Working machinery

Abstract

This invention provides a technology to improve the efficiency of maintenance work in a work machine that supports a counterweight inside the vehicle frame. [Solution] The work machine comprises a vehicle frame, a work device supported and operated on the front of the vehicle frame, and a counterweight detachably supported on the rear of the vehicle frame. An opening is formed in the rear wall of the vehicle frame, and a through hole is formed in the bottom wall of the vehicle frame for a bolt to pass through. The counterweight has an insertion part that is inserted into the vehicle frame from the opening, and a female threaded part provided on the insertion part. With the insertion part inserted into the vehicle frame from the opening, the male threaded part of a bolt that passes through the through hole in the bottom wall is screwed into the female threaded part, thereby fixing it to the vehicle frame.

Description

Technical Field

[0001] The present invention relates to a work machine that supports a counterweight inside a vehicle body frame.

Background Art

[0002] Conventionally, a work machine including a vehicle body frame, a work device supported at the front part of the vehicle body frame and operating, and a counterweight detachably supported at the rear part of the vehicle body frame and balanced with the weight of the work device is known. Here, the counterweight may be fixed to the vehicle body frame with bolts so that it can be removed during transportation of the work machine or the like. Further, maintenance is performed to check whether the bolts fixing the counterweight are loosened due to vehicle body vibrations or the like generated during operation of the work machine, or to tighten the bolts more firmly if they are loosened.

[0003] As an example of a work machine provided with a counterweight, in Patent Document 1, an additional counterweight is mounted inside the vehicle body frame so as not to affect the rear end radius during turning when a heavy work device is attached.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above circumstances, and its purpose is to provide a technology that improves the efficiency of maintenance work on bolts that fix a counterweight to a vehicle frame in a work machine that supports a counterweight inside the vehicle frame. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a work machine comprising a vehicle frame, a work device supported and operated on the front of the vehicle frame, and a counterweight detachably supported on the rear of the vehicle frame, wherein an opening is formed in the rear wall of the vehicle frame, a through hole is formed in the bottom wall of the vehicle frame for a bolt to pass through, the counterweight has an insertion portion that is inserted into the interior of the vehicle frame from the opening, and a female threaded portion provided on the insertion portion, and the counterweight is fixed to the vehicle frame by screwing the male threaded portion of a bolt that passes through the through hole in the bottom wall into the female threaded portion while the insertion portion is inserted into the interior of the vehicle frame from the opening. [Effects of the Invention]

[0008] According to the present invention, the efficiency of maintenance work can be improved in a work machine that supports a counterweight inside the vehicle frame. Other problems, configurations, and effects will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view of a wheel loader according to this embodiment. [Figure 2] This is a perspective view of the main parts of a wheel loader, seen from a diagonal rearward angle. [Figure 3] This is a perspective view of the main parts of a wheel loader with the counterweight removed, seen from a diagonal rearward angle. [Figure 4] Plan view (A) and perspective view (B) of the second counterweight. [Figure 5] This is a perspective view of the first counterweight. [Figure 6] These are rear view (A) and side view (B) of the first counterweight. [Figure 7] This is a side view of the attachment / detachment jig. [Figure 8] This is a side view of the rear frame before the first counterweight is attached. [Figure 9] This is a side view after the first counterweight has been attached to the rear frame. [Figure 10] This figure shows the relationship between the opening in the rear wall and the insertion and exposure portions of the first counterweight. [Figure 11] This is a cross-sectional view of the frame after the first counterweight has been attached. [Figure 12] This is a plan view of the first counterweight according to a modified example. [Modes for carrying out the invention]

[0010] Hereinafter, with reference to the drawings, a wheel loader 10, an example of a work machine according to the present invention, will be described. In this specification, front, back, left, and right refer to the viewpoint of the operator riding and operating the wheel loader 10, unless otherwise specified. Furthermore, the specific work machine is not limited to the wheel loader 10, but any work machine equipped with a front work machine and counterweight (for example, a hydraulic excavator or crane) may be used.

[0011] [Overall configuration of wheel loader 10] FIG. 1 is a side view of a wheel loader 10 according to the present embodiment. As shown in FIG. 1, the wheel loader 10 has a vehicle body frame composed of a front frame 11 and a rear frame 12. The front frame 11 and the rear frame 12 are connected by a center pin 13 so as to be rotatable in the left - right direction. Further, the front frame 11 and the rear frame 12 are connected by a pair of left - right steering cylinders 14L and 14R. The pair of steering cylinders 14L and 14R extend and contract by receiving the supply of hydraulic oil from a hydraulic pump (not shown).

[0012] By extending one of the pair of steering cylinders 14L and 14R and retracting the other, the front frame 11 bends in the left - right direction with respect to the rear frame 12 around the center pin 13. As a result, the relative mounting angle between the front frame 11 and the rear frame 12 changes, and the vehicle body bends and turns. That is, this wheel loader 10 is an articulated type in which the front frame 11 and the rear frame 12 are bent around the center pin 13.

[0013] The front frame 11 supports a pair of left - right front tires 15L and 15R and a front working machine 16 (working device). The front working machine 16 has a lift arm 17, a bucket 18, a pair of lift arm cylinders 19, a bucket cylinder 20, and a bell crank 21.

[0014] The lift arm 17 extends in the front - rear direction. More specifically, the lift arm 17 is rotatably connected at its front end to the bucket 18 and rotatably connected at its rear end to the front frame 11. Then, the lift arm 17 rotates (pitches) in the up - down direction by the extension and contraction of the pair of lift arm cylinders 19.

[0015] The bucket 18 has a concave space capable of accommodating a load (such as earth and sand). Further, the bucket 18 is supported at the front end of the lift arm 17 so as to be rotatable (tilt or dump). More specifically, the bucket 18 rotates in the up - down direction as the bell crank 21 rotates with the extension and contraction of the bucket cylinder 20.

[0016] The rear frame 12 supports a pair of left and right rear tires 22L and 22R, a cab 23, an engine housing 24 (housing), and a counterweight 25.

[0017] The cab 23 has an internal space where an operator who operates the wheel loader 10 rides. Inside the cab 23, a seat (not shown) on which the operator sits and an operating device (not shown) operated by the operator sitting on the seat are arranged. By operating the operating device by the operator boarding the cab 23, the wheel loader 10 travels and the front work implement 16 operates. The operating device includes, for example, a steering wheel, pedals, levers, switches, and the like.

[0018] [[ID=The engine housing 24 is supported by the rear frame 12 behind the cab 23 and in front of the rearmost end of the counterweight 25. The engine housing 24 has an internal space for accommodating components (for example, an engine, a cooling fan, a heat exchanger) for driving the wheel loader 10.

[0019] The counterweight 25 is supported at the rear part of the rear frame 12. The counterweight 25 serves to balance the weight of the front work implement 16 supported at the front part of the front frame 11. More specifically, the counterweight 25 has a weight that balances the weight balance (in other words, the rotational moment) before and after the wheel loader 10 when the bucket 18 scoops up earth and sand or the like.

[0020] FIG. 2 is a perspective view of the main part of the wheel loader 10 as seen obliquely from the rear. As shown in FIG. 2, the wheel loader 10 includes a first counterweight 25C and a pair of second counterweights 25L and 25R (these may be collectively referred to as "counterweight 25"). The counterweight 25 is configured to be detachable from the rear frame 12. More specifically, the first counterweight 25C and the pair of second counterweights 25L and 25R are each independently attached to and detached from the rear frame 12.

[0021] The first counterweight 25C is mounted in the center of the rear frame 12 in the left-right direction. The pair of second counterweights 25L and 25R are mounted at both ends of the rear frame 12 in the left-right direction. In other words, the pair of second counterweights 25L and 25R are positioned on both sides of the first counterweight 25C in the left-right direction. To put it another way, the first counterweight 25C is positioned between the pair of second counterweights 25L and 25R in the left-right direction.

[0022] Figure 3 is a perspective view of the main parts of the wheel loader 10 with the counterweight 25 removed, viewed from the rear at an oblique angle. As shown in Figure 3, the rear frame 12 comprises a rear wall 26 defining the rear surface of the rear frame 12, a left wall 27 defining the left side of the rear frame 12, a right wall 28 defining the right side of the rear frame 12, and a bottom wall 29 defining the bottom surface of the rear frame 12. The rear wall 26, left wall 27, right wall 28, and bottom wall 29 are examples of the outer walls of the rear frame 12 that are exposed to the outside.

[0023] The rear wall 26 is a wall perpendicular to the front-rear direction at the rear end of the rear frame 12. Openings 26C, 26L, and 26R are formed in the rear wall 26. The openings 26C, 26L, and 26R penetrate the rear wall 26 in the thickness direction (i.e., the front-rear direction). Opening 26C is formed in the center of the rear wall 26 in the left-right direction. Openings 26L and 26R are formed on both sides of opening 26C in the left-right direction. Opening 26C is the space through which the insertion portion 36 (described later) of the first counterweight 25C is inserted and removed. Openings 26L and 26R are the spaces through which the projections 35L and 35R (described later) of the second counterweights 25L and 25R are inserted and removed.

[0024] The left wall 27 is a wall perpendicular to the left-right direction at the left end of the rear frame 12. The right wall 28 is a wall perpendicular to the left-right direction at the right end of the rear frame 12. The left wall 27 and the right wall 28 extend forward from the rear wall 26. The left wall 27 and the right wall 28 are spaced apart in the left-right direction. Furthermore, the left wall 27 and the right wall 28 each have multiple bolt holes 27a, 28a (see Figure 11 for 28a) into which bolts (not shown) that fix the second counterweights 25L, 25R to the rear frame 12 are screwed. The bolt holes 27a, 28a penetrate the left wall 27 and the right wall 28 in the thickness direction (i.e., the left-right direction).

[0025] The bottom wall 29 is a wall that slopes in the front-rear direction at the lower end of the rear frame 12. More specifically, the bottom wall 29 slopes downward toward the front from the rear wall 26. In other words, the bottom wall 29 slopes upward toward the rear. The bottom wall 29 also has multiple through holes 29a through which bolts 59 (see Figure 11) that fix the first counterweight 25C to the rear frame 12 are inserted. The through holes 29a penetrate the bottom wall 29 in the thickness direction.

[0026] In this embodiment, the thickness direction of the bottom wall 29 (more specifically, the direction perpendicular to the upper surface of the bottom wall 29) is defined as the "first direction," and the thickness direction of the rear wall 26 (more specifically, the direction perpendicular to the rear surface of the rear wall 26) is defined as the "second direction." That is, the first direction and the second direction are directions that intersect each other. Note that the first direction and the second direction are not limited to the above example as long as they intersect each other.

[0027] [Second counterweight configuration: 25L, 25R] Figure 4 shows a plan view (A) and an oblique view (B) of the second counterweights 25L and 25R. Since the second counterweights 25L and 25R are identical in shape except for the left and right sides being reversed, the second counterweight 25L will be described in detail below. As shown in Figure 4, the second counterweight 25L has a left portion 31L and a rear portion 32L, and when viewed from above in plan, it has an outer shape that is roughly L-shaped.

[0028] The left portion 31L is the part of the rear frame 12 that faces the left side wall 27. That is, the left portion 31L extends in the front-rear direction along the outer surface of the left side wall 27. A through hole 33L is formed in the left portion 31L at a position where it can face the bolt hole 27a of the left side wall 27, and it penetrates in the left-right direction. The second counterweight 25L is fixed to the rear frame 12 (left side wall 27) by inserting a bolt through the through hole 33L from the outer surface of the left portion 31L and screwing it into the bolt hole 27a. In addition, a bolt hole 34L is formed on the upper surface of the left portion 31L, into which an eyebolt (not shown) for attaching and detaching the second counterweight 25L to the rear frame 12 is screwed.

[0029] The rear portion 32L protrudes to the right from the rear end of the left portion 31L. That is, the rear portion 32L is a portion that extends in the left-right direction along the rear surface of the rear wall 26. A projection 35L that protrudes forward is formed on the front surface of the rear portion 32L. The projection 35L enters the opening 26L of the rear wall 26 when the second counterweight 25L is attached to the rear frame 12 and plays a role in positioning the second counterweight 25L. In addition, the projection 35L abuts against the peripheral wall of the opening 26L when an external force is applied in a direction that tilts the second counterweight 25L in the front-rear direction, and plays a role in preventing the second counterweight 25L from tilting.

[0030] A wire (not shown) is attached to an eyebolt (not shown) screwed into bolt hole 34L, and the second counterweight 25L is lifted by a crane. Next, the second counterweight 25L is moved by the crane and the projection 35L is inserted into the opening 26L. Then, the counterweight 25L is attached to the rear frame 12 by screwing a bolt (not shown) inserted into the through hole 33L from the outer side of the left portion 31L into the bolt hole 27a. Finally, the eyebolt is removed from bolt hole 34L. To remove the second counterweight 25L from the rear frame 12, the procedure is the reverse of the above.

[0031] The second counterweight 25R has a right portion 31R and a rear portion 32R, and when viewed from above in a plan view, it has an outer shape that is roughly L-shaped. The right portion 31R faces the right wall 28, and the rear portion 32R faces the rear wall 26. The right portion 31R is the shape of the left portion 31L inverted in the left-right direction. The rear portion 32R is the shape of the rear portion 32L inverted in the left-right direction. The position and function of the through hole 33R, bolt hole 34R, and projection 35R are the same as those of the through hole 33L, bolt hole 34L, and projection 35R. The method for attaching and detaching the second counterweight 25R is the same as that for the second counterweight 25L.

[0032] The second counterweights 25L and 25R may have the same configuration as the counterweights mounted on the conventional wheel loader 10. On the other hand, if, for example, components within the engine building 24 are omitted from the conventional wheel loader 10 (for example, if part of the aftertreatment device (SCR system) is omitted in accordance with regulations in each country), it is necessary to additionally install the first counterweight 25C in order to balance the weight balance of the wheel loader 10 in the longitudinal direction.

[0033] [Configuration of the first counterweight 25C] Figure 5 is a perspective view of the first counterweight 25C. Figure 6 is a rear view (A) and a side view (B) of the first counterweight 25C. As shown in Figures 5 and 6, the first counterweight 25C comprises an insertion portion 36 and an exposed portion 37. When the counterweight 25C is mounted on the rear frame 12, the insertion portion 36 is the part located inside the rear frame 12, and the exposed portion 37 is the part located outside the rear frame 12.

[0034] The insertion portion 36 is the front part of the first counterweight 25C. The insertion portion 36 has a roughly rectangular parallelepiped shape. The insertion portion 36 protrudes diagonally downward and forward from the front surface 44 of the exposed portion 37 and extends in the left-right direction. A recess 39 is formed on the upper surface 38 of the insertion portion 36. On the other hand, the lower surface 40 of the insertion portion 36 is a flat surface. Furthermore, a bolt hole 41 (female thread portion) is formed in the insertion portion 36 at the location of the recess 39, penetrating in the thickness direction. The male thread portion of a bolt 59, which has passed through the through hole 29a of the bottom wall 29 from the outside, is screwed into the bolt hole 41.

[0035] The exposed portion 37 is the rear portion of the first counterweight 25C. The exposed portion 37 consists of a central portion 42, a left end portion 43L located to the left of the central portion 42, and a right end portion 43R located to the right of the central portion 42. The front surfaces 44 of the central portion 42, the left end portion 43L, and the right end portion 43R (i.e., the exposed portion 37) are flush and flat surfaces perpendicular to the front-rear direction.

[0036] The central portion 42 is a flat plate-shaped section perpendicular to the vertical direction. The central portion 42 has a through hole 45 and a second insertion hole 46. The through hole 45 penetrates the central portion 42 in the thickness direction (i.e., the vertical direction), and a bolt (not shown) of the attachment / detachment jig 50, which will be described later, is inserted into it. The second insertion hole 46 penetrates the central portion 42 in the thickness direction (i.e., the vertical direction), and receives the tip of the traction pin 61 inserted into the first insertion hole 63 of the traction pin support portion 62, which will be described later. Of the exposed portion 37, the bolt holes 49L, 49R, the through holes 45, 55, and the central portion 42 constitute an example of a jig fixing portion that can fix the attachment / detachment jig 50.

[0037] The left end 43L and the right end 43R are portions that protrude upward and downward from the central portion 42. That is, the exposed portion 37 is recessed vertically at the position of the central portion 42 compared to the positions of the left end 43L and the right end 43R. Also, the upper surfaces 47L and 47R of the left end 43L and the right end 43R are horizontal planes perpendicular to the front surface 44. On the other hand, the bottom surfaces 48L and 48R of the left end 43L and the right end 43R are inclined surfaces that slope upward toward the rear. Furthermore, bolt holes 49L and 49R are formed in the upper surfaces 47L and 47R of the left end 43L and the right end 43R, into which eye bolts 58, which will be described later, are screwed.

[0038] [Installation procedure for the first counterweight 25C] Referring to Figures 7 to 10, the procedure for attaching the first counterweight 25C to the rear frame 12 will be described. Figure 7 is a side view of the attachment / detachment jig 50. Figure 8 is a side view of the rear frame 12 before attaching the first counterweight 25C. Figure 9 is a side view of the rear frame 12 after attaching the first counterweight 25C. Figure 10 is a diagram showing the relationship between the opening 26C of the rear wall 26 and the insertion portion 36 and exposed portion 37 of the first counterweight 25C. Figure 11 is a cross-sectional view of the rear frame 12 with the first counterweight 25C attached.

[0039] As shown in Figure 7, the attachment / detachment jig 50 has an outer shape that is roughly inverted T-shaped, with a clamping portion 51, a balancing portion 52, and a suspension portion 53. The clamping portion 51 and the balancing portion 52 are the front and rear parts of a flat plate shape that extends horizontally. The suspension portion 53 is the part that protrudes upward from between the clamping portion 51 and the balancing portion 52. In other words, of the flat plate shape, the part in front of the suspension portion 53 is the clamping portion 51, and the part behind the suspension portion 53 is the balancing portion 52.

[0040] A slit 54 is formed in the clamping portion 51. The slit 54 is open at the front end, left end, and right end of the clamping portion 51. In addition, a through hole 55 is formed in the clamping portion 51 at the location of the slit 54, extending vertically. The slit 54 is the portion into which the central portion 42 of the first counterweight 25C enters. The through hole 55 faces the through hole 45 of the central portion 42 that has entered the slit 54. Then, by screwing a nut (not shown) onto the tip of a bolt that has passed through the through holes 45, 55, the attachment / detachment jig 50 is attached to the first counterweight 25C as shown in Figure 8.

[0041] The balance unit 52 is the part that adjusts the center of gravity position G of the first counterweight 25C attached to the attachment jig 50. As shown in Figure 8, the center of gravity position G' of the first counterweight 25C and the entire attachment jig 50 is located behind the center of gravity position G of the first counterweight 25C alone. In other words, the balance unit 52 moves the center of gravity position G of the first counterweight 25C backward when the first counterweight 25C is attached to the attachment jig 50.

[0042] The suspension section 53 is the part to which the lower end of the wire 56 is attached. The position of the suspension section 53 is behind the center of gravity G'. In addition, eye bolts 58 attached to the lower end of the wire 57 are screwed into bolt holes 49L and 49R of the first counterweight 25C. The positions of bolt holes 49L and 49R are in front of the center of gravity G'. Then, by lifting the wires 56 and 57 with a crane, the first counterweight 25C can be lifted and moved.

[0043] As shown in Figure 8, when the first counterweight 25C is advanced with the insertion portion 36 facing forward behind the rear wall 26, the insertion portion 36 passes through the opening 26C and enters the interior of the rear frame 12, as shown in Figure 9. Here, as shown by the diagonal lines in Figure 10, gaps are formed in the vertical and horizontal directions between the outer surface of the insertion portion 36 that has entered the opening 26C and the peripheral wall defining the opening 26C. That is, the area of ​​the insertion portion 36 as viewed from the front-rear direction is smaller than the area of ​​the opening 26C. This allows the insertion portion 36 to pass through the opening 26C smoothly. Furthermore, after the insertion portion 36 has passed through the opening 26C, and before the wire 57 interferes with the rear of the engine building 24, the eye bolts 58 are removed from the bolt holes 49L and 49R.

[0044] Furthermore, the lower surface 40 of the insertion portion 36 is parallel to the upper surface of the bottom wall 29. As shown in Figure 11, the lower surface 40 of the insertion portion 36 makes surface contact with the upper surface of the bottom wall 29, thereby positioning the first counterweight 25C in a first direction perpendicular to the bottom wall 29. In addition, the recess 39 prevents interference between the first counterweight 25C and components housed inside the rear frame 12 (e.g., radiator core, fuel tank, hydraulic oil tank).

[0045] On the other hand, as shown in Figure 10, the area of ​​the front surface 44 of the exposed portion 37, as viewed from the front-rear direction, is larger than the area of ​​the opening 26C. Therefore, the exposed portion 37 cannot pass through the opening 26C. Also, when the insertion portion 36 is fixed to the bottom wall 29, the front surface 44 of the exposed portion 37 covers the entire outer circumference of the opening 26C, closing the opening 26C. Furthermore, the front surface 44 of the exposed portion 37 is parallel to the rear surface of the rear wall 26. Then, as shown in Figure 11, with the bolt hole 41 and the through hole 29a overlapping in the direction of bolt 59 insertion, the front surface 44 of the exposed portion 37 makes surface contact with the rear surface of the rear wall 26, thereby positioning the first counterweight 25C in a second direction perpendicular to the rear wall 26. As a result, the through hole 29a of the bottom wall 29 and the bolt hole 41 of the insertion portion 36 are in communication. Furthermore, when the first counterweight 25C is viewed from the front, the portion of the exposed portion 37 that protrudes upward, downward, left, and right from the insertion portion 36 (in other words, the portion that constitutes the front surface 44) constitutes an example of a protruding portion.

[0046] Then, the male threaded portion of the bolt 59, which has passed through the through hole 29a from the outside of the bottom wall 29, is screwed into the bolt hole 41, thereby fixing the first counterweight 25C to the rear frame 12. The attachment / detachment jig 50 is then removed from the first counterweight 25C. On the other hand, to remove the first counterweight 25C from the rear frame 12, the procedure is the reverse of the above. In this way, the first counterweight 25C can be attached to and detached from the rear frame 12 by working only from outside the wheel loader 10, without opening the door of the engine building 24 or removing any components of the wheel loader 10.

[0047] Furthermore, as shown by the dashed line in Figure 11, the bottom surface 60R of the second counterweight 25R slopes upward toward the rear. The bottom surface 60L of the second counterweight 25L is similar, although it is not shown in the illustration. The entire first counterweight 25C, fixed to the rear frame 12, is located above the bottom surfaces 60L and 60R of the second counterweights 25R and 25L when viewed from the side of the rear frame 12. More specifically, the bottom surfaces 48L and 48R of the exposed portion 37 of the first counterweight 25C overlap with the bottom surfaces 60L and 60R of the second counterweights 25L and 25R when viewed from the side of the rear frame 12.

[0048] The angle between the mounting surface of the wheel loader 10, shown by the dashed line in Figure 11, and the bottom surfaces 48L, 48R, 60L, and 60R is called the "departure angle θ". The departure angle θ is the angle of the bottom surface of the wheel loader 10, which slopes upward toward the rear so that the rear end does not come into contact with the mounting surface when the front of the wheel loader 10 is lifted while traveling on uneven ground. In other words, according to this embodiment, even if the first counterweight 25C is newly added, it does not affect the departure angle θ of the conventional (i.e., second counterweights 25L and 25R).

[0049] [Configuration of the traction pin 61 and traction pin support part 62] As shown in Figures 2, 3, 8, and 11, the wheel loader 10 includes a towing pin 61 and a towing pin support 62. The towing pin 61 is used to secure a wire (towing device) attached to another vehicle when the wheel loader 10 is towing another vehicle.

[0050] The towing pin support portion 62 is the part that supports the towing pin 61. The towing pin support portion 62 is a plate-shaped member that protrudes rearward from the rear wall 26. As shown in Figure 3, the towing pin support portion 62 is provided above the opening 26C. As shown in Figure 11, a first insertion hole 63 is formed in the towing pin support portion 62, penetrating in the vertical direction. The towing pin 61 is inserted into the first insertion hole 63.

[0051] As shown in Figure 2, when the first counterweight 25C is attached to the rear frame 12, the towing pin support portion 62 is positioned in the recessed area between the left end portion 43L and the right end portion 43R. Also, as shown in Figure 11, when the first counterweight 25C is attached to the rear frame 12, the first insertion hole 63 and the second insertion hole 46 face each other in the vertical direction. As a result, the tip of the towing pin 61, which is inserted into the first insertion hole 63 from above the towing pin support portion 62, is inserted into the second insertion hole 46. In addition, a wire for towing another vehicle is secured between the first insertion hole 63 and the second insertion hole 46 (in other words, the towing pin support portion 62 and the first counterweight 25C).

[0052] [Effects of the Embodiment] According to the above embodiment, the insertion portion 36 that enters the interior of the rear frame 12 is fixed by a bolt 59 that penetrates the bottom wall 29 from the outside. Therefore, the bolt 59 can be tightened by working only from the outside of the wheel loader 10, without having to open the door of the engine building 24 or remove any components of the wheel loader 10. In other words, the efficiency of maintenance work on the first counterweight 25C is improved.

[0053] Furthermore, because the insertion section 36 is positioned inside the rear frame 12, the internal weight of the rear frame 12 can be increased, allowing for a reduction in the size of the exposed section 37 and the second counterweights 25L and 25R provided on the outside of the rear frame 12. In other words, it is possible to balance the weight of the front work implement 16 while keeping the overall length of the wheel loader 10 from increasing.

[0054] Furthermore, from the perspective of improving the efficiency of maintenance work, it is not limited to the case that only a portion of the first counterweight 25C is located inside the rear frame 12, but the entire first counterweight 25C may be located inside the rear frame 12.

[0055] Furthermore, according to the above embodiment, the insertion portion 36, which enters the interior of the rear frame 12 through the opening 26C, is fixed with bolts 59, and the first counterweight 25C can be attached and detached by attaching the attachment / detachment jig 50 to the exposed portion 37 located on the outside of the rear frame 12. This allows the first counterweight 25C, including the insertion portion 36, to be removed when it is necessary to temporarily lighten the wheel loader 10, such as during transportation. In addition, since the first counterweight 25C can be attached and detached from the rear frame 12 by working only from the outside of the wheel loader 10, the attachment and detachment work is made easier. In other words, it is possible to maintain good attachment and detachment while placing a heavy object inside the rear frame 12. However, the first counterweight 25C may be attached and detached without using the attachment / detachment jig 50.

[0056] Furthermore, according to the above embodiment, by positioning the first counterweight 25C above the bottom surfaces 60L and 60R of the second counterweights 25L and 25R, the conventional departure angle θ can be maintained. As a result, the first counterweight 25C can be newly added while utilizing the configuration of the existing wheel loader 10.

[0057] Furthermore, according to the above embodiment, by bringing the upper surface of the bottom wall 29 and the lower surface 40 of the insertion portion 36 into surface contact, and the rear surface of the rear wall 26 and the front surface 44 of the exposed portion 37 into surface contact, the first counterweight 25C can be positioned in the first and second directions that intersect with each other, and also functions as an anti-rotation device when fastening the bolt 59. This makes it easier to attach the first counterweight 25C to the rear frame 12.

[0058] Furthermore, according to the above embodiment, by providing a gap between the outer surface of the insertion portion 36 and the peripheral wall defining the opening 26C, the insertion portion 36 can pass through the opening 26C smoothly. Modifications for the smooth passage of the insertion portion 36 through the opening 26C will be described later with reference to Figure 12.

[0059] Furthermore, according to the above embodiment, by closing the opening 26C from the outside with the front surface 44 of the exposed portion 37, it is possible to prevent dust and water droplets from entering the interior of the rear frame 12 through the opening 26C.

[0060] Furthermore, according to the above embodiment, the posture of the towing pin 61 is stabilized by supporting the tip of the towing pin 61 with the first counterweight 25C. As a result, other vehicles can be towed stably.

[0061] Furthermore, according to the above embodiment, the first counterweight 25C can be stably attached to and detached from the rear frame 12 by using the attachment / detachment jig 50. More specifically, an eyebolt cannot be attached to the insertion portion 36 that enters the interior of the rear frame 12. Therefore, if an eyebolt is attached only to the exposed portion 37 and the first counterweight 25C is lifted by a crane, the first counterweight 25C will rotate in the direction that the insertion portion 36 is lowered. Therefore, by adjusting the center of gravity position G' using the attachment / detachment jig 50, the posture of the first counterweight 25C lifted by the crane can be stabilized.

[0062] [Differentiation] Figure 12 is a plan view of the modified first counterweight 25C'. A detailed explanation of the similarities with the above embodiment will be omitted, and the differences will be explained in detail. The modified first counterweight 25C' differs from the above embodiment in that tapered surfaces 64L and 64R are provided in the insertion portion 36, while other aspects are the same as the above embodiment.

[0063] The tapered surfaces 64L and 64R are formed on both end faces of the insertion portion 36 in the left-right direction. The tapered surfaces 64L and 64R are inclined to approach each other towards the tip of the insertion portion 36. In other words, the width of the insertion portion 36 in the left-right direction according to the modified example is smallest at the tip and gradually increases towards the base end (the end on the exposed portion 37 side).

[0064] In the modified version, as the tip of the insertion portion 36 passes through the opening 26C, the gap between the outer surface of the insertion portion 36 and the peripheral wall of the opening 26C increases, allowing the insertion portion 36 to pass through the opening 26C more smoothly. On the other hand, since the gap between the outer surface of the base end of the insertion portion 36 and the peripheral wall of the opening 26C is the same as in the above embodiment, the lateral displacement of the first counterweight 25C can be minimized. This makes it easier to position the first counterweight 25C.

[0065] The embodiments described above are illustrative for explaining the present invention and are not intended to limit the scope of the invention to those embodiments only. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the invention. [Explanation of Symbols]

[0066] 10: Wheel loader 11: Front frame 12: Rear frame 13: Center Pin 14L, 14R: Steering Cylinder 15L, 15R: Front tire 16: Front work machine 17: Lift Arm 18: Bucket 19: Lift Arm Cylinder 20: Bucket Cylinder 21: Bell Crank 22L, 22R: Rear tire 23: Driver's cab 24: Engine building 25C, 25C': First counterweight (counterweight) 25L, 25R: Second counterweight (counterweight) 26: Back wall 26C, 26L, 26R: Opening 27: Left side wall 27a, 28a, 34L, 34R, 41: Bolt holes (female thread portion) 28: Right side wall 29: Bottom wall 29a,33L,33R,45,47:Through hole 31L: Left side part 31R: Right side part 32L, 32R: Rear part 35L,35R:Protrusion 36: Insertion part 37:Exposed part 38,47L,47R:Top surface 39: Recess 40: Bottom surface 42: Central section (jig fixing section) 43L: Left end 43R: Rightmost part 44: Front (protruding part) 45, 55: Through holes (for fixing the jig) 46: Second insertion hole 48L, 48R, 60R: Bottom 49L, 49R: Bolt holes (for fixing the jig) 50: Detachable jig 51: Holding part 52: Balance section 53: Hanging part 54: Slit 56, 57: Wire 58: Eyebolt 59: Bolt 61: Towing pin 62: Traction pin support section 63: First insertion hole 64L, 64R: Tapered surface G,G': Center of gravity position θ: Departure angle

Claims

1. The vehicle frame and A work device that is supported and operates on the front of the vehicle body frame, A work machine comprising a counterweight detachably supported at the rear of the vehicle frame, An opening is formed in the rear wall of the vehicle body frame. Through holes are formed in the bottom wall of the vehicle frame through which bolts pass. The counterweight has an insertion portion that is inserted from the opening toward the interior of the vehicle frame, and a female threaded portion provided on the insertion portion. A work machine characterized in that, with the insertion portion inserted into the interior of the vehicle frame through the opening, the male threaded portion of a bolt passing through the through hole in the bottom wall is screwed into the female threaded portion, thereby fixing it to the vehicle frame.

2. In the work machine described in claim 1, The counterweight is characterized by comprising an exposed portion located outside the vehicle frame, with the insertion portion inserted into the vehicle frame through the opening.

3. In the work machine described in claim 2, The bottom wall of the vehicle body frame is formed to slope upward toward the rear, The working machine is characterized in that the exposed portion of the counterweight has a protruding portion that contacts the rear surface of the rear wall in a state where the female thread portion and the through hole overlap in the direction in which the bolt is inserted.

4. In the work machine described in claim 2, A working machine characterized in that the left and right end faces of the insertion portion are tapered surfaces that are inclined to approach each other toward the tip of the insertion portion.

5. In the work machine described in claim 3, The working machine is characterized in that the protruding portion of the exposed portion is formed to be larger than the opening so as to close the opening when the insertion portion is fixed to the bottom wall.

6. In the work machine described in claim 2, A towing pin for securing a towing device for towing other vehicles, It comprises a traction pin support portion that protrudes rearward from the rear wall above the opening and has a first insertion hole into which the traction pin is inserted in the vertical direction, The working machine is characterized in that the exposed portion has a second insertion hole formed therein for receiving the tip of the traction pin inserted into the first insertion hole.

7. In the work machine described in claim 2, The work machine is characterized in that the exposed portion has a jig fixing portion to which a detachable jig for inserting and removing the counterweight can be fixed to the opening in the vehicle frame.

Images