JP2001146714A - Inspection device for steel box girder bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device for a steel box girder bridge capable of quickly and accurately inspecting the steel box girder bridge and, at the same time, also inspecting the steel box girder bridge in any place. SOLUTION: An inspection device for a steel box girder bridge is equipped with a set of front and rear traveling units 11 and 12 suspended on a flange 4 of a steel box girder 6 by independently driven front and rear traveling wheels 16 and 17 provided respectively to right and left driving blocks 14 connected with joint frames 13 at required intervals, links 18 for connecting both right and left driving blocks 14 in both traveling units 11 and 12 in a horizontally rotatable manner in front and rear, inspecting TV cameras 19 mounted to the traveling units 11 and 12 and wheel sheltering mechanisms 25 for preventing a rib on the flange 4 by independently making the traveling wheels 16 and 17 shelter from the flange 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device for a steel box girder bridge used for inspecting the back of a road structure, particularly an elevated road having a steel box girder such as an expressway.

[0002]

2. Description of the Related Art In recent years, road structures in Japan have become obsolete and damaged due to an increase in traffic volume, an increase in the size of vehicles, and their use for many years. Maintenance of such damaged bridges, such as ensuring safety and extending their life, is expected to become increasingly important in the future.

Conventionally, such a bridge inspection has been carried out by assembling a scaffold for inspection with the bridge, and visually inspecting the worker while moving along the scaffold.

However, in this method, a large number of days and costs are required for assembling a scaffold for inspection, and the cost of assembling the scaffold occupies most of the inspection cost, which has been an obstacle to reducing the inspection cost.

[0005] For this reason, in recent years, a bridge inspection vehicle in which an articulated arm robot equipped with a television camera is installed in an automobile such as a truck is prepared, and inspection is performed by running such a bridge inspection vehicle along the bridge. Inspection has been carried out by running a bridge inspection vehicle as described above along the ground.

[0006]

However, in the above-described inspection using a bridge inspection vehicle, the inspection using a bridge inspection vehicle from above the bridge involves traffic regulation, and use on heavy traffic roads causes social problems such as traffic congestion. Was difficult. Also, traffic regulation for inspection only is not practical and difficult to implement. Furthermore, in the inspection by a multi-joint arm robot from a bridge inspection vehicle, not all parts of the bridge can be inspected, and when inspecting from the bridge, the robot arm is used every time there is a sign or lighting. It is necessary to repeat the operation of once raising and retracting and then lowering it again to a predetermined position, which has taken a very long time.

[0007] Inspection by a bridge inspection vehicle from the ground under the bridge cannot be performed unless there is a road or something equivalent to the road on the ground. Is difficult. In addition, bridges built high above the ground, railway bridges,
Inspection was not possible even on bridges over rivers and seas, and over mountain bridges.

The present invention has been made to solve such a conventional problem. Inspection of a steel box girder bridge can be performed quickly and accurately, and a steel box girder bridge can be inspected at any place. It aims to provide an inspection device for steel box girder bridges.

[0009]

According to the present invention, there are provided left and right side plates,
An inspection device for a steel box girder bridge provided with a steel box girder comprising a bottom plate provided at the lower part of the left and right plates and having a flange protruding left and right and reinforced by ribs, which is connected at a required interval by a connection frame. A set of front and rear traveling units that are suspended on the flange by independently driven front and rear traveling wheels provided on each of the left and right drive blocks,
A link that connects the left drive block and the right drive block of both traveling units so that they can rotate horizontally, a television camera for inspection attached to the traveling unit, and each traveling wheel is independently retracted from the flange. The present invention relates to an inspection device for a steel box girder bridge, comprising a wheel retreat mechanism for avoiding a rib on a flange.

[0010] The connecting frame may be adjustable in length by attaching and detaching a connecting piece, and the drive block may be provided with a transmitting device for transmitting a video signal of a television camera.

The wheel retreat mechanism includes an arm supporting each traveling wheel, a rotating shaft rotatably supporting each arm on a drive block so that the traveling wheel can retreat from above the flange,
Driven bevel gears provided so as to face each of the rotating shafts on which the front and rear running wheels in each drive block are mounted, and provided at right angles to the rotating shaft so that the driven bevel gears mesh with each driven bevel gear. A drive shaft, a spur gear provided on each drive shaft, two rotation restricting wheels provided inside a side surface of the spur gear, and arranged between the spur gears and meshing with the spur gears within a required range. A drive rotary plate having a sector gear and an outer peripheral portion having no sector gear and having an overhanging portion for restricting rotation of the spur gear in contact with the two rotation restricting wheels, and a retraction drive motor for rotating the drive rotary plate May be provided.

The drive block may be provided with a rib detector for detecting the approach of the rib and controlling the drive of the retraction drive motor, and the drive block may be provided with a battery.

In the inspection apparatus for a steel box girder bridge according to the present invention, the front and rear traveling units having the left and right drive blocks connected at required intervals by the connection frame are connected by links, and each drive block is provided with its own. It can be hung on the flange by the running wheels before and after being driven, so it can be easily assembled and installed on the flange part of the steel box girder, and each running wheel is independently retracted from the flange The inspection device can be run without causing the inspection device to interfere with the ribs, and the steel box girder bridge can be automatically inspected by the television camera.

Since the length of the connecting frame can be adjusted by attaching and detaching the connecting piece, it is possible to cope with a change in the width of the steel box girder.

If the drive block is provided with a transmission device for transmitting the video signal of the television camera, inspection work at a high place or on the water can be easily performed.

[0016] By the wheel retreat mechanism, when one traveling wheel of each drive block is retracted, the other traveling wheel can be operated so as to be reliably positioned on the flange, and when traveling while avoiding the ribs. Problems such as the inspection device falling off the flange can be reliably prevented.

By providing the drive block with a rib detector that detects the approach of the rib and controls the driving of the retraction drive motor, the retraction operation of the traveling wheels can be performed reliably.

By providing the drive block with a battery, various drive devices can be easily driven even in inspection work at a high place or on water.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 21 to 23 show an example of a steel box girder bridge to which the present invention is applied. The steel box girder bridge includes an upper plate 2, a left and right side plate 3, 3 and a steel box girder 6 having a bottom plate 5 provided below the left and right side plates 3 and 3 and having flanges 4 projecting to the left and right. Further, the steel box girder 6 is provided at a required interval position in the longitudinal direction (for example, every 5 meters) from the side plate 3 to be provided further between the flanges 4 of the upper plate 2 and the bottom plate 5 so as to reinforce. The rib 7 is fixed. 7 'is a rib flange. The steel box girder 6 is supported on a bridge pier 8 via a bearing 9.

FIGS. 1 to 3 show an embodiment of the inspection device 10 of the present invention applied to the steel box girder bridge shown in FIGS. 21 to 23. The inspection device 10 is shown in FIG. As described above, is constituted by a pair of traveling units 11 and 12 arranged in front and behind.

Each of the traveling units 11 and 12 includes a drive block 14 provided to travel on the left and right flanges 4.
And a fixing portion 14 provided on the rear surface of both drive blocks 14.
a and 14b and a connecting frame 13 for connecting between the connecting frames 13a and 14b.

Each drive block 14 is provided with running wheels 16 and 17 provided with its own drive motor 15 so as to run on the flange 4 so that the running units 11 and 12 can move the running wheels. It is hung on the flange 4 via 16 and 17.

Further, the left drive blocks 14 and 14 and the right drive blocks 14 and 14 of the front and rear traveling units 11 and 12 are connected by a horizontally rotatable link 18, respectively. A four-node link structure is formed by the pair of traveling units 11 and 12 and the left and right links 18.

The drive block 14 of the traveling unit 11 has a television camera 19 such as a CCD camera
The lower surface of the steel box girder bridge photographed by the television camera 19, for example, the elevated road 1
The video signal on the lower surface is transmitted by a transmission device 21 provided in the drive block 14 or the like. Further, the drive block 14 is provided with a battery 22 for driving various drive devices described later.

The length of the connecting frame 13 connecting the left and right drive blocks 14 can be adjusted according to the width of the steel box girder 6 by attaching and detaching the connecting piece 23. Reference numeral 24 in FIG. 1 denotes a bend detector configured to detect the bend of the steel box girder bridge at the end surface of the flange 4.

Each of the running wheels 16 and 17 is supported by the drive block 14 by a wheel retreat mechanism 25 which can retreat independently from the flange 4 to avoid the rib 7 on the flange 4.

FIGS. 4 to 6 show an example of the wheel retracting mechanism 25. FIG. As shown in FIGS. 4 to 6, the traveling wheels 16,
Numerals 17 are respectively supported by independent rotating shafts 27 and 28 provided on the drive block 14 via arms 26, and the running wheels 16 and 17 are
It can be evacuated from above.

The traveling wheel 1 in each drive block 14
A driven bevel gear 29 is provided on each of the rotating shafts 27 and 28 to which the rotating shafts 6 and 17 are attached, and both driven bevel gears 29 are 90 ° with respect to the rotating shafts 27 and 28. The drive bevel gear 32 provided on the drive shafts 30 and 31 extending in the direction of.

Each of the drive shafts 30 and 31 has a spur gear 33 as shown in FIG.
The rotation restraining wheels 34 and 35 are provided.

Further, the spur gears 3 of the drive shafts 30 and 31
The spur gear 33 is set in a range smaller than 180 °
A sector gear 36 meshing with the
A drive rotary plate having an overhanging portion 37 which wraps around both ends and has no sector gear 36 and which is in contact with the two rotation restraining wheels 34 and 35 to restrain the rotation of the spur gear 33 on the outer periphery of the portion having no sector gear 36. 38 are arranged.

Further, the drive rotary plate 38 is driven to rotate by a retreat drive motor 40 via a bevel gear 39.

Further, as shown in FIG. 5, ribs 7 (FIGS. 21 and 22) are provided at the front and rear positions of the running wheels 16 and 17, respectively.
A rib detector 41 is provided to detect the approach of the rib (the approach of the rib flange 7 ′) and control the retraction drive motor 40. Reference numeral 42 in FIG. 6 denotes a connection plate 43 (FIGS. 11 to 11) connecting the flanges 4 from above and below at the connection portions of the steel box girders 6.
This is a connection plate detection sensor for detecting FIG. 13).

FIGS. 14 to 20 show an apparatus for installing the inspection device 10 on the steel box girder 6 and an installation method.

In FIG. 14, reference numeral 44 denotes a mounting device for mounting the drive block 14 on the flange 4 of the steel box girder 6. The mounting device 44 can be fixed to the drive block 14 and has a flange at its upper end. 4 has a main body 46 provided with a clamp portion 45 extending over the upper surface.
6 is provided with a pressing portion 48 that is pressed against the lower surface of the flange 4 by the rotation of the lever 47. The flange 4 is clamped between the clamp portion 45 and the pressing portion 48 by the rotation of the lever 47. The drive block 14 can be supported by the flange 4.

FIGS. 15 and 16 show a connecting frame 1.
3 is a connecting frame assembling device for connecting the drive blocks 14 and 14 with each other.
Are guide rods 50, which are upright in a row in front and back.
As shown in FIG. 16, 51 has a substantially gutter shape and a required length, and a lower surface is provided with a rolling wheel 52 that can guide the connecting frame 13 and move in the longitudinal direction. Further, casters 53 are provided below the connecting frame assembling device 49 so that the upper surface of the pier 8 can be moved.

The connecting frame assembling device 49 includes a fixture 55
The guide rod 50 on the front side provided so as to form a substantially gutter shape is provided by the rotation of the drive shaft 54 as shown by an arrow in FIG. It can be raised and lowered.

As shown in FIG. 1, one end of the connection frame 13 is connected to a fixed portion 1 of the drive block by a connection portion 13a.
4a so as to be able to be connected to the connecting frame 13 in a horizontally rotatable manner. At the end, an adjustment block 56 as shown in FIG. 17 is provided. Adjustment block 56
One side of the fitting portions 57 and 58 having a split shape and fitted to the outer peripheral surface of the connecting frame 13 is connected by a hinge (not shown), and the opening / closing end opposite to the hinge is connected. It is configured to be tightened by a clamp wrench 59 and can be connected to the fixed portion 14b via a connecting portion 60 so as to be horizontally rotatable.

The operation of installing the inspection device 10 on the flange 4 of the steel box girder 6 will be described with reference to the plan views shown in FIGS.

First, as shown in FIG. 14, the running wheels 16 and 17 of the drive block 14 to which the mounting device 44 is mounted are placed on the flange, and the lever 47 is operated from above the pier 8 to clamp the flange 4. By doing so, the drive block 14 is fixed to the left and right flanges 4 as shown in FIG.

Next, as shown in FIG. 19, the connecting frame assembling apparatus 49 shown in FIGS. 15 and 16 is connected to the upper side of the pier 8 and the steel box girder from one side (the left side in the figure) of the steel box girder 6. 6 and is fixed to the flange 4 by the fixture 55. Subsequently, the connecting frame 13 is pushed into the right driving block 14 while connecting the connecting pieces 23 with the connecting frame assembling device 49 as a guide. At this time, if the adjusting block 56 of FIG. 17 is attached to the connecting frame 13,
Cannot be moved along the connecting frame assembling device 49, so that the adjusting block 56 is not attached at the time of pushing. Since the distance between the upper surface of the pier 8 and the steel box girder 6 shown in FIG. 21 is as narrow as about 300 mm, and the distance between the bearing 9 and the front surface of the pier 8 is as narrow as about 300 mm, the connecting frame 13 is placed in this narrow space. It is necessary to use the connecting frame assembling device 49 as described above in order to dispose it safely and securely.

The connecting portion 13a at one end of the connecting frame 13
(FIG. 1) is connected to the fixed portion 14a of the left drive block 14, and the adjustment block 56 is located at a position corresponding to the fixed portion 14b of the right drive block 14 in the connection frame 13.
And the connecting portion 60 of the adjustment block 56 is connected to the fixing portion 14b of the drive block 14 on the right side. As a result, the front traveling unit 11 is assembled as shown in FIGS. 19, 21 and 23.

When the connection frame 13 is connected, the drive block 14 is hung by the flange 4 and is stabilized, so the mounting device 44 shown in FIG. 14 is removed from the drive block 14 and the link 18 is connected to the left and right drive blocks 14. Are connected to each other. Further, by manually turning the drive shaft 54 shown in FIGS. 15 and 16, the guide rod 51 is tilted as shown by the arrow in FIG.
By pushing, the traveling unit 11 is advanced to the position shown in FIG.

Subsequently, another drive block 14 is fixed to the left and right flanges 4 in the same manner as described above.
The rear running unit 12 is assembled by pushing in the connecting frame 13 through the connecting frame assembling device 49 in which the guide rod 50 is erected by the drive shaft 54 of No. 6 and connecting the driving frame 14 with the driving blocks 14. Subsequently, by connecting the other end of the link 18 to the drive block 14 of the traveling unit 12, the inspection device 10 shown in FIG. 1 can be assembled.

Next, the operation of inspecting the steel box girder bridge by the inspection device 10 installed on the flange 4 as described above will be described.

As shown in FIGS. 1 to 3, the inspection device 10 supported by the flange 4 rotates all the running wheels 16 and 17 simultaneously in the same direction by the drive motor 15 so that the inspection device 10 can rotate at a predetermined speed. 4 can be run along. Therefore, the lower surface of the steel box girder bridge can be continuously photographed by the television camera 19, and the video signal photographing the lower surface of the elevated road 1 is transmitted to a predetermined position by radio or the like by the transmitting device 21 for analysis and analysis. Be recorded. At this time,
Neither of the spur gears 33 of the drive shafts 30 and 31 shown in FIG.
Since the rotation restricting wheels 34 and 35 are in contact with the overhanging portion 37 to restrict the rotation, the arm 26 maintains the upright state, so that the traveling wheels 16 and 17 are securely positioned on the upper surface of the flange 4. I have.

On the other hand, as shown in FIG. 8, when the traveling unit 11 of the inspection device 10 comes to the position of the rib 7 by traveling, the rib detector 41 on the front side of the traveling wheel 16 shown in FIGS. The flange 7 'is detected. Rib detector 41
Detects the rib flange 7 ', the traveling wheels 16, 17
Is stopped, the movement of the inspection device 10 is stopped, and then the retraction drive motor 40 is driven to retreat the traveling wheel 16 approaching the rib 7 from the flange 4.

That is, the drive rotating plate 38 shown in FIG. Then, the sector gear 36 meshes with the spur gear 33 of the drive shaft 30 and the drive shaft 30
When the driven bevel gear 32 is rotated to the left, and the driven bevel gear 29 in FIG. 6 is rotated to the right, the arm 26 is rotated outward, and the traveling wheel 16 is placed on the flange 4 as shown in FIG. Is evacuated to the outside. At this time, the rear running wheel 17 cannot rotate because the rotation restraining wheels 34 and 35 provided on the spur gear 33 of the drive shaft 31 in FIG. Therefore, there is no retreat from above the flange 4.

Thus, the traveling wheels 17 other than the retracted traveling wheels 16 and the traveling wheels 1 of the other traveling units 12
6 and 17 are driven to move the inspection device 10 (FIG. 1).
0). Subsequently, the rib detector 41 on the rear side of the traveling wheel 16 detects the rib flange 7 ', and when there is no detection signal thereafter, it is detected that the retracted traveling wheel 16 has passed the position of the rib 7, so that The movement of the inspection device 10 is stopped, and the retraction drive motor 40 is driven so as to rotate the drive rotary plate 38 counterclockwise in the opposite direction. Then, only the rear running wheel 17 is retracted from above the flange 4 this time, so that the inspection device 10 can move. By repeating the above operation, the traveling wheels 16, 1
The inspection device 10 can be moved along the flange 4 without causing the rib 7 to interfere with the rib 7.

According to the above, the front and rear traveling wheels 16, 17
Is always located on the flange 4, so that it is possible to reliably prevent the inspection device 10 from falling off the flange 4. The driving of the drive motor 15 and the retraction drive motor 40 can be easily performed by the battery 22 provided in the drive block 14.

Further, since the end face of the flange 4 is detected by the bend detector 24 shown in FIG. 1, if the steel box girder 6 is bent (the bridge is curved), it is detected. Therefore, by changing the drive speed of the left and right running wheels 16 and 17 based on the detected value of the bending detector 24, the vehicle can be stably driven even on a curve.

The flange 4 is provided with a connecting plate 43 for connecting the connecting portions of the steel box girders 6 as shown in FIGS. 11 to 13, and is fixed by a large number of bolts 43a.
Since the traveling wheels 16 and 17 are driven by the drive motor 15, the inspection device 10 can easily run over the vehicle. At this time, when the connection plate detection sensor 42 of FIG. 6 detects the approach of the connection plate 43, the moving speed of the inspection device 10 is reduced, and the inspection device 10 does not receive an impact when riding on the connection plate 43. So you can. In addition, the traveling units 11 and 1 are mounted so that the inspection device 10 can easily get on and off the connection plate 43.
2 is connected to the link 18 so as to be able to rotate horizontally.
It is effective to connect them so that there is some margin in the twisting direction.

As described above, the front and rear traveling units 11 and 12 having the left and right drive blocks 14 and 14 connected at required intervals by the connection frame 13 are connected by the link 18 and provided on each drive block 14. Since the inspection device is constructed so that it can be suspended and moved on the flange 4 by the front and rear traveling wheels 16 and 17 which are independently driven, it can be easily assembled and installed on the flange 4 of the steel box girder 6. In addition, since the wheel retreat mechanism 25 is provided so that each of the traveling wheels 16 and 17 can be independently retracted from the flange 4 to avoid the rib 7 on the flange 4, the inspection device 10 can be attached to the flange 4. While traveling along, the television box 19 attached to the traveling unit 11 can automatically inspect the steel box girder bridge.

It should be noted that the present invention is not limited only to the above-described embodiment, and it is needless to say that various changes can be made without departing from the spirit of the present invention.

[0055]

According to the inspection apparatus for a steel box girder bridge of the present invention, the front and rear traveling units having the left and right drive blocks connected at required intervals by the connection frame are connected by links, and each drive block is connected to each drive block. Since it can be suspended and moved on the flange by the independently driven front and rear traveling wheels provided, it can be easily assembled and installed on the flange part of the steel box girder, and further, each of the traveling wheels can be Since it is possible to independently evacuate from above, there is an effect that the inspection device can be run without interfering with the ribs, and the steel box girder bridge can be automatically inspected by the television camera.

Since the length of the connecting frame can be adjusted by attaching and detaching the connecting piece, there is an effect that it can cope with a change in the width of the steel box girder.

If the drive block is provided with a transmission device for transmitting the video signal of the television camera, there is an effect that inspection work at a high place or on the water can be easily performed.

By the wheel retreat mechanism, when one traveling wheel of each drive block retreats, the other traveling wheel can be operated so as to be reliably positioned on the flange, so that when traveling while avoiding the ribs. In addition, there is an effect that it is possible to reliably prevent the problem that the inspection device falls off from the flange.

By providing the drive block with a rib detector that detects the approach of the rib and controls the drive of the retraction drive motor, there is an effect that the retraction operation of the traveling wheels can be reliably performed.

The provision of the battery in the drive block has an effect that various drive devices can be easily driven even in inspection work at a high place or on water.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an embodiment of a steel box girder bridge inspection device of the present invention.

FIG. 2 is a view taken in the direction of arrows II-II in FIG.

FIG. 3 is a view in the direction of arrows III-III in FIG. 1;

FIG. 4 is a plan view showing an example of a wheel retreat mechanism.

FIG. 5 is a view in the direction of arrows VV in FIG. 4;

FIG. 6 is a view taken in the direction of arrows VI-VI in FIG. 4;

FIG. 7 is a side view showing details of a rotation restricted wheel in the wheel retracting mechanism.

FIG. 8 is a side view showing a state in which a traveling wheel of the traveling unit approaches a rib.

FIG. 9 is a side view showing a state where traveling wheels of the traveling unit are retracted.

FIG. 10 is a side view showing a state in which traveling wheels of the traveling unit move around the ribs.

FIG. 11 is a side view showing a state in which the inspection device approaches the connection plate.

FIG. 12 is a side view showing a state where the front portion of the inspection device rides on the connection plate.

FIG. 13 is a side view showing a state in which the inspection device moves on the connection plate.

FIG. 14 is a side view showing an example of a drive block mounting device.

FIG. 15 is a side view showing an example of a connecting frame assembling apparatus.

FIG. 16 is a view taken in the direction of arrows XVI-XVI in FIG. 15;

FIG. 17 is a perspective view showing an example of an adjustment block fixed to a connection frame.

FIG. 18 is a plan view showing a state where a drive block is fixed to a flange.

FIG. 19 is a plan view showing a state in which drive blocks are connected by a connection frame.

FIG. 20 is a plan view showing a state where one traveling unit is assembled.

FIG. 21 is a side view showing an example of a steel box girder bridge.

FIG. 22 is a view in the direction of arrows XXII-XXII in FIG. 21;

23 is a view in the direction of arrows XXIII-XXIII in FIG. 21.

[Explanation of symbols]

 Reference Signs List 3 Side plate 4 Flange 5 Bottom plate 6 Steel box girder 7 Rib 10 Inspection device 11, 12 Traveling unit 13 Connecting frame 14 Drive block 16, 17 Running wheel 18 Link 19 TV camera 21 Transmitting device 22 Battery 25 Wheel retraction mechanism 26 Arm 27, 28 Rotating shaft 29 driven bevel gear 30, 31 drive shaft 32 drive bevel gear 33 spur gear 34, 35 rotation restricting wheel 36 sector gear 37 overhang 38 drive rotating plate 40 retraction drive motor 41 rib detector

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tadanobu Miyamura 1720 Kamai, Higashi-machi, Inashiki-gun, Ibaraki Pref. In Kasumigaura Works (72) Inventor Toshiaki Suzuki 1720 Kamai, Higashi-machi, Inashiki-gun, Ibaraki Prefecture Ishikawajima Inspection & Measurement Co., Ltd. Kasumigaura Works F-term (reference) 2D059 AA08 EE02 GG39

Claims (6)

[Claims] An inspection device for a steel box girder bridge comprising a steel box girder comprising a left right side plate and a bottom plate provided at a lower portion of the left and right side plates and having a flange extending to the left and right and reinforced by a rib, A pair of front and rear traveling units that are suspended on a flange by independently driven front and rear traveling wheels provided on each of the left and right drive blocks connected at a required interval by a coupling frame, and the left side of both traveling units A link that connects the drive blocks on the right and the drive blocks on the right side so that they can rotate horizontally, a TV camera for inspection attached to the traveling unit, and each of the traveling wheels is independently retracted from the flange and placed on the flange. An inspection device for a steel box girder bridge, comprising a wheel retreat mechanism for avoiding a rib. 2. The inspection device for a steel box girder bridge according to claim 1, wherein the length of the connection frame can be adjusted by attaching and detaching a connection piece. 3. The inspection device for a steel box girder bridge according to claim 1, wherein the drive block includes a transmission device for transmitting a video signal of a television camera. 4. A wheel retreat mechanism comprising: an arm supporting each traveling wheel; a rotating shaft rotatably supporting each arm on a drive block so that the traveling wheel can retreat from above the flange; Driven bevel gears provided so as to face each of the rotating shafts on which the traveling wheels are mounted, a drive shaft provided in a direction perpendicular to the rotating shaft so that the driven bevel gears mesh with each driven bevel gear, and It has a spur gear provided on the drive shaft, two rotation restricting wheels provided inside a side surface of the spur gear, and a sector gear disposed between the spur gears and meshing with the spur gear in a required range. A driving rotary plate having an overhanging portion on the outer peripheral portion having no sector gear for restricting the rotation of the spur gear in contact with the two rotation restricting wheels, and a retraction drive motor for rotating the driving rotary plate. The steel box girder according to claim 1, wherein Bridge inspection equipment. 5. The inspection system for a steel box girder bridge according to claim 4, wherein the drive block is provided with a rib detector for detecting approach of the rib and controlling the drive of the retraction drive motor. . 6. The drive block according to claim 1, wherein the drive block is provided with a battery.
Or the inspection device of the steel box girder bridge according to 5.