JP4397678B2 - Jib fall prevention mechanism of crane truck - Google Patents

Description

  The present invention relates to a jib fall prevention mechanism for a crane vehicle having a function of preventing a jib from falling when a boom is raised and a jib is swung out in a state where the jib is pivotally attached to a jib foot.

  As a jib fall prevention mechanism for a crane vehicle which prevents the fall of a jib folded with a jib connection means constituted by a jib base and a boom head jib foot as a fulcrum, for example, Patent Document 1 and Patent Document The one disclosed in 2 is already known.

  Patent Document 1 describes a boom by means of a jib coupling means constituted by a base part of a jib and a jib foot part of a boom head, and two sets of jib fixing means for fixing a folded jib to an outer cylinder of the boom. The jib is fixed to the outer cylinder of the glove, and the one described in Patent Document 2 includes a jib coupling means constituted by a jib base and a boom head jib foot, and a folded jib. A jib fixing means for fixing to the outer cylinder of the boom and a diblock means comprising an engaging piece provided on the jib side and an engaging / disengaging piece provided on the outer cylinder side of the boom Is supposed to be fixed.

  Each has a bifurcated engagement protrusion formed by providing a substantially U-shaped notch at the base of the jib, and the base of the jib made of this bifurcated engagement protrusion is used as the jib foot portion of the boom head. In this state, the base of the jib is rotatably pivoted with respect to the jib foot by passing a jib pivot pin through the tip of the bifurcated engagement projection.

  Jib pivoting using a jib pivot pin is only required when the jib is raised at the end of the boom and the crane work is performed. It is fixed to the outer cylinder of the boom by two sets of jib fixing means, or one set of jib fixing means and diblock means, and it is necessary to allow the boom head to protrude and retract while the jib is folded. The jib pivot pin is removed from the base of the jib so that the jib foot can be freely engaged with and disengaged from the bifurcated engagement protrusion formed on the base of the jib.

  When the folded jib is raised at the tip of the boom, first, the base of the jib is engaged with the jib foot, and a jib pivot pin is attached to the tip of the bifurcated engagement projection, and the jib is attached to the jib foot. Pivot.

  Then, the jib fixing by the jib fixing means is released, the boom is raised to an angle of about 60 °, then the jib block means is opened, and the tip is turned around the base of the boom in advance along the longitudinal direction of the jib. While gradually loosening the auxiliary winding wire that is locked, the jib is swung out using its own weight.

In this way, the jib swinging work is performed by pivoting the base of the jib to the jib foot and starting up the boom while the tip of the jib is fixed to the outer cylinder of the boom with diblock means and auxiliary winding wire. However, if the jib is to be launched after crane operation using only the boom, it is forgotten that the jib pivot pin is attached to the base of the jib engaged with the jib foot. There is also a possibility that the boom will be launched.
Since the base of the jib is engaged with the jib foot of the boom head via a bifurcated engagement protrusion, and the tip of the jib is fixed to the outer cylinder of the boom via diblock means and auxiliary winding wire. This is because the boom can be raised to a predetermined angle without any trouble without attaching a jib pivot pin to the base of the jib.

  Therefore, if the jib swinging operation is started as described above while forgetting to attach the jib pivot pin, the tip end side of the jib is fixed at the moment when the jib block means is opened or the auxiliary winding wire is loosened. There is a drawback that the bifurcated engagement protrusion provided on the base of the jib is easily separated from the jib foot of the boom head and the jib falls to the ground.

Japanese Utility Model Publication No. 54-10682 (first column, right column, lines 21 to 23) Japanese Utility Model Publication No. 51-46779 (the first column, right column, lines 26 to 33)

  Accordingly, an object of the present invention is to eliminate the drawbacks of the prior art, and in a state where the jib is not pivotally attached to the jib foot, more specifically, the boom is mounted without attaching the jib pivot pin to the base of the jib. An object of the present invention is to provide a jib fall prevention mechanism for a crane vehicle that prevents the jib from being accidentally dropped even when the jib is swung up after being started up.

The present invention is pivotally attached to a jib foot part of a boom head by a jib pivoting pin in a state in which it enters and engages with the jib foot part of the boom head along the longitudinal direction of the jib from the radial outside of the jib foot part. A jib connecting means constituted by a base of the jib and the jib foot part;
Jib fixing means for fixing the folded jib to the outer cylinder of the boom with the jib connecting means as a fulcrum;
Jib drop prevention for a crane truck provided with a jib block means for fixing the jib to the boom by fitting between an engaging piece provided on either the jib or the outer cylinder of the boom and an engaging / disengaging piece provided on the other In order to achieve the above-mentioned problem, in particular,
A first drop-off preventing engagement portion independent of the jib fixing means and the diblock means is provided on the surface of the jib that is folded and faces the outer cylinder of the boom;
When the jib is folded, the surface of the outer cylinder of the boom that faces the jib engages with the first drop-off prevention engaging portion when the jib is moved to the base side of the boom with the jib being swung out. A second drop-off prevention engagement portion is offset from the first drop-off prevention engagement portion to the base side of the boom within the predetermined amount, and is provided independently of the jib fixing means and the diblock means. It has the structure characterized by being characterized.

When the folded jib is raised at the tip of the boom, as in the conventional case, first, a predetermined amount of the jib base is engaged with the jib foot of the boom head from the outside in the radial direction of the jib foot along the longitudinal direction of the jib. In the combined state, the base of the jib is pivotally attached to the jib foot by a jib pivot pin.
Then, the jib fixing by the jib fixing means is released, the boom is raised to an angle of about 60 °, and then the jib block means is released to release the fixing between the jib and the boom, and is hung in advance along the longitudinal direction of the jib. The jib is swung out by utilizing the weight of the jib while gradually loosening the auxiliary winding wire that is turned and locked at the base of the boom. Alternatively, the auxiliary winding wire is not used, and the jib swinging can be started immediately after opening the diblock means.
If the jib base is properly pivoted to the jib foot using the jib pivot pin, the jib base will not be detached from the jib foot, so the jib is connected to the jib base consisting of the jib base and the jib foot. While being suspended from the boom head with the means as a fulcrum, it is swung out from the boom until its posture becomes substantially vertical by its own weight.
Since there is an offset between the first drop-off prevention engagement portion provided on the jib and the second drop-off prevention engagement portion provided on the outer cylinder of the boom, the first drop prevention when the jib is swung out The engaging portion and the second drop-off preventing engaging portion do not interfere with each other.
Also, if you forget to attach the jib pivot pin to the base of the jib and start to swing out the jib, the base of the jib will be disengaged from the jib foot, and the jib will move downward or under the boom. The first drop-off prevention engagement portion provided on the jib is moved along with the second drop-off prevention engagement portion provided on the outer cylinder of the boom. By engaging, the load of the jib is supported by the boom via the first drop-off prevention engagement portion and the second drop-off prevention engagement portion.
At this time, the base part of the jib engaged with the jib foot part from the longitudinal direction of the jib moves toward the lower side, that is, the base side of the boom, but the first drop-off prevention engagement part and the second drop-off prevention Since the amount of offset between the engaging portion, that is, the amount of movement of the base of the jib is within the range of the amount of engagement of the jib in the longitudinal direction with respect to the jib foot, the base of the jib is not completely detached from the jib foot. .
Thus, the load of the jib is supported by the boom via the first drop-off prevention engagement portion and the second drop-off prevention engagement portion, and the engagement between the jib base and the jib foot portion is also maintained. The jib is held on the boom without falling.
Therefore, even if the jib swing-out operation is started while forgetting to attach the jib pivot pin, the jib will not fall to the ground.

Furthermore, when the boom is raised and the jib is folded, a jib guide means is provided for regulating the vertical position of the jib while supporting the load of the jib approaching the boom,
The second drop-off prevention engagement portion is formed when the jib is moved to the base side of the boom in a state where the jib is swung out to a position where the jib guide means does not support the load of the jib. Deploy in a position to engage with.

When such a configuration is applied, if you forget to attach the jib pivot pin and start to swing out the jib, first the jib guide that regulates the vertical position of the jib at the initial stage of the jib swing Means support the load of the jib and prevent the jib from falling.
When the jib is swung out to a position where the jib guide means can no longer support the load of the jib, there is no element that fixes or supports the tip side of the jib, and the jib moves to the lower side, that is, the base side of the boom by its own weight. However, since the downward movement of the jib starts in a state where the movement start position of the jib is accurately regulated by the jib guide means, the first drop-off preventing engagement portion provided on the jib is provided on the outer cylinder of the boom. It is possible to reliably engage with the second drop-off preventing engaging portion.
In this way, as a result of the first drop-off prevention engagement portion and the second drop-off prevention engagement portion being reliably engaged, the jib is more reliably prevented from falling.

Since the jib fall prevention mechanism of the crane vehicle according to the present invention is offset to the base side of the boom with respect to the first drop prevention engagement part provided on the jib side, the second drop prevention engagement part is provided. If the jib is swung out without properly pivoting the jib base to the jib foot, the jib moves to the base side of the boom and the first drop-off preventing engagement part provided on the jib side and the outside of the boom A second drop-off prevention engagement portion provided on the cylinder is engaged, and the load of the jib is supported by the boom via the first drop-off prevention engagement portion and the second drop-off prevention engagement portion. Further, the offset amount between the first falling-off prevention engaging portion and the second captive engagement portion is adjusted to within the longitudinal engagement of the jib which rushes in pairs Jibufuto portion Therefore, even if the jib moves to the base side of the boom to the position where the first drop-off prevention engagement portion engages with the second drop-off prevention engagement portion, the engagement between the jib base and the jib foot portion Will never come off. That is, the load of the jib is supported by the boom via the first drop-off prevention engagement portion and the second drop-off prevention engagement portion while the engagement between the jib base portion and the jib foot portion is maintained. Therefore, the problem that the jib falls to the ground can be surely solved by starting the jib swinging operation while forgetting to attach the jib pivot pin.

  In addition, jib guide means that regulates the vertical position of the jib while supporting the jib load approaching the boom is provided, and the jib moves to the base side of the boom while the jib is swung out to a position where the jib guide means can no longer support the jib load. Since the second drop-off prevention engagement part is provided at a position where it engages with the first drop-off prevention engagement part, the jib is moved in a state where the jib guide means accurately regulates the movement start position of the jib by its own weight. Thus, the first drop-off prevention engagement portion can be reliably engaged with the second drop-off prevention engagement portion, and the jib can be more reliably prevented from falling.

  A second drop-off prevention engagement portion is provided offset from the first drop-off prevention engagement portion provided on the jib side to the base side of the boom within the range of the engagement amount of the jib in the longitudinal direction with respect to the jib foot portion.

  If you forget to attach the jib pivot pin to the base of the jib and the jib is swung out to a position where the jib guide means can no longer support the jib load, the jib will move to the base of the boom and be installed on the jib. The first drop-off prevention engagement portion and the second drop-off prevention engagement portion provided on the outer cylinder of the boom are engaged, and the first drop-off prevention engagement portion and the second drop-off prevention engagement portion And the load of the jib is supported by the boom.

  The offset amount between the first drop-off prevention engagement portion and the second drop-off prevention engagement portion is adjusted within the range of the engagement amount in the longitudinal direction of the jib with respect to the jib foot portion. Even if the jib moves to the base side of the boom to the position where the prevention engagement portion engages with the second drop-off prevention engagement portion, the engagement between the base portion of the jib and the jib foot portion is maintained.

  Therefore, the load of the jib is supported by the boom via the first drop-off prevention engagement portion and the second drop-off prevention engagement portion while the engagement between the base portion of the jib and the jib foot portion is maintained, Even if the jib swinging operation is started while forgetting the attachment of the jib pivot pin required for pivoting the jib, the jib will not fall to the ground.

  Next, embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a front view showing an appearance of a crane truck of an embodiment in which a jib fall prevention mechanism for a crane truck to which the present invention is applied is shown, and FIG. 2 shows a crane 2 removed from the crane truck 1 of FIG. FIG. FIG. 3 is a plan view showing the boom 3 constituting the crane 2 and the jib 4 folded on the lower surface of the boom 3 as seen through.

  First, the entire structure of the crane 2 will be briefly described with reference to FIGS. 2 and 3.

  The crane 2 includes a boom 3 having a telescopic structure that is expanded and contracted by a derrick cylinder (not shown), and a jib 4 attached to the boom 3.

  A boom head 5 is provided at the tip of the boom 3, and a main winding wire top sheave, a main winding wire guide sheave, an auxiliary winding wire top sheave, and an auxiliary winding wire guide sheave are rotatably attached to the boom head 5. However, since these sheaves are not directly related to the gist of the present invention, the description in the drawing is omitted together with the main winding wire and the auxiliary winding wire, and the boom head 5 protrudes on both the left and right sides. Only the jib foot portion 6 is specifically described in FIGS. 2 and 3.

  As shown in FIG. 2, bifurcated engaging projections 8, 8 are formed on the base 7 of the jib 4, and the base 7 of the jib 4 is connected to the jib foot portion 6 of the boom head 5 via the engaging projections 8, 8. It is designed to be pivotally attached to the shaft.

  On the other hand, a cylinder bottom of a hydraulic cylinder 9 that functions as a tension rod capable of adjusting a sheave offset angle is pivotally attached to the tip of the jib 4, and the jib 4 is raised with respect to the boom 3, and the hydraulic cylinder 9 When the tip of the tension rod 11 attached to the piston rod 10 is pivotally attached to the rod fixing portion 12 of the boom head 5, the rising state of the jib 4 is maintained.

  Fixing the folded jib 4 to the outer cylinder 14 of the boom 3 with the jib connecting means 13 formed by the bifurcated engaging projections 8 and 8 formed on the base 7 of the jib 4 and the jib foot 6 as a fulcrum 2 As shown in FIGS. 2 and 3, the set of jib fixing means 15, 16 is provided at a predetermined interval along the longitudinal direction of the jib 4.

  Details of the jib fixing means 15 are shown in FIG. FIG. 4 is a partial view showing the structure of the jib fixing means 15 from the direction corresponding to the right side view when FIG. 2 is defined as a front view.

  As shown in FIG. 4, the jib fixing means 15 is fixed to one side of the jib 4 and a substantially L-shaped jib fixing bracket 17 fixed to one side of the lower surface of the outer cylinder 14 of the boom 3. The bottom surface of the outer cylinder 14 of the boom 3 is formed by inserting a jib pivoting pin 19 through the jib fixing bracket 17 and the jib fixing bracket 18. The jib 4 is fixed to the frame. The jib pivot pin 19 is the same as that used when pivoting the base 7 of the jib 4 to the jib foot 6 of the boom head 5.

  Details of the jib fixing means 16 are shown in FIGS. 5 (a), 5 (b), and 5 (c). 5A is a partial view showing the structure of the jib fixing means 16 from a direction corresponding to a plan view when FIG. 2 is defined as a front view, and FIG. 5B is a case where FIG. 2 is defined as a front view. FIG. 5C is a partial view showing the structure of the jib fixing means 16 from the direction corresponding to the left side view, and FIG. 5C shows the structure of the jib fixing means 16 from the direction corresponding to the front view as in FIG. FIG.

  As shown in FIGS. 5 (a), 5 (b), and 5 (c), the jib fixing means 16 is provided with a drop-off prevention engaging portion / jib fixed to one side of the outer cylinder 14 of the boom 3. The fixing bracket 20 and a jib fixing bracket 21 fixed to one upper surface of the jib 4 are configured to pass through the drop prevention engagement portion / jib fixing bracket 20 and the jib fixing bracket 21. The jib 4 is fixed to the lower surface of the outer cylinder 14 of the boom 3 by inserting the contact pin 22. The jib pivot pin 22 is the same as that used when pivoting the base portion 7 of the jib 4 to the jib foot portion 6 of the boom head 5, and its shape and dimensions are the same as those of the aforementioned jib pivot pin 19.

  Jib block means 23 for releasably fixing the jib 4 to the outer cylinder 14 of the boom 3 and a jib guide for regulating the vertical position of the jib 4 while supporting the load of the jib 4 approaching the boom 3 when the jib 4 is folded. As shown in FIGS. 2 and 3, the means 24 is provided at a position away from the tip of the jib 4 at a predetermined distance from the jib fixing means 16.

  Details of the diblock means 23 and the jib guide means 24 are shown in FIGS. 6 (a), 6 (b) and 6 (c). 6A is a partial view showing the structure of the diblock means 23 and the jib guide means 24 as seen through from the direction corresponding to the plan view as in FIG. 3 when FIG. 2 is defined as a front view. b) is a partial view showing the structure of the diblock means 23 and the jib guide means 24 from the direction corresponding to the front view as in FIG. 2 when FIG. 2 is defined as a front view, and FIG. It is the fragmentary figure which showed the structure of the diblock means 23 and the jib guide means 24 from the direction equivalent to a right view when 2 is prescribed | regulated with a front view.

  6 (a), 6 (b), and 6 (c), the diblock means 23 includes an engagement piece 25 fixed on the upper surface of the jib 4 and the outer cylinder 14 of the boom 3. The jib guide piece 26, the stay 27, and the engagement / disengagement piece 29 attached via a bracket 28 on one side of the lower surface side. As shown in FIGS. 6A and 6B, the engagement / disengagement piece 29 includes a retainer 31 fixed to the other end of the L-shaped connection fitting 30 fixed to the bracket 28 at one end. In the direction from right to left in FIG. 6B, the coil spring 32 is held by the bracket 28 so as to be movable in the axial direction, and supported at both ends between the large diameter portion of the engagement / disengagement piece 29 and the retainer 31. The protrusion limit of the tip end portion is regulated by the abutment of the retainer 31 and the fixing nut 33 that is constantly urged and fixed to the base side of the engagement / disengagement piece 29. A substantially arc-shaped tapered surface as shown in FIG. 6B is formed at the tip of the large-diameter portion of the engagement / disengagement piece 29, and when the jib 4 is folded, the jib 4 is moved to the lower surface of the outer cylinder 14 of the boom 3. When pressed to the side, the engaging piece 25 on the jib 4 side presses the taper surface of the engaging / disengaging piece 29 to forcibly move the engaging / disengaging piece 29 in the direction from left to right in FIG. Thereafter, when the engagement piece 25 further moves, the tip of the engagement / disengagement piece 29 urged by the coil spring 32 enters the hole of the engagement piece 25 to fix the jib 4 to the lower surface of the outer cylinder 14 of the boom 3. It is like that.

  Further, a lock release lever 34 as shown in FIG. 2 is provided on one side of the outer cylinder 14 of the boom 3, and the engagement / disengagement piece 29 is attached to the coil spring 32 via the wire 35 by operating the lock release lever 34. When it is pulled against the force, the tip of the engagement / disengagement piece 29 is retracted from the hole of the engagement piece 25 so that the lock of the diblock means 23 is released.

  On the other hand, as shown in FIGS. 6A and 6B, the jib guide means 24 is a shim 36 fixed to one side of the lower surface side of the outer cylinder 14 of the boom 3 via a jib guide piece 26. And a roller 38 rotatably attached to a stay 37 fixed on the jib 4. A tapered surface 36a for smoothly receiving the roller 38 is formed on one side of the shim 36. When the jib 4 is folded, the roller 38 provided on the jib 4 rides on the shim 36 on the outer cylinder 14 side. Is easily tolerated. Further, the gradient of the tapered surface 36a of the shim 36 accurately regulates the vertical position of the roller 38 with respect to the shim 36, more specifically, the vertical position of the jib 4 with respect to the outer cylinder 14 of the boom 3. The engaging piece 25 is guided to the tip position of the engaging / disengaging piece 29 on the outer cylinder 14 side. At this time, a part of the load of the jib 4 is supported by the outer cylinder 14 of the boom 3 via the stay 37, the roller 38, and the shim 36 that constitute the jib guide means 24.

  Further, the jib guide piece 26 fixed on one side of the lower surface side of the outer cylinder 14 has a wedge-shaped cross-sectional shape as shown in FIG. 6 (c), and when the jib 4 is folded, As shown in FIG. 3, the jib 4 obliquely intersects the outer cylinder 14 of the boom 3 by restricting the movement locus of the substantially arc-shaped sliding contact piece 39 fixed to It is stored in the state.

  Next, the details of the first drop-off prevention engagement portion and the second drop-off prevention engagement portion, which are structures unique to the present embodiment, will be specifically described.

  As shown in FIG. 2, the first drop-off preventing engagement portion 40 in the present embodiment is provided on the upper surface side of the jib 4 that faces the lower surface of the outer cylinder 14 when the jib 4 is folded. As shown in detail in FIGS. 5 (a), 5 (b), and 5 (c), the first drop-off prevention engagement portion 40 includes a stay 41 fixed on the jib 4 and the stay 41. It is comprised by the engaging pin 42 fixed so that it might protrude toward the front end side of the jib 4 in the front-end | tip. As shown in FIG. 3, since the jib 4 of the present embodiment is folded in a state of being obliquely crossed with respect to the boom 3, the first drop-off preventing engaging portion including the stay 41 and the engaging pin 42 is provided. 40 itself does not interfere with the outer cylinder 14 of the boom 3.

  On the other hand, the second drop-off prevention engagement portion in this embodiment is a drop-off prevention engagement portion provided on one side of the lower surface side of the outer cylinder 14 that faces the upper surface of the jib 4 when the jib 4 is folded. The jib fixing bracket 20 is also used. As shown in FIG. 2 and FIG. 5C, the disposition position of the drop-off prevention engagement portion / jib fixing bracket 20 is slightly smaller than the disposition position of the first drop-off prevention engagement portion 40. Is offset from the base of This offset amount h, that is, the separation distance h between the tip of the engagement pin 42 and the drop-off preventing engagement portion / jib fixing bracket 20 is a predetermined amount H as shown in FIG. 2 and FIG. The bifurcated engagement protrusions 8 of the jib 4 are engaged with the jib foot 6 of the boom head 5 along the longitudinal direction of the jib 4 from the outer side in the radial direction of the jib foot 6 so that the base 7 of the jib 4 is engaged with the jib foot. It is within the range of the engagement amount H when pivotally attached to the part 6. That is, the magnitude relationship between the offset amount h and the predetermined amount H is h <H, and the value of H is substantially equal to the length of the forked engagement protrusions 8 and 8.

  Further, as shown in FIG. 5 (b), an engagement pin 42 constituting a part of the first drop-off prevention engagement portion 40 is provided at a substantially central portion of the drop-off prevention engagement portion / jib fixing bracket 20. A long hole 43 that allows the rushing is formed. The positional relationship between the engaging pin 42 and the elongated hole 43 is as shown in FIG. 5B. In the state where the jib 4 is completely folded, the two do not overlap, but the roller 38 on the jib 4 side is connected to the outer cylinder 14 side. When the jib 4 is swung out to such a position that the shim 36 that functions as the jib guide means by disengaging from the shim 36 is no longer able to support the load of the jib 4, both positions are superposed. When the 4 is moved to the base side of the boom 3, the engagement pin 42 that constitutes a part of the first drop-off prevention engagement portion 40 functions as the second drop-off prevention engagement portion. The bracket 20 is inserted into and engaged with the elongated hole 43 of the fixing bracket 20.

  The oblong hole 43 is an oblong hole formed with the jib 4 swinging direction as an ellipse, and the margin of the oblong circle causes a change in the timing at which the roller 38 is detached from the shim 36 or the jib 4 swinging speed. Even in this case, when the jib 4 moves toward the base of the boom 3 with the roller 38 detached from the shim 36, the engaging pin 42 surely enters the elongated hole 43.

  In the above configuration, the jib drop prevention mechanism of the present embodiment includes the jib connection means 13, the jib fixing means 15, 16, the jib block means 23, the jib guide means 24, the first drop prevention engagement portion 40, and the second. The anti-drop-off engaging portion and jib fixing bracket 20 functioning as a drop-off preventing engaging portion, and jib pivot pins 19 and 22 functioning as part of the jib fixing means 15 and 16 part-time.

  Next, based on the above-described configuration, a specific operation of the jib drop prevention mechanism of the present embodiment will be described in detail.

  First, when the crane work is performed only by the protruding and retracting operation of the boom 3 without using the jib 4, or when the crane 1 is moved, the jib 4 is configured as shown in FIGS. From the pin holes 44, 44 that are folded on the lower surface of the outer cylinder 14 of the boom 3 and drilled at the foremost portion of the bifurcated engagement projections 8, 8 formed at the base of the jib 4, Pins 19 and 22 are removed.

  Of the jib pivot pins 19 and 22 removed from the base of the jib 4, the jib pivot pin 19 is, as shown in FIG. 4, a jib fixing bracket on the outer cylinder 14 side constituting the jib fixing means 15. 17 and the jib fixing bracket 18 on the jib 4 side are connected to each other, and the jib pivot pin 22 is configured as shown in FIGS. 5 (a), 5 (b) and 5 (c). The jib fixing bracket 16 on the side of the outer cylinder 14 constituting the jib fixing means 16 and the bracket 20 for fixing the jib and the jib fixing bracket 21 on the jib 4 side are connected to each other, and the jib 4 is attached to the lower surface of the outer cylinder 14. Is fixed.

  Further, the jib block means 23 is in a locked state as shown in FIG. 6 (b), and the jib fixing means 23 is engaged with the engagement piece 25 on the jib 4 side and the engagement / disengagement piece 29 on the outer cylinder 14 side. The jib 4 is held on the lower surface of the outer cylinder 14 together with 15 and 16.

  In such a folded state of the jib 4, as shown in FIG. 2, the bifurcated engagement protrusions 8, 8 formed on the base of the jib 4 simply circumscribe the outer peripheral surface of the jib foot 6. Thus, the linear movement of the jib foot part 6 with respect to the base part 7 of the jib 4, that is, the expansion and contraction operation of the boom 3 accompanied by the protruding and retracting operation of the boom head 5 is free. Work is allowed.

  On the other hand, when it becomes necessary to start up the jib 4 and perform crane work, first, the jib pivot pins 19 and 22 are removed from the jib fixing means 15 and 16 with the boom 3 fully retracted, The fixing of the jib 4 by the fixing means 15 and 16 is released. At this time, by completely retracting the boom 3, the bifurcated engagement protrusions 8 of the jib 4 along the longitudinal direction of the jib 4 from the radial outside of the jib foot 6 with respect to the jib foot 6 of the boom head 5, 8 is engaged with the jib foot portion 6 by the predetermined amount H described above.

  Even when the jib 4 is not fixed by the jib fixing means 15, 16, the bifurcated engagement protrusions 8, 8 formed on the base of the jib 4 are engaged with the outer peripheral surface of the jib foot 6. In addition, since the jib block means 23 also holds the jib 4 by the engagement of the engagement piece 25 and the engagement / disengagement piece 29, the jib 4 falls to the ground or the jib 4 is attached to the outer cylinder 14. It does not move along the longitudinal direction.

  Next, the operator causes the jib pivot pins 19 and 22 removed from the jib fixing means 15 and 16 to pass through the pin holes 44 and 44 located at the most distal end portions of the bifurcated engagement protrusions 8 and 8 of the jib 4. The base 7 of the jib 4 is pivotally attached to the jib foot 6 for attachment.

  Since the outer peripheral surface of the jib foot 6 is surrounded by the engaging protrusions 8 and 8, the connecting portion of the engaging protrusions 8 and 8, and the jib pivot pin 19 or the jib pivot pin 22, the jib 4 The base 7 is securely pivoted to the jib foot 6.

  In this embodiment, since the jib pivot pins 19 and 22 are also used for the fixing work by the jib fixing means 15 and 16, the fixing of the jib fixing means 15 and 16 is released and the jib fixing means 15 and 16 are released from the jib fixing means 15 and 16. After the pivot pins 19 and 22 are removed, it is necessary to pivot the base portion 7 of the jib 4 to the jib foot portion 6 by using the jib pivot pins 19 and 22, but the jib pivot pins 19 and 22 are fixed to the jib. If a dedicated pin is prepared for the jib fixing means 15, 16 without diverting to the means 15, 16, the jib fixing means 15, 16 is released after the jib 4 is pivotally attached to the jib foot portion 6. It is also possible to do.

  That is, basically, either the jib 4 fixing release operation or the jib 4 pivoting operation in the jib fixing means 15, 16 may be performed first.

  When the pivoting operation of the jib 4 with respect to the jib foot portion 6 is thus completed, the operator drives a derrick cylinder (not shown) and raises the boom 3 to an angle of about 60 ° as shown in FIG. Thereafter, the lock release lever 34 is operated to disengage the engagement / disengagement piece 29 from the engagement piece 25 of the diblock means 23 to open the diblock means 23.

  If the bifurcated engagement protrusions 8 and 8 of the jib 4 are appropriately pivoted to the jib foot 6 using the jib pivot pins 19 and 22, the base 7 of the jib 4 is detached from the jib foot 6. Therefore, the jib 4 remains suspended from the boom head 5 with the jib connecting means 13 comprising the base 7 of the jib 4 and the jib foot 6 as a fulcrum, until the posture becomes substantially vertical by its own weight. It will be drawn from 3.

  The tip 20 of the engaging pin 42 constituting the first drop prevention engagement portion 40 on the jib 4 side and the drop prevention engagement portion / jib fixing bracket 20 that functions as the second drop prevention engagement portion on the outer cylinder 14 side. Since the above-described offset amount h is interposed between the engagement pin 42 and the drop-off preventing engagement portion / jib fixing bracket 20 when the jib 4 is swung out. The posture of the jib 4 when the swinging is completed is indicated by a two-dot chain line in FIG.

  It should be noted that the auxiliary winding wire is hung in advance along the longitudinal direction of the jib 4 so that the tip of the auxiliary winding wire is locked to the base of the outer cylinder 14 and the lock of the diblock means 23 is released. If the jib 4 is swung out using its own weight while gradually loosening, it is possible to reduce the time required for stopping the pendulum movement of the jib 4 that occurs during the swing-out.

  The above is the normal swinging operation of the jib 4, but depending on the case, the jib pivot pins 19, 22 removed from the jib fixing means 15, 16 are connected to the pin holes 44 of the bifurcated engagement projections 8, 8 of the jib 4. , 44, there is no possibility that the operator will forget the work.

  Even if such work is forgotten, the bifurcated engagement protrusions 8, 8 formed at the base of the jib 4 are engaged with the outer peripheral surface of the jib foot 6, and the diblock Since the position from the tip of the jib 4 is fixed to the outer cylinder 14 by the diblock means 23 until the lock of the means 23 is released, the operation of starting up the boom 3 itself is possible. Until the lock of the means 23 is released, the operator does not notice his work mistake, and the lock of the diblock means 23 is released while leaving the abnormality related to the pivotal attachment of the base 7 of the jib 4.

  Even when such an erroneous operation is performed, the initial stage of swinging out, that is, the jib 4 through the stay 37, the roller 38, and the shim 36 constituting the jib guide means 24 for regulating the vertical position of the jib 4 is used. While the load is supported by the outer cylinder 14 of the boom 3, the jib 4 does not move up and down.

  However, when the jib 4 is swung out to a position where the jib guide means 24 can no longer support the load of the jib 4, that is, the position where the roller 38 is separated from the tapered surface 36a of the shim 36, the tip side of the jib 4 is fixed or supported. There are no elements at all, and the jib 4 is moved downward, that is, toward the base side of the boom 3 by its own weight, and the first drop-off preventing engagement portion 40 on the jib 4 side is configured as shown in FIG. The distal end of the engaging pin 42 enters and engages with the long hole 43 of the drop-off prevention engagement portion / jib fixing bracket 20 that functions as the second drop-off prevention engagement portion on the outer cylinder 14 side.

  Then, the boom through the stay 41 that is part of the first drop-off prevention engagement portion 40 and the drop-off prevention engagement portion / jib fixing bracket 20 that functions as the second drop-off prevention engagement portion. 3 is supported by the outer cylinder 14 and the engagement of the engagement pin 42 and the elongated hole 43 prohibits further swinging out of the jib 4 so that the posture of the jib 4 as shown in FIG. Continue to be held.

  Under such circumstances, when the roller 38 is detached from the tapered surface 36a of the shim 36, the bifurcated engagement protrusions 8 of the jib 4 engaged with the jib foot 6 from the longitudinal direction of the jib 4; 8 moves downward to a certain extent toward the base side of the boom 3, but the offset amount h between the tip of the engagement pin 42 and the drop-off prevention engagement portion / jib fixing bracket 20, that is, the jib 4 Since the movement amount of the base 7 is within the range of the predetermined amount H, that is, the engagement amount H of the bifurcated engagement projections 8 and 8 with respect to the jib foot portion 6, the dibut foot portion 6 and the bifurcated engagement projection 8 and The engagement amount of [H−h]> 0 is still left between the base member 8 and the base portion 7 of the jib 4 is not completely detached from the jib foot portion 6.

  In this way, the load of the jib 4 is supported by the outer cylinder 14 of the boom 3 via the stay 41 and the drop-preventing engagement portion / jib fixing bracket 20, and the base portion 7 of the jib 4 and the jib foot portion 6 are also engaged. As a result, the jib 4 is held by the boom 3 while being supported at two points.

  Therefore, even if the operator starts to swing out the jib 4 while forgetting to attach the jib pivot pins 19 and 22, there is no inconvenience that the jib 4 falls to the ground.

  However, in this embodiment, the probability that the operator forgets the work of attaching the jib pivot pins 19 and 22 to the pin holes 44 and 44 of the bifurcated engagement protrusions 8 and 8 of the jib 4 is extremely low.

  As described above, in this embodiment, the jib 4 cannot be swung out unless the jib pivot pins 19 and 22 are removed from the jib fixing means 15 and 16, and from the jib fixing means 15 and 16. As long as the operator himself removes the jib pivot pins 19 and 22, the operator will always have the jib pivot pins 19 and 22 once before the jib 4 swinging operation. If not, it can be said that there is almost no work mistake when forgetting to attach the jib pivot pins 19 and 22 to the base 7 of the jib 4.

As described above, as an example, the jib foot portion 6 is formed by a columnar projection, and the bifurcated engagement projections 8 of the jib 4 are engaged with the outer peripheral surface of the jib foot portion 6 so that the base portion 7 of the jib 4 is engaged with the jib foot portion 6. However, on the contrary, the jib foot part 6 itself is configured to be rotatable with respect to the boom head 5, and the jib foot part 6 projecting on both sides of the boom head 5 is provided. A diametrical through hole is formed by forming an enlarged diameter portion, the base portion 7 of the jib 4 is inserted into the through hole, and the base portion 7 of the jib 4 is fixed to the jib foot portion 6 to thereby fix the jib 4 to the boom head 5. It is also possible to pivot about the motor.
When such a structure is applied, a pin hole in a direction perpendicular to the above-described through hole provided in the enlarged diameter portion of the jib foot portion 6 is formed in the enlarged diameter portion of the jib foot portion 6, and the pin hole is formed in the pin hole. The passed jib pivot pins 19 and 22 are penetrated in the radial direction of the base portion 7 of the jib 4 to fix the jib 4 to the enlarged diameter portion of the jib foot portion 6. At this time, the length corresponding to the above-mentioned predetermined amount H is from the drilling position of the through hole drilled in the base portion 7 of the jib 4 to penetrate the jib pivot pins 19 and 22 to the end of the jib 4. This is the length, which is the amount of engagement between the jib foot 6 and the base of the jib 4.

Further, in the above-described embodiment, the drop-off preventing engagement portion / jib fixing bracket 20 constituting a part of the jib fixing means 16 is also used as the second drop-off prevention engaging portion. The prevention engaging portion may be constituted by a member independent of the jib fixing means 16.
In such a case, it is still an indispensable requirement that the second drop-off prevention engagement portion be offset from the first drop-off prevention engagement portion within the predetermined amount H and disposed on the base side of the boom 3. As long as the relative positional relationship between the first drop-off prevention engagement portion and the second drop-off prevention engagement portion (h <H interval) is maintained, the first drop-off prevention engagement portion and the second drop-off prevention engagement portion The position of providing the drop-off preventing engagement portion itself may be substantially anywhere in the section from the base side end of the jib 4 to the tip. However, from the viewpoint of suppressing the vibration of the jib 4 that occurs when the swing-out operation is performed in an incompletely pivoted state, for example, as in the above-described embodiment, the jib 4 that engages with the jib foot portion 6 It is desirable to provide the first drop-off prevention engagement portion and the second drop-off prevention engagement portion at a position where the jib 4 can be held with a certain two-point support at a certain distance from the base portion.

In addition, an engagement pin directed to the tip of the boom 3 is provided on the outer cylinder 14 side of the boom 3 to serve as a second drop-off preventing engagement portion, and a plate member having a long hole formed on the jib 4 side is fixed. And it is good also as a 1st drop-off prevention engagement part.
The function required for these drop-off prevention engagement portions is that when the boom 3 is raised, the first drop-off prevention engagement portion and the second drop-off prevention engagement portion overlap each other to apply the total load of the jib 4. Mechanical strength to the extent that it can be supported, and the extent that no side slip occurs between the first drop-off prevention engagement portion and the second drop-off prevention engagement portion even when some vibrations occur When the jib 4 moves toward the base of the boom 3 when the swing-out operation is performed with the pivoting incomplete state (for example, prevention of positional displacement due to the engagement pin and the elongated hole) When the first drop-off prevention engagement portion and the second drop-off prevention engagement portion are securely engaged and proper pivoting is performed and the jib 4 swings around the jib connection means 13 as a fulcrum. This is only a relative positional relationship in which the first drop-off prevention engagement portion and the second drop-off prevention engagement portion do not interfere with each other.

It is the front view which showed the external appearance of the crane vehicle of one Example which mounted the jib fall prevention mechanism of the crane vehicle. (Example 1) It is the front view which removed and showed the crane from the crane vehicle. (Example 1) It is the top view which looked through and showed the boom which comprises a crane, and the jib folded by the lower surface of the boom. (Example 1) FIG. 3 is a diagram showing details of the jib fixing means from the direction corresponding to the right side view with FIG. 2 defined as a front view. (Example 1) FIG. 5A is a diagram showing the details of another jib fixing means. FIG. 5A is a diagram showing the structure of the other jib fixing means from the direction corresponding to the plan view, with FIG. b) is a view showing the structure of another jib fixing means from the direction corresponding to the left side view, defining FIG. 2 as a front view, and FIG. 5 (c) corresponds to the front view as in FIG. It is the figure which showed the structure of the other jib fixing means from a direction. (Example 1) FIG. 6A is a front view showing FIG. 2 as a front view, and shows the structure of the diblock means and the jib guide means from the direction corresponding to the plan view as in FIG. FIG. 6B is a perspective view showing FIG. 2 as a front view, showing the structure of the diblock means and the jib guide means from the direction corresponding to the front view as in FIG. 6 (c) is a diagram showing the structure of the diblock means and the jib guide means from the direction corresponding to the right side view with FIG. 2 defined as a front view. (Example 1) It is the conceptual diagram which showed the outline of the jib swing-out operation | work when the jib pivot attachment was performed appropriately. (Example 1) It is the conceptual diagram which showed the outline of the jib swing-out operation | work at the time of not performing pivot attachment of a jib appropriately. (Example 1)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crane vehicle 2 Crane 3 Boom 4 Jib 5 Boom head 6 Jib foot part 7 Base part 8 Bifurcated engagement protrusion 9 Hydraulic cylinder 10 Piston rod 11 Tension rod 12 Rod fixing part 13 Jib connecting means 14 Outer cylinder 15 Jib fixing means 16 Jib Fixing means 17 Jib fixing bracket 18 Jib fixing bracket 19 Jib pivot pin 20 Detachment prevention engagement part and jib fixation bracket (second fallout prevention engagement part)
21 Jib fixing bracket 22 Jib pivot pin 23 Jib block means 24 Jib guide means 25 Engagement piece 26 Jib guide piece 27 Stay 28 Bracket 29 Engaging / disconnecting piece 30 Connecting bracket 31 Retainer 32 Coil spring 33 Fixing nut 34 Unlocking lever 35 Wire 36 Shim 36a Tapered surface 37 Stay 38 Roller 39 Sliding contact piece 40 First drop-off prevention engagement portion 41 Stay 42 Engagement pin 43 Long hole 44 Pin hole H Predetermined amount h Offset amount

Claims (2)

A base part of a jib pivotally attached to a jib foot part by a jib pivoting pin in a state in which it enters and engages with the jib foot part of the boom head from the radial outer side of the jib foot part along the longitudinal direction of the jib. And a jib coupling means constituted by the jib foot part,
A jib fixing means for fixing the folded jib to the outer cylinder of the boom with the jib connecting means as a fulcrum;
Jib drop prevention for a crane truck provided with a jib block means for fixing the jib to the boom by fitting between an engaging piece provided on either the jib or the outer cylinder of the boom and an engaging / disengaging piece provided on the other Mechanism,
A first drop-off preventing engagement portion independent of the jib fixing means and the diblock means is provided on the surface of the jib that is folded and faces the outer cylinder of the boom;
When the jib is folded, the surface of the outer cylinder of the boom that faces the jib engages with the first drop-off prevention engaging portion when the jib is moved to the base side of the boom with the jib being swung out. A second drop-off prevention engagement portion is offset from the first drop-off prevention engagement portion to the base side of the boom within the predetermined amount range, and is provided independently of the jib fixing means and the diblock means. A jib fall prevention mechanism for a crane truck, characterized in that Jib guide means for regulating the vertical position of the jib while supporting the load of the jib approaching the boom when the boom is raised and the jib is folded,
The second drop-off prevention engagement portion is formed when the jib is moved to the base side of the boom in a state where the jib is swung out to a position where the jib guide means does not support the load of the jib. The jib drop prevention mechanism for a crane truck according to claim 1, wherein the jib fall prevention mechanism is disposed at a position where the crane truck engages with the crane.

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