Abstract:
A boom hoisting device comprising a mast having a pivotable front end portion connected to a front end portion of a boom through a guy line, a mast-side spreader provided at the front end portion of the mast, a frame-side spreader removably mounted to an upper rotating body and with a hoisting rope being stretched between and spread on both mast-side spreader and frame-side spreader, and a hoisting winch adapted to unwind and wind the hoisting rope to raise and lower the mast and the boom, the hoisting winch being mounted to the mast so that the mast and the hoisting winch are together removed from the upper rotating body by separation of a base end portion of the mast from the upper rotating body.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a crane and a boom hoisting device of the crane, permitting easy removal of a mast or a gantry for raising and lowering a boom attached to a body frame. 
   2. Description of the Related Art 
   The related art will be described below with reference to  FIG. 4  showing a crawler crane as an example. 
   This crane has a body frame comprising a lower travel body  1  of a crawler type and an upper rotating body  2  mounted on the lower travel body  1  so as to be rotatable about a vertical axis. 
   The upper rotating body  2  is basically composed of a boom  4  mounted on a rotating frame  3  as a base, three winches  5 ,  6 ,  7  as main hoist, auxiliary hoist and boom hoisting winches, respectively, and a mast  8  for raising and lowering the boom  4 . 
   A base end portion  8   a  of the mast  8  is attached to a front side portion  3   a  of the rotating frame  3  so as to be pivotable about a horizontal axis and attached detachably to the front side portion  3   a  of the rotating frame  3 . In order to avoid mutual interference of wire ropes delivered from the winches  5  to  7 , these winches are mounted at intervals on the rotating frame  3  in the order of main hoist winch, auxiliary hoist winch and boom hoisting winch from the front side. 
   As shown in  FIG. 4 , a hoisting wire rope  12  of the boom hoisting winch  7  is stretched through an upper spreader  9  provided at an upper end portion of the mast  8  and is spread like a rattan blind on both a sheave of the upper spreader  9  and a sheave of a lower spreader  10  mounted on a rear portion of the rotating frame  3 . Thus, when the boom hoisting winch  7  is operated to unwind or wind the hoisting rope  12 , thereby changing the distance between the upper spreader  9  and the lower spreader  10 , the mast  8  rises or lowers, so that the boom  4 , which is connected to the mast  8  through a guy line  11 , also rises or lowers. 
   As another upper rotating body, as shown in  FIG. 5 , one provided as a substitute for the mast  8  with a gantry  30  having a gantry compressing member  31  and a gantry pulling member  32  is known (see, for example, Japanese Registered Utility Model No. 2542385). 
   In the gantry  30  shown in  FIG. 5 , a base end portion  31   a  of the gantry compressing member  31  is connected to a front side portion of the rotating frame  3  and a base end portion  32   a  of the gantry pulling member  32  is connected to the rear side portion of the rotating frame  3  each pivotably in the hoisting direction. At a gantry top  33  to which front end portions  31   b  and  32   b  of both members  31  and  32  are connected in a relatively pivotable manner there is provided a gantry-side spreader  20 . A guy line  22  is connected at one end thereof to a front end of the boom  4  and a guy line-side spreader  21  is connected to an opposite end of the guy line  22 . A wire rope  47  drawn out from the boom raising/lowering winch  7  is spread on both spreaders  20  and  21 . Therefore, when the boom hoisting winch  7  is operated to unwind or wind the hoisting rope  47 , thereby changing the distance between both spreaders  20  and  21 , the boom  4  rises or lowers. In  FIG. 5 , the numeral  23  denotes a mounting portion for mounting the boom  4 , numeral  5  denotes a main hoist winch, and numeral  6  denotes an auxiliary hoist winch. In  FIG. 5 , the same portions as in  FIG. 4  are identified by the same reference numerals as in  FIG. 4 . 
   Further, as described later, there is known a crane of the construction wherein both mast and gantry are used in combination and the mast is raised and lowered by the gantry to raise and lower a boom. 
   When moving to a work site, this crane is dismantled for transport by a trailer or the like. This dismantling is performed so as to satisfy the transport weight allowed for the trailer or the like. 
   For reducing the transport weight in the above upper rotating body, the boom which is heavy and a counterweight are removed of course. Besides, in a large- or ultra-large-sized crane having a very heavy upper rotating body, there sometimes is a case where it is necessary to remove a mast or a gantry. 
   However, since a hoisting wire rope connected to the boom hoisting winch is spread on the mast or the gantry, there has been the problem that the removal and mounting of the mast and the gantry are troublesome. More particularly, for removing the mast or the gantry it is necessary to pull out the hoisting wire rope and thus a very troublesome work requiring a long time is needed. Conversely, when mounting the mast or the gantry, it is necessary to pass the hoisting wire rope therethrough and thus here again a very troublesome work requiring a long time is needed. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a crane and a boom hoisting device of the crane, permitting easy removal of a mast or a gantry from a body frame without pulling out a hoisting wire rope connected to a boom hoisting winch. 
   The crane and boom hoisting device of the crane according to the present invention have the following basic configurations. 
   A boom hoisting device of a crane according to the present invention is mounted on a body frame of the crane having a boom capable of rising and lowering and causes the boom to rise and lower, the boom hoisting device comprising a mast, the mast having a base end portion connected to the body frame removably and pivotably about an approximately horizontal axis and further having a pivotable front end portion connected to a front end portion of the boom through a guy line, a mast-side spreader provided at the front end portion of the mast, a frame-side spreader removably mounted on the body frame side, with a hoisting rope being stretched between and spread on both frame-side spreader and the mast-side spreader, and a raising/lowering winch adapted to unwind and wind the hoisting rope to raise and lower the mast and the boom, the hoisting winch being installed to the mast so that the mast and the hoisting winch are together removed from the body frame by separation of the base end portion of the mast from the body frame. 
   The installation of the frame-side spreader is not limited to the installation to the body frame, but the frame-side spreader may be installed to a member (e.g., gantry) fixed to the body frame side. The spreader indicates a spreader having a sheave and a support member which journals the sheave pivotably and capable of being removed from the mast, the gantry or the body frame to which it is to be mounted. 
   A crane according to the present invention has the above boom hoisting device and comprises a body frame, a boom mounted on the frame body so that it can rise and lower, and a guy line providing connection between a front end portion of the boom and the front end portion of the mast in the boom hoisting device, the base end portion of the mast and the frame-side spreader in the boom hoisting device being mounted to the body frame removably. 
   In this case, since a hoisting winch for raising and lowering the mast and the boom is installed to the mast, the mast and the hoisting winch are together removed from the body frame easily by separating the base end portion of the mast from the body frame. If the frame-side spreader is removed from the body frame side at this time or beforehand, it is not necessary to pull out the hoisting wire rope connected to the boom hoisting winch from both spreaders. 
   Another boom hoisting device of a crane according to the present invention is mounted on a body frame of the crane having a boom capable of rising and lowering and causes the boom to rise and lower, the boom hoisting device comprising a gantry connected to the body frame removably, a gantry-side spreader provided in the gantry, a guy line-side spreader provided at an opposite end of a guy line connected at one end to the boom or at a front end portion of a mast to which the opposite end of the guy line is connected, with a hoisting rope being stretched between and spread on the guy line-side spreader and the gantry-side spreader, and a hoisting winch adapted to unwind and wind the hoisting rope, thereby raising and lowering the boom, the hoisting winch being installed to the gantry so that the gantry and the hoisting winch are together removed from the body frame by separation of the gantry from the body frame. 
   A crane according to the present invention has the this boom hoisting device and comprises a body frame, a boom mounted on the body frame so that it can rise and lower, and a guy line connected at one end thereof to a front end portion of the boom and with the guy line-side spreader in the boom hoisting device being provided at an opposite end of the guy line, the gantry in the boom hoisting device being mounted to the body frame removably. 
   In this case, since the hoisting winch for raising and lowering the boom is installed to the gantry, the gantry and the hoisting winch are together removed easily from the body frame by separating the gantry from the body frame. If the guy line-side spreader is removed from the opposite end of the guy line or the front end portion of the mast at this time or beforehand, it is not necessary to pull out the hoisting wire rope connected to the boom hoisting winch from both spreaders. 
   What is called jib is also included in the above boom. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A and 1B  are right side views of a crane having a boom hoisting device according to a first embodiment of the present invention, of which  FIG. 1A  shows the state of the crane just before removal of a mast and  FIG. 1B  shows the state of the crane after removal of the mast. Further,  FIG. 1C  shows the state of the mast after removal as seen in the same direction as the above right side views; 
       FIG. 2  is a right side view showing a crane having a boom hoisting device according to a second embodiment of the present invention; 
       FIGS. 3A and 3B  are related to a hoisting winch shown in  FIG. 2 , of which  FIG. 3A  is a plan view showing an installed place of the hoisting winch and  FIG. 3B  is a right side view showing an installed place of the hoisting winch; 
       FIG. 4  is a right side view showing a crane having a mast as a boom hoisting device according to the related art; and 
       FIG. 5  is a right side view showing a crane having a gantry as a boom hoisting device according to the related art. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will be described concretely hereinunder. 
   First Embodiment 
   A boom hoisting device according to this first embodiment of the present invention is of the type using a mast and its basic configuration is the same as that of the related art shown in  FIG. 4  except that the layout of a winch for raising and lowering a boom and a mast is different, and therefore an explanation of the basic configuration will be omitted. 
     FIG. 1  is a right side view showing a crane having a boom hoisting device according to the first embodiment, in which  FIG. 1A  shows the state of the crane just before removal of a mast,  FIG. 1B  shows the state of the crane after removal of the mast, and  FIG. 1C  shows the state of the mast after removal. The same portions as in  FIG. 4  are identified by the same reference numerals. 
   In this crane, as noted above, the layout of a hoisting winch  7  for raising and lowering a boom and a mast is different from that in the related art. That is, in the related art the hoisting winch  7  is installed on the rotating frame  3 , but in this first embodiment it is installed directly on a mast  8 . 
   The hoisting winch  7  has a drum  7   a  and a shaft  7   b  serving as a rotational center of the drum, both ends of the shaft  7   b  being supported rotatably by brackets (not shown) secured respectively to a pair of left and right frames which constitute the mast  8 . 
   In a preparatory stage just before removal of the mast  8  in the crane of this configuration, as shown in  FIG. 1A , a boom and a counterweight are removed from an upper rotating body  2  on a body frame and a guy line connected at both ends to the boom and the mast  8  is also removed, the mast  8  being brought down to the rear side. A frame-side spreader  10  (see  FIG. 1C ) is in a removed state from an upper rotating body  2 . The timing for removal of the frame-side spreader  10  is not specially limited insofar as it is before removal of the mast  8 . 
   After completion of such a preparatory work, a work for removing the mast  8  is performed. This work is done, for example, by lifting the mast  8  with another crane, not the crane related to the present invention, and removing it from the body frame. At this time the mast  8  and the hoisting winch  7  are together removed from the body frame as shown in  FIG. 1C  because the winch  7  is installed to the mast  8 . This mast removing work can be done in a state in which the mast-side spreader  9  is connected to the mast  8  and the both mast-side spreader  9  and frame-side spreader  10  are connected together through a hoisting rope  12 . Therefore, it is not necessary to pull out the hoisting rope  12  from both spreaders  9  and  10  and the mast  8  can be removed easily from the body frame. In this mast removing work it is preferable that both spreaders  9  and  10  be drawn close to each other by the hoisting winch  7  to make the frame-side spreader  10  difficult to shake during transport. 
   As to the form of the body frame when removing the mast  8 , there are included an integrally combined state of both lower travel body  1  and upper rotating body  2  and a separated state thereof. 
   Second Embodiment 
   A boom hoisting device according to this second embodiment of the present invention uses both mast and gantry. According to a basic configuration thereof, a hoisting winch for raising and lowering both boom and mast is installed to the gantry. 
   A detailed description will be given below. 
     FIG. 2  is a right side view showing a crane having the boom hoisting device of this second embodiment,  FIG. 3A  is a plan view showing an installed place of a hoisting winch, and  FIG. 3B  is a right side view showing an installed place of a hoisting winch. 
   In this crane, a mast  40  is disposed behind a boom  4  and a gantry  41  is disposed behind the mast  40 . The gantry  41  has a pair of right and left gantry compressing (compression) members  42  and a pair of right and left gantry pulling (tension) members  43 , the gantry compressing members  42  and the gantry pulling members  43  being connected together at their front end portions to form a gantry top. The gantry  41  is configured so as to operate in the same way as the gantry  30  shown in  FIG. 5  with a difference being recognized in only size. 
   As shown in  FIGS. 3A and 3B , a hoisting winch  7  is installed the gantry  41  according to this second embodiment. On this regard, a description will now be given in detail. The hoisting winch  7  has a drum  7   a  and a shaft  7   b  serving as a rotational center of the drum. Both ends of the shaft  7   b  are supported rotatably by brackets  14  provided respectively in the pair of right and left gantry compressing members  42 . 
   As shown in  FIG. 2 , a guy line  44  is connected between the mast  40  and the boom  4 . A mast-side spreader  45  is connected to the mast  40  and a gantry-side spreader  46  is connected to the gantry  41 . A hoisting rope  47  extending from the hoisting winch  7  mounted to the gantry  41  is spread on both spreaders  45  and  46 . When the mast  40  is raised or lowered by the winch  7 , the boom  4  connected to the mast  40  through the guy line  44  is raised or lowered. 
   Thus, in the boom hoisting device of this second embodiment, since the hoisting winch  7  is installed to the gantry  41 , the hoisting winch  7  can be removed together with removal of the mast-side spreader  45  from the mast  40  and removal of the gantry  41  from the upper rotating body  2 . In this way the gantry  41  can be removed easily from the body frame without the need of pulling out the hoisting rope  47  from both spreaders  45  and  46 . In this gantry removing work, as noted earlier, it is preferable that the mast-side spreader  45  is drawn close to the gantry-side spreader  46  by the hoisting winch  7  to make the mast-side spreader  45  difficult to shake during transport. The mast  40  may be left removed or mounted in accordance with transport weight. 
   AS to the form of the body frame when removing the gantry  41  in this second embodiment, there are included an integrally combined state of both lower travel body  1  and upper rotating body  2  and a separated state thereof. 
   Although in the above second embodiment the raising/lowering winch  7  is installed on the gantry compressing member  42  side, the winch  7  may be installed on the gantry pulling member  43  side to the contrary. 
   Moreover, although in the above second embodiment the hoisting winch  7  is installed not on the mast  40  side but on the gantry  41  side, no limitation is made thereto. It goes without saying that the hoisting winch  7  may be installed on the mast  40  side and that the hoisting rope  47  from the hoisting winch  7  may be conducted to the gantry-side spreader  46 . 
   Further, although in the above first and second embodiments a description has been given about a constructional example wherein the boom hoisting device has a mast or both mast and gantry, no limitation is made thereto, but the present invention is also applicable to a boom hoisting device having a gantry with a mast omitted. 
   In this case, there may be adopted a configuration wherein the gantry is installed on the upper rotating body removably and a hoisting winch is installed to the gantry. More specifically, there may be adopted a configuration wherein the hoisting winch  7  shown in  FIG. 5  is installed to the gantry compressing member  31  or the gantry pulling member  32  of the gantry  30 . 
   Although the invention has been described with reference to the preferred embodiments in the attached figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.