by the electric 
corrosion of threaded portions. 
As described above, in the manhole cover receiving frame according to the 
present invention, the adjustment of the height and the adjustment of the 
angle of inclination can be accomplished simply from the top by rotating 
the bolts 18. Therefore, the time required to perform the level adjusting 
operation, and the time required for adjusting the angle of inclination 
can be shortened, and an exceptional manhole cover receiving frame can be 
provided. 
THIRD EMBODIMENT 
FIG. 11 shows a third embodiment of the present invention. When the cover 
receiving frame 20 is adjusted to the inclination of the road surface, the 
cover receiving frame 20 becomes firmly stabilized. 
That is, variable slope spacers 191, 192, in contact with one another at 
concave surface P and convex surface Q, in addition to a suitable number 
of level adjusting spacers 27 and fine adjusting spacers 28 are provided 
between the outer tube 1' and the cover receiving frame 20 which are 
similar in construction to the second embodiment as shown in FIG. 2. 
Hence, stability is improved as compared with cases where the slope of the 
cover receiving frame 20 is adjusted merely by the level adjusting spacers 
27 and the fine adjusting spacers 28.