Quay crane and control method therefor

Abstract

To provide a crane that is able to accurately detect a state of a rail laid on a ground surface, and a control method therefor.SOLUTION: Installed in a crane 1 in advance are: a wheel 11 having a tread in contact with a rail 5 and having a flange set to a predetermined length; and a connection mechanism 12 having a configuration in which the wheel 11 is connected to the crane 1 while kept movable in a vertical direction z and the wheel 11 is caused to follow the rail 5 in the vertical direction z. The height of the wheel 11 with respect to the crane 1 in the vertical direction z is measured, and the height of the rail 5 with respect to the crane 1 in the vertical direction z is measured.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a crane that travels along rails laid on the ground surface and a control method thereof, and more particularly to a crane and a control method thereof that can accurately detect the condition of rails laid on the ground surface. [Background technology]

[0002] Various cranes that travel along rails laid on the ground surface have been proposed (see, for example, Patent Document 1). Patent Document 1 discloses the configuration of a crane equipped with a rail clamping mechanism that grips the sides of the head of the rail from both sides. The rail is laid in a trench formed on the ground surface.

[0003] Asphalt and other materials that make up the ground surface can rise over time and cover the sides of the rails. Rails with their sides covered by the raised asphalt are in an abnormal state where they cannot be clamped properly by the rail clamping mechanism. When the rails are in an abnormal state, there is a problem in which the rail clamping mechanism cannot generate sufficient braking force. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 6650173 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above problems, and its object is to provide a crane and a method for controlling the crane that can accurately detect the condition of rails laid on the ground surface. [Means for solving the problem]

[0006] A crane for achieving the above-mentioned object is a crane that travels along rails laid on the ground surface, and is equipped with wheels having treads and flanges that come into contact with the rails, a connecting mechanism that connects the wheels to the crane in a state that allows them to move in the vertical direction, so that the wheels follow the rails in the vertical direction, and is also characterized by being equipped with a first sensor that measures the height of the wheels relative to the crane in the vertical direction, and a second sensor that measures the height of the rails relative to the crane in the vertical direction.

[0007] A method of controlling a crane to achieve the above object is a method of controlling a crane that runs along rails laid on the ground surface, characterized in that wheels having treads and flanges that come into contact with the rails and a coupling mechanism that connects the wheels to the crane in a state that allows them to move up and down, causing the wheels to follow the rails in the vertical direction, are installed in advance on the crane, and the height of the wheels relative to the crane in the vertical direction is measured, and the height of the rails relative to the crane in the vertical direction is also measured. [Effects of the Invention]

[0008] According to the present invention, when at least a portion of the side of the rail is covered by a material that constitutes the ground surface, the wheels lift off the rail. In other words, from the values ​​obtained from the first and second sensors, it is possible to detect sections of the rail that are in an abnormal state due to the side being covered. This is advantageous for accurately detecting the condition of rails laid on the ground surface. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram illustrating an outline of a crane. [Figure 2] 2 is an explanatory diagram illustrating an enlarged view of the vicinity of a traveling device of the crane in FIG. 1. FIG. [Figure 3] 3 is an explanatory diagram illustrating an enlarged view of the rail clamp mechanism and its vicinity in FIG. 2. FIG. [Figure 4]FIG. 10 is an explanatory diagram illustrating the state of the wheels and clamps when the rail is in a sound state. [Figure 5] FIG. 10 is an explanatory diagram illustrating the state of the wheels and clamps when the rail is in an abnormal state. [Figure 6] FIG. 3 is an explanatory diagram illustrating an outline of measurements by a first sensor and a second sensor. [Figure 7] 10 is a graph illustrating measurement results obtained by a first sensor and a second sensor. [Figure 8] 10 is a graph illustrating measurement results obtained by a first sensor and a second sensor. DETAILED DESCRIPTION OF THE INVENTION

[0010] The crane and its control method will be described below based on the embodiment shown in the drawings. In the drawings, the direction of rail extension is indicated by arrow y, the width direction perpendicular to this extension direction is indicated by arrow x, and the up-down direction is indicated by arrow z.

[0011] As shown in FIG. 1, crane 1 comprises a leg structure 2 and a plurality of traveling devices 3 attached to the lower ends thereof. A ground surface 4 constituting the quay is made of asphalt, concrete, or the like. Rails are laid on ground surface 4. Traveling devices 3 are configured to allow crane 1 to travel along these rails. Crane 1 may be a container crane placed on the quay for loading and unloading containers, or an unloader for loading and unloading bulk cargo such as ore. Crane 1 may also be a gantry crane that loads and unloads containers while traveling on rails laid in a container yard.

[0012] As shown in Figure 2, rails 5 are laid buried in the ground surface 4. For the sake of explanation, the rails 5 are shown by dashed lines in Figure 2. The leg structure 2 has a lower horizontal member 6 that extends in the extension direction y of the rails 5. A traveling device 3 is arranged below the lower horizontal member 6. The crane 1 is equipped with a column 7 that protrudes downward from the lower horizontal member 6. A rail clamp mechanism 8 is connected near the lower end of this column 7. An inspector's room 9 is also arranged below the lower horizontal member 6. In this embodiment, the column 7 and the inspector's room 9 are arranged between two traveling devices 3 that are arranged side by side in the extension direction y of the rails 5.

[0013] As shown in Figure 3, the rail clamp mechanism 8 has clamps 10 that open and close in the width direction x to grip the sides of the head of the rail 5 from both sides, and wheels 11 that roll in contact with the rail 5. The clamps 10 and wheels 11 are arranged inside a box that makes up the rail clamp mechanism 8. For ease of explanation, the box is shown by a dashed line in Figure 3. The ground surface 4 is also omitted from Figure 3.

[0014] The rail clamp mechanism 8 is connected to the column 7 of the crane 1 by a connecting mechanism 12. In this embodiment, the connecting mechanism 12 is configured with a parallel link. This connecting mechanism 12 allows the rail clamp mechanism 8 to move in the vertical direction z while maintaining its horizontal posture. Therefore, the wheels 11 are able to follow the rail 5 in the vertical direction z.

[0015] The configuration of the connecting mechanism 12 is not limited to a parallel link. The connecting mechanism 12 only needs to have a configuration that allows the wheels 11 to be connected to the crane 1 in a state that allows them to move in the vertical direction z. It is desirable that the connecting mechanism 12 has a configuration that keeps the rail clamp mechanism 8 in a horizontal position. The connecting mechanism 12 may also have a configuration that allows the rail clamp mechanism 8 to tilt.

[0016] The crane 1 is equipped with a first sensor 13 that measures the height of the wheel 11 relative to the crane 1 in the vertical direction z. In this embodiment, the first sensor 13 is installed at the end of an arm member 14 that protrudes from the column 7 in the extension direction y. The first sensor 13 is located at a position above the rail clamp mechanism 8. The first sensor 13 is configured, for example, as a laser rangefinder.

[0017] The first sensor 13 can measure the position in the vertical direction z of the rail clamp mechanism 8, which moves in the vertical direction z via the connecting mechanism 12. The position at which the wheel 11 is installed in the rail clamp mechanism 8 is predetermined. Therefore, by measuring the position of the rail clamp mechanism 8, the first sensor 13 can indirectly measure the position of the wheel 11.

[0018] The crane 1 is equipped with a second sensor 15 that measures the height of the rail 5 relative to the crane 1 in the vertical direction z. In this embodiment, the second sensor 15 is installed at the end of an arm member 14 that protrudes from the column 7 in the extension direction y. The second sensor 15 is located at a position above the rail 5. The second sensor 15 is configured, for example, by a laser range finder. The second sensor 15 can measure the position of the top surface of the head of the rail 5 in the vertical direction z.

[0019] The installation positions of the first sensor 13 and the second sensor 15 are not limited to those described above. Furthermore, the first sensor 13 and the second sensor 15 are not limited to laser range finders. The first sensor 13 may have a configuration that can directly or indirectly measure the position of the wheel 11 in the vertical direction z. For example, the first sensor 13 fixed to the arm member 14 extending from the column 7 may be disposed above the wheel 11, and the first sensor 13 may directly measure the position of the wheel 11 in the vertical direction z. Alternatively, the first sensor 13 may be configured as an inclinometer that measures the inclination of the parallel links that make up the connecting mechanism 12, and the first sensor 13 may be installed on the connecting mechanism 12. The height of the wheel 11 can be indirectly obtained by calculation from the inclination of the parallel links obtained by the inclinometer.

[0020] Similarly, the second sensor 15 may have a configuration that can directly or indirectly measure the position of the rail 5 in the vertical direction z. For example, the second sensor 15 may have a configuration that indirectly measures the position of the rail 5 by bringing a roller that can move in the vertical direction z into contact with the rail 5 and measuring the position of this roller.

[0021] The crane 1 may be equipped with a position sensor 16 that acquires the position of the crane 1 in the extension direction y of the rails 5. The position sensor 16 may be configured, for example, by a GNSS (Global Navigation Satellite System) installed on the leg structure 2 of the crane 1. The configuration of the position sensor 16 is not limited to the above, as long as it has a configuration that can acquire the position of the crane 1 in the extension direction y. For example, the position sensor 16 may be configured by an encoder of the motor of the traveling device 3. The position sensor 16 may also be configured by a proximity sensor, camera, etc. that detects landmarks such as magnetic bars or markers placed on the ground surface 4. The position sensor 16 is not an essential component of the present invention.

[0022] As illustrated on the left side of FIG. 4, the wheel 11 has a tread 11a that contacts the rail 5, and flanges 11b that are arranged on both sides of the tread 11a in the width direction x. The length f of the flange 11b in the radial direction is set to a predetermined length. The length of the flange 11b refers to the length f from the tread 11a to the outer periphery of the flange 11b in the radial direction of the wheel 11, for example, as illustrated in FIG. 4. The length f of the flange 11b can also be said to be the length of the flange 11b that protrudes radially from the tread 11a. The wheel 11 is configured to roll with the tread 11a in contact with the upper surface of the head 5a of the rail 5. The wheel 11 may also be configured so that the flange 11b is arranged on only one side of the tread 11a in the width direction x.

[0023] In this embodiment, the rail 5 is disposed inside a groove 4a formed in the ground surface 4 along the extension direction y. It is desirable that the rail 5 is disposed so that the top surface of the head 5a of the rail 5 and the ground surface 4 are at the same height.

[0024] The height of the wheel 11 measured by the first sensor 13 refers to the position of the lower end of the tread 11a. The height of the wheel 11 measured by the first sensor 13 may also be the position of another part of the wheel 11, such as the height of the axle 11c of the wheel 11. The height of the rail 5 measured by the second sensor 15 refers to the position of the upper surface of the head 5a of the rail 5.

[0025] As illustrated on the right side of Figure 4, the clamp 10 opens and closes along the width direction x to grip the side surfaces of the head 5a of the rail 5 from both sides in the width direction x. The clamp 10 grips the rail 5, thereby enabling the crane 1 to be fixed.

[0026] As shown in Fig. 5, the asphalt or the like that makes up the ground surface 4 may bulge due to deterioration over time, partially covering the side of the rail 5. If the groove 4a is deformed by the bulging asphalt or the like, as shown in the left side of Fig. 5, the flange 11b of the wheel 11 may come into contact with the ground surface 4 or the groove 4a, and the tread 11a may not come into contact with the head 5a of the rail 5. In other words, when the rail 5 falls into an abnormal state, the wheel 11 will lift up from the rail 5. The rail clamp mechanism 8 supported by the wheel 11 will also lift up from the rail 5 together with the wheel 11.

[0027] In such a case, the clamp 10 also rises upward, as shown in the right side of Figure 5. Therefore, even when the clamp 10 is closed, it is unable to adequately grip the side of the head 5a of the rail 5. This causes a problem in that the clamp 10 is unable to grip the rail 5 properly. Because the contact area between the head 5a of the rail 5 and the clamp 10 is reduced, the rail clamp mechanism 8 is unable to generate sufficient braking force. This causes a problem in that the rail clamp mechanism 8 is unable to secure the crane 1.

[0028] The same problem as above can occur when the rails 5 sink relative to the ground surface 4. Even when the rails 5 are laid on a flat ground surface 4 without forming grooves 4a in the ground surface 4, the rails 5 may become in an abnormal state as shown in Fig. 5 instead of the healthy state shown in Fig. 4 due to the rise of the asphalt or the sinking of the rails 5.

[0029] As shown in Fig. 6, while the crane 1 is traveling, the first sensor 13 can measure the height of the wheel 11. The first sensor 13 indirectly or directly measures the height of the wheel 11, for example, the distance h1 from the first sensor 13 to the bottom end of the tread 11a of the wheel 11. Similarly, while the crane 1 is traveling, the second sensor 15 can measure the height of the rail 5. The second sensor 15 indirectly or directly measures the height of the rail 5, for example, the distance h2 from the second sensor 15 to the top surface of the head 5a of the rail 5.

[0030] 6, for the sake of explanation, the part of the rail 5 sandwiched between the pair of flanges 11b and the tread surface 11a are indicated by dashed lines. Also, the directions in which the first sensor 13 and the second sensor 15 move as the crane 1 travels are indicated by outline arrows.

[0031] Figure 7 is a graph showing how the values ​​obtained by the first sensor 13 and the second sensor 15 change in the extension direction y of the rail 5. In the graph of Figure 7, the vertical axis indicates the position of the wheel 11 etc. in the up-down direction z, and the horizontal axis indicates the position in the extension direction y of the rail 5. The graph of Figure 7 corresponds to the results of measuring the state of the rail 5 with the first sensor 13 etc. in Figure 6.

[0032] The first sensor 13 and the second sensor 15 may be disposed at different positions in the vertical direction z and the extension direction y on the crane 1. In such a case, the graph can be reconstructed by correcting the positions in the vertical direction z and the extension direction y, respectively, so that the position of the wheel 11 obtained by the first sensor 13 and the position of the rail 5 obtained by the second sensor 15 coincide with each other.

[0033] As shown in the example of FIG. 6, when the first sensor 13 and the second sensor 15 are installed in the extension direction y with a predetermined distance D, such as 1 m, offset, the graph obtained from the second sensor 15 is reconstructed by shifting it by the distance D in a direction approaching the first sensor 13. Similarly, when the first sensor 13 and the second sensor 15 are installed in the vertical direction z with a predetermined distance H, such as 1 m, offset, the graph is reconstructed using this distance H. The distances D and H are constants that are determined when the first sensor 13 and the second sensor 15 are installed on the crane 1, so the graph can be easily reconstructed. The graph in FIG. 7 is reconstructed based on the distance D. Reconstruction based on the distance H is not performed.

[0034] As shown in FIG. 7, in section T1 where the rail 5 is in a healthy state, the graphs created based on the first sensor 13 and the second sensor 15 are linked. In section T2 where the rail 5 is in an abnormal state, the graphs created based on the first sensor 13 and the second sensor 15 are not linked. In section T2, the height h2 of the rail 5 obtained by the second sensor 15 is constant, but the height h1 of the wheel 11 obtained by the first sensor 13 is changing. This graph shows that the wheel 11 is lifting up. It is possible to understand the condition of the rail 5 by comparing the values ​​obtained by the first sensor 13 and the second sensor 15.

[0035] Figure 8 is a graph showing the results of a measurement experiment using the crane 1. As with the graph shown in Figure 7, the graph shown in Figure 8 has a vertical axis indicating the position of the wheels 11, etc. in the vertical direction z, and a horizontal axis indicating the position in the extension direction y of the rail 5.

[0036] The graph shown by the solid line in Fig. 8 indicates the height of the wheel 11 and is constructed based on the values ​​obtained by the first sensor 13. The graph shown by the dashed dotted line indicates the height of the rail 5 and is constructed based on the values ​​obtained by the second sensor 15. In order to remove the influence of the installation positions of the first sensor 13 and the second sensor 15, the graph in Fig. 8 has been reconstructed based on the distance D and the distance H.

[0037] Because the rails 5 are laid over a length of several hundred meters, they may bend in the vertical direction z. Due to this bending, the height of the rails 5, indicated by the dashed dotted line, fluctuates within a range of approximately ±10.0 mm in the vertical direction z. If the rails 5 are in a sound condition without any bumps or the like occurring in the asphalt that makes up the ground surface 4, the height of the wheels 11 will also fluctuate in accordance with the bending of the rails 5.

[0038] In section T2 where the flange 11b of the wheel 11 runs over raised asphalt or the like and the tread 11a separates from the rail 5, the height of the wheel 11, as shown by the solid line, is higher than the height of the rail 5, as shown by the dashed line. The height of the wheel 11, as shown by the solid line, does not follow the height of the rail 5, as shown by the dashed line. In section T2 where the rail 5 is in an abnormal state, the height of the wheel 11 and the height of the rail 5 do not move in tandem.

[0039] From the graph in Figure 8, it can be seen that the rail 5 is in an abnormal state in section T2 where the dashed dotted line and the solid line do not match, and that the rail 5 is in a sound state in other sections where the dashed dotted line and the solid line are relatively consistent.

[0040] In section T2 where the rail 5 is in an abnormal state, measures such as repairing the rail 5 can be taken. Specifically, measures such as re-paving the ground surface 4 with asphalt or concrete, or re-laying the rail 5 on the ground surface 4 can be taken. If the crane 1 is equipped with a position sensor 16, it will be possible to know the position of section T2 more accurately. Section T2 is a location where the head 5a of the rail 5 cannot be sufficiently gripped by the clamp 10. Therefore, when operating the rail clamp mechanism 8, it is possible to operate the crane 1 so as to avoid section T2. ​​This is advantageous in avoiding a malfunction in which the rail clamp mechanism 8 cannot generate sufficient braking force even before the rail 5 is repaired.

[0041] The crane 1 can detect whether the rail 5 is in a healthy state or an abnormal state from the values ​​obtained from the first sensor 13 that measures the height of the wheels 11 and the second sensor 15 that measures the height of the rail 5. This is advantageous for accurately detecting the state of the rail 5 laid on the ground surface 4.

[0042] Since the first sensor 13 and the second sensor 15 are configured to be installed on the crane 1, it is possible to detect the state of the rail 5 while the crane 1 is traveling. The work of detecting the state of the rail 5 does not interfere with the loading and unloading work of the crane 1. This is advantageous in avoiding a decrease in the loading and unloading efficiency of the crane 1.

[0043] Measurements can be made by the first sensor 13 etc. while the crane 1 is traveling. The first sensor etc. can measure the condition of the rail 5, including the effect of the load of the crane 1. For example, if the rail 5 is lifted up from the groove 4a in the ground surface 4 due to deflection, a visual inspection may lead to the mistaken belief that the side of the rail 5 is exposed and there is no problem. The first sensor 13 etc. can measure the condition of the rail 5 when such a lifted rail 5 is pressed against the bottom of the groove 4a by the load of the crane 1. The first sensor 13 etc. can measure the condition of the rail 5 in an environment that is the same as the environment in which the rail clamp mechanism 8 is actually used. This is advantageous for accurately detecting the condition of the rail 5.

[0044] The crane 1 may be equipped with an auxiliary mechanism 17 that outputs or stores values ​​obtained from the first sensor 13 and the second sensor 15. As illustrated in FIG. 3, the auxiliary mechanism 17 is connected to the first sensor 13 and the second sensor 15 by a wired or wireless signal line. For the sake of explanation, the signal line is shown by a dashed dotted line in FIG. 3. If the crane 1 is equipped with a position sensor 16, the auxiliary mechanism 17 may be connected to the position sensor 16 by a wired or wireless signal line. The crane 1 may not be configured to include the auxiliary mechanism 17.

[0045] The auxiliary mechanism 17 is disposed, for example, inside the inspector's room 9. For the sake of explanation, the auxiliary mechanism 17 is shown by a dashed line in Figure 3. The location at which the auxiliary mechanism 17 is installed is not limited to the above, and it may be installed in another part of the crane 1, such as the traveling gear 3 or the lower horizontal member 6.

[0046] The auxiliary mechanism 17 can be configured, for example, by a data logger. The data logger has a configuration for storing values ​​obtained from at least the first sensor 13 and the second sensor 15. The data logger may also have a configuration for storing values ​​obtained from the position sensor 16. The auxiliary mechanism 17 is not limited to a data logger, and may be configured to store values ​​obtained from the first sensor 13, etc.

[0047] The auxiliary mechanism 17 can be configured, for example, by a communication device. The communication device has a configuration that can transmit values ​​obtained from the first sensor 13 and the like to an external location such as the operator's cab of the crane 1. The auxiliary mechanism 17 may also have a configuration that can communicate with a management building that manages the crane 1.

[0048] The auxiliary mechanism 17 may have both the function of storing the values ​​obtained by the first sensor 13 and the like and the function of transmitting these values ​​to the outside.

[0049] The crane 1 may be equipped with a determination mechanism 18 that acquires values ​​obtained by the first sensor 13, etc., and determines the state of the rail 5 based on these values. As shown in the example of FIG. 3, the determination mechanism 18 can be connected to the auxiliary mechanism 17 by a wired or wireless signal line. If the crane 1 does not have the auxiliary mechanism 17, the determination mechanism 18 may be configured to be connected to the first sensor 13, etc., by a signal line. The crane 1 may not be configured to have the determination mechanism 18.

[0050] The determination mechanism 18 is placed, for example, inside the inspector's room 9. For the sake of explanation, the determination mechanism 18 is shown by a dashed line in Figure 3. The location at which the determination mechanism 18 is installed is not limited to the above, and it may be installed in other parts of the crane 1, such as the traveling gear 3 or the lower horizontal member 6. The determination mechanism 18 may also be installed in the operator's cab of the crane 1 or in a management building that manages the crane 1.

[0051] The determination mechanism 18 is configured to acquire values ​​from the first sensor 13 etc. directly or indirectly via the auxiliary mechanism 17. The determination mechanism 18 is configured to determine whether or not there is a malfunction in the rail 5 based on the values ​​obtained from the first sensor 13 and the second sensor 15.

[0052] Specifically, the height of the rail 5 and the height of the wheel 11 are determined based on the values ​​obtained from the first sensor 13 and the second sensor 15. If the difference between the height of the rail 5 and the height of the wheel 11 exceeds a predetermined range, for example, greater than 3.0 mm, it is determined that there is a malfunction, and if the difference is within a predetermined range, for example, 3.0 mm or less, it is determined that there is no malfunction. It is desirable to set the length f of the flange 11b to a length greater than the range in which it is determined that there is a malfunction. The length f of the flange 11b is not limited to the above and can be set appropriately. When detecting the difference between the height of the rail 5 and the height of the wheel 11, the detectable range can be adjusted by the length f of the flange 11b.

[0053] The determination mechanism 18 may be configured to determine whether or not the rail clamp mechanism 8 can obtain a predetermined braking force based on the value obtained from the first sensor 13 or the like.

[0054] If the rail clamp mechanism 8 needs a gripping margin of, for example, 40.0 mm or more in the vertical direction z to grip the rail 5 in order to exert a predetermined braking force, the length f of the flange 11b is set in advance to be greater than 40.0 mm. The length f of the flange 11b can be set to, for example, 45.0 mm. In this case, when the difference in height between the rail 5 and the wheel 11 exceeds, for example, 5.0 mm, the gripping margin when the rail clamp mechanism 8 grips the rail 5 will be less than 40.0 mm. In this case, the determination mechanism 18 can be configured to determine that sufficient braking force cannot be obtained. When the difference in height between the rail 5 and the wheel 11 is 5.0 mm or less, the gripping margin of the rail clamp mechanism 8 will be 40.0 mm or more. In this case, the determination mechanism 18 can be configured to determine that sufficient braking force can be obtained. It is desirable to set the length f of the flange 11b in advance to a length greater than the gripping margin of the rail clamp mechanism 8.

[0055] The flange 11b may be arranged at a position outside the clamp 10 of the rail clamp mechanism 8 in the width direction x. In this case, it is possible to avoid a problem in which the clamp 10 hits raised asphalt or the like.

[0056] While the crane 1 is traveling for cargo handling or other operations, the judgment mechanism 18 judges along the extension direction y of the rail 5 whether the rail 5 is in a sound state in a section T1 or in a section T2 where it is in an abnormal state. By outputting this information as a map, for example, workers can easily know the locations of the ground surface 4 or the rail 5 that require repair.

[0057] If the crane 1 is configured without the determination mechanism 18, the worker determines the defective section T2 of the rail 5 based on a graph obtained from the first sensor 13 of the crane 1, etc. For example, the worker determines the defective section T2 of the rail 5 based on the graph shown in FIG. 8. After that, repair measures such as re-laying the rail 5 can be taken.

[0058] The rail clamp mechanism 8 is not an essential component of the crane 1. The wheels 11 and the connecting mechanism 12 may be configured as an independent mechanism separate from the rail clamp mechanism 8 and installed on the crane 1. With this crane 1, too, it is possible to detect the condition of the rail 5 with high accuracy. [Explanation of symbols]

[0059] 1 crane 2 leg structure 3 Running gear 4 Ground surface 4a groove 5 Rail 5a head 6 Lower horizontal member 7. Column 8 Rail clamp mechanism 9 Inspector's Room 10 Clamp 11 wheels 11a Tread 11b flange 11c axle 12 Connection mechanism 13 First Sensor 14 Arm member 15 Second sensor 16 Position Sensor 17 Auxiliary mechanism 18 Judgment mechanism x width direction y Extension direction z Vertical direction f flange length h1 Distance to wheels h2 Distance to rail

Claims

1. In a crane that travels along rails laid on the ground surface, a wheel having a tread and a flange that contacts the rail, and a connecting mechanism that connects the wheel to the crane in a state where the wheel can move up and down, and causes the wheel to follow the rail in the up and down direction; A crane comprising: a first sensor for measuring the height of the wheels relative to the crane in the vertical direction; and a second sensor for measuring the height of the rail relative to the crane in the vertical direction.

2. The rail clamp mechanism is provided to open and close along a width direction perpendicular to the extending direction of the rail to grip the side surfaces of the head of the rail from both sides, The crane according to claim 1 , wherein the rail clamping mechanism has the wheels and is connected to the crane by the connecting mechanism.

3. The crane according to claim 1 , further comprising a determination mechanism for determining whether or not there is a malfunction in the rail based on values ​​obtained from the first sensor and the second sensor.

4. a position sensor for acquiring the position of the crane in the extending direction of the rail, The crane according to any one of claims 1 to 3, further comprising an auxiliary mechanism that outputs or stores values ​​obtained from the first sensor, the second sensor, and the position sensor.

5. A method for controlling a crane that travels along rails laid on the ground surface, comprising: A wheel having a tread and a flange that contacts the rail, and a coupling mechanism configured to couple the wheel to the crane in a state in which the wheel can move up and down and cause the wheel to follow the rail in the up and down direction are installed in advance on the crane, A method for controlling a crane, comprising measuring the height of the wheels relative to the crane in the vertical direction, and measuring the height of the rail relative to the crane in the vertical direction.

6. The crane is provided with a rail clamp mechanism that opens and closes along a width direction perpendicular to the extending direction of the rail to grip the side surfaces of the head of the rail from both sides, 6. The method for controlling a crane according to claim 5, wherein the wheels are pre-installed on the rail clamping mechanism, and the rail clamping mechanism is pre-connected to the crane via the connecting mechanism.

7. The crane control method according to claim 5, wherein the presence or absence of a defect in the rail is determined by comparing the height of the wheel with the height of the rail.

8. A crane control method according to any one of claims 5 to 7, further comprising acquiring the position of the crane in the direction of extension of the rail, and outputting or storing the height of the wheels, the height of the rail, and the position of the crane as data.

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