A jib hold rod securing device for cranes

Abstract: Disclosed herein is a jib hold rod securing device for cranes comprising a jib (3) to be stretched out and taken in its relative position to a boom (2) and a jib hold rod (7) suspended between the jib (3) and the top portion of the boom (2) to support the jib (3) in its stretched-out position and characterized in that the jib hold rod (7) has its top portion engaged and linked with the jib (3) to serve as its fulcrum to swing between its taken-in position with its base portion attached to the base portion of the jib (3) and its jib holding position with its base portion attached to the top portion of the boom (2) and the jib hold rod (7) is provided with a rod holding means (11) suspended between the jib hold rod (7) and the jib (3) with the jib hold rod set in its jib holding position to hold the jib hold rod (7) in its jib holding position, thereby making its structure simple and its cost low and allowing easy jib re-positioning operations with assured safety and less labor.

Description: Background of the Invention: (Field of the Invention) This invention relates to a jib hold rod securing device to reposition or change the position of the base end of a jib hold rod (or a desired suspension rod) holding a jib in its stretched-out position, between the top portion of a boom and the base end of the jib in a manner to match the jib in its stretched-out and take-in position. (Description of the Prior Art) In Figs. 7 and 8, numerals 1, 2 and 3 represent an upper rotary body of a crane, a boom liftably mounted to the upper rotary body and a jib (a pneumatic jib), respectively. When not in use, the said jib 3 is taken in and held under the lower surface of the boom in a desired manner as shown in Fig. 7 with imaginary lines and, for its lift-up operation, stretched out to the position of the top portion of the boom as described hereinbeIow. (I) Jib feet 3a provided on the two sides of the end portion of the jib are engaged and linked with point pins 4 provided on the two sides of a boom head 2a and, with an auxiliary hook 5 engaged to the top portion of the jib, an auxiliary rope 6 is taken up while the boom 2 is lifted up. Thus, the jib 3 is swung forward with the said engagement linkage as its fulcrum as shown in Fig. 7 with imaginary lines. (II) After the boom is turned down almost horizontally and, with the jib 3 left supported by the auxiliary hook 5 and the auxiliary take-up rope 6, a pair of right and left jib hold rods 7 and 7 are laid to bridge between the boom head 2a and the top portion of the jib to support the jib 3 in its stretched-out position as shown in Figs. 7 and 8 with solid lines, the auxiliary rope 6 is loosened. As shown in Figs. 7 and 8 with solid lines, the jib hold rods 7 are taken into the jib 3 with their top portions and base portions pinned down to the top portion and base portion of the jib, respectively. When the jib is stretched out, both of the said rods 7 have their base portions released from the base portion of the jib and shift their position upward with their top portions fixed to the top portion of the jib serving as their fulcrum to have their base portions fixed to the summit portion of the boom head 2a as shown in Figs. 7 and 8 with solid lines. According to the conventional technology, however, it has not been made possible to change the position of a jib in a manner to match its stretched-out and taken-in state, allowing: a. The base portion of a rod to be released from either of the base portion of the jib and the boom head 2a; and b. The heavy rod 7 weighing roughly 20kgs to be lifted up and down and its base portion to be pinned down to the other. All the above-described operations have conventionally needed to be carried out only when the jib is in its stretched-out position as shown in the said two drawings with solid lines. Thus, the conventional technology, inevitably requiring high-place work standing on a stepladder as shown in Fig. 7 or on the jib 3, forces stress on workers engaged in such a jib repositioning and exposes them to a danger and risk. Against the above-described background, the present invention has its purpose to provide a jib hold rod securing device for cranes to enable such a jib repositioning with less danger and risk as well as labor. Summary of the Invention: According to an aspect of the present invention, there is provided a jib hold rod securing device for cranes comprising a jib to be unfolded and folded in a relative position to a boom and a jib hold rod having a top and base portion, said jib hold rod being suspended between the said jib and the top portion of the boom to support the jib in the unfolded position, wherein the said jib hold rod has its top portion engaged and linked with the jib to serve as a fulcrum to swing between a folded position with its base portion attached to the base portion of the jib and a jib holding position with its base portion attached to the top portion of the boom and the said jib hold rod is provided with a rod holding means suspended between the said jib hold rod and the jib with the said jib hold rod set in its jib holding position to hold the jib hold rod in its jib holding position. According to another aspect of the present invention, there is provided a jib hold rod securing device for cranes with a structure as described in the above, wherein the rod holding means is composed of a link, brackets provided to the jib and the jib hold rod and pins to fix the two ends of the link to the brackets. According to yet another aspect of the present invention, there is provided a jib hold rod securing device for cranes with a structure as described in the above, wherein either of the brackets on the side of the jib or the jib hold rod has extending in its longitudinal direction an elongate hole, through which one end of the link is pinned down to the bracket to allow the link to shift up and down in correspondence to the position of the jib hold rod swinging between its jib holding position and its taken-in position. According to another different aspect of the present invention, there is provided a jib hold rod securing device for cranes with a structure as described in the above, wherein two of the link are pinned to each other at their one ends to form a link changing its position in correspondence to the position of the jib hold rod swinging between its jib holding position and its taken-in position and there is provided a means to hold the said link in its stretched position when the jib hold rod is in its jib holding portion. According to yet another different aspect of the present invention, there is provided a jib hold rod securing device for cranes with a structure as described in the above, wherein the said means to hold the link in its stretched position is provided with gas springs between the fulcrum of the link in its bending and stretching and the jib to keep the link in its longitudinal direction. According to further yet another aspect of the present invention, there is provided a jib hold rod securing device for cranes with a structure as described in the above, wherein the rod holding means is structured with gas springs provided between the jib and the jib hold rod. A jib hold rod securing device for cranes according to an aspect of the present invention makes it possible to preset the jib hold rod in its jib holding position with the use of the rod holding means at a stage of jib stretching-out operation where the jib is still operable from the ground before stretched out and thus allows laborious rod shifting work associated with a danger and risk to be carried out easily and safely from the ground. A jib hold rod securing device for cranes according to another aspect of the present invention is made simple in structure with the rod holding means composed of a link and pins which, in turn, makes it low in cost and simple in handling. A jib hold rod attaching device for cranes according to yet another aspect of the present invention is structured with the rink kept suspended between the jib and the jib holding rod which makes its handling far more easier. A jib hold rod securing device for cranes according to another different aspect of the present invention is structured with gas springs employed as a means to hold the link in its stretched position which, under the influence of the gas springs, stretches and holds the link in its stretched position (to set the jib hold rod in its jib holding position), requiring far less labor. A jib hold rod securing device for cranes according to yet another different aspect of the present invention employs gas springs which themselves serve as the rod holding means, requiring a far simpler structure. Brief Description of the Drawings: Fig. 1 is a side view of a jib hold rod attaching device representing the first embodiment of the present invention. Fig. 2 is a side view of a crane equipped with the first embodiment of the present invention, outlining it in a whole. Fig. 3 is a side view of the second embodiment of the invention. Fig. 4 is a side view of the third embodiment of the invention. Fig. 5 is a side view of the fourth embodiment of the invention. Fig. 6 is a side view of the fifth embodiment of the invention. Fig. 7 is a corresponding drawing to Fig. 2, showing a conventional device of the same kind as the present invention. Fig. 8 is a partially-expanded view of the device shown in Fig. 7. Detailed Description of the Preferred Embodiments: The present invention is described hereinbelow along with its preferred embodiments as shown in Fig. 1 to 6. First Embodiment (shown in Figs. 1 and 2) The first preferred embodiment of the invention is described hereinbelow only with respect to differences from its conventional counterpart. Designated by a numeral 7 is a jib hold rod (shown on only one side) having its base portion provided fixed thereto a two-pronged rod-side bracket 8 which, with a pin 10, is fixed to a jib-side bracket 9 projecting under the base portion of a jib when the jib is taken in as shown in Fig. 1 with imaginary lines C (jib-side bracket projecting over the base portion of the jib when the latter is taken out) and to a boom head 2a when the jib is stretched out as shown in Figs. 1 and 2 with solid lines. The jib 3 has at its base portion right and left links 11 which, coming under the lower surface of the jib when the latter is taken in, form rod holding means. The link 11 has its base portion pivoted to the jib-side bracket 9 with a fulcrum-side pin 12 provided through the latter horizontally to swing around the said fulcrum-side pin 12 between its turned-down non-operational position and its turned-up operational position almost perpendicular to the jib 3. The link 11 has its top portion fixed with a securing pint 14 to a link securing bracket 13 provided to the jib 3 in its turned-down position and to the rod-side bracket 8 of the jib hold rod 7 in its turned-up position. In the above-described device, the jib hold rod 7 has its position changed as described hereinbelow. In order to get the jib stretched out, the rod-side bracket 8 of the jib hold rod 7 is released from the jib-side bracket 9 when the jib is in its taken-in position as shown in Figs. 1 and 2 with solid lines, and the said jib hold rod 7 is swung downward around the jib top engagement and linkage point serving as a fulcrum. At the same time, the link 11 is lifted into its turned-up position and the top portion of the link 11 fixed to the rod-side bracket 8 with the pin 14. By this, the jib hold rod 7 is set in its jib holding position ready to have the jib in its stretched-out position allowing the rod-side bracket 8 to be fixed to the boom head 2a in a position as shown in Fig. 1 with imaginary lines D or Fig. 1 with solid lines. In an operational state resulting from the above, the rod-side and jib-side brackets 8 and 9 position themselves at a height manually accessible from the ground, allowing operations to be executed easily from the ground to swing the jib downward and secure the link 11. Even with a large crane rising high in its position, the said operations can be carried out from the ground to a satisfactory degree if its crane body (boom 2) is slightly inclined forward with an outrigger operated. When the jib 3 is thereafter stretched out to its position as shown in Figs. 1 and 2 with solid lines, the rod-side bracket 8 of the jib hold rod 7 shifts itself to its fixing pre-set position on the tip of the boom head 2, needing only to be fixed to the boom head 2a with the pint 10. As the device according to the present invention requires its high-place operations only to carry out the said pin-fixing, it makes possible to, when the jib is in its stretched-out position, reposition or change the position of the jib hold rod more easily and with far less labor as compared with a conventional device of its kind. When the jib is in its taken-in position, the jib hold rod is allowed to be changed or its position changed in operational order contrary to the above-described jib repositioning with the jib hold rod in its stretched-out position. Second Embodiment (shown in Fig. 3) Other embodiments of the present invention are described hereinbelow with respect to their differences from the first embodiment of the invention. In the second embodiment of the present invention, the jib hold rod 7 has provided at its base portion a rod-side bracket 16 having extending in its longitudinal direction an elongate hole 15, through which the top portion of the link 17 is fixed to the bracket 16 with the pin 14. With the above-described structure, the link 17 has its position upward in correspondence to the position of the jib hold rod 7 swinging between its jib holding position and jib taken-in position as shown in Fig. 3 with solid and imaginary lines. In order to get the link 17 stable in its turned-up position, the elongate hole 15 has provided on its base portion a recess 15a to receive the pin 14 fitted therein. In this second embodiment of the invention, the link 17 automatically shifts its position upward following the rotation of the jib hold rod 7, making a replacing of the link top portion unnecessary and the re-positioning of the jib hold rod easier. Third Embodiment (shown in Fig. 4) In the third embodiment of the present invention, a pair of link elements 18 and 19 are engaged and linked together at their respective ends with a pin 20 to form a collapsible (to fold and open) link 21 which is structured to shift collapsible in correspondence to the position of the jib hold rod 7 swinging between its taken-in and jib holding positions. The link 21 is kept in its stretched-out position with a lock pin provided in the vicinity of its collapsible engagement and linkage point. Fourth Embodiment (shown in Fig. 5) Like in the third embodiment of the present invention, the fourth embodiment of the invention has a collapsible link 23 formed with a pair of link elements 24 and 25 linked together with a pin 25. The link 23 is structured to stay impressed in its longitudinal direction under the influence of gas springs suspended between the collapsible engagement and linkage point of the link and the jib 3. With the above-described structure, the link 23 is stretched out and stays kept in its stretched-out position under the influence of the gas springs 27 (setting the jib hold rod 7 in its jib holding position), a factor which serves to reduce a work load greatly. Fifth Embodiment (shown in Fig. 6) In the fifth embodiment of the present invention, there are provided gas springs 28 suspended between the jib 3 and the rod-side bracket 8 of the jib hold rod 7 by the means of pins 29 and 30. The gas springs 28 are structured to serve as an extensible rod hold means to hold the jib hold rod 7 in its jib holding position. Like in the fourth embodiment of the present invention, the fifth embodiment of the invention with the above-described structure is simple in structure and requires less labor for the work required for its operation. In the above, the present invention is described with reference to its embodiments in a crane taking in a jib under its boom. It is needless to say, however, that the invention can be employed in a desired crane of the type which takes in a jib on its side. Disclosed herein is a jib hold rod securing device for cranes comprising a jib to be unfolded and folded in a relative position to a boom and a jib hold rod suspended between the jib and the top portion of the boom to support the jib in its unfolded position wherein the jib hold rod has its top portion engaged and linked with the jib to serve as its fulcrum to swing between its folded position with its base portion attached to the base portion of the jib and its jib holding position with its base portion attached to the top portion of the jib and the jib hold rod is provided with a rod holding means suspended between the jib hold rod and the jib with the jib hold rod set in its jib holding position to hold the jib hold rod in its jib holding position, thereby making its structure simple and its cost low and allowing easy jib re-positioning operations with assured safety and less labor.

Claims: A jib hold rod securing device for cranes comprising a jib (3) to be unfolded and folded in a relative position to a boom (2) and a jib hold rod (7) having a top and base portion, said jib hold rod being suspended between said jib (3) and said top portion (2a) of said boom (2) to support said jib (3) in said unfolded position, wherein said jib hold rod (7) has its top portion engaged and linked with said jib (3) to serve as a fulcrum to swing between a folded position with its base portion attached to said base portion of said jib (3) and a jib holding position with its base portion attached to the top portion (2a) of said boom (2), characterized in that said jib hold rod (7) is provided with a rod holding means (11; 17; 21; 23; 28) suspended between said jib hold rod (7) and said jib (3) for holding said jib hold rod (7) in said jib holding position when said jib hold rod (7) is set in said jib holding position. A jib hold securing device as claimed in Claim 1, characterized in that said rod holding means is composed of a link (11), brackets (8, 9) provided at said jib (3) and said jib hold rod (7) and pins (12, 14) to fix the two ends of said link (11) to said brackets (8, 9). A jib hold rod securing device for cranes as claimed in Claim 2, characterized in that either of said brackets (8, 16; 9) on the side of said jib (3) or said jib hold rod (7) has, extending in its longitudinal direction, an elongate hole (15) through which one end of said link (11) is pinned down to said bracket (8, 16; 9) to allow said link (11) to shift up and down in correspondence to the position of said jib hold rod (7) swinging between said jib holding position and said taken-in position. A jib hold rod securing device for cranes as claimed in Claim 2, characterized in that said link (21) has two links (18, 19; 24, 25) which are pinned down to each other at their one ends to form a link (21, 23) changing its position in correspondence to the position of the jib hold rod (7) swinging between said jib holding position and its taken-in position, and in that a means (22, 27) is provided to hold the said link (21) in its stretched position when said jib hold rod (7) is in said jib holding position. A jib hold rod securing device for cranes as claimed in Claim 4, characterized in that said means to hold the link in its stretched position is provided with gas springs (27) between fulcrum of said link (23) in its bending and stretching and said jib (3) to keep said link (23) in its longitudinal direction. A jib hold rod securing device for cranes as claimed in Claim 1, characterized in that the rod holding means is structured with gas springs (28) provided between said jib (3) and said jib hold rod (7).

Inventors: KOIZUMI YUKIO, KOIZUMI, YUKIO
Applicants: KOBE STEEL LTD, KABUSHIKI KAISHA KOBE SEIKO SHO ALSO KNOWN AS KOBE STEEL LTD.
Application year: 1990
Main classification: B66C23
IPC codes: B66C23