JPH0117593Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a crane (mainly tower crane) equipped with a luffing jib that can be raised and lowered at the tip of the boom. This invention relates to improvements in backstop devices.

(Prior art) A conventional backstop device for a jib has a pipe-shaped backstop fixedly attached to the tip of the boom at a predetermined angle, and the jib is set at a predetermined offset angle (hereinafter referred to as the backstop angle) with respect to the boom. When the jib is reached, the tip of the backstop engages with a stop engaging portion provided on the jib to prevent further rearward rotation of the jib.

However, according to the conventional device in which the backstop is attached to the boom with its angle unchanged, and the stop engages with the stop engaging portion whenever the jib reaches the above-mentioned backstop angle with respect to the boom, the boom Also, the backstop action is exerted even when the boom is lowered to the ground when disassembling or assembling the jib. Therefore, in the conventional device, the boom and jib can be completely lowered to the ground in this lowered state.
The backstop angle of the jib is set to the jib offset angle (approximately -5 degrees) in this fully laid down state. However, at this backstop angle, the jib is actually in an inverted state with the jib tilted backwards from the boom axis, so the device's original backstop function is not fully performed, and if the lowering of the hoisted load is suddenly stopped, the jib will be reversed. This had become a serious problem in terms of crane work safety, such as the increased impact caused by the movement.

(Purpose of the invention) In view of the above circumstances, the present invention is designed to provide an appropriate backstop function during crane work, while also releasing the backstop function when the boom collapses.
Moreover, it is an object of the present invention to provide a backstop device for a crane that can automatically switch between the backstop function state and the backstop function release state.

(Structure of the invention) In the present invention, a jib that can be raised and rotated and a backstop for the jib are provided at the tip of the boom, and when the offset angle of the jib with respect to the boom reaches the backstop angle, the tip of the backstop In a crane configured to engage with a stop engaging portion provided on the jib to prevent rearward rotation of the jib, the backstop may be rotated in the jib hoisting direction around the base end. At the same time, the boom tip is provided with a stop receiver that restricts the rotation angle of the backstop within a certain range. An arm is pivotally attached to the back surface of the arm so that it can rotate about the middle part as a fulcrum so that one end is in a vertical position facing the back stop. A stop support part is provided that engages with the backstop and pushes up the backstop when the arm is rotated by an angle greater than the backstop angle, and an arm stop is provided on the backstop and the jib to hold the arm at an angle that allows the arm to push up the backstop. They are set up separately.

(Example) Figure 1 shows the crane working position, Figure 3 shows the boom fully lowered position for disassembling or assembling the boom and jib, and Figure 2 shows the boom lowered (erected) intermediate position, which is the intermediate position between the two positions. It shows. Also,
FIG. 4 shows the backstop operation state of the jib backstop device according to the embodiment of the present invention in the crane working position shown in FIG. 1, and FIG. Each state is shown.

1 is a boom attached to the crane main body (base machine) A, and 2 is a jib attached to the tip of the boom 1 so that it can be raised and lowered. The luffing operation is performed below a predetermined offset angle α (for example, +15°, hereinafter referred to as the backstop angle) with respect to the boom 1, and the backstop device prevents the boom from rotating rearward beyond the backstop angle α. On the other hand, when boom 1 and jib 2 are disassembled, if boom 1 is laid down as shown in FIG. Finally, as shown in FIG. 3, the boom 1 and the jib 2 are completely laid down, with both the boom 1 and the jib 2 touching the ground in a substantially horizontal state. At this time, the jib 2 is at an offset angle β (approximately -5°) exceeding the backstop angle α.

That is, in this backstop device, during crane work, the rotation of the jib 2 is restricted at a position forward of the boom axis to effectively perform the device's inherent jib reversal prevention function, and when the boom 1 is toppled, The structure is such that the backstop function of the jib 2 can be released. This configuration and operation will be described in detail below with reference to FIGS. 4 and 5.

Reference numeral 3 designates a backstop, which is made up of an outer 31 made of a pipe, an inner 32, and a buffer spring 33 provided at the fitting portion of both 31 and 32.
By attaching the proximal end of the backstop 3 to the boom tip 11 via a pin 13 parallel to the jib foot pin 12, the backstop 3 is pivotably mounted to be rotatable in the direction of raising and lowering the jib. Further, the tip end portion (hereinafter referred to as the backstop tip portion) of the inner 32 of the backstop 3 is formed into a bifurcated shape, and the backstop tip portion 34 is connected to the stop engaging portion 21 fixed to the back of the base of the jib 2. When engaged, a backstop action is performed at a backstop angle α shown by the imaginary line in FIG. On the other hand, a stop receiver 4 is provided at an intermediate point between the jib attachment point and the backstop attachment point on the boom tip 11 so as to protrude toward the backstop 3 side. This stop receiver 4 is provided with receiving surfaces 41 and 42 at the tip and intermediate portions, so that the back stop 3 can be rotated only between the two receiving surfaces 41 and 42, that is, the rotation angle of the back stop 3 is adjusted to this angle. It is configured such that it can be regulated within a predetermined range by both receiving surfaces 41 and 42. Backstop 3 is
While supported by the intermediate receiving surface 42, its tip 34 engages with the stop engaging portion 21, and exhibits a backstop function with a buffering margin from this position until the buffer spring 33 contracts. On the other hand, when the boom is lowered, the backstop 3 is pushed up by the arm 5 and finally comes into contact with the tip receiving surface 41, and at this time the jib 2 is in the offset angle β state when the boom is completely lowered as shown in FIG. .

The arm 5 is connected to the stop engaging portion 2 of the jib 2.
A bracket 22 fixed on the back side of the proximal side of the bracket 1
It is pivotably attached to the middle part so as to be rotatable about the middle part as a fulcrum. This arm 5 has a stop support part 51 at one end that can be engaged with the back stop 3, and a weight 52 at the other end. It is in a vertical position protruding from the top and facing backstop 3.

To explain the action of pushing up the backstop by the arm 5, that is, the action of releasing the backstop function, when the boom 1 is lowered from the crane working position shown in Fig. 1 to the intermediate lodging position shown in Fig. 2, and then to the fully laid down position shown in Fig. 3. The offset angle of the jib 2 with respect to the boom 1 is the backstop angle α.
At the jib position shown by the imaginary line in FIG. 5, which approaches the jib position, the stop support portion 51 of the arm 5 in the vertical position abuts the back stop 3, which is oriented slightly downward from the horizontal, from below. From this state, when the boom 1 is further lowered and the jib 2 is relatively rotated in the upright direction,
Arm 5 pushes up backstop 3. As a result, the backstop tip 34 is lifted above the stop engaging portion 21 of the jib 2.
Even when jib 2 reaches backstop angle α, no backstop action is performed and backstop 3
The boom 1 and the jib 2 are allowed to rotate until they come into contact with the tip receiving surface 41 of the stop receiver 4. In this way, the boom 1 and the jib 2 are completely laid down on the ground with the jib offset angle β as shown in FIGS. 3 and 5.

By the way, in the state shown in the imaginary line A in FIG. 5 when the arm 5 starts to push up the backstop, the backstop 3 is oriented slightly downward from horizontal with respect to the arm 5 in the vertical position, so that the arm 5
There is a concern that it may rotate counterclockwise. Therefore, by providing a first arm stopper 6 on the jib 2 and bringing the lower end of the arm 5 into contact with the stopper 6, the arm 5 is prevented from rotating counterclockwise from the vertical position. There is. In another case, the arm 5 may gradually rotate clockwise due to the frictional resistance between the stop support portion 51 and the backstop 3 while the backstop is being pushed up. Therefore, a second arm stopper 7 is provided protruding near the tip of the backstop 3 to prevent the arm 5 from rotating clockwise beyond a certain angle, as shown by the imaginary line B in FIG.
This ensures the backstop pushing action.

Next, when the boom 1 is made to stand on its own from the boom completely laid down state shown in FIG. 3 to the state shown in FIG.
is supported by the intermediate receiving surface 42 of the stop receiver 4. When the boom 1 is further raised from this state to the crane working position shown in FIG. 1, the backstop 3 is placed in an upward position. Therefore, in this state, the backstop 3 cannot be pushed up with the arm 5 in the vertical position.
As shown in FIG. 4, when the jib 2 reaches a predetermined backstop angle α, the backstop tip 34 engages with the stop engaging portion 21 regardless of the arm 5, and the desired backstop function is performed without any hindrance. It is hit.

(Effects of the invention) As described above, the jib backstop device of the present invention exhibits an appropriate backstop function that restricts the rotation of the jib in front of the boom axis during crane work, and releases the backstop function when the boom is lowered. Moreover, it is possible to automatically switch between the backstop function state and the backstop function release state based on changes in the ups and downs of the boom, and is of extremely high practical value.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, with Fig. 1 showing the crane working position, Fig. 2 showing the boom mid-folding position, Fig. 3 an overall side view of the crane showing the boom fully-folding position, and Fig. 4 showing the backstop operating state. , and FIG. 5 are enlarged views of the device showing the backstop action released state. 1...Boom, 11...Boom tip, 2...
Jib, 21... Stop engaging portion of the same jib, 3...
Back stop, 34... Back stop tip, 4... Stop receiver, 5... Arm, 6...
Arm stop on the jib side, 7... Arm stop on the back stop side, α... Back stop angle.

Claims (1)

[Scope of utility model registration request] The tip of the boom is provided with a jib that can be rotated up and down and a backstop for the jib, and when the offset angle of the jib with respect to the boom reaches the backstop angle, the tip of the backstop engages the stop provided on the jib. In a crane configured to engage with a joint part to prevent rearward rotation of the jib, the backstop is pivoted to the tip of the boom so as to be able to rotate in the direction of raising and lowering the jib about the base end. At the same time, there is a
A stop receiver is provided to restrict the rotation angle of the backstop within a certain range, and on the other hand, the arm is placed in a vertical position with one end facing the backstop on the back side of the jib on the proximal side of the stop engaging part. Pivotally attached so that it can rotate using the middle part as a fulcrum,
This arm is provided with a stop support part at the end facing the backstop that engages with the backstop and pushes up the backstop when the jib rotates by an angle greater than the backstop angle when the boom is in the down position. , a backstop device for a jib of a crane, characterized in that each arm is provided with an arm stopper for holding the arm at an angle capable of pushing up the backstop.