JP2005163539A - Excavation work arm structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in a pivot structure with a pivot pin provided at each part of an excavation work arm wherein, if a rotation is prevented with only one locking bolt, the bolt is not strong enough to resist the rotation force applied to the pivot pin when the excavation work arm is bent and stretched, the bolt may be cut off and the pivot pin may fall off. <P>SOLUTION: In a structure where a boss provided at each part of the excavation work arm is pivoted with a pivot pin 22 loosely installed between arm-bracket plates 5, 5, an end of the pivot pin 22 on which a washer 23 is fixedly mounted is screwed to one of the arm-bracket plates 5L with one locking bolt 24 while on the other end a washer 27 is fixedly mounted or a C-type retaining ring 28 is annularly provided, so that the pivot pin is prevented from being pulled out of the arm-bracket panel 5R on the other side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention mainly relates to the structure of a pivotal support portion of a boom in an excavation work arm supported by a turning work vehicle or an excavation work vehicle.

  Excavation work arms such as excavation work vehicles are provided with pivot portions in each part. For example, a structure in which a boss at the base end of the arm is pivotally supported by a pivot pin between the left and right bracket plates at the tip of the boom can be seen. In such a pivot structure with the pivot pins, the pivoting force is applied to the pivot pins by the bending and stretching operation of the excavation work arm. Therefore, the pivot pin needs to have a detent structure. Conventionally, a washer fixed to one end of the pivot pin is screwed to one bracket plate of the left and right bracket plates, or a member for preventing rotation has been provided.

  Among these, as the former structure, those shown in FIGS. 18 to 20 which will be described in detail later are publicly known, and among these, the one shown in FIG. 18 is a basic structure with one detent bolt. 19 and 20, two bolts are used, and in addition, a member for preventing rotation is used.

The structure disclosed in Japanese Patent Laid-Open No. 7-208448 is similar to this. As the latter structure, a rotation-preventing plate is disposed in the vicinity of a washer fixed to the pivot pin shown in FIGS. 21 and 22, which will be described in detail later, and the other end of the pivot pin is prevented from coming off. A structure in which a bolt (or a split pin) is inserted in the radial direction is known.
Further, the pivot structure disclosed in Japanese Utility Model Publication No. 7-35552 is a pivot structure of the bucket base end with respect to the arm tip, but here, the end portion side where the washer of the pivot pin is not fixed is bolted. A structure in which the rotation is prevented by, for example, is disclosed.
JP-A-7-208448 Japanese Utility Model Publication No. 7-35552

  The present invention relates to an improvement in an arm of a turning work vehicle or the like, and relates to an improvement in a welding position or the like that increases the strength of the arm.

  In the pivot structure using pivot pins provided at each part of the work arm, the rotation is prevented by one rotation-preventing bolt as shown in FIG. There is a possibility that the bolt cannot resist the rotational force applied to the support pin, the bolt is cut, and the pivot pin falls off.

  As shown in FIGS. 19 and 20 and Japanese Patent Application Laid-Open No. 7-208448 and Japanese Utility Model Application Laid-Open No. 7-35552, if other members or a plurality of bolts are used for preventing rotation, the rotation of the pivot pin can be strengthened. However, the number of parts is large, resulting in high cost. On the other hand, as shown in FIGS. 21 and 22, in the structure in which the side where the washer of the pivotal support pin is fixed is prevented and the other end is prevented from coming off with a bolt or a split pin, the bolt or the split pin is likely to be deformed. If you repeat the work of attaching and detaching the pivot pin, there is anxiety about reuse.

The present invention solves the problems as described above, and uses the following means to reduce the weight and secure the strength at the tip of the boom and to enable mass production and ensure the strength corresponding to the increase in the size of the boom.
In a structure in which a boss provided on each part of the excavation work arm is pivotally supported by loosely fitting a pivot pin 22 between the arm bracket plates 5 and 5, a washer 23 is fixed to one end of the pivot pin 22 to provide one piece. Is screwed to one arm bracket plate 5L with a non-rotating bolt 24, and a washer 27 is fixed to the other end or a C-type retaining ring 28 is provided to the other end so that it can be removed from the other arm bracket plate 5R. It has a structure to stop.

Since this invention comprised the excavation work arm as mentioned above, there exist the following effects. In a structure in which a boss provided on each part of the excavation work arm is pivotally supported by loosely fitting a pivot pin 22 between the arm bracket plates 5 and 5, a washer 23 is fixed to one end of the pivot pin 22 to provide one piece. Is screwed to one arm bracket plate 5L with a non-rotating bolt 24, and a washer 27 is fixed to the other end or a C-type retaining ring 28 is provided to the other end so that it can be removed from the other arm bracket plate 5R. Since it is structured to be fixed, the rotation prevention structure of the pivot pin itself is as simple as screwing the washer fixed to the pivot pin to the bracket plate with a single locking bolt. The cost is low and the cost is low.
On the other hand, the pin is prevented from falling off by screwing a washer or ringing a C-type retaining ring at the other end of the pivot pin so as to compensate for this weak detent structure. The Further, the screwing of a washer as a retaining ring and the ringing of a C-type retaining ring are unlikely to be deformed unlike conventional retaining bolts and split pins, and are low in cost and withstand reuse.
From the above, the pivot pin can be prevented from falling off at low cost, and this can be used not only for excavation work arms but also for all other similar pivot structures.

Embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a side view of a boom 1 according to the present invention, FIG. 2 is a side view of the boom 1 in a state where the boom 1 is disassembled into a front side plate 2a, a rear side plate 2b, a back plate 3 and a belly plate 4 as basic components. 4 is a front side view, FIG. 5 is a front side view of the boom 1 with a conventional arm bracket plate 5 ′ attached, FIG. 6 is a rear view of the front half of the boom 1, and FIG. FIG. 8 is a rear view of the rear part of the boom 1 in a state where it is supported by the excavation work vehicle, FIG. 10 is a rear view of the rear part of the boom 1, and FIG. 12 is a partial rear view of the boom 1 showing the welded structure of the clamp seat 11, FIG. 12 is a front sectional view of the pipe clamp C, and FIG. 13 is a boom 1 showing the welded structure of the pipe clamp part 11 to which the grease hose 15 can be fixed. 14 is a partial rear view, and FIG. 14 is for piping that enables the grease hose 15 to be fixed. FIG. 15 is a front cross-sectional view of the clamp C, FIG. 15 is a front cross-sectional view showing a retaining structure by a washer 27 of the pivot pin 22 in the pivot portion of the arm base end boss 17a to the arm bracket plates 5 and 5, and FIG. FIG. 17 is a front sectional view showing a retaining structure in which a shim 29 is added to the structure of FIG. 16, and FIG. 18 is an arm base to a conventional arm bracket plate 5/5. 19 is a front sectional view showing a retaining structure using only the locking bolt 24 of the pivot pin 22 in the pivot portion of the end boss 17a. FIG. 20 is a side view, FIG. 21 is a front sectional view showing a retaining structure using a conventional anti-rotation plate 5Lb and retaining bolt 32, and FIG. 22 is a side view. 23 is an overall perspective view of the excavation work vehicle, FIG. 24 is a plan view showing the arrangement positions of the levers in the vicinity of the seat, FIG. 25 is a side view showing the lock mechanism of the work arm operation lever, and FIG. FIG. 27 is an electric circuit diagram showing another embodiment of the present invention. FIG.

  As shown in FIG. 23, in the excavation work vehicle according to the embodiment of the present invention, the main body frame 20 is turnably mounted on the crawler traveling device 21, and the boom bracket 19 can swing left and right at the front end of the main body frame 20. The base end of the boom 1 is pivotally supported at the upper end thereof, the base end of the arm 17 is pivotally supported at the distal end of the boom 1, and the bucket 18 is pivotally supported at the distal end of the arm 17. Forms working arms. A boom cylinder CY1 is disposed on the abdomen side of the boom 1 and is pivotally supported by a boom cylinder end bracket plate 9 that has a base end projecting from the front end of the boom bracket 19 and a piston rod projecting from the boom 1 abdomen. doing. The arm cylinder CY2 is pivotally supported by an arm cylinder proximal bracket plate 8 projecting from the rear side of the boom 1 at the base end thereof, and the piston rod distal end is provided near the base end of the arm 17 at the arm cylinder distal end bracket. It is pivotally supported on the plate 17b. And bucket cylinder CY3 is connected with bucket link 18a for bucket 18 base end rotation from bucket cylinder base end bracket board 17c projected on the back side of arm 17.

  The present invention relates to the configuration of the boom 1 shown in FIG. First, as shown in FIGS. 1 and 2, the main part of the boom 1 includes left and right side plates 2 and 2 (only the left side plate 2 is shown in FIGS. 1 and 2), and an opposing back. The plate 3 and the abdomen 4 are welded to each other, and the left and right side plates 2 are divided into a front plate 2a and a rear plate 2b, which are welded to form a single side plate 2. Yes. About these board | plate materials 2 (2a * 2b) * 3 * 4, an original plate is cut out and comprised.

  The longest of the working arms is the boom 1, and the side plate 2 is the longest of the side plates 2, the back plate 3, and the abdominal plate 4 that are constituent plates of the boom 1. If the vehicle body and the working arm are enlarged, the yield will be exceeded when the side plate 2 is cut out from the original plate. Therefore, as described above, it is necessary to divide the side plate 2 into the front side plate 2a and the rear side plate 2b. The front plate 2a is a common side plate member for both the large boom side plate and the small boom side plate so that at least one of the front plate 2a and the rear plate 2b can be shared. That is, when configuring a large boom, a long rear plate 2b is bonded to the front plate 2a, and when a small boom is configured, a short rear plate 2b is bonded to the same front plate 2a.

  In addition, since a big stress generate | occur | produces in the boom 1 at the time of an operation | work, it will lead to the fall of intensity | strength to increase a welding site | part by dividing into 2 parts to the back plate 3 and the abdominal plate 4. Since the back plate 3 and the abdomen plate 4 are shorter than the side plate 2, the back plate 3 and the abdomen 4 are formed as a single plate even if the side plate 2 is divided into two parts due to an increase in the size of the working arm.

  Next, the arm bracket plate 5 pasting portion at the tip of the boom 1 will be described with reference to FIGS. 1 and 3 to 6. The left and right arm bracket plates 5 and 5 for pivotally supporting the base end of the arm 17 are attached to each distal end portion of the left and right side plates 2 and 2 and welded to each other. Since this portion has a large difference in strength between the portion where the hard arm bracket plate 5 is disposed and the portion where the side plate 2, the back plate 3 and the abdomen 4 of the soft boom 1 are disposed, the portion is weak against torsional force. Here, the arm bracket plate 5 in this embodiment is provided with bulging portions 5a and 5a on the back side and the abdomen side as shown in FIGS. The welded portions 6a and 6b of the tip rib 6 disposed on the back plate 3 and the abdomen plate 4 are covered so that they are not exposed to the outside. In the conventional boom 1 in which the arm bracket plate 5 ′ not provided with the bulging portions 5a and 5b is pasted on the back side and the abdomen side, both welded portions 6a and 6b of the tip rib 6 are shown in FIG. It was exposed like this.

  The front rib 6 is a member that bends in the shape of “<” in a side view and connects the two tips of the back plate 3 and the abdominal plate 4. In this way, from the welded portion 6 a to the back plate 3 The entire portion up to the welded portion 6b is disposed between the arm bracket plates 5 and 5, so that the arm bracket plates 5 and 5 are reinforced and supported from the inside by the entire tip rib 6. And the arrangement | positioning part of this arm bracket board 5 * 5 and the front-end | tip rib 6 becomes a big box, and stress tolerance is strengthened.

  As the stress resistance is improved, the arm bracket plates 5 and 5 can be shortened. Conventionally, a middle rib 7 at the front end is located at a position slightly closer to the base end side than the front end rib 6. 3. It is arranged so as to be surrounded by the abdominal plate 4. Conventionally, as shown in FIG. 5, in order to secure the strength of the arm bracket plate 5 ', it is superposed on the portion where the rib 7 in the tip is arranged. The rear end of the arm bracket plate 5 ′ is extended to the position where it is. That is, as viewed from the side, the arm bracket plate 5 ′ and the middle tip rib 7 are overlapped, and the arm bracket plate 5 ′ is reinforced and supported from the inside by the middle tip rib 7. As described above, the length of the arm bracket plate 5 ′ is limited by the extension of the rear end of the arm bracket plate 5 ′, thus preventing the weight of the entire boom 1 from being reduced. The arm bracket plate 5 'has a large plate thickness, and if this arrangement area is large, the weight and cost increase accordingly.

  At the tip of the boom 1 according to the present invention, as described above, the bulging portions 5a and 5b are provided on the arm bracket plates 5 and 5 so as to cover the welded portions 6a and 6b of the tip rib 6. The arm bracket plates 5 and 5 are reinforced and supported by the tip ribs 6 to ensure stress resistance. Therefore, it is not necessary to superimpose the arm bracket plate 5 on the rib 7 at the tip, and the arm bracket plate 5 is shortened so that the rib 7 at the tip can be made as shown in FIGS. 1, 3, 4 and 6. Alternatively, the rear end of the arm bracket plate 5 may be disposed near the tip. In this manner, the arm bracket plate 5 can ensure the stress resistance at the tip rib 6 and can be shortened, which contributes to the weight reduction and cost reduction of the boom 1.

  Furthermore, by increasing the strength of the portion where the arm bracket plates 5 and 5 are arranged, thin plates can be used for the side plate 2, the back plate 3 and the abdomen plate 4 constituting the boom 1, thereby reducing the weight and cost of the boom 1. realizable. Even if the boom 1 itself is reduced in weight in this way, the arm bracket plate 5 is shortened and reduced in weight, so that the weight balance before and after the boom 1 is not impaired.

  Next, the piping clamp seat 11 disposed on the back plate 3 of the boom 1 will be described. As shown in FIGS. 1, 6, and 7, the clamp seat 11 for piping is welded to an appropriate portion of the back plate 3. On this, a rubber clamp 12 and a metal clamp holding plate 13 are screwed with bolts 14 and 14 as shown in FIG. The welded portion α of the piping clamp seat 11 to the back plate 3 is at both ends of the piping clamp seat 11 as shown in FIGS. 11 and 12, but conventionally, the side plates 2 and 2 are attached to the back plate 3. Irrespective of the contact portion, the welding was performed on the upper surface of the back body 3, and the strength of the welded portion against the torsional stress generated in the boom 1 was weak. In this embodiment, as shown in FIGS. 11 and 12, the side plate 2 overlaps with the contact portion of the side plate 2 with the back plate 3, so that the welded portion α of the piping clamp seat 11 to the back plate 3 is obtained. The side plate 2 is reinforced and supported, and the resistance to the stress generated in the boom 1 is improved.

  The other structure regarding the piping clamp member C is demonstrated. As shown in FIG. 1, FIG. 7, FIG. 13, FIG. 14 and the like, the piping clamp seat 11 arranged closest to the base end protrudes outward from the back plate 3, and grease is formed at the side end. A hose terminal fixing member 11a is fixed. On the back plate 3 of the boom 1, as shown in FIGS. 9 and 10, a grease hose for injecting grease into each pivotal portion of the work arm in parallel with the hydraulic hose H to the arm cylinder CY 2, bucket cylinder CY 3, etc. 15 is piped. Correspondingly, the rubber clamp 12 of the piping clamp member C is provided with a hose hole 12a for guiding the grease hose 12 as shown in FIG. In the piping clamp C closest to the base end portion having the grease hose terminal fixing member 11a, the terminal of the grease hose 15 is fitted and fixed to the grease hose terminal fixing member 11a.

  Conventionally, as shown in FIG. 9, the grease hose 15 ′ is piped on the side plate 2 and the terminal is fixed. However, the appearance is bad, and various indications are given to the side plate 2. The degree of freedom is limited. In the midway position of the boom 1 as shown in FIG. The clamping member C for piping having the grease hose terminal fixing member 11a is closest to the base end, and is accessible to the grease hose terminal fixing member 11a. The injection work can be performed.

  Next, the structure regarding the boom lamp 16 is demonstrated. As shown in FIGS. 8 and 9, the boom lamp 16 is disposed so as to be covered between the left and right boom cylinder end bracket plates 9 and 9 welded to a curved portion in the middle of the belly plate 4 of the boom 1. And protected. In addition, although the side is covered with the boom cylinder end bracket plates 9 and 9 as described above, the lamp irradiation surface is open, so that it has been conventionally covered with a cover for protection. It was. In this embodiment, as shown in FIGS. 8 and 9, the boom rib 16 cover is also used by the reinforcing rib 9a of the boom end bracket plate 9 which is separate from the cover. That is, the reinforcing rib 9a connects the left and right boom cylinder end bracket plates 9 and 9 to reinforce and support both boom cylinder end bracket plates 9 and 9, but has an opening 9b in this, The mounting portions 9c and 9c of the boom lamp 16 are projected inward. When the boom lamp 16 is mounted, both ends of the boom lamp 16 are pivotally supported by the mounting portions 9c and 9c, and the irradiation surface of the boom lamp 16 is opposed to the opening 9b. 9a is an attachment member and a cover for the boom lamp 16 as they are.

  Furthermore, a harness must be wired to the boom lamp 16 from the base end side. Conventionally, the boom lamp 16 is arranged on the one side plate 2 and the harness is also wired to the hydraulic hose piped on the back plate 3 with a bundle band. Wiring by is time consuming, looks bad, and lacks protection. In this embodiment, as shown in FIGS. 1 and 8, the boom lamp 16 is disposed between the boom cylinder end bracket plates 9 and 9, and on the other hand, at one end of the belly plate 4 of the boom 1. The boom lamp harness guide tube 10 welded along the wire is inserted into the harness and wired. 10 is easy to insert.

  Next, the retaining structure of the pivot pin 22 at the pivot portion of the proximal end boss 17a of the arm 17 to the arm bracket plates 5 and 5 at the distal end portion of the boom 1 will be described with reference to FIGS. Note that this pivot pin retaining structure includes other pivot portions in the excavation work arm, for example, a pivot portion to the boom bracket 19 at the base end of the boom 1, a pivot portion to the tip of the arm 17 at the base end of the bucket 18, and 23, the base end of each cylinder CY1 to CY3 and the pivot part of the tip, and the base end pivot part of the earth removal blade 47 provided in the excavation work vehicle shown in FIG. It can also be applied to the pivot unit. Furthermore, regardless of the excavation work arm or excavation work vehicle, it can be applied to all structures in which the boss is pivotally supported by the pivot pin between the left and right brackets.

  First, a conventional retaining structure for the pivot pin 22 will be described with reference to FIGS. Basically, as shown in FIG. 18, only one end of the pivot pin 22 is inserted into the right arm bracket plate 5R, and a washer 23 is welded to the other end, and the other end is inserted. The left arm bracket plate 5L is screwed with a non-rotating bolt 24 on the outer surface. In this structure, in FIG. 18, the portion inserted into the right arm bracket plate 5R is in a substantially loose fit state, and the pivot pin 22 is in a rotatable state within the shaft hole of the right arm bracket plate 5R. Yes. Accordingly, the rotation of the pivot pin 22 is limited only by the rotation stop bolt 24 that screws the washer 23 to the left arm bracket plate 5L. If a large amount of torsional stress is applied, the pivot pin 22 is pivotally supported. The retaining bolt 24 is sheared by the force to rotate the pin 22, and the pivot pin 22 becomes freely rotatable. In the worst case, the end portion of the pivot pin 22 comes off from the right arm bracket plate 5R.

  Therefore, in order to reinforce the detent of the pivot pin 22, a structure as shown in FIGS. 19 to 22 has been conventionally used. First, in FIG. 19 and FIG. 20, a detent plate 30 is straddled on the washer 23 outside the left arm bracket plate 5L, and two detent bolts 31. At 31, a screw seat 5La projecting from the left arm bracket plate 5L is screwed. In other words, the washer 23 in the left arm bracket plate 5L is prevented from being rotated by the rotation stop plate 30, and the fixing strength of the rotation stop plate 30 to the left arm bracket plate 5L is increased. With this structure, the anti-rotation effect is improved, but the anti-rotation plate 30 and two bolts are required, and the cost increases due to an increase in the number of parts.

  21 and 22, the non-rotating bolt is not used in the left arm bracket 5L. That is, the pivot pin 22 is rotatable in the shaft hole of the left arm bracket plate 5L. Instead, the pivot pin 22 is fixed to the tip of the washer 23 'fixed at the tip thereof. In the vicinity of the washer 23 ', a detent plate member 5Lb is projected from the left arm bracket plate 5L. Thus, although the pivot pin 22 can be prevented from rotating, unlike the bolt fastening, the axial movement of the pivot pin 22 cannot be restricted. That is, in this state, the pivot pin 22 may slide in the axial direction (left side in FIG. 21) and fall off from the arm bracket plate 5. Therefore, on the outside of the right arm bracket plate 5R, a retaining bolt 32 (a split pin may be used) penetrates the pivot pin 22 in the radial direction, and the pivot pin 22 moves in the axial direction. However, the retaining bolt 32 (or split pin) is not caught by the right arm bracket plate 5R, and the pivot pin 22 does not fall off.

  However, in this structure, if the retaining bolt 32 is used, the screw thread is liable to be crushed, and there is a concern about reuse. In addition, when a split pin is used, it is easy to be lost when the split pin is pulled out, and it is easy to deform, so there is still concern about reuse.

  The pivot structure of the pivot pin 22 shown in FIGS. 15 to 17 employs a retaining structure that solves such a problem. First, in both FIGS. 15 to 17, the rotation of the pivot pin 22 (and the washer 23 fixed to the left arm bracket plate 5L) on the left arm bracket plate 5L is fixed to a single locking bolt 24 as in the conventional FIG. The washer 23 is screwed to the left arm bracket plate 5L, and the cost is low. In FIG. 15, the right arm bracket plate 5R has a structure in which a washer 27 is screwed to the right end of the pivot pin 22, and in FIG. 16, the tip of the pivot pin 22 is moved from the right arm bracket plate 5R. As a structure in which a C-type retaining ring 28 is provided so as to protrude, the retaining from the right arm bracket plate 5R is prevented.

  Further, in FIG. 17, a C-type retaining ring 28 is also provided, and a shim 29 is interposed between the C-type retaining ring 28 and the right arm bracket plate 5 </ b> R, so that the pivot pin 22 and the right arm are provided. The pressure contact force with the bracket plate 5 can be adjusted. In addition, a bush 25 and a dust seal 26 are fitted in the arm base end boss 17a to which the pivot pin 22 is loosely fitted so as to be provided around the pivot pin 22; If the fitting pin 23 is provided with a fitting groove so as to circulate, the dust seal 26 may be damaged when the fitting groove comes into contact with the dust seal 26 when the pivoting pin 23 is attached or detached. There is. Therefore, in the pivot pin 22 of FIG. 17, the annular portion of the C-type retaining ring 28 is not a groove but is provided with a step portion 22 a so that the dust seal 26 is not caught when contacting the dust seal 26.

  Finally, referring to FIG. 23 to FIG. 27, the abnormality warning mechanism of the electric system when operating the work arm will be described. First, as shown in FIGS. 23 and 24, the cylinders CY1 to CY3 for driving the working arms of the boom 1, the arm 17 and the bucket 18 and the swing cylinder (not shown) for swinging the boom bracket 19 are a seat. It is operated in front of 33 by working arm operation levers 34L and 34R arranged on the left and right. Among these, the left work arm operation lever 34L is disposed on the operation box 36 on the left side of the seat 33, and from the front of the operation box 36, at the front position of the left work arm operation lever 34L. A lock lever 35 is protruded. In FIG. 24, 37 indicates the position of the starter switch 37.

  In the operation box 36, as shown in FIG. 25, the base end of the lock lever 35 is pivotally supported so as to be pivotable up and down, and a lever lock switch 38 is disposed in the vicinity of the base end pivot support portion. . When the lock lever 35 is pulled up to the X position, the base end portion of the lock lever 35 presses against the lever lock switch 38 to turn off the switch (OFF when pressed, ON when not pressed). ). An electromagnetic solenoid 39 (shown in FIGS. 26 and 27) for supplying a pilot pressure is provided for a hydraulic circuit to the hydraulic cylinders CY1 to CY3 for driving the work arm. The oil is set to be supplied, and when no power is supplied, the pilot pressure supply is stopped, and the hydraulic cylinders CY1 to CY3 cannot be driven and the working arm cannot be operated. The lever lock switch 38 is for de-energizing the electromagnetic solenoid 39 when the switch is turned off. That is, when the lock lever 35 is pulled up to the X position, the hydraulic system for driving the work arm becomes inoperable. When the work arm is not operated, it is possible to avoid a situation in which the work arm is moved by mistakenly pressing the work arm operation levers 34L and 34R.

  Further, even if the lock lever 35 itself pulled up to the X position is erroneously rotated, the working arm is erroneously operated. Therefore, as shown in FIG. 25, the operation box 36 can be rotated to the Y position while the lock lever 35 is pulled up, so that neither the work arm operation lever 34L nor the lock lever 35 can be operated.

  In the state where the lock lever 35 is released, the work arm can be driven by the work arm operation levers 34L and 34R as long as the electrical system is normal and the electromagnetic solenoid 39 is kept energized. If the work arm cannot be driven, there are two possible causes for the failure: a hydraulic system failure and an electrical system failure. This is because when the electrical system fails, the electromagnetic solenoid 39 is de-energized and pilot pressure is not supplied. (Some pilot solenoid solenoids for supplying pilot pressure can be supplied with pilot pressure without being energized. In this case, if the work arm cannot be driven during operation, it can be determined that the hydraulic system has failed. Even if the electric system breaks down during operation, the electromagnetic solenoid remains in a non-energized state from the beginning, so that the supply of pilot pressure oil to the hydraulic system for driving the work arm is maintained and the drive of the work arm is continued. In this case, since there is a problem that the failure of the electric system is not noticed during the work, in the present embodiment, a type capable of supplying pilot pressure when energized is used like the electromagnetic solenoid 39 described above.)

  If the cause of the failure cannot be identified immediately, it will be delayed to return to normal. Therefore, if the electromagnetic solenoid 39 is de-energized when the lock lever 35 is released (when the lever lock switch 38 is ON), it is determined that it is caused by a failure of the electric system, and a system for issuing an abnormality alarm at this time is provided. .

  The alarm system at the time of abnormality in the electrical system shown in FIGS. 26 and 27 will be described. 26 and 27, 40 is a battery, 41 is a fuse, 42 is a current detector, 43 is a determination device, 43a is a power supply circuit, 43b is an operational amplifier, 43c is a NAND circuit, 44 is an abnormal alarm lamp, and 45 is abnormal. It is an alarm buzzer.

  In the electric circuit of FIG. 26, a separate switch (or sensor) 46 as a lever lock state detector is provided so that the disconnection of the electric system before the lever lock switch 38 can be detected, and the circuit to the separate switch 46 is provided. The lever lock switch 38 is branched from before the lever lock switch 38, and the lever lock switch 38 and the separate switch 46 are arranged in parallel. In FIG. 27, disconnection of the electrical system after the lever lock switch 38 can be detected.

  This will be described with reference to the electric circuit of FIG. The lever lock switch 38 and the separate switch 46 are both turned ON / OFF by the movement of the lock lever 35, and are turned ON when the lock lever 35 is lowered to release the lock. A harness is wired from the lever lock switch 38 to the negative side of the operational amplifier 43b in the detector 43 via the electromagnetic solenoid 39 and the current detector 42. On the other hand, in the detector 43, the positive side of the operational amplifier 43b is connected. Is supplied with a voltage from the power supply circuit 43a. Here, even if a disconnection occurs between the fuse 41 and the lock lever switch 38 connected thereto, a voltage is supplied from the power supply circuit 43a to the + side of the operational amplifier 43b, but the electromagnetic solenoid 39 is not turned on. In the operational amplifier 43b, the + side voltage becomes higher than the − side voltage, and is output from the operational amplifier 43b to the a side of the NAND circuit 43c. On the other hand, the separate switch 46 is ON when the lock lever 35 is lowered, and an output is made to the b side of the NAND circuit 43c. The NAND circuit 43c has an output of 0 only when output is made on both sides a and b, whereby the abnormality alarm lamp 44 is turned on and the abnormality alarm buzzer 45 is sounded.

  In the electric circuit of FIG. 27, the separate switch 46 that can determine the disconnection between the fuse 41 and the lever lock switch 38 is not provided, and the disconnection can be detected after the lever lock switch 38. That is, the harness h is branched immediately after the lever lock switch 38, and a voltage is supplied to the b side of the NAND circuit 43c in the detector 43. When a disconnection occurs after the branch point of the harness h immediately after the lever lock switch 38, outputs are made to both sides a and b of the NAND circuit, the output from the NAND circuit becomes 0, the abnormality alarm lamp 44 and An abnormality alarm is issued by the abnormality alarm buzzer 45.

It is a side view of the boom 1 which concerns on this invention. It is a side view of the state which decomposed | disassembled the boom 1 into the front side board 2a of the basic composition board | plate material, the rear side board 2b, the back board 3, and the abdominal board 4. FIG. It is a front end side view of the boom. It is also a ventral view. It is a front end side view of boom 1 which attached conventional arm bracket board 5 '. It is a rear view of the front half part of the boom. Similarly, it is a rear view of the latter half part. Similarly, it is a rear view of the abdomen. It is a side view of the latter half part of boom 1 of the state supported by the excavation work vehicle. Similarly, it is a rear view of the latter half part. It is a partial rear view of the boom 1 which shows the welding structure of the clamp seat 11 for piping. It is front sectional drawing of the clamp C for piping. It is a partial rear view of the boom 1 which shows the welding structure of the clamp part 11 for piping which enables the grease hose 15 to be fixed. It is front sectional drawing of the clamp C for piping which enables the grease hose 15 to be fixed. It is front sectional drawing which shows the retaining structure by the washer 27 of the pivot pin 22 in the pivot part of the arm base end boss | hub 17a to the arm bracket board 5 * 5. 3 is a front cross-sectional view showing a retaining structure using a C-type retaining ring. FIG. FIG. 17 is a front sectional view showing a retaining structure in which a shim 29 is added to the structure of FIG. 16. It is front sectional drawing which shows the retaining structure only by the non-rotating bolt 24 of the pivot pin 22 in the pivot part of the arm base end boss | hub 17a to the conventional arm bracket board 5 * 5. Similarly, it is a front cross-sectional view showing a conventional retaining structure with a rotation prevention member 30 and a rotation prevention bolt 31. It is a side view similarly. Similarly, it is a front sectional view showing a retaining structure with a conventional locking plate material 5Lb and retaining bolt 32. It is a side view similarly. It is the whole excavation work vehicle perspective view. It is a top view which shows the arrangement | positioning position of each lever near a seat. It is a side view which shows the lock mechanism of a work arm operation lever. It is an electric circuit diagram which shows the alarm mechanism at the time of the electric system abnormality at the time of operation of a work arm. It is the electrical circuit diagram which shows another Example similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boom 2 Side plate 2a Front side plate 2b Rear side plate 3 Back plate 4 Abdomen plate 5 Arm bracket plate 5a, 5b Expansion part 5L Left arm bracket plate 5R Right arm bracket plate 6 Tip rib 6a, 6b Welded part 7 Tip middle rib 11 Piping Clamp seat α welded portion 17 arm 17a arm base end boss 22 pivot pin 22a stepped portion 23 washer 24 rotation stop bolt 25 bush 26 dust seal 27 washer 28 C-type retaining ring 29 shim

Claims (1)

  In a structure in which a boss provided on each part of the excavation work arm is pivotally supported by loosely fitting a pivot pin 22 between the arm bracket plates 5 and 5, a washer 23 is fixed to one end of the pivot pin 22 to provide one piece. Is screwed to one arm bracket plate 5L with a non-rotating bolt 24, and a washer 27 is fixed to the other end or a C-type retaining ring 28 is provided to the other end so that it can be removed from the other arm bracket plate 5R. Excavation work arm structure characterized by having a structure to stop.

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