JP2005200206A - Tower crane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an upper spreader from interfering with an obstacle on the upper surface side of a boom in moving while adopting a safe horizontal movement system with excellent working efficiency. <P>SOLUTION: A pair of left and right support legs 28 and 29 are downwardly installed on both front and rear sides of the upper spreader 9 for derricking a jib fitted to the tip of the boom. Rollers 31, ... are fitted to the support legs 28 and 29, and the upper spreader 9 is moved by rails 19 and 19 installed on both right and left upper surface sides of the boom and the rollers 31, ... between a base end side position and a tip end side position on the upper surface of the boom. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tower crane constructed by attaching a jib to a tip of a boom so that it can be raised and lowered.

  A tower crane has a boom (tower) attached to a base machine consisting of a lower traveling body and an upper swing body, and a jib attached to the tip of the boom so that it can be raised and lowered.Basically, the jib is held with the boom held at a fixed angle. Raise and lower the crane.

  In addition, there is a thing (roughing type) in which both the boom and the jib are raised and lowered, and the present invention includes this type of crane.

  In such a tower crane, a jib hoisting winch provided in a base machine (upper turning body) as a jib hoisting device for hoisting the jib, a jib hoisting rope wound and unwound by the jib hoisting winch, Both lower and upper spreaders around which the jib hoisting rope is hung, a strut attached to the top of the boom so as to be pivotable in the front-rear direction around the horizontal axis, a jib guy line connecting the strut and the jib, and the strut and the upper And a strut guy line connecting the spreader.

  Prior to assembly, the upper spreader is placed on the upper surface of the boom proximal end for reasons such as making the jib hoisting rope easy to hang by reducing the distance from the lower spreader secured to the boom proximal end. At the time of assembly, it is pulled out to the front end side of the boom, that is, a position where it can be connected to the strut guy line.

  In this case, since the upper spreader is heavy and difficult to move by human power, conventionally, a method has been employed in which the upper spreader is pulled out and pulled back during disassembly using the hoisting force of the winch.

  For example, by fastening the tow rope pulled out from the auxiliary winch dedicated to assembly / disassembly to the upper spreader and rewinding the jib hoisting rope while winding this tow rope, the upper spreader is moved from the position on the boom proximal side to the distal side. This is a method of moving horizontally along the upper surface of the boom to the position.

  On the other hand, a method of using a hook hoisting winch as an auxiliary winch is also known (see Patent Document 1).

  In this known technique, a guide sheave dedicated to assembly and disassembly is provided at the tip of the rear member constituting the strut, and the hook hoisting rope pulled out from the hook hoisting winch is passed through the guide sheave and folded back to the boom proximal end side. After the tip is fixed to the upper spreader, the jib hoisting rope is rewound while winding the hook hoisting rope.

  Thus, the upper spreader is floated in the air and moved to the boom tip side, and then the hook hoisting rope is rewound to lower the spreader to the boom tip side upper surface and connected to the strut guy line.

At the time of disassembly, the upper spreader is moved to the position on the boom base end side by the reverse procedure.
JP 11-292471 A

  However, according to the conventional horizontal movement method in which the upper spreader is moved horizontally along the boom upper surface, when the spreader moves, the spreader interferes with members (ropes, piping, etc., hereinafter referred to as obstacles) located on the boom upper surface side, Not only was the movement of the spreader impeded, but there was a risk of damage to each other.

  On the other hand, in the air suspension system in which the upper spreader is floated in the air, this interference can be avoided, but since the heavy upper spreader of 300 kg or more is lifted and moved, there is a risk of dropping or the like, which is not preferable for safety. Further, since the winch operation must be taken care of, the work efficiency is worse than in the case of the horizontal movement method.

  Therefore, the present invention provides a tower crane that can prevent interference between an upper spreader and an obstacle on the upper surface side of a boom during movement while adopting a horizontal movement method that is safe and has high work efficiency.

  According to the first aspect of the present invention, there is provided a jib hoisting winch and a jib hoisting winch as a jib hoisting device in which a boom is attached to a base machine, and a jib is attached to the tip of the boom.・ The jib hoisting rope to be rewound, the lower and upper spreaders for the jib hoisting on which the jib hoisting rope is wound, and the top of the boom are attached to the top of the boom so as to be pivotable in the front-rear direction around the horizontal axis. A strut, a jib guy line connecting the strut and the jib, and a strut guy line connecting the strut and the upper spreader, and when the crane is assembled and disassembled, the upper spreader is installed along the boom upper surface on the boom proximal side. It is moved between the position and the position on the tip side where it is connected / disconnected to the strut guy line. In the tower crane configured as described above, a support leg for supporting the spreader above the upper surface of the boom protrudes downward from the upper spreader, and a support leg guide for moving and guiding the support leg on the upper surface of the boom. A member is provided.

  According to a second aspect of the present invention, in the configuration of the first aspect, a pair of left and right support legs are provided on both front and rear sides of the upper spreader, and the upper spreader is configured to be capable of self-supporting on the upper surface of the boom.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, a rail is provided on the upper surface of the boom as a support leg guide member, and a roller that rolls on the rail is provided at the lower end of the support leg.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, the rail is formed in a closed cross-sectional shape having a horizontal upper surface when the boom is horizontal, and the roller contacts over the entire upper surface of the rail. It is formed in a cylindrical shape.

  According to a fifth aspect of the present invention, in the configuration of the third or fourth aspect, the support leg is provided with a roller guide portion that prevents the roller from deviating from the rail.

  The invention of claim 6 is the structure according to any one of claims 3 to 5, wherein a hook-shaped support plate extending in the front-rear direction is provided at the lower end of the support leg, and a roller is provided on the lower surface of the support plate. is there.

  According to a seventh aspect of the present invention, in the configuration of the sixth aspect, warping portions extending obliquely upward are provided at both front and rear end portions of the support plate.

  According to an eighth aspect of the present invention, in the configuration according to any one of the first to seventh aspects, the spreader is mounted on the end of the upper spreader on the front end side of the boom on the straight line in the front-rear direction passing through the center of gravity of the upper spreader or the vicinity thereof. A tow rope fixing portion for stopping a rope to be pulled from the proximal end side toward the distal end side is provided.

  According to a ninth aspect of the present invention, in the configuration of the eighth aspect, the tow rope fixing portion is provided at a position lower than the center of gravity of the upper spreader.

  According to a tenth aspect of the present invention, there is provided a vertical sheave block having a plurality of vertical sheaves rotating around a horizontal sheave shaft on one side in the front-rear direction of the upper spreader in the configuration according to any one of the first to ninth aspects, on the opposite side And a horizontal sheave block provided with a plurality of horizontal sheaves rotating around a vertical sheave shaft.

  The invention of claim 11 is the structure of claim 10, wherein the center line in a plan view of the vertical sheave block is set to a position that substantially coincides with a straight line in the front-rear direction passing through the center of the sheave shaft in the horizontal sheave block. It is.

  According to the present invention, the upper spreader is horizontally moved while being lifted from the upper surface of the boom by the support leg and the support leg guide member. Therefore, when the spreader is moved, interference between the spreader and the obstacle on the upper surface side of the boom does not occur.

  In this case, since the support leg and the support leg guide member may be provided partially on the spreader and the boom upper surface and at a position avoiding the obstacle, interference between the support leg and the obstacle can be easily avoided. Can do.

  Therefore, since the problem of interference with obstacles during movement of the spreader can be solved, the spreader can be smoothly moved between the position on the boom proximal end side and the position on the distal end side, and interference between the spreader and the obstacles can be achieved. Can prevent mutual damage.

  According to the invention of claim 2, since the spreader can be self-supported on the boom by the support legs provided on the left and right sides of the front and rear sides, the spreader is stable without tilting or overturning, and It can be moved more smoothly.

  According to the third to fifth aspects of the present invention, the spreader can be moved lightly and smoothly by the rails on the upper surface of the boom and the rollers of the support legs.

  In this case, according to the invention of claim 4, since the rail itself has a closed cross-sectional shape, it becomes high rigidity and high strength as a whole, and the roller comes into contact with the entire width portion of the rail, so that the guide action is performed stably over a long period of time. Is called.

  According to the invention of claim 5, since the roller guide portion can prevent the roller from deviating from the rail, derailment when a lateral force is applied to the spreader can be prevented and the spreader can be moved more safely.

  According to the inventions of claims 6 and 7, the hook-shaped support plate extending in the front-rear direction is provided at the lower end of the support leg, and the roller is provided on the lower surface of the support plate. It can be prevented from falling and moved more safely and smoothly.

  In particular, according to the invention of claim 7, since the warping portions are provided obliquely upward at the front and rear end portions of the support plate, even if the spreader is inclined in the front-rear direction, smooth movement can be secured in the warping portion. Further, even when the spreader is tilted in the front-rear direction when the spreader is lowered to the top surface of the boom when the crane is disassembled, the spreader can be smoothly brought into contact with the top surface of the boom by the warping portion, and damage to the top surface of the boom can be prevented.

  According to the eighth and ninth aspects of the present invention, when the spreader is pulled by a rope, the pulling force can be applied to the center of gravity of the spreader or a position close to the center of gravity of the spreader. can do.

  In particular, according to the invention of claim 9 in which the traction rope fixing portion is provided at a position lower than the center of gravity of the upper spreader, the spreader can be moved more stably because the traction force is applied at a position lower than the center of gravity of the spreader. .

  According to the tenth and eleventh aspects of the invention, since the cross sheave arrangement in which the vertical sheave block is provided on one side of the spreader and the horizontal sheave block is provided on the opposite side, a large number of sheaves can be efficiently arranged in a narrow area. As a result, the spreader can be reduced in size, and in particular, the spreader width dimension can be reduced, so that the effect of preventing interference between the spreader and the obstacle becomes higher.

  In addition, according to the invention of the eleventh aspect, the tension of the rope wound around the sheave of the spreader can be exerted almost symmetrically with respect to the center line of the spreader. For this reason, the left-right inclination of the spreader due to the unbalanced rope tension can be suppressed.

  FIG. 1 shows the state of the tower crane during crane operation (assembled state), and FIGS. 2 to 10 show the crane assembly / disassembly process.

  In each figure, 1 is a crawler type lower traveling body, and 2 is an upper revolving body mounted on the lower traveling body 1 so as to be able to swivel. These constitute a base machine A, and the upper revolving body of the base machine A A boom (tower) 3 is mounted on 2 by a boom foot pin 4 so as to be raised and lowered.

  A jib 5 projects from the tip of the boom 3, and the jib 5 is raised and lowered (in the luffing type, the boom 3 is also raised and lowered) to perform a crane operation.

  The jib hoisting device for raising and lowering the jib 5 includes a jib hoisting winch 6 mounted on the upper swing body 2 of the base machine A, a jib hoisting rope 7 wound / rewinded by the jib hoisting winch 6, The lower and upper spreaders 8 and 9 on which the jib hoisting rope 7 is multi-staged, and the struts 10 attached to the top of the boom so as to be rotatable around a horizontal axis are provided. The upper spreader 9 and the struts 10 are connected to the strut guy line 11. And the strut 10 and the jib tip are connected by the jib guy line 12, respectively.

  The strut 10 receives a forward / backward turning moment due to the weight of the strut, a forward tilting moment due to the weight of the jib 5, and a backward tilting moment due to the winding force of the jib hoisting rope 7. The jib 5 is supported while rotating in the front-rear direction in accordance with the undulation of the jib 5 by the supporting force of the jib undulation rope 7 that opposes this.

  The jib hoisting rope 7 is multi-staged between the sheaves of the lower and upper spreaders 8 and 9, and the ends thereof are fixed to the lower spreader 8.

  A strut mast 13 with a sheave is provided at the top of the boom as means for holding the strut guy line 11 above the boom during assembly / disassembly.

  On the other hand, the hook hoisting device for hoisting / rewinding the suspension hook 14 from the tip of the jib includes a hook hoisting winch 15 mounted on the upper swing body 2 of the base machine A, and the hook hoisting winch. 15, a hook hoisting rope 16 that is wound / rewinded by a hook 15, and the hook hoisting rope 16 is hung between the hanging hook 14 and the jib tip sheave 17 and is fastened to the jib tip.

  Here, the hook hoisting guide sheave 18 is attached to the middle part in the height direction of the strut mast 13 so as to be rotatable around a horizontal axis in the left-right direction, and the hook hoisting rope 16 is attached to the hook hoisting guide sheave 18 at the boom base end. From the side to the tip side.

  The hook hoisting rope 16 passed through the sheave 18 is guided to the jib tip side during crane operation shown in FIG. 1, and is folded back to the boom base end side as shown in FIG. Is fastened to the upper spreader 9 (this fastening portion is shown in an enlarged manner in FIGS. 3 to 5).

  The structure for moving the upper spreader 9 between the position on the boom base end side and the position on the tip end side will be described with reference to FIGS.

  On the upper surface of the boom over a certain section from the base end side to the distal end side of the boom (the upper surface in a state where the boom 3 is tilted horizontally on the ground as shown in FIG. 2 and the like. The same applies to the vertical direction described below) A pair of left and right rails 19, 19 are provided as support leg guide members.

  Both rails 19 and 19 are formed in a closed cross-sectional shape having a horizontal upper surface such as a square steel pipe.

  On the other hand, the upper spreader 9 includes a vertical sheave block 22 having a plurality of (two in the illustrated example) vertical sheaves 21, 21 rotating around a horizontal sheave shaft 20, and a plurality of rotating around a vertical sheave shaft 23. A horizontal sheave block 25 having two (two in the illustrated example) horizontal sheaves 24, 24 is integrated with the vertical sheave block 22 on the front side (the boom tip side).

  By adopting such a cross sheave arrangement, a large number of sheaves can be efficiently arranged within a small area. For this reason, the upper spreader 9 can be reduced in size, and in particular, the spreader width can be reduced.

  Here, the center line L (shown in FIG. 4) of the vertical sheave block 22 in plan view coincides with a straight line in the front-rear direction passing through the center of the vertical sheave shaft 23 in the horizontal sheave block 25 (roughly not nearly identical). It may be a matching position).

  The center line L is a center line of the entire upper spreader in plan view, and is also a straight line in the front-rear direction passing through the center of gravity of the spreader 9 in plan view. Hereinafter, this is referred to as a spreader center line.

  Guyline fastening portions 26 and 26 to which the ends of the strut guyline 11 are fastened are provided on both the left and right sides of the horizontal sheave block 25, and a pulling rope (hook hoisting rope) is provided on the front end surface of the vertical sheave block 22 when the spreader is moved. A tow rope fixing portion 27 to which the terminal 16) is fixed is provided.

  The tow rope fixing portion 27 is provided on the spreader center line L at a position lower than the spreader center of gravity.

  M in FIG. 5 is a spreader center line in a side view, and is also a straight line passing through the center of gravity of the spreader in a side view.

  In the upper spreader 9, front support legs 28, 28 are provided on the left and right sides of the vertical sheave block 22, and rear support legs 29, 29 are provided on the left and right sides of the horizontal sheave block 25. A pair of hook-shaped support plates 30 and 30 are horizontally attached across the front and rear support legs 28 and 29.

  The left and right support plates 30 and 30 are provided with warped portions 30a and 30a (see FIG. 5) extending obliquely upward at both front and rear ends, and roll on the boom-side rails 19 and 19 on both front and rear sides. Rollers 31 are provided so as to be rotatable around a horizontal axis.

  The rollers 31 are formed in a cylindrical shape longer than the rail width as shown in FIGS. 4 and 6 and are in contact with each other over the entire upper surface of the rails 19 and 19.

  Further, on both front and rear sides of the both side support plates 30, 30, roller guide portions 32, which prevent the rollers 31 from escaping from the rail 19, project downward.

  2 to 7 show a state where the boom 3 is placed on the upper surface on the proximal end side. At this time, the upper spreader 9 is supported on the boom upper surface by the support legs 29, the support plates 30, 30, the rollers 31, and the rails 19.

  In this state, the end of the boom hoisting rope 17 turned back by the hook hoisting guide sheave 19 is fastened to the traction rope fastening portion 27 of the upper spreader 9 as shown in FIGS. Rewind the jib hoisting rope 7 while winding up.

  Thus, the upper spreader 9 is pulled to the boom tip side along the boom upper surface while providing the guide action of the rails 19 and 19 and the rollers 21 and 21, and the struts as shown in FIGS. The movement is stopped at a position where it can be connected to the guy line 11.

  In this case, since the vertical and horizontal sheave blocks 22 and 25 are arranged symmetrically with respect to the spreader center line L, the tension of the jib undulation rope 7 that is multi-staged on the sheave blocks 22 and 25 is applied to the center of the spreader. It can be made to work almost symmetrically with respect to the line L. For this reason, when the upper spreader 9 is moved, it is possible to prevent the spreader 9 from tilting left and right due to the unbalanced rope tension.

  Further, since the tow rope fixing portion 27 is provided on the spreader center line L at a position lower than the center of gravity of the spreader, the following effects can be obtained.

  I) The rope pulling force can be applied to the center of gravity of the spreader. For this reason, it is possible to prevent left-right inclination during movement of the spreader.

  II) Since the traction force is applied at a position lower than the center of gravity of the spreader, it is possible to prevent the forward / backward inclination during the movement of the spreader and to move the upper spreader 9 in a horizontal posture.

  Furthermore, since the rail 19 has a quadrangular section and the roller 31 is brought into contact with the entire upper surface of the rail 19, the upper spreader 9 can be slid while being stably supported. In addition, since the rail 19 itself has high rigidity and high strength as a whole, the guide action is performed stably over a long period of time.

  Thereafter, as shown in FIG. 8 (b), the hook hoisting rope 16 is removed from the rope fastening portion 27 of the upper spreader 9, and the strut guy line 11 is connected to the guy line fastening portions 26, 26 instead. The hoisting rope 16 is set to the working posture, and then the boom 3 and the jib 5 are raised as shown in FIG. 9 to obtain the working posture shown in FIG.

  In this case, the spreader 9 is separated from the rails 19 and 19 (boom upper surface) in a state where the tension of the strut guy line 11 is larger than the weight component of the upper spreader 9.

  The horizontal movement of the upper spreader 9 can also be used for self-assembly of the strut 10, that is, for the operation of opening the strut 10 folded at the tip of the boom. In this case, an operation of opening the upper spreader 9 by pulling the strut guy line 11 by moving the upper spreader 9 from the distal end side of the boom to the proximal end side is performed. Thereby, the self-assembling work of the strut 10 can be performed safely and efficiently.

  When disassembling the crane, the operation is performed in the reverse order of the above assembly.

  In this way, the upper spreader 9 is moved horizontally in a state where it is floated from the upper surface of the boom by the support legs 28 and 29, the support plates 30 and 30, the rollers 31 and the rails 19 and 19 (hereinafter referred to as support legs and the like). When the spreader moves, there is no interference between the upper spreader 9 and the obstacle on the boom upper surface side.

  In this case, the support legs and the like may be partially provided on the upper spreader 9 and the boom upper surface, and the position can be selected as a position where an obstacle can be avoided, so that interference between the support legs and the obstacle can be easily performed. It can be avoided.

  Therefore, since the problem of interference with obstacles during movement of the spreader can be solved, the upper spreader 9 can be smoothly moved between the position on the boom proximal end side and the position on the distal end side, and the upper spreader 9 and Damage due to obstacle interference can be prevented.

  In addition, the upper spreader 9 is supported on the boom 3 by the supporting legs or the like, and is stable without tilting or falling, and lightly with minimal frictional resistance by the rollers 31 and the rails 19 and 19. Can be moved.

  Furthermore, since the diagonally upward warped portions 30a and 30a are provided at both front and rear ends of the support plates 30 and 30, even if the upper spreader 9 is tilted in the front and rear direction, smooth movement can be secured by the warped portions 30a and 30a. .

  Further, when the upper spreader 9 is lowered to the upper surface of the boom at the time of disassembling the crane, even if the upper spreader 9 is inclined in the front-rear direction, the spreader 9 is smoothly brought into contact with the upper surface of the boom by the warped portions 30a, 30a. Can be prevented.

  On the other hand, according to this embodiment, the hook hoisting guide sheave 18 originally provided at the top of the boom as a part of the hook hoisting device is used as a guide sheave for guiding the hook hoisting rope 16 to the upper spreader 9 during crane assembly / disassembly. In order to share this, a guide sheave dedicated to moving the upper spreader is separately provided at the top of the boom while taking the technique of moving the upper spreader 9 between the boom proximal end and the distal end with the hook hoisting rope 16 and the jib hoisting rope 7. There is no need to provide it.

  Thereby, it can be set as the tower crane which can be assembled by itself, without increasing the weight of a boom front-end | tip part.

Other embodiments
(1) In the above embodiment, the case where the hook hoisting rope 16 is used as the tow rope of the upper spreader 9 is illustrated, but an auxiliary rope of a dedicated auxiliary winch provided separately may be used as the tow rope. However, the traction force may be obtained by another crane.

  (2) In the above embodiment, the support plates 30 and 30 are provided at the lower ends of the support legs 28 and 29, and the rollers 31 are provided on the support plates 30 and 30, but the support plates 30 and 30 are omitted, and each support is provided. The rollers 31 may be provided directly at the lower ends of the legs 28 and 29.

  (3) In the above embodiment, the rails 19, 19 are provided on both the left and right sides of the upper surface of the boom. However, on the condition that the upper spreader 9 can be stably moved, only one rail 19 is provided at the center to provide a monorail type. It is good. In this case, the support legs 28 and 29 on the upper spreader side are also provided one on each of the front and rear sides of the center part of the spreader.

  Alternatively, the support legs of the upper spreader 9 may be provided only on the left and right sides of the central portion, and the both side support legs may be moved along the left and right rails 19 and 19.

  (4) The rail 19 is not limited to the quadrangular cross section exemplified in the above embodiment, but may have a triangular cross section, a semicircular shape, a trapezoidal shape, or the like, and a roller structure corresponding to the rail cross sectional shape may be employed.

  (5) Instead of the rail 19 as a support leg guide member, a slide guide plate made of a slippery material may be provided on the upper surface of the boom. In this case, the rollers 31 of the support legs may be directly rolled on the slide guide plate, or a guide groove is provided on the guide plate, and the rollers 31 are rolled in the guide groove. May be.

  (6) As a means for pulling the upper spreader 9, instead of using a winch mounted on the base machine A, a fixed or detachable winch is provided on the upper surface of the boom or the like, and from this winch to the inside of the boom or the lower surface of the boom The rope may be pulled out and guided from the boom proximal end side to the distal end side, and the upper spreader 9 may be pulled.

It is a schematic side view of the crane working state of the tower crane concerning the embodiment of the present invention. It is a schematic side view of the state which mounted the upper spreader in the boom base end side in the middle of the assembly of the tower crane. FIG. 3 is a partially enlarged plan view of the state of FIG. 2. It is the figure which expanded a part of FIG. 3 further. FIG. 5 is a side view of FIG. 4. FIG. 6 is an enlarged sectional view taken along line VI-VI in FIG. 4. It is a schematic side view of the state which moved the upper spreader to the boom tip side from the state of FIG. (B) is a partially enlarged view of the state where the upper spreader and the strut guy line are further connected. It is a schematic side view in the middle of raising the boom and jib from the state of FIG.

Explanation of symbols

A Base machine 3 Boom 5 Jib 6 Jib hoisting winch 7 Jib hoisting rope 8 Lower spreader constituting the jib hoisting device 9 Same, upper spreader 10 Same, strut 11 Same, strut guy line 12 Same, jib guy line 16 Upper spreader pulling rope Hook hoisting rope 18 Same as above, hook hoisting guide sheave 19, 19 Rail as supporting leg guide member 20 Horizontal sheave shaft 21 Vertical sheave 22 Vertical sheave block 23 Vertical sheave shaft 24 Lateral sheave 25 Lateral sheave block 27 Tow rope stopper Attaching part 28, 29 Support leg 30, 30 Support plate 30a, 30a Curving part 31 ... Roller 32 Roller guide part

Claims (11)

  A boom is attached to the base machine, and a jib is attached to the tip of the boom so that the jib can be raised and lowered. As a jib raising and lowering device for raising and lowering the jib, a jib raising and lowering winch and a jib wound and unwound by the jib raising and lowering winch are operated. A hoisting rope, lower and upper spreaders for raising and lowering the jib around which the jib hoisting rope is hung, a strut attached to the top of the boom so as to be pivotable around a horizontal axis, and the strut and jib And a strut guy line connecting the strut and the upper spreader, and when assembling and disassembling the crane, the upper spreader is positioned on the boom proximal side along the boom upper surface, and the strut guy line. It is configured to move between the position on the tip side that is connected and disconnected In the tower crane, the upper spreader is provided with a support leg for supporting the spreader above the boom upper surface, and is provided with a support leg guide member for moving and guiding the support leg on the boom upper surface. A tower crane characterized by   2. The tower crane according to claim 1, wherein a pair of left and right support legs are provided on both front and rear sides of the upper spreader, and the upper spreader is configured to be able to stand on the upper surface of the boom by the support legs.   The tower crane according to claim 1 or 2, wherein a rail is provided on the upper surface of the boom as a support leg guide member, and a roller that rolls on the rail is provided at a lower end of the support leg.   The rail is formed in a closed cross-sectional shape having a horizontal upper surface when the boom is horizontal, and the roller is formed in a cylindrical shape that contacts the entire upper surface of the rail. Tower crane   The tower crane according to claim 3 or 4, wherein the support leg is provided with a roller guide portion for preventing deviation of the roller from the rail.   The tower crane according to any one of claims 3 to 5, wherein a hook-shaped support plate extending in the front-rear direction is provided at a lower end of the support leg, and a roller is provided on a lower surface of the support plate.   The tower crane according to claim 6, wherein warping portions extending obliquely upward are provided at both front and rear ends of the support plate.   A tow rope stopper that attaches a rope that pulls the spreader from the base end of the boom toward the front end on the end of the upper spreader boom on the straight line in the front-rear direction passing through the center of gravity of the upper spreader or the vicinity thereof. The tower crane according to any one of claims 1 to 7, wherein an attaching portion is provided.   9. The tower crane according to claim 8, wherein the tow rope fixing portion is provided at a position lower than the center of gravity of the upper spreader.   A vertical sheave block with multiple vertical sheaves rotating around a horizontal sheave shaft on one side of the upper spreader in the front-rear direction, and a horizontal sheave with multiple horizontal sheaves rotating around a vertical sheave shaft on the opposite side The tower crane according to any one of claims 1 to 9, wherein each sheave block is provided.   The tower crane according to claim 10, wherein a center line in a plan view of the vertical sheave block is set at a position that substantially coincides with a straight line in the front-rear direction passing through the center of the sheave shaft in the horizontal sheave block.

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