JPH10212091A - Expansion boom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain pad fastening force of a fastener over a long period of time so as to ensure the fitted state of a sliding pad. SOLUTION: In this expansion boom, a fitting hole 16 for fitting a sliding pad 14 to a pad carrier 13 is formed into stepped hole shape provided with a small diameter hole and a large diameter hole. In this fitting hole 16, a spacer 17 with a collar part is provided between a rivet head part and the pad carrier 13 in such a state that the fastening force of a rivet 15 acts upon the pad carrier 13 through the spacer 17 and that the sliding pad 14 is held between the collar part and the pad carrier 13. The expansion boom is also provided with a porous grease feeding body containing lubricating oil, and a current carrying brush for making a current flow between adjacent unit booms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a box-shaped telescopic boom in which a plurality of unit booms are telescopically fitted.

[0002]

2. Description of the Related Art FIGS.
As shown in FIG. 12, the prior art will be described by taking as an example a two-stage boom comprising a fixed boom 1 and a movable (tip) boom 2.

Pad carriers 3, 3 as pad mounting portions are fixed to the left and right sides (boom width direction) of the inner surface of the bottom plate at the distal end of the fixed boom 1 by welding, screwing, or the like. Sliding pads 4, 4 for keeping these gaps constant while reducing frictional resistance between mating unit booms are mounted by one or more mounting screws 5.

Further, since the sliding resistance between the booms is still large with only the sliding pads 4 and 4, grease as a lubricant is applied to a boom surface (hereinafter referred to as a sliding surface) slidingly contacting the pads 4 and 4. Is done.

On the other hand, at the end of the movable boom 2, a limit switch (not shown) constituting an overwinding prevention device is provided. As a means for electrically connecting the switch and a battery mounted on the crane main body, a cord is provided. Both the positive and ground (negative) wires wound on the reel are passed through the boom.

[0006]

A conventional telescopic boom having such a configuration has the following problems.

The sliding pad 4 usually has
A slippery synthetic resin such as a nylon resin is used.

The sliding pad 4 made of this synthetic resin
According to the plastic deformation by the tightening force of the mounting screw 5,
With the passage of time, the tightening force is reduced and the screw 5 is likely to be loosened. This loosening exposes the screw head to the outside of the mounting hole and comes into contact with the sliding surface of the movable boom 2 to easily damage the sliding surface. .

As shown in Japanese Utility Model Application Laid-Open No. 5-14083, a sliding pad is formed in a trapezoidal cross section, and the pad is inserted into a pad carrier having a shape corresponding to the sliding pad to remove a screw. Although a method of mounting the pad has been proposed, the pad fixing state tends to be unstable, such as insufficient pad fixing force, especially when the pad is large, such that the center portion is lifted.

In the method of applying grease to the sliding surface, the so-called stick-slip phenomenon, in which the effect of applying the grease is not long-lasting, the lubricating action is lost at an early stage, and the boom stretching movement becomes jerky, tends to occur.

Alternatively, grease must be frequently applied to prevent this, and maintenance has been troublesome.

It is to be noted that a method of providing a grease plate behind the sliding pad 4, injecting and filling grease, and applying the grease to the sliding surface by the expansion and contraction movement of the boom is also adopted. It is not a fundamental solution because it loses its effect.

According to a system in which a total of two wires on the plus side and the ground side are fed out of the cord reel as a method for energizing the overwinding prevention limit switch, the wire diameter becomes large, so that a large code reel is required. Costly. In addition, since the wire diameter was large, turbulence on the code reel was likely to occur.

Therefore, the present invention can (i) secure the mounting state of the sliding pad by maintaining the pad tightening force of the fastener for a long period of time, and (ii) secure the lubrication effect of the boom sliding surface for a long period of time. (Iii) A telescopic boom that can reduce the size of a cord reel by using a single electric wire for energizing a limit switch and prevent turbulence.

[0015]

According to a first aspect of the present invention, a plurality of unit booms are telescopically fitted to each other and configured to be extendable and contractable, and a pad mounting portion of each unit boom is provided between adjacent unit booms. Is a telescopic boom in which a sliding pad that keeps a constant gap is attached by a fastener, wherein the sliding pad has a small-diameter hole through which a shaft portion of the fastener passes and a large-diameter hole into which a head of the fastener fits. A stepped mounting hole is provided, and a spacer having a flange portion is provided between the head of the fastener and the pad carrier in the mounting hole, and the fastening force of the fastener is applied to the pad through the spacer. While acting on the mounting part, it is provided with the sliding pad sandwiched between the flange part and the pad carrier,
Further, it is provided with a porous greasing body capable of containing lubricating oil, and an energizing brush for energizing between adjacent unit booms.

According to a second aspect of the present invention, a plurality of unit booms are telescopically fitted to each other so as to be extendable and contractable, and a gap between adjacent unit booms is kept constant at a pad mounting portion of each unit boom. A sliding boom in which a sliding pad is attached by a fastener, wherein the sliding pad has a stepped hole having a small-diameter hole through which a shaft portion of the fastener passes and a large-diameter hole into which a head of the fastener is fitted. A mounting hole is provided, and a spacer having a flange is provided between the head of the fastener and the pad carrier in the mounting hole, and the fastening force of the fastener acts on the pad mounting portion via the spacer. The sliding pad is provided between the flange portion and the pad carrier so as to sandwich the sliding pad.

According to a third aspect of the present invention, in the configuration of the second aspect, the sliding pad is attached to an end portion in the boom width direction, and the center of the mounting hole of the pad is located on the center side in the boom width direction with respect to the center of the pad. It is offset.

According to a fourth aspect of the present invention, in the configuration of the second or third aspect, a stopper for restricting the movement of the sliding pad in the boom length direction is provided on the pad mounting portion, and the end surface of the sliding pad in the boom length direction is provided. And a gap larger than the above-mentioned sliding gap is provided between the circumferential surface of the spacer and the circumferential surface of the mounting hole.

According to a fifth aspect of the present invention, a plurality of unit booms are telescopically fitted to each other to extend and contract, and each unit boom is provided with a sliding pad for maintaining a constant gap between adjacent unit booms; A porous greasing body capable of containing lubricating oil is provided side by side in the boom length direction.

According to a sixth aspect of the present invention, in the configuration of the first or fifth aspect, the greasing body is provided with a greasing hole into which lubricating oil is injected from the outside, and a lubrication surface is provided on a sliding surface with respect to the unit boom. A groove-shaped oil reservoir for storing oil is provided in communication with the greasing hole.

According to a seventh aspect of the present invention, in the configuration of the sixth aspect, the oil reservoir is provided so as to be open to the outside at the end face of the greasing body.

According to an eighth aspect of the present invention, in the configuration of the sixth or seventh aspect, a plurality of oil sumps are provided branching from the greasing hole, and each oil sump is branched from a branch point of the oil sump in the greasing hole. It is configured such that the distance to the end is substantially the same for each oil sump.

According to a ninth aspect of the present invention, there is provided a telescopic boom in which a plurality of stages of unit booms are telescopically fitted to extend and contract, and provided with an energizing brush for energizing adjacent unit booms. It is.

According to a tenth aspect of the present invention, in the configuration of the ninth aspect, the energizing brush is provided in series with the sliding pad in the boom length direction.

The invention of claim 11 is the invention of claim 9 or 10
In the configuration of, the energizing brush is formed by a leaf spring,
It is mounted in a state of elastically contacting adjacent booms.

According to a twelfth aspect of the present invention, in the configuration of any of the ninth to eleventh aspects, the energizing brush is provided with a projection as a contact for an adjacent boom.

According to the first to fourth aspects of the present invention, the pad is sandwiched between the flange portion of the spacer and the pad carrier in a state where the fastening force of the fastener acts on the pad mounting portion via the spacer. Therefore, the fastening force is kept constant for a long time regardless of the presence or absence of plastic deformation of the sliding pad, and a stable pad mounting state can be maintained.

By the way, the sliding pads are usually provided at both ends in the boom width direction as described in claim 2.

Both ends in the width direction of the boom are portions having the highest rigidity and being hardly elastically deformed as characteristics of the box-shaped structure, and the surface pressure acting on the sliding pad is also high. It gets higher as you get closer. That is, when roughly divided, the boom corner portion side from the pad center is a high surface pressure portion, and the boom center side is a low surface pressure portion.

Here, the effective area of the high surface pressure portion is increased by positioning the mounting hole of the pad with respect to the center of the boom in the width direction of the boom, that is, at the low surface pressure portion. Thus, the load on the pad as a whole is reduced.

Further, stress concentration on the mounting hole can be reduced.

With these two points, the load capacity of the pad can be increased, and the life of the pad can be improved.

On the other hand, according to the configuration of claim 4, the gap between the peripheral side surface of the fastener and the peripheral surface of the large diameter hole in the mounting hole is:
Since the pad is larger than the sliding gap of the pad mounting portion, even if the pad moves within the sliding gap due to sliding resistance when the boom expands and contracts, no load is applied to the fastener. For this reason, loosening (in the case of a screw) or bending of the fastener does not occur, and the pad mounting state is further stabilized.

According to the first or fifth aspect of the present invention, the lubricating oil is contained in the porous lubricating body (for example, sponge), and the lubricating oil is brought into contact with the boom so that a necessary amount of the lubricating oil is supplied to the boom sliding portion. Can be applied automatically.

By the way, according to this configuration, one problem is that the lubricating body is formed by fine particles such as abrasion powder of the pad caused by repeated sliding of the movable boom and the sliding pad and sand and dust which have entered the boom. May cause clogging to prevent the grease from oozing out, and the desired lubricating action may not be performed.

In this respect, according to the configuration of claims 6 to 8, the fine foreign matter is captured by the lubricating oil accumulated in the oil sump in the process of moving on the surface of the greasing body by the sliding action of the unit boom. The lubricating oil in the oil sump is replaced by the oil supply, and foreign matter is discharged to the outside together with the old lubricating oil. Clogging can be suppressed. Therefore, the lubricating action of the boom sliding portion can be stably obtained.

In this case, according to the configuration of claim 7, since the oil reservoir is provided so as to open to the outside at the end face of the lubricating body, old lubricating oil containing fine foreign matter is supplied when lubricating oil is supplied. It is easy to be discharged outside the oil body.

Further, according to the configuration of the eighth aspect, the lubricating oil supplied from the greasing hole spreads evenly in each oil reservoir, and there is no variation in the lubricating oil accumulation state in each oil reservoir.

Therefore, according to the seventh and eighth aspects,
The effect of preventing clogging of the greasing body becomes higher.

On the other hand, according to the constructions of the first, ninth to twelfth aspects, the energizing action between the adjacent unit booms is performed by the energizing brush.

In this case, according to the configuration of the tenth aspect, the energizing brush is provided in series with the sliding pad in the length direction of the boom, and comes into contact with the sliding surface on which rust and soil do not adhere, so that the energizing brush is reliably energized. Action can be obtained.

In particular, according to the structure of the eleventh aspect, the energizing brush made of a leaf spring elastically contacts the sliding surface, a stable contact state can be obtained, and a more reliable energizing operation can be obtained.

Further, according to the structure of the twelfth aspect, in which the projection as a contact is provided on the energizing brush, the contact pressure between the brush and the sliding surface of the boom increases, so that even if there is a coating film or an oxide film, they are peeled off. Contact, and a more reliable energizing effect can be obtained.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

In the following embodiment, a two-stage boom composed of both fixed and movable booms 1 and 2 is used as an example of application according to the conventional description.

First Embodiment (see FIGS. 1 to 5) Pad carriers 13, 13 serving as pad mounting portions are welded to the left and right sides of the inner surface of the bottom plate at the distal end of the fixed boom 1.
The pad carrier 1 is fixed by screws or the like.
Sliding pads 14, 14 are attached to the 3, 3 by means of a plurality of (three in the example of FIG. 2) rivets 15..

The mounting structure of the sliding pad 14 on both sides will be described. Mounting holes 16 and 17 corresponding to the pad 14 and the pad carrier 13 are provided.

As shown in FIG. 3, the pad-side mounting hole 16 is formed in a stepped hole shape having a small-diameter hole 16a through which the shaft of the rivet 15 penetrates, and a large-diameter hole 16b into which the rivet head is fitted. ing.

A spacer 17 is provided between the rivet head and the pad carrier 13 in the pad-side mounting hole 16, and the tightening force of the rivet 15 is
Through the pad carrier 14.

The spacer 17 has a flange 17a, and the sliding pad 14 is mounted in a state of being sandwiched between the flange 17a and the pad carrier 14.

In this case, as shown in the drawing, the flange portion 17a and the pad 14 are arranged so that the tightening force of the rivet 15 does not directly act on the sliding pad 14 via the flange portion 17a.
Leave a slight gap in the axial direction between them, or bring them into contact with no pressure applied.

Alternatively, if a state where the tightening force of the rivet 15 acts on the pad carrier 13 via the spacer 17 is ensured, the state may be such that the tightening force acts on the pad 14.

According to this pad mounting structure, since the tightening force of the rivets 15... Acts on the pad carrier 13 via the spacer 17 as described above, the pad mounting state can be maintained regardless of whether the sliding pad 14 is plastically deformed. It is kept stable for a long time.

Also, the pad carrier 13 has the structure shown in FIGS.
As shown in FIG. 3, stoppers 18 are provided at both ends of the front and rear (boom length direction) to restrict the movement of the sliding pad 14 in the front and rear direction. A sliding gap C1 for allowing a slight movement in the length direction is provided.

On the other hand, a gap C2 is also provided between the peripheral side surface of the spacer 17 and the peripheral surface of the pad-side mounting hole 16, and the relationship between the two gaps C1 and C2 is set to C1 <C2.

In this way, even if the pad 14 moves within the sliding gap C1 due to the sliding resistance at the time of boom expansion and contraction, no load is applied to the rivet 15, so that the rivet 15 does not bend for a long time. .

Also, as shown in FIG.
Numeral 6 is provided so as to be offset toward the center in the boom width direction with respect to the center line L of the sliding pad 14.

In this case, the pad mounting portion by the rivets 15 is located at the low surface pressure portion of the pad 14 (on the boom center side with respect to the pad center line), so that the effective area of the high surface pressure portion is reduced. growing.

As a result, the load on the pad as a whole is reduced, and the concentration of stress on the mounting hole 16 can be alleviated.
Pad life can be improved.

On the other hand, a greasing body 19 is provided behind the pad carrier 13 (on the base end side of the boom).

The lubricating body 19 is formed of a porous material such as sponge or felt into a rectangular thick plate shape, and the lubricating body mounting plate 20 is in a state where its surface is in contact with the lower surface of the movable boom 2.
And is attached to the fixed boom 1 via a.

The greasing body 19 is provided with a round greasing hole 19a in the center, and grease as lubricating oil supplied from the grease nipple 21 by a grease gun or the like passes through the greasing hole 19a. It strikes the movable boom bottom plate and diffuses into the greasing body 19 to be impregnated.

In this way, the required amount of grease is applied to the sliding surface by the contact between the lubricating body 19 and the movable boom 2 due to the boom expansion and contraction movement, so that the lubrication action is ensured for a long time.

Further, behind the greasing body mounting plate 20, an energizing brush 22 made of a leaf spring is mounted on a line passing through the sliding pad 14 and the greasing body 19.

The energizing brush 22 has protrusions 22a, 22a as contacts on both left and right ends of the tip.
2a and 22a elastically contact the bottom plate outer surface of the movable boom 2 to prevent over-winding attached to the battery ground terminal-crane body-fixed boom 1-current brush 21-movable boom 2-movable boom tip. Energized in the path of the limit switch.

The positive terminal of the battery is connected to a limit switch via a positive electric wire drawn from a cord reel (not shown).

As described above, the energizing brush 22 is provided side by side with the sliding pad 14 in the length direction of the boom so that the energizing brush 22 comes into contact with a sliding surface free of rust or soil that hinders energization, so that a reliable energizing operation can be achieved. Can be obtained.

Moreover, (a) the brush 22 is formed of a leaf spring and elastically contacts the sliding surface. (B) The contact pressure between the brush 22 and the sliding surface is increased by the projections 22a and 22a. Even if there is a coating film or an oxide film on the sliding surface, the contact state is maintained while peeling the coating film or the oxide film, so that a more reliable and stable energizing action can be obtained.

The projections 22a, 22a with respect to the sliding surface
In the sense that the contact pressure of
It is desirable that the a and 22a be pointed (triangular or pen point).

Second Embodiment (See FIG. 6) As a fastener for attaching the sliding pad 14 to the pad carrier 13, it is desirable to use the rivet 15 described in the first embodiment in that no loosening occurs. However, the screw 23 may be used as in the second embodiment.

Also in this case, the pad 14 is sandwiched between the spacer flange 17a and the pad carrier 13 in a state where the tightening force of the screw 23 does not directly act on the sliding pad 14. Is basically the same as in the first embodiment.

Third Embodiment (See FIGS. 7 to 9) The third embodiment shows another variation of the greasing body.

That is, the greasing body 24 shown here is provided with a greasing hole 25 in the center thereof, which is elongated in the length direction of the greasing body (in the boom sliding direction, the horizontal direction in FIGS. 7 and 8). The grease nipple 21 is provided at the center of the greasing hole 25.

The greasing hole 25 is formed to have a width dimension larger than the diameter dimension of the grease nipple 21 and a length dimension larger than the width dimension, and to be larger than the greasing hole 19a in the greasing body 19 of the first embodiment. Also have a large volume.

Further, the movable boom 2 is
A plurality of groove-shaped oil reservoirs 2 on the surface which is a sliding surface against
6 are provided in communication with the greasing holes 25.

Each of the oil reservoirs 26 branches from the periphery of the greasing hole 25 in the length direction of the greasing body and in the width direction of the greasing body, and the branched ends thereof open to the outside at the greasing body end faces. It is provided in the state where it does.

Here, the width of each oil reservoir 26 is substantially the same, and the distance a from the branch point of each oil reservoir 26 in the greasing hole 25 to the end of each oil reservoir 26 is The shape, size, and the like of the greasing hole 25 are set so as to be substantially the same for the oil sumps 26.

Grease nipple 2 with grease gun
After the grease supplied from 1 is filled in the greasing hole 25, the grease is distributed and stored in the respective oil sumps 26, and the bottom plate of the movable boom 2 is brought into contact with the greasing body 24 and the movable boom 2 by the boom expansion and contraction movement. It is applied to the outer surface.

According to this lubricating body configuration, clogging of the lubricating body 24 due to abrasion powder of the sliding pad 4 or fine foreign matter such as sand or dust entering from the outside prevents the oil sump 26 from being provided. It is much less likely to occur as compared to the greasing body 19) of the embodiment.

The reason is that the fine foreign matter is caught and held by the grease accumulated in the oil sump 26... In the process of moving in the boom sliding direction on the greasing body surface by the boom sliding movement. This is because it is discharged in an overflow manner in the width direction or the length direction together with the old grease.

Since the oil reservoirs 26 are open to the outside at the end faces of the greasing body 24, old grease containing fine foreign matter is easily discharged to the outside of the greasing body when grease is supplied.

Since the distance a from the branch point of each oil sump 26 to the oil sump end is set to be substantially the same, the grease supplied from the greasing hole 25 is evenly distributed to each oil sump 26. There is no variation in the state of grease accumulation in the oil sumps 26.

Therefore, the effect of preventing the greasing body 24 from being clogged becomes higher.

The sectional shape of the oil reservoirs 26 may be a quadrangle, a trapezoid, a semicircle, or the like, in addition to the inverted trapezoid as shown in the figure.

Of the oil sumps 26, those extending in the width direction of the greasing body are inclined with respect to the width direction of the greasing body, and those extending in the length direction of the greasing body are inclined with respect to the length direction of the greasing body. May be provided.

Further, the oil sump 26 is moved only in the lubricating body width direction.
Alternatively, it may be provided only in the lubricating body length direction.

Although the energizing brush 22 is not shown in FIGS. 7 and 8, the energizing brush 22 can be provided after the greasing body 24 in the third embodiment as in the first embodiment.

Alternatively, the energizing brush 22 may be provided as needed, and it is of course possible to adopt an embodiment in which the brush 22 is not provided as shown in FIGS.

On the other hand, in the above-mentioned embodiment, only the case where the sliding pads 14 are provided on the left and right sides of the inner surface of the bottom plate at the tip of the movable boom 2 in the two-stage boom has been exemplified for the sake of easy understanding. 14 are provided on the left and right sides of the outer surface of the top plate at the base end of the fixed boom 1 and also on each unit boom of three or more booms in the same manner as described above.

In the first embodiment, the sliding pad 14, the greasing body 19, and the energizing brush 22 are used. In the third embodiment (FIGS. 7 and 8), the sliding pad 1 is used.
Although the lubricating body 4 and the lubrication body 24 are provided continuously in front and back, respectively, they may be separately provided side by side in the boom length direction.

[0091]

As described above, according to the first to fourth aspects of the present invention, when the fastening force of the fastener acts on the pad mounting portion via the spacer, the gap between the flange portion of the spacer and the pad carrier is provided. Since the pad is sandwiched between the sliding pads, the tightening force is kept constant for a long time regardless of the presence or absence of plastic deformation of the sliding pad, and a stable pad mounting state can be maintained.

According to the third aspect of the present invention, since the mounting hole of the pad is located on the center side of the boom in the width direction of the boom with respect to the center of the pad, that is, at the low surface pressure portion, the effective area of the high surface pressure portion is reduced. As a result, the load on the pad as a whole is reduced, and the concentration of stress on the mounting hole can be reduced.

Thus, the load capacity of the pad can be increased, and the pad life can be improved.

On the other hand, according to the fourth aspect of the present invention, the clearance between the peripheral side surface of the fastener and the peripheral surface of the mounting hole is larger than the sliding clearance of the pad mounting portion. Even if the pad moves within the sliding gap, no load is applied to the fastener. For this reason, loosening (in the case of a screw) or bending of the fastener does not occur, and the pad mounting state is further stabilized.

According to the first or fifth to eighth aspects of the present invention, the lubricating oil is impregnated in the porous lubricating body (for example, sponge), and the lubricating oil is brought into contact with the boom so that the required amount of lubricating oil is boom-slided. It can be automatically applied to moving parts.

According to the invention of claims 6 to 8, the fine foreign matter is trapped by the lubricating oil accumulated in the oil sump in the process of moving on the surface of the greasing body by the sliding action of the unit boom. The oil in the oil reservoir is replaced by lubrication, and foreign matter is discharged to the outside together with the old lubricating oil. Clogging can be suppressed. Therefore, the lubricating action of the boom sliding portion can be stably obtained.

In this case, according to the seventh aspect of the present invention, since the oil reservoir is provided so as to open to the outside at the end face of the greasing body, old lubricating oil containing fine foreign matter is supplied when lubricating oil is supplied. It is easy to be discharged outside the oil body.

According to the eighth aspect of the present invention, the lubricating oil supplied from the greasing hole evenly spreads over the respective oil sumps, and the state of the lubricating oil accumulation in each oil sump does not vary.

Therefore, according to the seventh and eighth aspects of the present invention,
The effect of preventing clogging of the greasing body becomes higher.

On the other hand, according to the first, ninth to twelfth aspects of the present invention, an energizing action is performed between adjacent unit booms by the energizing brush.

In this case, according to the tenth aspect of the present invention, the energizing brush is provided in series with the sliding pad in the length direction of the boom, and comes into contact with the sliding surface on which rust and dirt do not adhere. Action can be obtained.

In particular, according to the eleventh aspect of the present invention, the energizing brush made of a leaf spring elastically contacts the sliding surface, a stable contact state can be obtained, and a more reliable energizing operation can be obtained.

Furthermore, according to the twelfth aspect of the present invention, in which the projection as a contact is provided on the energizing brush, the contact pressure between the brush and the sliding surface of the boom is increased. Contact, and a more reliable energizing effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view of a telescopic boom according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged sectional view taken along the line III-III of FIG. 2;

FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG. 2;

FIG. 5 is an enlarged view of an energizing brush portion in FIG.

FIG. 6 is a diagram corresponding to FIG. 3, showing a second embodiment of the present invention.

FIG. 7 is a vertical sectional view showing a third embodiment of the present invention.

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a perspective view of a greasing body according to a third embodiment.

FIG. 10 is a partial cross-sectional view of a boom for explaining a conventional technique.

FIG. 11 is a sectional view taken along line XI-XI of FIG. 10;

FIG. 12 is a partially enlarged view of FIG. 10;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fixed boom as a unit boom 2 Same movable boom 13 Pad carrier as a pad attaching part 14 Sliding pad 15 Rivet as a fastener 16 Mounting hole of a sliding pad 16a Small hole of the same mounting hole 16b Large hole of the same diameter 17 Spacer 17a Spacer 18 Flip portion of pad carrier 18 C1 Sliding gap between front and rear end faces of pad and stopper C2 Gap between peripheral side surface of spacer and peripheral surface of pad-side mounting hole L Center line of sliding pad 19 Greasing Body 19a Greasing hole 22 Electric brush 22a, 22a Projection of the brush 24 Greasing body 25 Greasing hole 26 Oil reservoir

Claims (12)

[Claims] A plurality of unit booms are telescopically fitted so as to be extendable and contractable, and a sliding pad for maintaining a constant gap between adjacent unit booms is provided at a pad mounting portion of each unit boom. A telescopic boom attached by the sliding pad, the sliding pad is provided with a stepped hole-shaped mounting hole having a small-diameter hole through which the shaft of the fastener penetrates and a large-diameter hole into which the head of the fastener is fitted; In this mounting hole, between the head of the fastener and the pad carrier,
A spacer having a flange is provided in a state where the tightening force of the fastener acts on the pad mounting portion via the spacer, and a sliding pad is sandwiched between the flange and the pad carrier. A telescopic boom comprising: a porous greasing body capable of containing oil; and an energizing brush for energizing an adjacent unit boom. 2. A plurality of unit booms are telescopically fitted so as to be extendable and contractible, and a sliding pad for maintaining a constant gap between adjacent unit booms is provided on a pad mounting portion of each unit boom. A telescopic boom attached by the sliding pad, the sliding pad is provided with a stepped hole-shaped mounting hole having a small-diameter hole through which the shaft of the fastener penetrates and a large-diameter hole into which the head of the fastener is fitted; In this mounting hole, between the head of the fastener and the pad carrier,
A spacer having a flange is provided so that the tightening force of the fastener acts on the pad mounting portion via the spacer and a sliding pad is sandwiched between the flange and the pad carrier. Characteristic telescopic boom. 3. The telescopic boom according to claim 2, wherein a sliding pad is attached to an end portion in a boom width direction.
A telescopic boom characterized in that the center of the mounting hole of the pad is offset toward the center of the boom in the width direction with respect to the center of the pad. 4. A telescopic boom according to claim 2, wherein a stopper for restricting movement of the sliding pad in the boom length direction is provided between the pad mounting portion and the end surface of the sliding pad in the boom length direction. A telescopic boom provided in a state where a dynamic gap is formed, wherein a gap larger than the sliding gap is provided between the peripheral side surface of the spacer and the peripheral surface of the mounting hole. 5. A multi-stage unit boom is telescopically fitted to extend and contract, and each unit boom contains a sliding pad for keeping a constant gap between adjacent unit booms, and a lubricating oil. A telescopic boom characterized in that the obtained porous greasing body is provided side by side in the boom length direction. 6. The telescopic boom according to claim 1, wherein the greasing body is provided with a greasing hole into which lubricating oil is injected from the outside, and a sliding surface with respect to the unit boom is provided.
A telescopic boom, wherein a groove-shaped oil reservoir for storing lubricating oil is provided in communication with the greasing hole. 7. The telescopic boom according to claim 6, wherein the oil sump is provided so as to open to the outside at an end surface of the greasing body. 8. The telescopic boom according to claim 6, wherein a plurality of oil sumps are provided branching from the greasing holes, and a portion from a branch point of each oil sump in the greasing hole to an end of each oil sump. A telescopic boom characterized in that the distance is configured to be substantially the same for each oil sump. 9. An extendable telescopic boom in which a plurality of stages of unit booms are telescopically fitted to each other and provided with an energizing brush for energizing adjacent unit booms. boom. 10. The telescopic boom according to claim 9, wherein the energizing brush is provided in series with the sliding pad in the boom length direction. 11. An electric brush is formed by a leaf spring.
The telescopic boom according to claim 9 or 10, wherein the telescopic boom is mounted in a state of elastically contacting an adjacent boom. 12. The telescopic boom according to claim 9, wherein the energizing brush is provided with a projection as a contact for an adjacent boom.