JP7097331B2 - crane - Google Patents

Description

The present invention relates to a crane.

In a crane such as a container crane, a suspender called a spreader that lifts a container is lifted by a wire, and the wire is wound around a drum to raise the spreader for cargo handling.
During cargo handling, the spreader may not be able to rise due to the spreader, container or wire getting caught in the structure of the ship, or forgetting to remove the cone or lashing of the container.
If such a state continues, the wire cannot be wound and the drum cannot be rotated, but the drum is tried to be rotated by a motor or the like. Therefore, all the force for rotating the drum is transmitted to the wire. An impact load called a snag load is applied to the wire.
When a snag load occurs, the energy of the impact can cause wire breaks and spreader damage. Furthermore, the tension of the wire, which is the reaction force of the force applied to the wire, pulls other structures constituting the crane, and the crane may collapse.
Therefore, in a crane that raises and lowers a hanger with a wire, a structure that absorbs the energy of impact when a snag load occurs is required. Further, a structure that reduces the tension of the wire transmitted to the structure constituting the crane is required.
As such a structure, a structure using a shear pin is known. In Patent Document 1, a holding portion of a sheave that guides a wire is pivotally supported on a structure constituting a crane, and the shaft of the holding portion is fixed by a shear pin. When a snag load occurs, the shear pin breaks and the holding portion is freely rotated to loosen the tension of the wire, thereby reducing the tension of the wire transmitted to the structure of the crane.
The structure using only the shear pin as in Patent Document 1 is an excellent structure in that the tension of the wire can be surely relaxed when a snag load occurs with a relatively simple structure, but a member for absorbing energy is separately prepared. There is a need to. Further, in this structure, after removing the cause of the snag load, it is necessary to return the holding portion to the position before the snag loading occurs and insert a new shear pin into the holding portion. However, the holding portion and the shear pin are heavy objects that are difficult to be transported by human power, and there is room for improvement in that it takes time and effort to align them.
Patent Document 2 describes a structure in which a hydraulic damper is provided in a holding portion of a sheave. In this structure, energy is absorbed by expanding and contracting the damper when a snag load occurs. Further, by rotating the holding portion to loosen the tension of the wire, the tension of the wire transmitted to the structure of the crane is reduced.
The structure using a hydraulic damper is an excellent technique in that the tension of the wire can be surely relaxed when a snag load occurs and energy can be absorbed. On the other hand, the snag load usually reaches several to several tens of times the load applied to the wire during cargo handling. Therefore, in order to receive the snag load, a large hydraulic damper with an extremely large flow rate and high pressure is required, and there is room for improvement in terms of cost and installation space.

JP-A-2007-246177 Japanese Unexamined Patent Publication No. 2007-261734

The present invention has been made in view of the above problems, and is a crane having a structure capable of absorbing energy when a snag load is generated with a simple structure and reducing the tension of a wire transmitted to a structure constituting the crane. The purpose is to provide.

In order to solve the above-mentioned problems, the crane according to the first aspect of the present invention is provided on the support structure, a hanger that is held by the support structure with a wire and moves up and down, and the support structure. A crane provided with a drum that winds and holds the wire, and winds and unwinds the wire by rotation to move the hanger up and down, and a path of the wire from the drum to the hanger. Of these, a guide sheave that is provided at a position where the direction of the wire is changed and is rotatably supported by the support structure by a holding shaft parallel to the axis of the guide sheave to hold the guide sheave. A linear motion member that is connected to the sheave holding section and moves linearly following the rotation of the sheave holding section, and a linear motion member that is connected to the linear motion member and converts the linear motion into rotation for power. A conversion member rotatably connected to the conversion member and a rotation shaft to which the rotational force applied to the conversion member is transmitted, and a rotation shaft connected to the rotation shaft to restrain the rotation, and predetermined. It is characterized by comprising a rotary brake having a braking portion configured to release the restraint of the rotating shaft by rotating when a torque of a predetermined value or more is applied.

In this embodiment, the tension of the wire is transmitted in the order of the guide sheave, the sheave holding portion, the linear motion member, the conversion member, and the rotating shaft of the brake. The rotation of the wire relaxes the tension of the wire. Energy is also absorbed by the rotational resistance during braking operation.
Therefore, the tension of the wire transmitted to the crane structure when a snag load occurs can be reduced and energy can be absorbed only by the rotary brake, and the crane can be prevented from collapsing and being damaged when a snag load occurs with a simple structure.
Further, in this embodiment, since the brake is a rotary type, the restriction of the stroke at the time of operation is smaller than that of the hydraulic cylinder, and the size can be easily reduced.

The crane according to the second aspect of the present invention has a support structure, a hanger that is held by the support structure with a wire and moves up and down, and a hanger provided on the support structure to wind and hold the wire. A crane provided with a drum that moves the hanger up and down by winding and unwinding the wire by rotation, and changes the direction of the wire in the path of the wire from the hanger to the drum. A guide sheave provided at a position to guide the wire, a sheave holding portion rotatably supported by the support structure by a holding shaft parallel to the axis of the guide sheave, and holding the guide sheave, and the holding shaft. A rotating shaft that is rotatably connected to and to which the rotational force applied to the holding shaft is transmitted, and a rotating shaft that is connected to the rotating shaft and restrains its rotation, and rotates when a torque of a predetermined value or more is applied. A rotary brake having a braking portion configured to release the restraint of the rotating shaft, and a tilting portion that holds the sheave holding portion in the support structure so as to be tiltable about an axis parallel to the holding shaft. It is characterized by having a mechanism .

In this aspect, the tension of the wire is transmitted in the order of the guide sheave, the sheave holding portion, the holding shaft, and the rotation shaft of the brake. When the tension exceeds a predetermined value, the restraint of the rotating shaft is released, and the sheave holding portion rotates to loosen the tension of the wire. Energy is also absorbed by the rotational resistance during braking operation.
Therefore, the tension of the wire transmitted to the crane structure when a snag load occurs can be reduced and energy can be absorbed only by the rotary brake, and the crane can be prevented from collapsing and being damaged when a snag load occurs with a simple structure.
Further, in this embodiment, the rotational force applied to the sheave holding portion can be transmitted to the rotary shaft of the brake as the rotational force, so that the structure can be made simpler and smaller.

According to the present invention, it is possible to provide a crane having a structure capable of absorbing energy when a snag load is generated with a simple structure and reducing the tension of a wire transmitted to a structure constituting the crane.

The figure which shows the schematic structure of the crane which concerns on 1st Embodiment. The perspective view which shows the positional relationship between the wire and a drum of FIG. An enlarged view of the vicinity of the guide sheave in FIG. The X-direction arrow view of FIG. An enlarged view of the vicinity of the guide sheave of the crane according to the second embodiment. An enlarged view of the vicinity of the guide sheave of the crane according to the third embodiment. The X-direction arrow view of FIG. An enlarged view of the vicinity of the guide sheave of the crane according to the fourth embodiment. The X-direction arrow view of FIG.

Hereinafter, embodiments suitable for the present invention will be described in detail with reference to the drawings.
First, the configuration of the crane 1 according to the first embodiment will be described with reference to FIGS. 1 to 4.
Here, as the crane 1, a quay crane that handles cargo with and from the container ship 48 berthed at the quay is exemplified.
As shown in FIGS. 1 and 2, the crane 1 according to the first embodiment includes a support structure 3, a spreader 5, a wire 7, a drum 9, and a guide sheave 11. As shown in FIGS. 3 and 4, the crane 1 also includes a sheave holding portion 13, a rack 15, a pinion 17, and a rotary brake 19.

The support structure 3 is a structure that supports another structure of the crane 1, and includes a leg structure 3a, a traveling device 20, a girder 21, and a trolley 23 as shown in FIG. The leg structure 3a is a leg that serves as a support column for supporting the other structure of the crane 1, and a pair is arranged so as to face the X direction in FIG. The pair of leg structures 3a are connected by a portal tie 3b, which is a beam extending in the X direction. The traveling device 20 is a device including wheels for traveling the crane 1 in the Y direction (traveling direction) and a drive mechanism thereof, and is provided at the lower end of the leg structure 3a. The girder 21 is a structure that is supported on the upper portion of the leg structure 3a and extends in the X direction (also referred to as a transverse direction or an extension direction), which is one direction orthogonal to the traveling direction. The trolley 23 is a trolley that is supported by the girder 21 and travels in the X direction. The trolley 23 runs by itself or is pulled by a running wire (not shown) along a rail (not shown) provided on the girder 21. In FIG. 1, the trolley 23 is provided with a driver's cab 25. The driver's cab 25 is a room in which the driver of the crane 1 enters during operation, and in the present embodiment, a control table (not shown) for maneuvering the crane 1 is provided.

The spreader 5 is a hanger that is supported by the trolley 23 of the support structure 3 by a wire 7 and moves in the vertical direction (Z direction) to lift the container 10 to be loaded and unloaded. The mechanism by which the spreader 5 holds the container 10 is not particularly limited, but a general spreader 5 for container handling includes a rotary long tightening device called a twist lock pin as a holding mechanism. In this mechanism, the twist lock pin is inserted into the elongated holes provided at the four corners of the upper surface of the container 10 in the longitudinal direction of the twist lock pin, and after the insertion, the twist lock pin is rotated to cross the longitudinal direction. Lock it.

The wire 7 is a rope that holds the spreader 5 and transmits the power generated when the drum 9 rotates to the trolley 23 or the spreader 5. In FIG. 2, four wires 7a to 7d are provided as the wire 7, and each of the four wires 7 supports the four places of the spreader 5 via the spreader sheaves 25a to 25d provided on the spreader 5.
The structure and material of the wire 7 are not particularly limited as long as they have durability to the extent that they are not damaged by the load normally applied during cargo handling. Generally, a wire 7 is used by twisting several ropes called strands, which are made by twisting and bundling steel wires.

The drum 9 is a rotating body that winds up and holds the wire 7, and here, is a cylindrical member that is rotatably held by the girder 21. In FIG. 1, the drum 9 is arranged in the machine room 30 provided in the girder 21.
In FIG. 2, the crane 1 includes four drums 9 of drums 9a to 9d. The drums 9a to 9d are driven by a motor (not shown), and by controlling this motor, the rotation direction and the rotation speed of the drum 9 are adjusted.

As shown in FIG. 2, the drums 9a to 9d are tubular members that hold the wires 7a to 7d. In FIG. 2, the wires 7a to 7d are unwound from the drums 9a to 9d toward the land side in the X direction, respectively. The unwound wires 7a to 7d are guided by guide sheaves 11a to 11d provided near the land side end in the X direction of the girder 21, and their directions can be changed to the sea side in the X direction. The wires 7a to 7d are further changed in the vertical direction downward by the first trolley sheaves 23a to 23d provided in the trolley 23, and the directions thereof are vertically changed by the spreader sheaves 25a to 25d provided in the spreader 5. Can be turned upwards. The wires 7a to 7d can be further oriented toward the sea side in the X direction by the second trolley sheaves 24a to 24d provided on the trolley 23.

The ends of the wires 7a to 7d are fixed to the fixing portion 32 provided at the X-direction sea-side end of the girder 21 via the sea-side end sheaves 26a to 26d provided on the girder 21.

In this structure, the vertical movement of the spreader 5 can be controlled by controlling the winding and unwinding of the wires 7a to 7d by the drums 9a to 9d.

For example, the drums 9a to 9d can raise the spreader 5 by winding the wires 7a to 7d, respectively. Further, the drums 9a to 9d can lower the spreader 5 by feeding out the wires 7a to 7d.

The guide sheave 11 is a fixed pulley provided near the land side end of the girder 21, which is one of the support structures 3.
The guide sheave 11 is provided at a position in the path of the wire 7 from the drum 9 to the spreader 5 at a position where the direction of the wire 7 is changed, and guides the wire 7. The guide sheave 11 in FIG. 2 is provided at a position where the direction of the wire 7 is changed from the land side in the X direction to the sea side in the X direction.
The X-direction position where the guide sheave 11 is provided is the end on the land side in the X-direction movement range of the spreader 5. Therefore, the X-direction position of the guide sheave 11 is set according to the X-direction movement range of the spreader 5. Ru. In FIG. 1, since four wires 7 are provided, the guide sheaves 11 are also provided with four guide sheaves 11a to 11d, each of which guides one wire 7.

The sheave holding portion 13 is a member that holds the guide sheave 11 in the support structure 3. The sheave holding portion 13 is held by the holding arm 35 of the holding girder 33 provided on the girder 21 which is one of the support structures 3 in FIGS. 3 and 4. The holding girder 33 is a member provided on the upper portion of the girder 21 in a direction orthogonal to the extending direction of the girder 21. The holding arm 35 is a pair of plate-shaped members projecting from the vicinity of both ends of the holding girder 33 toward the sea side in the X direction.
The sheave holding portion 13 includes a guide sheave shaft 27, a holding shaft 29, and a pair of guide sheave holding plates 28.

The guide sheave shaft 27 is a shaft that rotatably holds the guide sheave 11 and is provided by inserting the rotation center of the guide sheave 11 into the guide sheave shaft 27. The holding shaft 29 is a shaft that holds the guide sheave 11 on the holding arm 35, and is an axis whose axial direction is parallel to the guide sheave shaft 27. In FIG. 3, the guide sheave shaft 27 is provided by inserting the holding arm 35, and holds the guide sheave 11 rotatably in the directions of A1 and A2. In addition, "parallel in the axial direction" here means that even if one of the sheave holding portion 13 or the guide sheave 11 rotates, the axial directions coincide with each other to the extent that the rotation around the other rotation axis is not hindered. Means that you are. Therefore, the holding shaft 29 and the guide sheave shaft 27 are not limited to a completely parallel configuration.

The guide sheave holding plate 28 is a pair of plate-shaped members that hold the guide sheave shaft 27 and the holding shaft 29.
The pair of guide sheave holding plates 28 are arranged so as to sandwich the guide sheave 11 in the rotation axis direction. Both ends of the guide sheave shaft 27 are fixed in the vicinity of the center in the longitudinal direction of the guide sheave holding plate 28. As a result, the guide sheave holding plate 28 rotatably holds the guide sheave 11 in the directions A1 and A2 of FIG.

Further, the upper end of the guide sheave holding plate 28 in the longitudinal direction is arranged at a position sandwiched between the pair of holding arms 35 in the rotation axis direction of the guide sheave 11. The holding shaft 29 penetrates the guide sheave holding plate 28, and both ends thereof are fixed to the holding arm 35. As a result, the guide sheave holding plate 28 is rotatably held by the holding arm 35 about the holding shaft 29.

As shown in FIG. 4, the sheave holding portions 13 are provided with four sheave holding portions 13a to 13d, each holding one guide sheave 11a to 11d.
As shown in FIG. 4, the guide sheaves 11a and 11b are arranged at the front end of the holding girder 33 in the Y direction. The guide sheaves 11c and 11d are arranged at the Y-direction side end of the holding girder 33.

The rack 15 is a linear motion member that linearly moves following the rotation of the sheave holding portion 13. The rack 15 is a linear gear mechanism. In FIGS. 3 and 4, the rack 15 has a prismatic shape, and gears are arranged on the upper surface along the longitudinal direction. However, the positions of the gears of the rack 15 are not limited to the upper surface as long as they are arranged along the longitudinal direction. It may be the bottom surface or the side surface.
One end of the rack 15 in the longitudinal direction is pivotally supported at the lower end of the guide sheave holding plate 28 via the link member 37. The link member 37 is a rod-shaped member, and one end in the longitudinal direction is pivotally supported by one end of the rack 15 by a link member shaft 37a. The other end of the link member 37 in the longitudinal direction is pivotally supported by the link member shaft 37b at the lower end of the guide sheave holding plate 28.
The axial direction of each of the link member shafts 37a and 37b is parallel to the axial direction of the rotation shaft of the guide sheave 11.
The rack 15 is constrained in the direction of direct movement to B1 and B2 in FIG.
Specifically, first, the lower surface of the rack 15 is in contact with the guide roller 41, and the downward movement of the rack 15 is restricted by the guide roller 41. The guide roller 41 is fixed to a pair of holding plates 33a protruding from below the holding girder 33 so that the axis of the roller is orthogonal to the longitudinal direction of the rack 15. Next, as shown in FIG. 4, both side surfaces of the rack 15 are sandwiched by the brake portion 45 of the rotary brake 19, and the movement to the side (Y direction) is restricted. Further, since the rack 15 is toothed with the pinion 17, the upward movement of the rack 15 is also restricted to the pinion 17.

When the sheave holding portion 13 rotates around the holding shaft 29 in the directions A1 and A2 of FIG. 3, a rotational force about the holding shaft 29 is applied to the rack 15 via the link member 37. However, the rack 15 is restricted from moving downward, laterally, and upward by the guide roller 41, the rotary brake 19, and the pinion 17. Therefore, this rotational force is transmitted to the rack 15 as a force that directly moves in the directions of B1 and B2.
The structure of the restraining member is not limited to the structure shown in FIG. 3 as long as the movement of the rack 15 can be constrained to the linear motion. If there is at least a member that is in contact with the lower surface and both side surfaces of the rack 15 and restricts the movement of the rack 15 downward and to both sides, the upward movement is restricted by the pinion 17, so that the movement is constrained to direct motion. can. These members may be integrated or separate.
Further, since the moving direction of the rack 15 may be limited to the linear movement, the moving direction of the rack 15 may be inclined with respect to the horizontal direction.

The pinion 17 is a conversion member that converts the direction of the power transmitted from the rack 15 from linear motion to rotation and transmits it to the rotary brake 19. The pinion 17 meshes with the gears of the rack 15.
However, the rack 15 and the pinion 17 do not necessarily have to be directly connected if the linear motion can be converted into rotation. The rack 15 and the pinion 17 may be connected via other gears.
The rack 15 and the pinion 17 do not necessarily have to be equipped with gears if the linear motion can be converted into rotation. For example, a non-contact structure using magnetism may be used.
Furthermore, if linear motion can be converted into rotation. For example, a cylinder crank mechanism in which a cylinder is used as a linear motion member instead of the rack 15 and a crank is used as a conversion member instead of the pinion 17 may be used.
Further, FIGS. 3 and 4 illustrate a structure in which the rack 15 and the pinion 17 are exposed to the outside in order to clarify the positional relationship between the rack 15 and the pinion 17, but the rack 15 and the pinion 17 are exposed to the outside. You don't have to. For example, the rack 15 and the pinion 17 may be covered with a cover member or the like in order to prevent malfunction due to the generation of rust or the adhesion of dust.

The rotary brake 19 is a mechanism that rotates the holding girder 33 to loosen the tension of the wire 7 when a snag load occurs. Specifically, the rotary brake 19 is configured so that the rotation of the sheave holding portion 13 is restrained when the snag load is not generated, and the restraint of the sheave holding portion 13 is released when the snag load is generated. ..
Four rotary brakes 19 are provided here corresponding to the four sheave holding portions 13, and are fixed to the girder 21 via the holding plate 33a and the holding girder 33, respectively.

The case where a snag load occurs means a case where a load that does not occur in normal cargo handling is applied to the wire 7 when the spreader 5 rises or the trolley 23 traverses. Since some types of cranes do not have the trolley 23, the following description exemplifies the snag load generation standard when raising the spreader 5. However, this example is not limited to the snag load generation standard only when rising.
Further, when there are a plurality of wires 7 as in the present embodiment, a snag load is generated when a load that does not occur in normal cargo handling is applied to at least one wire 7. The reason is that the cause of the snag load is that the wire 7 is caught or the cone or lashing is forgotten to be removed. be.

As shown in FIGS. 3 and 4, the rotary brake 19 includes a rotary shaft 43 and a brake portion 45.
The rotary shaft 43 is a member that transmits the rotational force of the pinion 17 to the brake portion 45, and is a shaft fixed to the center of rotation of the pinion 17 here. Therefore, the pinion 17 is coaxially fixed to the rotating shaft 43 of the rotary brake 19. However, since the rotating shaft 43 only needs to be able to transmit the rotational force of the pinion 17 to the brake portion 45, it does not necessarily have to be directly connected to the pinion 17, and the power may be transmitted via other gears or the like.

The brake portion 45 is configured so that it cannot rotate if the torque is less than a predetermined value or more, which restrains the rotation of the rotating shaft 43. The brake portion 45 is configured to be rotatable when a torque equal to or higher than a predetermined value is applied, and the restraint of the rotating shaft 43 is released.
The predetermined predetermined value referred to here means the lower limit of the value of the torque applied to the brake portion 45 when the snag load occurs.
The brake portion 45 is fixed to the holding girder 33 of the girder 21 so that the rotating shaft 43 is parallel to the guide sheave 11 and the holding shaft 29. More specifically, the brake portion 45 is fixed to the holding plate 33a projecting from the lower surface of the holding girder 33.
In FIG. 4, two brake portions 45 share one rotation shaft 43. The two brake portions 45 sandwich the side surface of the rack 15 to restrict the movement of the rack 15 in the Y direction. However, the number of brake portions 45 is not limited to two. When a member for restricting movement to the side of the rack 15 is separately provided, a structure in which one rotating shaft 43 and one brake portion 45 are connected may be used.
Further, in FIG. 4, the adjusting motor 46 is connected to the rotary brake 19. The adjusting motor 46 is an electric motor that directly or indirectly transmits a rotational force to the rotating shaft 43. The adjusting motor 46 is a device that adjusts the positions of the rack 15 and the sheave holding portion 13 by rotating the rotating shaft 43 in a state where the brake portion 45 can rotate and adjusting the phase thereof. The adjusting motor 46 is not an indispensable configuration, but is provided as necessary when it is desired to easily adjust the phase of the rotating shaft 43.

The method of obtaining the rotational torque, which is the reference for the generation of snag load, is not particularly limited, but the following method can be exemplified.
When the crane 1 lifts the container 10, the spreader 5 raises the spreader 5 upward in the Z direction in FIG. 1 with the container 10 fixed by a twist lock pin or the like.
At this time, immediately after ascending, the load applied to the wire 7 changes temporarily due to the change in the position of the center of gravity of the container 10 or the sudden pulling of the loose wire 7. Further, since the spreader 5 normally accelerates and decelerates during lifting, the load applied to the wire 7 also changes with acceleration. Further, the load applied to the wire 7 also changes due to the position change such as the runout of the container 10.

The value obtained by multiplying the maximum value of the load generated by such normal cargo handling by the safety factor, etc. with reference to the rated torque of the motor driving the drum 9 and the capacity of the inverter is the standard load for the generation of snag load. It is the size.
For the maximum value of the load generated by normal cargo handling, the load applied to the wire 7 when the container 10 with the maximum total weight is lifted under the condition that snag load does not occur is obtained by actual measurement or simulation, and the maximum value is obtained. It can be obtained if it is extracted. The rotational torque applied to the rotary shaft 43 at the maximum value of the obtained load is the rotational torque that is the reference for the generation of snag load, and is the reference for the brake portion 45 to release the restraint of the rotary shaft 43.

The rotary brake 19 is not particularly limited as long as it includes a rotary shaft 43 and a brake portion 45 and the restraint of the rotary shaft 43 is released by the brake portion 45 only when the snag load generation condition is satisfied, but the following mechanism. Can be exemplified.

First, as a mechanism of the rotary brake 19, a dry brake mechanism can be mentioned.
The dry brake mechanism means a mechanism provided with at least one pair of brake members that rotatably contact with the brake portion 45 in a dry manner. In this mechanism, a rotating shaft 43 is provided on one of the brake members.
In this mechanism, the rotation of the rotating shaft 43 is restrained by the static friction force generated between the brake members. On the other hand, when a rotational force exceeding the torque corresponding to the maximum static friction force is applied to the rotary shaft 43, the brake members rotate relative to each other, the restraint of the rotary shaft 43 is released, and the sheave holding portion 13 rotates. To loosen the tension of the wire 7. Furthermore, since the brake member rubs when it rotates relative to each other, energy absorption due to the generation of snag load is realized by the frictional heat.

In the dry brake mechanism, the operating conditions of the rotary brake 19 can be set only by adjusting the coefficient of static friction of the brake member and the normal force with which the brake member abuts. Therefore, maintenance after installation becomes easier and costs are reduced as compared with the case of using a hydraulic damper.
The shape of the brake member is not particularly limited. A disk or an annular friction plate may be brought into contact with each other, or a mechanism such as a drum brake in which one or both of the brake members are not plate-shaped may be used.
Since at least one pair of brake members may be in contact with each other, a multi-plate type in which a plurality of brake plates are in contact with each other may be used.

The maximum static friction force between the brake members can be adjusted by changing the coefficient of static friction or the normal force. Examples of the means for changing the coefficient of static friction include means for changing the material of a brake member such as a brake pad.
As a means for changing the normal force, a mechanism for adjusting the load of pressing one brake plate against the other brake plate may be provided according to the reference torque for rotating the brake plate. The adjusting mechanism may be a mechanical mechanism such as a clip holding a pair of brake plates, or an electromagnetic mechanism using a coil. It may also be hydraulic.
The specific structure of the dry brake mechanism such as the number of friction plates, materials, dimensions, and the normal force adjustment mechanism is not particularly limited. These conditions may be appropriately set within a range in which the maximum static friction force corresponding to the assumed snag load can be obtained. A known product such as a commercially available product may be used as long as the maximum static friction force corresponding to the assumed snag load can be obtained.

As a mechanism of the rotary brake 19, a wet multi-plate brake mechanism can also be mentioned.
The wet multi-plate brake mechanism means a brake mechanism in which a plurality of brake plates rotatably abut in the lubricating oil. In this mechanism, the rotary shaft 43 is connected to at least one of the plurality of brake plates.

The specific mechanism of the wet multi-plate brake mechanism is basically the same as the mechanism using the dry type brake plate. However, a container that seals the lubricating oil together with the brake plate and a mechanism that injects the lubricating oil into the container are required, and a porous friction material that absorbs the lubricating oil must be provided on the surface of the brake plate. different. Further, in a wet environment, the coefficient of friction between the sliding members is smaller than that in the dry type, so that the frictional force is secured as a mechanism in which a plurality of brake plates are laminated.

The operation mechanism of the wet multi-plate brake is the same as that of the dry type, and when a rotational force exceeding the torque corresponding to the maximum static friction force is applied to the rotary shaft 43, the brake members rotate relative to each other to restrain the rotary shaft 43. Is released. Furthermore, energy absorption is also realized by the frictional heat when the brake plates rotate relative to each other in a wet environment.
On the other hand, the wet multi-plate brake mechanism is more resistant to changes in the external environment than the dry type because the brake plate and the outside air are blocked by the lubricating oil. Specifically, the brake plate is unlikely to undergo deterioration such as corrosion.
Further, in the wet multi-plate brake mechanism, since the frictional heat generated during rotation is released through the lubricating oil, a larger energy than the dry type can be released in a short time.
Further, the wet multi-plate brake mechanism has an advantage that the brake plate is less likely to be damaged during operation as compared with the dry type because the coefficient of friction between the sliding members is smaller than that of the dry type.
Further, in the wet multi-plate brake mechanism, it is advantageous that the friction coefficient can be adjusted not only by the material of the brake plate and the friction material but also by the composition of the lubricating oil.

Further, in the wet multi-plate brake mechanism, the sliding area can be adjusted by the number of brake plates to be laminated, and the frictional force can be adjusted. Further, in the wet case, the thickness of the brake plate itself is about several mm, so that the entire brake portion 45 does not become so thick even if it is laminated. Therefore, the brake portion 45 can be easily miniaturized.
The specific structure of the wet multi-plate brake mechanism, such as the number of friction plates, materials, dimensions, and composition of lubricating oil, is not particularly limited. These conditions may be appropriately set within a range in which the maximum static friction force corresponding to the assumed snag load can be obtained. A known product such as a commercially available product may be used as long as the maximum static friction force corresponding to the assumed snag load can be obtained.

As a mechanism of the rotary brake 19, a mechanism having a rotary generator can also be mentioned.
A rotary generator means an electric motor capable of outputting regenerative power.
In this mechanism, the rotating shaft 43 is connected to the rotor which is the driving unit of the generator. Further, a rotor restraining mechanism is provided so that the rotating shaft 43 does not rotate with a torque equal to or lower than the snag load generation reference.

In a rotary generator, the rotor of the generator rotates when a snag load occurs, so that electric energy is generated in a direction that hinders the rotation, and energy absorption is realized.
This mechanism is advantageous in that the generated electrical energy can be used.
Further, the portion that slides inside the brake portion 45 during rotation is the bearing or brush of the drive portion, and the frictional force applied to the sliding portion is smaller than that of a brake that uses frictional force, so that the brake portion is activated during operation. It is also advantageous that the 45 is not easily damaged.
The structure of the generator is not particularly limited as long as it has a power generation function. It may be a DC motor or an AC motor, with or without a brush. In the case of an AC motor, an induction motor may be used. In addition, power running may be possible.

The following can be exemplified as the rotor restraint mechanism.
First, a restraint mechanism using a shear pin can be exemplified.
In this restraint mechanism, a through hole is provided in the rotating shaft 43 in a direction intersecting the axial direction, and a shear pin is inserted through the through hole. Further, by fixing one end of the shear pin to a shaft hole (not shown) provided in the holding girder 33 or the like, the rotation of the rotating shaft 43 is restrained when the snag load is not generated. When a snag load occurs, the shear pin breaks due to the shear stress, and the restraint of the rotating shaft 43 is released.
With this structure, it is necessary to replace the shear pin after the snag load occurs. At this time, it is necessary to align the through hole and the shaft hole, but since the position of the through hole can be easily adjusted by supplying electric power to the generator and rotating the rotor, the shear pin is used alone. Unlike conventional techniques, alignment is easy.
As the restraint mechanism, in the case of an induction motor, a mechanism for applying an induced current that rotates the rotor in the direction opposite to the torque applied to the rotating shaft 43 can also be exemplified. This mechanism consumes electric power at all times because an induced current is applied, but it is advantageous in that a shear pin or the like is not required.
As the restraint mechanism, there is also a structure in which the rotational resistance is increased by increasing the electric resistance such as the contact resistance of the brush and the resistance of the coil.
The restraint mechanism may be a combination of the above mechanisms. If a binding force can be obtained, a known product such as a commercially available product may be used.
The above is the description of the configuration of the crane 1 according to the first embodiment.

Next, the operation of the crane 1 during cargo handling will be briefly described by taking as an example when the spreader 5 is raised.
When raising the spreader 5, first, the driver operates a control stick (not shown) in the driver's cab 25 to transmit information indicating an instruction to raise the spreader 5 to a control unit (not shown). Upon receiving the information, the control unit rotates the drum 9 by rotating a motor (not shown) that drives the drum 9, and winds up the wire 7. The wire 7 moves along the path shown in FIG. 2 and is wound around the drum 9, but presses the guide sheave 11 when the wire 7 is turned around by the guide sheave 11. For example, the guide sheave 11 is pressed in the direction C in FIG. Since the guide sheave 11 is pivotally supported by the holding arm 35 by the holding shaft 29 of the sheave holding portion 13, the pressed guide sheave 11 exerts a force rotating around the holding shaft 29 in the direction of A1 in FIG. It is transmitted to the link member 37 via the holding plate 28. The link member 37 transmits this force to the rack 15 as a force rotating in the direction of A1 in FIG. 3, but since the rack 15 is restricted from moving in the directions of B1 and B2 in FIG. 3, this force is B1. It is converted into a force that moves directly in the direction. Since the rack 15 is toothed with the pinion 17, this force is transmitted to the pinion 17. The force transmitted to the pinion 17 is converted into a rotational force and transmitted to the rotary shaft 43 of the rotary brake 19.
When the rotational torque due to the rotational force transmitted to the rotary shaft 43 is not more than a certain value, the rotation of the rotary shaft 43 is restricted by the brake portion 45, so that the rotary shaft 43 does not rotate. Therefore, the rack 15, the pinion 17, the link member 37, and the sheave holding portion 13 do not move or rotate under the tension of the wire 7.

On the other hand, when a snag load occurs, the rotational torque becomes a certain value or more, so that the rotation of the brake portion 45 releases the restraint of the rotary shaft 43, and the rotary shaft 43 rotates. In this state, the rack 15, the pinion 17, the link member 37, and the sheave holding portion 13 are not restricted from moving. Therefore, the sheave holding portion 13 is pressed by the wire 7 and rotates in the direction of A1 in FIG. , Loosen the tension of the wire 7. As a result, the tension of the wire 7 transmitted to the girder 21 is reduced.
Further, when the brake portion 45 rotates, energy is absorbed by frictional resistance or electric resistance. Therefore, it is possible to prevent the energy generated by the generation of the snag load from being applied to the members constituting the crane 1 such as the girder 21 and significantly damaging them.

After the snag load occurs, the cause of the snag load is identified and the identified cause is removed. For example, if the snag load is caused by forgetting to remove the cone or lashing, remove the cone or lashing. If the cause is that the spreader 5, the wire 7, or the container 10 is caught in the structure of the container ship 48, remove the catch.

After removing the cause of the snag load, it is confirmed whether or not the members constituting the crane 1 such as the wire 7 are damaged due to the occurrence of the snag load, and if it is damaged, repair or replacement of parts is performed. After that, the positions or rotation phases of the pinion 17, the rack 15, the link member 37, and the sheave holding portion 13 are adjusted so that the rotation angle of the sheave holding portion 13 returns to the state before the occurrence of the snag load.
When the rotary brake 19 has a structure including a dry or wet brake portion 45, a mechanism for adjusting the vertical load applied to the brake portion 45 is operated to reduce the vertical load so that the drive shaft can rotate. After that, the sheave holding portion 13 is rotated in the direction of A2 in FIG. 3 by driving the adjusting motor 46 or the like to adjust the rotation angle of the guide sheave holding plate 28 with respect to the holding shaft 29, whereby the sheave holding portion 13 is used. Return the position of to the position before the snag load occurred. Finally, the vertical load applied to the brake portion 45 is readjusted to a load corresponding to the occurrence of snag load.
When the brake unit 45 is a motor, the position of the sheave holding unit 13 can be adjusted by connecting the brake unit 45 to a power source and driving the brake unit to rotate.
The above is a description of the operation of the crane 1 during cargo handling.

Thus, according to the first embodiment, the crane 1 includes a sheave holding portion 13, a rack 15, a pinion 17, and a rotary brake 19 having a rotating shaft 43 and a braking portion 45.

In this structure, the tension of the wire 7 is transmitted in the order of the guide sheave 11, the sheave holding portion 13, the rack 15, the pinion 17, and the rotating shaft 43 of the rotary brake 19. If the tension is less than a predetermined value, the rotation of the rotating shaft 43 is restricted by the brake portion 45, so that the guide sheave 11 does not rotate. When the tension becomes equal to or higher than a predetermined value, the restraint of the rotating shaft 43 is released, and the sheave holding portion 13 rotates to loosen the tension of the wire 7. Energy is also absorbed by the rotational resistance of the brake unit 45 during the rotational operation.

Therefore, the tension of the wire 7 transmitted to the crane structure when the snag load occurs can be reduced and energy can be absorbed only by rotating the rotary brake 19, and the crane 1 collapses and is damaged when the snag load occurs with a simple structure. Can be prevented. Further, since the rotary brake 19 has a structure that naturally rotates when the tension becomes a predetermined value or more, a snag load generation detection mechanism, a control mechanism at the time of detection, and the like are unnecessary.

Further, in the first embodiment, since the brake portion 45 is a rotary type, the restriction of the stroke at the time of operation is smaller than that of the hydraulic cylinder, and the size can be easily reduced.
Further, in the first embodiment, when a snag load is generated, a force is transmitted from the sheave holding portion 13 to the rack 15, and the force is converted into a rotational force by the pinion 17 and transmitted to the rotary brake 19 to be transmitted to the brake portion 45. Rotates.
Therefore, the stroke at the time of operation can be easily adjusted by the gear ratio of the rack 15 and the pinion 17, and the miniaturization is easier.
Further, in the first embodiment, since the rotation of the guide sheave 11 is restrained by the rotary brake 19, the rotation of the guide sheave 11 due to the hydraulic leak does not occur unlike the known snag load protection mechanism using the hydraulic cylinder. Therefore, it is also advantageous that a mechanism for constantly monitoring and adjusting the rotation angle of the guide sheave 11 is not essential.

Next, the second embodiment will be described with reference to FIG.
In the second embodiment, in the first embodiment, the holding shaft 29 is fixed to the center of the guide sheave holding plate 28 in the longitudinal direction. Further, a ball screw mechanism using a nut 38 as a linear motion member and a screw shaft 40 as a rotating member is used.
In the second embodiment, the elements having the same functions as those in the first embodiment are assigned the same number, and the parts different from the first embodiment will be mainly described.

As shown in FIG. 5, in the crane 1a according to the second embodiment, both ends of the guide sheave shaft 27 are fixed to the lower ends of the guide sheave holding plate 28 in the longitudinal direction. Further, a sheave holding portion 13 in which both ends of the holding shaft 29 are fixed to the central portion in the longitudinal direction of the guide sheave holding plate 28 is used.
In this structure, the link member 37 is pivotally supported at the upper end of the guide sheave holding plate 28 in the longitudinal direction. Further, the rotary brake 19 is fixed to the brake holding portion 35a provided on the girder 21 so as to face the holding arm 35 in the X direction.

As shown in FIG. 5, the crane 1a according to the second embodiment includes a nut 38 and a screw shaft 40.
The nut 38 is a linear motion member having the same function as the rack 15 according to the first embodiment, and in FIG. 5, one end thereof is pivotally supported at the right end of the link member 37 so as to be movable in the X direction. The nut 38 has a screw hole 38a formed in the direction of linear motion, here in the directions B1 and B2 of FIG.
The screw shaft 40 is a conversion member having the same function as the pinion 17 according to the first embodiment, and is a screw rod screwed into the screw hole 38a. Therefore, the screw hole 38a is screwed coaxially with the screw shaft 40. One end of the screw shaft 40 is connected to the rotating shaft 43 so as to rotate about an axis in the same direction as the rotating shaft 43 of the rotary brake 19. Here, they are coaxially connected. Therefore, in FIG. 5, the axial direction of the rotary shaft 43 of the rotary brake 19 is parallel to the directions of B1 and B2, which are the linear motion directions of the nut 38.

In this configuration, when the guide sheave 11 is pressed by the wire 7 in the direction C in FIG. 5, a force that rotates in the direction A1 in FIG. 3 about the holding shaft 29 is applied to the link member via the guide sheave holding plate 28. It is transmitted to 37. The link member 37 transmits this force to the nut 38 as a force that rotates in the direction of A1 in FIG. Since the screw shaft 40 is screwed into the screw hole 38a of the nut 38, this force is converted into a force that moves linearly in the direction of B2. Further, since the screw shaft 40 is connected to the rotary shaft 43 of the rotary brake 19, the force transmitted from the nut 38 to the screw shaft 40 is converted into a rotational force and transmitted to the rotary shaft 43 of the rotary brake 19. ..

As described above, the mechanism for converting the linear motion into the rotation may be a mechanism using a ball screw. In the mechanism using the rack 15 and the pinion 17, the moving direction of the rack 15 and the rotation axis of the pinion 17 are orthogonal to each other, whereas in the mechanism using the ball screw, the moving direction of the nut 38 and the rotation axis of the screw shaft 40 are parallel. The same effect can be obtained, although it differs in some respects.

Next, the third embodiment will be described with reference to FIGS. 6 and 7.
The third embodiment is the one in which the rotating shaft 43 of the rotary brake 19 is connected to the holding shaft 29 of the sheave holding portion 13 in the first embodiment.
In the second embodiment, the configurations having the same functions as those in the first embodiment are assigned the same number, and the parts different from the first embodiment will be mainly described.

As shown in FIGS. 6 and 7, in the crane 1b according to the second embodiment, the rotating shaft 43 of the rotary brake 19 is connected to the holding shaft 29 of the sheave holding portion 13. The brake portion 45 of the rotary brake 19 is fixed to a pedestal 33b provided on the upper surface of the holding girder 33.
In this structure, the wire 7 wound up when the spreader 5 rises presses the guide sheave 11 in the direction C in FIG. Since the guide sheave 11 is pivotally supported by the holding arm 35 by the holding shaft 29, a force that rotates the pressed guide sheave 11 in the direction of A1 in FIG. 6 around the holding shaft 29 is applied from the wire 7. This force is not converted into a linear motion and is transmitted to the rotary shaft 43 as the rotational force. When the torque due to this rotational force is less than a predetermined value, the rotating shaft 43 is constrained by the brake portion 45, so that the guide sheave 11 does not rotate.

On the other hand, when the torque is equal to or more than a predetermined value, specifically, when the torque value exceeds the braking force capable of restraining the rotation of the rotating shaft 43, the rotating shaft 43 is released from the restraint by the braking part 45. , Rotates by rotational force.
In this state, the pinion 17, the rack 15, the link member 37, and the sheave holding portion 13 are not restrained from being driven. Therefore, the sheave holding portion 13 is pressed by the wire 7 and rotates in the direction of A1 in the figure. Loosen the tension of the wire 7. As a result, the tension of the wire 7 transmitted to the girder 21 which is the structure of the crane 1a is reduced.
Further, when the brake portion 45 rotates, energy is absorbed by frictional resistance or electric resistance. Therefore, it is possible to prevent the energy generated by the generation of the snag load from being applied to other members such as the girder 21 and significantly damaging them.

However, if the rotational force of the sheave holding portion 13 can be transmitted to the rotating shaft 43 as it is without being converted into linear motion, the rotating shaft 43 of the rotary brake 19 can be replaced with the holding shaft 29 of the sheave holding portion 13. It does not necessarily have to be directly connected. Power may be transmitted via other gears.
The structure of the brake portion 45 of the rotary brake 19 is the same as that of the first embodiment, and any of a dry type, a wet type, and a generator can be used.

Next, the fourth embodiment will be described with reference to FIGS. 8 and 9.
The fourth embodiment includes, in the third embodiment, a tilting mechanism 51 that holds the sheave holding portion 13 in the support structure 3 so as to be tiltable around an axis parallel to the holding shaft 29. In the fourth embodiment, the elements having the same functions as those in the third embodiment are assigned the same number, and a configuration different from that of the third embodiment will be mainly described.
As shown in FIGS. 8 and 9, the crane 1c according to the fourth embodiment includes a tilting mechanism 51.
The tilting mechanism 51 includes a holding shaft support portion 53 and a motor jack 55.

The holding shaft support portion 53 is a member that rotatably holds the holding shaft 29 in the directions A1 and A2 of FIG. 8, and is a member having an L-shape turned upside down in a side view. Specifically, in the holding shaft support portion 53, an L-shaped bent portion is pivotally supported by the holding arm 35 by a tilting shaft 57. Since the axial direction of the tilting shaft 57 is parallel to the axial direction of the holding shaft 29, the sheave holding portion 13 has A1 and A2 centered on the holding shaft 29 when the holding shaft 29 and the tilting shaft 57 are not restrained. It can rotate in the direction and can rotate in the directions of A1 and A2 about the tilting shaft 57.
The right end of the holding shaft support portion 53 holds the holding shaft 29.
The lower end of the holding shaft support portion 53 is connected to the motor jack 55.
The motor jack 55 is an electric jack that can be expanded and contracted in the X direction in FIG. 8, and in FIG. 8, the right end is rotatably supported at the lower end of the holding shaft support portion 53 in the directions of A1 and A2 in FIG. The left end is pivotally supported by the holding girder 33 so as to be rotatable in the directions A1 and A2 of FIG.

In this configuration, the rotation of the sheave holding portion 13 about the tilting shaft 57 is constrained by the motor jack 55. On the other hand, when the motor jack 55 is expanded and contracted, the holding shaft support portion 53 rotates around the tilting shaft 57 in the directions of A1 and A2 in FIG. 8, so that the sheave holding portion 13 also rotates in the directions of A1 and A2. Specifically, when the motor jack 55 is extended, the sheave holding portion 13 rotates in the direction of A1. When the motor jack 55 is contracted to the land side in the X direction, the sheave holding portion 13 rotates in the direction of A2.
By providing the motor jack 55 in this way, the sheave holding portion 13 can be tilted while the holding shaft 29 of the sheave holding portion 13 is restrained by the rotary brake 19.

Which configuration of the first to fourth embodiments may be adopted may be appropriately set in consideration of the crane structure, design restrictions, and the like.
For example, in the first and second embodiments, the rack 15, the pinion 17, the link member 37, and the rotary brake 19 replace the hydraulic cylinder. Therefore, the structure of the sheave holding portion 13 is almost the same as that of an existing crane equipped with a hydraulic cylinder, which is advantageous in that the sheave holding portion 13 does not need to be replaced or a major design change is not required.
On the other hand, in the third and fourth embodiments, the rack 15, the pinion 17, and the link member 37 are not required, and the mechanism for restraining the movement of the rack 15 in the directions of B1 and B2 is not required. This is advantageous when it is difficult to secure a space for providing the members of the above.
Further, since the fourth embodiment can tilt the sheave holding portion 13, it is advantageous when it is desired to add a function of tilting the sheave holding portion 13 in a state of being fixed by the rotary brake 19.

As described above, according to the second to fourth embodiments, the cranes 1a to 1c have a sheave holding portion 13, a holding shaft 29, and a brake portion 45.
Therefore, the same effect as that of the first embodiment is obtained.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the embodiments. It is natural for a person skilled in the art to come up with various modifications and improvements within the scope of the technical idea of the present invention, and these are also included in the technical scope of the present invention.

For example, in the above-described embodiment, the quay crane is exemplified as the cranes 1 to 1c, but the crane of the present invention is not limited to the quay crane. It may be a jib crane, a gantry crane, an unloader, or the like.

Further, in the above-described embodiment, the crane 1 in which the cab 25 is provided in the trolley 23 is exemplified, but the position of the cab 25 is not limited to the trolley 23. For example, the present invention can be applied to a remote-controlled crane in which the cab 25 is provided at a position away from the support structure 3.

1, 1a, 1b, 1c Crane 3 Support structure 3a Leg structure 3b Portal tie 5 Spreader 7, 7a, 7b, 7c, 7d Wire 9, 9a, 9b, 9c, 9d Drum 10 Container 11, 11a, 11b, 11c , 11d Guide sheave 13, 13a, 13b, 13c, 13d Sheave holder 15 Rack 17 Pinion 19 Rotary brake 20 Traveling device 21 Digit 23 Trolley 23a, 23b, 23c, 23d First trolley sheave 24a, 24b, 24c, 24d 2nd trolley sheave 25 Driver's cab 25a, 25b, 25c, 25d Spreader sheave 26a, 26b, 26c, 26d Seaside end sheave 27 Guide sheave shaft 28 Guide sheave holding plate 29 Holding shaft 30 Machine room 32 Fixed part 33 Holding girder 33a Holding plate 33b Pedestal 35 Holding arm 35a Brake holding part 37 Link member 37a, 37b Link member shaft 38 Nut 38a Screw hole 40 Screw shaft 41 Guide roller 43 Rotating shaft 45 Brake part 46 Adjusting motor 48 Container ship 51 Tilt mechanism 53 Holding shaft Support 55 Motor jack 57 Tilt shaft

Claims (7)

A support structure, a hanging tool that is held by a wire in the support structure and moves up and down, and a hanging tool provided in the support structure that winds and holds the wire, and winds and unwinds the wire by rotation. This is a crane equipped with a drum that moves the hanger up and down.
A guide sheave provided at a position where the direction of the wire is changed and guides the wire in the path of the wire from the drum to the hanger.
A sheave holding portion that is rotatably supported by the support structure by a holding shaft parallel to the axis of the guide sheave and holds the guide sheave.
A linear motion member connected to the sheave holding portion and linearly moving following the rotation of the sheave holding portion.
A conversion member that is connected to the linear motion member and converts linear motion into rotation to transmit power.
A rotating shaft that is rotatably connected to the conversion member and to which the rotational force applied to the conversion member is transmitted, and a rotating shaft that is connected to the rotating shaft to restrain the rotation, and a torque of a predetermined value or more is applied. A rotary brake having a braking portion configured to release the restraint of the rotating shaft by rotating when the rotating brake is applied.
A crane characterized by being equipped with. The conversion member is a pinion coaxially fixed to the rotation axis of the rotary brake.
The crane according to claim 1, wherein the linear motion member is a rack that meshes with the pinion and one end thereof is pivotally supported by the sheave holding portion. The conversion member is a screw shaft coaxially fixed to the rotary shaft of the rotary brake, and the linear motion member is a nut having a screw hole screwed coaxially with the screw shaft according to claim 1. The described crane. A support structure, a hanging tool that is held by a wire in the support structure and moves up and down, and a hanging tool provided in the support structure that winds and holds the wire, and winds and unwinds the wire by rotation. This is a crane equipped with a drum that moves the hanger up and down.
A guide sheave provided at a position where the direction of the wire is changed and guides the wire in the path of the wire from the hanger to the drum.
A sheave holding portion that is rotatably supported by the support structure by a holding shaft parallel to the axis of the guide sheave and holds the guide sheave.
A rotating shaft that is rotatably connected to the holding shaft and to which the rotational force applied to the holding shaft is transmitted, and a rotating shaft that is connected to the rotating shaft to restrain the rotation, and a torque of a predetermined value or more is applied. A rotary brake having a braking portion configured to release the restraint of the rotating shaft by rotating when the shaft is rotated.
A tilting mechanism that holds the sheave holding portion in the support structure so that it can be tilted around an axis parallel to the holding shaft.
A crane characterized by being equipped with. The brake part is
It is a dry brake mechanism equipped with a pair of brake plates that contact rotatably in a dry manner.
The crane according to any one of claims 1 to 4 , wherein the rotating shaft is provided on one of the brake plates. The brake part is
It is a wet multi-plate brake mechanism in which multiple brake plates rotatably contact in lubricating oil.
The crane according to any one of claims 1 to 4 , wherein the rotating shaft is connected to at least one of the brake plates. The crane according to any one of claims 1 to 4 , wherein the brake portion includes a rotary generator, and the rotary shaft is connected to the drive portion thereof.

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