JPH0912280A - Crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crane in which the total height can be decreased by laying a back stay in not-working, and tension of a boom rope is decreased by erecting the back stay to the specified height in work, concerning to the crane. SOLUTION: A back stay 5 provided on the rear end of a turning table 2 is provided with a back stay front 6 whose lower end is supported to the turning table 2 so as to be turned around right and axial cores, and a back stay rear 7 suspended from the upper rear side of the back stay front 6, and whose lower end is to be engaged with and disengaged from the rear part of the turning table 2 from below, the back stay front 6 is tilted rearward by its own weight by slacking the boom rope 9, the boom rope 9 is taken up, and the back stay front 6 is erected by the tension.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a crane,
In particular, the present invention relates to a crane in which the backstay can be lowered to reduce the overall height when not in operation, and the backstay can be raised to a predetermined height during operation to increase the maximum lifting load.

[0002]

2. Description of the Related Art As a conventional crane, a boom having one end rotatably supported on the front end portion of an underframe so as to be rotatable about its left and right axes,
A boom rope wound around a boom raising / lowering winch drum, one end of which is connected to the boom and the other end of which is arranged on the underframe, and a pulley around which an intermediate portion of the boom rope is wound are attached to a predetermined frame on the underframe. Some include a backstay that supports the position. The underframe is rotatably mounted on a vehicle such as a barge, a railway bogie, a self-propelled or non-self-propelled bogie, and a truck, or is fixed on the barge, the vehicle, or the ground.

For example, in a crane ship equipped with a crane of this type, as shown in a side view of FIG. 13, for example, a swivel underframe, that is, a swivel base 103 is swivelably mounted on a deck 102 of a hull 101. The boom 104 is supported at the front end of the swivel base 103 so that one end of the boom 104 is rotatable about the left-right axis. A tip of a boom rope 106 wound around a winch drum 105 arranged on the swivel base 103 is connected to the boom 104.
The middle portion of 06 is wound around a pulley 107 supported on an upper portion of a back stay 108 standing upright on the rear portion of the swivel base 103. Then, by winding the boom rope 106 around the winch drum 105, the boom 104 is raised, and conversely, the boom rope 106 is wound around the winch drum 1.
The boom 104 is laid down by being extended from 05.

The backstay 108 has a lower end fixed to the swivel base 103, a backstay front 109 inclined rearward, and an upper end of the backstay front 1.
The back stay rear 110 is connected to the upper end of the back stay 09, and the lower end of the back stay rear 110 is fixed to the swivel base 103 behind the back stay front 109.
0 opposes the force of pulling the upper end of the backstay front 109 forward, for example, the tension of the boom rope 106.

[0005]

By the way, when the boom 104 of the crane ship is lowered, the load acting on the boom rope 106 increases, and the tension of the boom rope 106 also increases. On the other hand, it is desired to reduce the diameter of the boom rope 106 as much as possible to reduce its weight and price.
In order to make the tension of the boom rope 106 as small as possible, it is advantageous to raise the position of the pulley 107,
Therefore, it is advantageous to raise the back stay 108. Therefore, for example, in the case of a crane ship having a lifting load of 500 tons, the back stay 108 is designed to have a height from the water surface (hereinafter, referred to as water height) near 30 m.

However, at present, among the road bridges bridged along the coastal areas, the bridge girders bridged along the route is designed with a clearance of 28m or more above the bridge and the water surface. When the water height of the back stay 108 is increased in this way, it becomes impossible to navigate under the bridge. For this reason, it may become impossible to enter or leave the port beyond the bridge, or you may have to choose a route that detours farther to your destination, which may result in higher voyage costs. or,
It is also a problem that the inspection and maintenance work of the pulleys 107 and 113 supported on the upper part of the back stay is performed at a high place.

In the case of a mobile crane traveling on the ground, a similar problem occurs when passing under a grade crossing road bridge, a pedestrian bridge, a railway viaduct, a power transmission line, a telephone communication line, or the like. In the case of a stationary crane where the underframe is fixed on the ground, the problem on the premise of such movement can be avoided by assembling the backstay at the installation site, but it was supported above the installed backstay. There is no change in that the inspection and maintenance work of the pulleys 107 and 113 is a work at a high place.

The present invention has been made in view of the above circumstances, and it is possible to lower the overall height by lowering the backstay during non-working, and raise the backstay to a predetermined height during working to increase the maximum lifting load. The object is to provide a crane that can be increased.

[0009]

SUMMARY OF THE INVENTION According to the present invention, an underframe, a boom whose one end is supported by a front end portion of the underframe so as to be rotatable about a left-right axis, and one end of which is connected to the boom and the other end of which is A crane provided with a boom rope wound around a boom raising / lowering winch drum arranged on the underframe, and a backstay for supporting a pulley around which an intermediate portion of the boom rope is wound at a predetermined position on the underframe. In order to achieve the above purpose, the following measures are taken.

That is, in the crane according to the present invention, the backstay has a lower end supported on the front part of the underframe so as to be rotatable about the left and right axes, and on the upper rear side of the backstay front. It is characterized in that it is provided with a back stay which is suspended and whose lower end is engaged with and disengaged from the lower part of the rear of the underframe.

In the crane of the present invention, when the boom rope is extended from the boom raising / lowering winch drum and the boom is laid down at a predetermined angle, for example, horizontally, and then the boom rope is further extended, the upper end of the backstay front is the backstay. The back stay is lowered by the weight, and at the same time, the lower end of the back stay rear is lowered below the underframe and separated from the underframe, so that the height of the backstay is lowered.

By lowering the backstay in this way, the crane can pass under the bridge, the power transmission line, the communication line, and the like, and the pulleys and the like supported on the upper end of the backstay are inspected and maintained. You will be able to do it safely in a low position.

When the boom rope is wound around the boom lifting winch drum with the backstay lowered, the backstay front is caused by the tension acting on the boom rope, and the backstay rear suspended by the backstay front is lifted. When the lower end is engaged with the rear portion of the underframe, the backstay front is restrained at a constant angle, and the backstay is held at a predetermined height.

By holding the backstay at a predetermined height in this way, the tension of the boom rope can be reduced, the diameter and weight of the boom rope can be reduced, and the winch drum for winding the boom rope can be miniaturized. Also, the weight can be reduced.

Here, in order to engage and disengage the lower end of the back stay rear from the lower part of the underframe from below, for example, an engaging portion engaged with the lower end of the back stay rear from below the underframe. Is provided, and an engagement receiving portion with which the frame is engaged is provided at a rear portion of the underframe. The shape of the engaging portion is not particularly limited, and it is conceivable to form the engaging portion into a hook shape, a pin shape, or the like. Further, the engagement receiving portion may be formed in such a shape that the engaging portion can come in and out from below and can be locked at a predetermined position, for example, hook type, groove type, pin type. And the like.

In the crane of the present invention, holding the engaging portion engaged with the engaging receiving portion at the engaged position is advantageous in enhancing the stability of work. From this point of view, the engaging portion or the engaging receiving portion is provided with means for preventing lateral movement of the engaging portion, means for preventing downward movement of the engaging portion, or And it is preferable to provide means for preventing lateral movement.

Further, in the crane of the present invention, a back stay rest for receiving an intermediate portion of the back stay front tilted rearward is provided upright at the rear portion of the underframe, and the back stay rear is provided at an upper end portion of the back stay rest. Can be configured to be disengaged. In this case,
The length of the backstay rear can be made lower than the height of the backstay, and the lower end of the backstay rear can be prevented from protruding below the underframe when the backstay is lowered. Even if there is a chassis, wheels, crawlers, etc., or even if there is the ground, the backstay can be lowered without interfering with the backstay rear.

Furthermore, in the crane of the present invention, the back stay rear and the underframe may be engaged at a plurality of locations or at a single location. That is, the number of the engaging portions and the corresponding engaging receiving portions may be one, or two or more. When the backstay rear and the underframe are engaged at two or more locations, there is an advantage that the shape retention of the backstay can be improved in the engaged state, and the backstay rear and underframe are provided at only one location. In the case of engagement, there is an advantage that the back stay and the underframe can be easily engaged at the time of engagement.

Another crane according to the present invention is an underframe, a boom whose one end is rotatably supported at the front end of the underframe so as to be rotatable about the left-right axis, and one end of which is connected to the other end of the boom. Is provided with a boom rope wound around a boom lifting winch drum arranged on the underframe, and a backstay for supporting a pulley around which an intermediate portion of the boom rope is wound at a predetermined position on the underframe. Assuming a crane, the following measures are taken to achieve the above objectives.

That is, according to another crane of the present invention, the backstay has a lower end supported at a lower end in an intermediate portion of an underframe so as to be rotatable about a left-right axis, an upper end of the backstay front, and a swivel base. And a pulling means for winding up the pulling rope or pulling an intermediate portion of the pulling rope toward the backstay front side to pull the upper portion of the backstay front toward the rear portion of the underframe. Characterize.

In this case, if the tension rope is wound around the winch by the pulling means while the boom rope is being loosened, or the middle portion of the tension rope is pulled toward the backstay front side, the upper portion of the backstay front becomes the underframe. The back stay can be lowered by being pulled toward the rear part of the vehicle.

Further, when the tension rope is unwound from the winch while winding the boom rope around the boom lifting winch drum, or when the pulling force of the pulling means is relaxed or released, the backstay front is caused by the tension of the boom rope, The back stay can be raised to a predetermined height.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a full swing type crane mounted on a crane ship will be described below in detail with reference to the drawings.

As shown in the perspective view of FIG. 1, a swivel base 2 is mounted on the rear part of the pontoon 1 of this crane ship so as to be fully swivelable. At the front end of the swivel base 2, one end of a boom 3 is left and right. A support frame 4 is rotatably supported around the axis and a receiving frame 4 for receiving the boom 3 is provided upright on the front portion.

A back stay 5 standing on the swivel base 2.
Is a gate-type backstay front 6 whose lower end is rotatably supported on the front part of the swivel base 2 about the left-right axis, and an upper end of the backstay front 6 with an appropriate space left and right above the backstay front 6. It is provided with a pair of backstay rears 7 that are rotatably connected around the left and right axis.

A pair of left and right boom raising / lowering winch drums 8 are mounted on the swivel base 2, and the tips of the boom ropes 9 extended from the respective boom raising / lowering winch drums 8 are connected to the free ends of the booms 3, respectively. Each boom rope 9 is wound around a pulley 10 rotatably supported on the upper part of the back stay front 6 between the boom raising / lowering winch drum 8 and its tip, whereby the boom raising / lowering winch drum 8 is attached to the boom rope. The boom 3 is erected when the boom 3 is wound up, and when the boom rope 9 is unwound from the boom lifting winch drum 8, the boom 3 is laid down.

However, another pulley is provided at the free end of the boom 3, and the pulley 10 provided with the boom rope 9 fed from each boom lifting winch drum 8 at the back stay front 6 and the pulley at the free end of this boom 3. The boom rope 9 may be wound around and connected to the back stay front 6, the pulley 10 or the swivel base 2.

As shown in the exploded perspective view of FIG. 2, pin-shaped engaging portions 11 projecting to the left and right sides are fixed to the lower end portion of the back stay rear 7, and the rear end of the swivel base 2 is fixed. An engaging metal fitting 12 is fixed to the upper part, and the engaging part 11 is engaged and disengaged obliquely from the lower rear side.

The engaging metal fitting 12 has a groove 13 through which the backstay rear 7 passes, and left and right side backstay rear 7 of the groove 13.
And a pair of left and right engaging grooves 14 that are open in a diagonally rearward and downward direction.

As will be described later, when a crane operation is to be performed with the backstay 5 lowered, the boom rope 9 is wound around the boom raising / lowering winch drum 8 and the tension applied to the boom rope 9 causes the boom to move. Three
Lighter back stay front 6 is raised forward. The back stay rear 7 hangs on the rear side of the upper end of the back stay front 6 rotatably around the left and right axis,
The lower end is locked to the rear part of the swivel base 2 by being pulled up obliquely upward and upward, and the engaging portion 11 at the lower end is inserted into the engaging groove 14 of the engaging fitting 12 obliquely upward and upward and cannot be pulled out.
The back stay front 6 is restricted from rotating forward from a predetermined angle.

In this way, the back stay front 6
By raising the back stay 5 to a predetermined angle, the position of the pulley 10 can be raised and the tension acting on the boom rope 9 can be reduced, and the boom rope 9 can be made smaller in diameter and lighter in weight. The size and weight of the boom raising / lowering winch drum 8 can be reduced.

In this embodiment, a stopper pin 7a is inserted in the lower portion of the back stay rear 7 with the engaging portion 11 engaged with the engaging fitting 12, and the stopper pin 7a is inserted into the engaging fitting 12. The back stay rear 7 is prevented from moving downward by allowing the upper surface to receive the back stay. Further, the back stay rear 7 engaged with the engaging fitting 12 is prevented from moving in the left-right direction by receiving the left and right side surfaces of the back stay rear 7 on the side surfaces of the groove 13. In this manner, the downward movement of the backstay rear 7 is prohibited by the stopper pin 16, and the lateral movement of the backstay rear 7 is prohibited by the side surface of the groove 13 of the engaging metal fitting 12, whereby the backstay rear 7 is prevented. Securely engage the lower end of the rear 7 with the fitting 1.
It is connected to the rear part of the swivel base 2 via 2 and can stabilize the shape of the back stay 5 at the time of work to enhance the work stability.

Thereafter, the boom rope 9 is further wound around the boom raising / lowering winch drum 8 and the boom 3 is lifted from the receiving frame 4 to perform a crane operation. During normal rounding,
For example, as shown in the perspective view of FIG. 3, the boom 3 is laid at a position where it is received by the receiving frame 4 of the pier 2, but passes under a low bridge lower than the water level of the backstay with a high clearance above the water level. Sometimes, after pulling out the stopper pin 16 with the boom 3 lying on the berth 1,
When the boom rope 9 is further extended from the boom raising / lowering winch drum 8, the engaging groove 14 of the engaging fitting 12 is opened obliquely rearward and downward, so that the lower end of the backstay rear 7 can be freely moved obliquely rearward and downward. As shown in FIG. 4, for example, the weight of the backstay 5 causes the backstay front 6 to tilt rearward, the backstay rear 7 to move diagonally rearward and downward, and the height of the backstay 5 decreases. When the height of the backstay 5 is lowered, the lower end of the backstay rear 7 descends behind the swivel base 2 and plunges into the water if necessary.

By thus lowering the height of the backstay 5 to a predetermined height, for example, 25 m or less, it is possible to navigate under a bridge installed at a predetermined sea level, for example 28 m above the sea level. It will be possible to enter and exit the port beyond the bridge and take the shortest route without making a detour.

When the backstay 5 is lowered, the pulley 10 supported on the upper end of the backstay 5 is also lowered, so that the pulley 10 and the like can be safely inspected and maintained at a low place.

When the boom rope 9 is wound around the boom up-and-down winch drum 8 with the back stay 5 kept low, the movement of the engaging portion 11 obliquely rearward and upward is caused by the engaging metal fitting 12.
The tension applied to the boom rope 9 causes the backstay front 6 to be lifted and the backstay rear 7 moves diagonally rearward and upward until the height of the backstay 5 required for crane work is restored until it is limited by. .

Another embodiment of the present invention is applied to a full swing type crane mounted on a vehicle. As shown in the perspective views of FIGS. 5 and 6, the frame of the vehicle body not shown is shown. A swivel base 2 is mounted on the frame so that it can be swiveled in its entirety, and a cradle 4 is provided on the frame at a position spaced from the swivel base 2 so that the boom 3 can be laid down at the time of forwarding. .

A back stay rest 23 having a height about 1/3 of the back stay 5 is provided at the rear of the swivel base 2.
The back stay front 6 laid down rearward is received by the back stay rest 23.

An engagement receiving portion 25 is provided at the upper end of the back stay rest 23, and is about 1 / height of the back stay 5.
An engaging portion 24 is formed by bending the lower end portion of the back stay rear 7 having a length of 3 forwardly into a hook shape.

As shown in the exploded perspective view of FIG. 7 and the vertical sectional side view of FIG. 8, the engagement receiving portion 25 is provided with a concave portion 26 into which the engaging portion 25 is engaged and disengaged obliquely from the lower rear side. The upper part of the above is formed so as to be slightly recessed at the back side (front side) corresponding to the warping of the tip of the engaging portion 24.
The left and right side surfaces of the recess 26 receive the left and right side surfaces of the engaging portion 24 to prevent the engaging portion 24 from sliding sideways.

Further, as shown in FIG. 8, stopper means 27 is provided in order to prohibit downward movement of the engaging portion 24 engaged with the engaging receiving portion 25, and the stopper means 27 is engaged. The stopper pin 2 supported by the engagement receiving portion so as to be able to move forward and backward so as to project and retract below the engagement portion 24 engaged with the receiving portion 25.
8 and an actuator 29 such as a cylinder for driving the stopper pin 28.

According to this embodiment, as in the previous example, the boom 2 is laid down at a predetermined angle, and the stopper pin 2
By retracting the boom rope 9 from the boom raising / lowering winch drum 8 in a state in which 8 is retracted from the lower side of the engaging portion 24, the backstay front 6 is tilted rearward and the backstay rear 7 is slanted rearward and downward. The height of the back stay 5 is lowered. At this time, the lower end of the back stay rear 7 does not project below the swivel base 2 but descends to a height near the upper surface of the swivel base 2 or near the lower surface of the swivel base 2, so that the lower part of the swivel base 2 is lowered. There is no risk of the back stay rear 7 interfering with the chassis, wheels, crawlers, etc. of the vehicle body located at, and the back stay 5 can be lowered with respect to the vehicle body regardless of the turning angle of the swivel base 2. .

Other configurations, operations and effects of this embodiment are the same as those of the above-described embodiment, and therefore, description thereof will be omitted to avoid duplication. In this embodiment, when the back stay 5 is lowered, the back stay rear 7
Since it does not protrude below the swivel base 2, it can be applied to a stationary crane in which an underframe corresponding to the swivel base 2 is installed on the ground so as not to rotate.

In another embodiment of the present invention, as shown in the exploded perspective view of FIG. 9, a bifurcated portion 30 is formed at the lower end portion of the back stay rear 7 and is divided into right and left, and a space between the bifurcated portions 30. The engaging portion 11 is composed of a pin arranged in the lower part of the, and the engaging metal fitting 12 fixed to the swivel base 2 is formed in a hook shape opened downward. The downward movement of the engaging portion 11 engaged with the engaging metal fitting 12 is prohibited by receiving the stopper pin 7a inserted into one of the forked portions 30 on the upper surface of the engaging metal fitting 12, and laterally. Is prohibited by receiving the hook both side surfaces of the engaging fitting 12 at the forked portion 30.

Other constitutions, functions and effects of this embodiment are the same as those of the embodiment of the present invention shown in FIGS. 1 to 4, and therefore their explanation is omitted to avoid duplication.

In a further embodiment of the present invention shown in FIG. 10, the lower end is rotatable around the left and right axial center on the front part of the swivel base 2 as in the embodiment of the present invention shown in FIGS. There is provided a backstay 15 including a gate-shaped backstay front 16 supported by the backside and a tensile rope 17 connecting an upper end of the backstay front 16 and a rear portion of the swivel base 2.

In order to reduce the tension of the tension rope 17, the swing rope 18 is wound around a pulley 18 rotatably supported by the swivel base 2 and a pulley 19 provided at the upper end of the backstay front 16 as necessary. A winch drum (not shown) is provided at an intermediate portion or a front portion of the platform 2 (may be the boat 1), and as shown in FIG. 11, a pulley 20 is attached to an intermediate portion of the tensile rope 17 at one end. A pull-in rope 21 is prepared which is attached and detached via the other end and is wound around the winch drum 22 for pulling in the other end.

During crane work, as shown in FIG. 10, the tension of the boom rope 9 is applied to the back stay front 1.
6 is pulled forward, and the tension of the tensile rope 17 limits the forward rotation of the backstay front 16 at a predetermined position.

Further, during normal rounding, as shown in FIG. 11, the tension of the boom rope 9 causes the back stay front 16 to move.
Is pulled forward and the tensile rope 17 is tensioned, whereby the forward rotation of the backstay front 16 is restricted to a predetermined position.

When passing under a bridge or the like whose clearance above the water surface of the backstay 15 is lower than the water surface height of the backstay 15 during traveling, as shown in FIG. 12 is unwound from the boom raising / lowering winch drum 8, the back stay front 16 is tilted rearward by its own weight and the back stay 15 is lowered, as shown in FIG.

Before the back stay front 16 is tilted rearward, the pulley 20 is hung on the tensile rope 17, and the pull-up winch drum is used to wind up the pull-in rope 21 and tilt the back stay front 16 rearward. 1
Prevent 7 from slackening and entanglement.

To raise the back stay 15 from a low state to a high state, the boom rope 9 may be wound around the boom raising / lowering winch drum 8. In this case, the pulley 20 and the pull-in rope 21 may be removed from the tensile rope 17 or may be hung on the tensile rope 17. Pulley 20
When the retractable rope 21 is hung on the tensile rope 17, the retractable winch drum 22 should be able to freely extend the retractable rope 21 to the extent that the retractable rope 21 and the tensile rope 17 are not loosened. Is preferred.

Although not shown, in another embodiment of the present invention, the pulley 20 and the retracting rope 21 of the preceding example are omitted, and one end of the tensile rope 17 is connected to the retracting winch drum 22.
It is wound around.

In this embodiment, when the boom rope 9 is unwound from the boom lifting winch drum 8 with the boom 3 lying at a predetermined position, the backstay front 16 is tilted rearward by its own weight, and the backstay 15 is lowered. . At this time, in order to prevent the tensile rope 17 from slackening and being entangled, the tensile rope 17 is wound around the retracting winch drum 22 while being tensioned to the extent that slack does not occur.

When raising the lowered back stay 15, the back stay front 16 is raised by winding up the boom rope 9, and the tension rope 17 is arranged so as not to hinder the winding of the boom rope 9. It is paid out from 22.

When the tension rope 17 reaches a predetermined amount, the tension rope 17 is stopped and tensioned, and the tension of the boom rope 9 causes the backstay front 16 to rotate forward. By attaching the tension rope 17 to the force, the back stay front 1
6 is held in a fixed position.

Other configurations, operations and effects of this embodiment are the same as those of the previous example, and therefore, description thereof will be omitted to avoid duplication.

[0058]

As described above, in the crane of the present invention, the backstay has the lower end supported by the front portion of the underframe so as to be rotatable about the left and right axis, and the backstay. Suspended on the upper back of the front,
The lower end of the back frame is provided with a back stay rear engaged and disengaged from below.

Therefore, according to the crane of the present invention, when the boom rope is unwound from the drum winch, the backstay front is laid down backward due to the weight of the backstay, and the backstay rear moves obliquely downward to move the backstay. The height can be reduced. This makes it possible to pass under bridges, power transmission lines, communication lines, etc., which have a clearance above the ground or above the water that is lower than the height of the backstay during crane work, and the bridge, the power transmission line, the port beyond the communication line, You will be able to enter and exit destinations such as parking lots,
Further, it is possible to reduce the forwarding cost and the traveling cost by shortening the route length and the route length to the destination. Further, it becomes possible to safely inspect and maintain the pulleys and the like supported by the lower ends of the backstays.

Further, according to the crane of the present invention, by winding the boom rope around the drum winch with the backstay lowered, the tension of the boom rope can raise the backstay to a height required for crane work. it can. As a result, the position of the pulley supported on the upper part of the back stay can be raised to reduce the tension acting on the boom rope wrapped around the pulley, and the boom rope can be reduced in diameter and weight, and the boom rope can be reduced. It is possible to reduce the size and the weight of the winch drum that winds up.

In the crane of the present invention, a back stay rest for receiving the back stay front tilted rearward is provided upright at the rear portion of the underframe, and the back stay rear is disengaged at the upper end of the back stay rest. In this case, the length of the backstay rear can be made shorter than the height of the backstay, and the lower end of the backstay rear can be prevented from protruding below the lower surface of the underframe when the backstay is lowered. As a result, it is possible to reliably prevent the descending backstay rear from interfering with the frame, wheels, crawlers, ground, etc. that exist under the underframe, making it suitable for use in vehicle-mounted full swing cranes and stationary cranes. The present invention can be applied.

In another crane of the present invention, the backstay has a lower end supported by a lower end of a swivel base at a front portion of the swivel base so as to be rotatable about a left-right axis, and an upper end of the backstay front and a swivel base. And a tensile rope connecting the rear part.

Therefore, according to another crane of the present invention,
By loosening the boom rope, the backstay front rotates backward due to the weight of the backstay, and the height of the backstay can be lowered. This makes it possible to pass under bridges, power transmission lines, communication lines, etc., which have a clearance above the ground or above the water that is lower than the height of the backstay during crane work, and the bridge, the power transmission line, the port beyond the communication line,
You will be able to enter and exit destinations such as parking lots, and shorten the route length to the destination, route length, etc.
Travel costs can be reduced.

Further, according to another crane of the present invention, by winding the boom rope around the drum winch with the backstay lowered, the backstay is erected to the height required for crane work by the tension of the boom rope. The backstay can be restrained in its position by the tension rope. As a result, the position of the pulley supported on the upper part of the back stay can be raised to reduce the tension acting on the boom rope wrapped around the pulley, and the boom rope can be reduced in diameter and weight, and the boom rope can be reduced. It is possible to reduce the size and the weight of the winch drum that winds up.

[Brief description of the drawings]

FIG. 1 is a perspective view of a working example of the present invention during a crane operation.

FIG. 2 is an exploded perspective view of a main part of one embodiment of the present invention.

FIG. 3 is a perspective view of an embodiment of the present invention during normal rounding.

FIG. 4 is a perspective view of an embodiment of the present invention when passing under a low bridge.

FIG. 5 is a perspective view of another embodiment of the present invention when the backstay is started up.

FIG. 6 is a perspective view of another embodiment of the present invention when the back stay is tilted.

FIG. 7 is an exploded perspective view of a main part of another embodiment of the present invention.

FIG. 8 is a vertical cross-sectional side view of a main part of another embodiment of the present invention.

FIG. 9 is an exploded perspective view of an essential part of another embodiment of the present invention.

FIG. 10 is a perspective view of a crane according to still another embodiment of the present invention during work.

FIG. 11 is a perspective view of a further embodiment of the present invention during normal rounding.

FIG. 12 is a perspective view of another embodiment of the present invention when passing under a low bridge.

FIG. 13 is a side view of a conventional example.

[Explanation of symbols]

 1 Barge 2 Swing platform 3 Boom 5 Back stay 6 Back stay Front 7 Back stay Rear 8 Winch drum 9 Boom rope 10 Pulley 15 Back stay 16 Back stay front 17 Tensile rope 23 Back stay rest

Claims (3)

[Claims] 1. An underframe, a boom whose one end is supported by a front end portion of the underframe so as to be rotatable about a left-right axis, one end of which is connected to the boom, and the other end of which is disposed on the underframe. In a crane comprising a boom rope wound around a boom lifting winch drum and a backstay supporting a pulley around which an intermediate portion of the boom rope is wound at a predetermined position on the underframe, the backstay has a lower end. A backstay front rotatably supported on the front part of the underframe so as to be rotatable about the left-right axis, and a backstay suspended from the upper rear side of the backstay front and the lower end engaged and disengaged from below to the rear part of the underframe. A crane having a rear. 2. A back stay rest for receiving a back stay front tilted rearward is provided upright on a rear portion of the underframe, and the back stay rear is disengaged from an upper end portion of the back stay rest. The listed crane. 3. An underframe, a boom whose one end is rotatably supported on the front end of the underframe so as to be rotatable about the left-right axis, one end of which is connected to the boom, and the other end of which is arranged on the underframe. In a crane including a boom rope wound around a winch drum and a backstay supporting a pulley around which an intermediate portion of the boom rope is wound at a predetermined position on the underframe, the backstay has a lower end in front of the underframe. Part of the backstay rotatably supported around the left and right axis, a tensile rope connecting the upper end of the backstay front and the rear part of the underframe, and winding the tensile rope or backing the middle part. A crane comprising: pulling means for pulling the stay front side to draw the upper part of the back stay front toward the rear part of the underframe.