Deep foundation excavator

Abstract

The base arm (11) is formed as a cylindrical body which is provided with a left side panel (11A), a right side panel (11B), a second lifting pulley shaft (24) and a second opening and closing pulley shaft (29), the left side panel (11A), the right side panel (11B), the second lifting pulley shaft (24) and the second opening and closing pulley shaft (29) facing each other at intervals in a direction orthogonal to the longitudinal direction, and the cylindrical body is arranged between an upper guide arm connecting pin (13B) and a lower guide arm connecting pin (14B) in the vertical direction of the base arm (11). The base arm (11) is provided with a reinforcing plate (12) extending in the longitudinal direction of the base arm (11) in a state where the left side panel (11A) and the right side panel (11B) are connected, and a part of the reinforcing plate (12) is disposed between the upper guide arm connecting pin (13B) and the lower guide arm connecting pin (14B) in the vertical direction of the base arm (11).

Description

Technical Field

[0001] The present disclosure relates to a deep foundation excavator suitable for excavation work such as shaft excavation work. Background Art

[0002] As a work machine suitable for excavation work such as shaft excavation work, a deep foundation excavator is known. The working device of the deep foundation excavator includes: a boom mounted on a vehicle body; an arm rotatably mounted at the front end of the boom; a clamshell bucket provided so as to be able to move up and down relative to the arm; and a bucket lifting / closing device that controls the lifting and closing actions of the clamshell bucket. The bucket lifting / closing device is configured to include: a movable pulley that can move in the longitudinal direction of the arm; a fixed pulley fixed to the arm; a lifting rope and a closing rope wound around the movable pulley and the fixed pulley; a lifting cylinder that lifts the clamshell bucket; and a closing cylinder that closes the clamshell bucket.

[0003] The lifting cylinder winds out and winds up the lifting rope by changing the distance between the movable pulley and the fixed pulley, thereby lifting the clamshell bucket. The closing cylinder winds out and winds up the closing rope by changing the distance between the movable pulley and the fixed pulley, thereby closing the clamshell bucket. The deep foundation excavator places the clamshell bucket into the shaft with the front end of the arm positioned above the shaft, and excavates sand by opening and closing the clamshell bucket (Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-161716 Summary of the Invention

[0007] However, in order to improve the stability during winding out and winding in of the lifting rope and the closing rope by changing the distance between the movable pulley and the fixed pulley, the main components of the bucket lifting / closing device of the prior art deep foundation excavator are arranged at the rear side of the arm. Therefore, in the prior art deep foundation excavator, stress concentration is likely to occur in the rear side of the arm, that is, in the range from the mounting portion to the rear end of the arm. As a result, the prior art deep foundation excavator has a problem that the strength of the arm is likely to be reduced, leading to an early reduction in life.

[0008] An object of the present invention is to provide a deep foundation excavator capable of improving the strength of the base arm.

[0009] The present invention relates to a deep - foundation excavator, which is composed of a vehicle body capable of autonomous driving and a working device provided on the vehicle body. The working device includes: a base arm, which is rotatably provided relative to the vehicle body, and a clamshell bucket is arranged at one end side in the length direction in a liftable manner; an upper guiding arm and a lower guiding arm, which are connected to the other end side of the base arm at a certain interval in the vertical direction via an upper guiding arm connecting pin and a lower guiding arm connecting pin, and extend along the length direction of the base arm; a first lifting pulley and a first opening - closing pulley, which are arranged to be movable along the upper guiding arm and the lower guiding arm; a lifting cylinder, which is installed on the base arm and moves the first lifting pulley and the first opening - closing pulley; a second lifting pulley and a second opening - closing pulley, which are separated from the first lifting pulley and the first opening - closing pulley and are rotatably arranged on the base arm respectively with a pulley shaft as the center; a lifting rope, which is wound around the first lifting pulley and the second lifting pulley to lift the clamshell bucket; and an opening - closing rope, which is wound around the first opening - closing pulley and the second opening - closing pulley to open and close the clamshell bucket. The deep - foundation excavator is characterized in that the base arm is formed as a cylindrical body, the cylindrical body has a pair of side plates oppositely arranged at an interval in a direction orthogonal to the length direction, the pulley shafts of the second lifting pulley and the second opening - closing pulley are arranged between the upper guiding arm connecting pin and the lower guiding arm connecting pin in the vertical direction of the base arm, a reinforcing plate fixed to at least one of the pair of side plates of the base arm and extending along the length direction of the base arm is provided on the base arm, and a part of the reinforcing plate is arranged between the upper guiding arm connecting pin and the lower guiding arm connecting pin in the vertical direction of the base arm.

[0010] According to the present invention, by fixing the reinforcing plate to at least one of the pair of side plates of the base arm, deformation, stress concentration, etc. of the pair of side plates caused by external forces can be suppressed, and the strength of the base arm can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a left - hand view showing the deep - foundation excavator according to an embodiment of the present invention.

[0012] Figure 2 It is a left - hand view showing the arm, the lifting and opening - closing devices of the bucket, etc.

[0013] Figure 3 It is a top - view showing the arm, the lifting and opening - closing devices of the bucket, etc.

[0014] Figure 4 It is a right - hand view with partial section showing the arm, the lifting and opening - closing devices of the bucket, etc.

[0015] Figure 5It is an exploded view of the arm.

[0016] Figure 6 It is from Figure 5 A cross-sectional view of the cylinder holding part of the base arm observed in the direction of arrow VI-VI in

[0017] Figure 7 It is a left side view showing an enlarged view of the base arm, the second lifting pulley, etc.

[0018] Figure 8 It is from Figure 7 A cross-sectional view of the base arm, the second lifting pulley, etc. observed in the direction of arrow VIII-VIII in

[0019] Figure 9 It is a right side view showing an enlarged view of the base arm, the second opening and closing pulley, the opening and closing cylinder, etc.

[0020] Figure 10 It is a top view showing an enlarged view of the base arm, the opening and closing cylinder, the lifting rope mounting bracket, the opening and closing rope mounting bracket, etc.

[0021] Figure 11 It is in the state where the ropes are omitted and from Figure 2 A bottom view of the base arm, the boom mounting bracket, the second lifting pulley, the second opening and closing pulley, etc. observed in the direction of arrow XI-XI in

[0022] Figure 12 It is a left side view of the base arm showing a modified example.

[0023] Figure 13 It is from Figure 12 A cross-sectional view of the base arm, the second lifting pulley, etc. observed in the direction of arrow XIII-XIII in Detailed Embodiment

[0024] Hereinafter, the deep foundation excavator according to the embodiment of the present invention will be described in detail with reference to the drawings. In addition, in the embodiment, the traveling direction of the deep foundation excavator is defined as the front-rear direction, and the direction orthogonal to the traveling direction is defined as the left-right direction for description.

[0025] The deep foundation excavator 1 is manufactured based on, for example, a crawler-type hydraulic excavator. The deep foundation excavator 1 includes a crawler-type lower traveling body 2 capable of autonomous traveling, an upper revolving body 3 rotatably mounted on the lower traveling body 2, and a working device 5 described later provided on the upper revolving body 3. The lower traveling body 2 and the upper revolving body 3 constitute the vehicle body of the deep foundation excavator 1.

[0026] The cab 4 is provided on the left front side of the upper rotating body 3. The cab 4 demarcates a driver's cab, and a driver's seat 4A for an operator to sit on is provided inside the cab 4. Around the driver's seat 4A, an operating device (not shown) for operating the traveling action of the lower traveling body 2, the rotating action of the upper rotating body 3, and the working device 5 is provided.

[0027] The working device 5 is configured to include a boom 6 rotatably mounted on the upper rotating body 3 in the vertical direction, a later-described arm 10, a clamshell bucket 9, and a bucket lifting and opening / closing device 16. A boom cylinder 7 is provided between the upper rotating body 3 and the boom 6, and the boom 6 rotates relative to the upper rotating body 3 according to the telescopic action of the boom cylinder 7. An arm cylinder 8 is provided between the boom 6 and the arm 10, and the arm 10 rotates relative to the boom 6 or the upper rotating body 3 according to the telescopic action of the arm cylinder 8.

[0028] The clamshell bucket 9 is disposed at the front end (one end in the length direction) side of a later-described base arm 11 and is suspended in a liftable manner by a later-described lifting rope 38. The clamshell bucket 9 has a bucket support portion 9A, a pair of buckets 9B, a connecting bracket 9C, and a pair of opening / closing arms 9D. The pair of buckets 9B are provided on the lower side of the bucket support portion 9A in an openable / closable manner. The pair of buckets 9B are rotatably connected to the connecting bracket 9C. The pair of opening / closing arms 9D connect between the bucket support portion 9A and the pair of buckets 9B respectively. A plurality of upper pulleys 9E are provided on the bucket support portion 9A of the clamshell bucket 9, and a plurality of lower pulleys 9F opposed to the upper pulleys 9E in the vertical direction are provided on the connecting bracket 9C.

[0029] The other end 38B of the lifting rope 38 is installed on the bucket support portion 9A of the clamshell bucket 9. A later-described opening / closing rope 40 is alternately wound around the upper pulleys 9E and the lower pulleys 9F of the clamshell bucket 9, and the other end 40B of the opening / closing rope 40 is installed on the bucket support portion 9A of the clamshell bucket 9.

[0030] The arm 10 is rotatably mounted at the front end of the boom 6. As Figure 5 shown, the arm 10 is configured to be divisible into a base arm 11 formed by a hollow cylinder and extending in the front-rear direction, an upper guide arm 13 and a lower guide arm 14 detachably provided on the rear side of the base arm 11, and a pulley mounting member 15 movably mounted on the upper guide arm 13 and the lower guide arm 14.

[0031] The base arm 11 serves as the base of the dipper stick 10 and is formed as a square tube body having a rectangular cross-sectional shape extending in the vertical direction. The base arm 11 is surrounded by a left side panel 11A, a right side panel 11B, a front upper panel 11C, a rear upper panel 11D, and a lower panel 11E. The left side panel 11A and the right side panel 11B are a pair of side panels opposed to each other in a direction (left-right direction) orthogonal to the length direction (front-rear direction) of the dipper stick 10. The front upper panel 11C connects between the front upper ends of the left side panel 11A and the right side panel 11B. The rear upper panel 11D connects between the rear upper ends of the left side panel 11A and the right side panel 11B. The lower panel 11E connects between the lower ends of the left side panel 11A and the right side panel 11B. The height dimensions in the vertical direction of the left side panel 11A and the right side panel 11B are set to be smaller on the front side than on the rear side. Therefore, a step in the vertical direction is formed at the boundary between the front upper panel 11C and the rear upper panel 11D.

[0032] The front end (one end in the length direction) of the base arm 11 is closed by a front panel 11F, and the rear end (the other end in the length direction) 11G of the base arm 11 is an open end. An arm mounting bracket 11H and a cylinder mounting bracket 11J are provided on the lower panel 11E of the base arm 11.

[0033] As Figure 11 shown, the arm mounting bracket 11H is composed of two plate bodies opposed to each other at a certain interval in the left-right direction. The left arm mounting bracket 11H is arranged at a position vertically overlapping with the left side panel 11A of the base arm 11, and the right arm mounting bracket 11H is arranged at a position vertically overlapping with the right side panel 11B of the base arm 11. The arm mounting bracket 11H is rotatably connected to the front end of the arm 6 via an arm connection pin 11K (refer to Figure 1 ). The base end of the cylinder mounting bracket 11J is joined to the front end of the dipper stick cylinder 8 mounted on the arm 6 by a pin. Therefore, the base arm 11 rotates in the front-rear direction or the vertical direction around the arm connection pin 11K according to the telescopic movement of the dipper stick cylinder 8.

[0034] On the rear end sides of the left side panel 11A and the right side panel 11B, two pin insertion through holes 11L, 11M that are vertically separated and penetrate in the left-right direction are respectively formed (refer to Figure 5 ). The upper guide dipper stick connection pin 13B described later is inserted through the upper pin insertion through hole 11L, and the lower guide dipper stick connection pin 14B described later is inserted through the lower pin insertion through hole 11M. In addition, at positions on the left side panel 11A and the right side panel 11B that are closer to the front side than the pin insertion through holes 11L, 11M, trunnion pin insertion through holes 11N that penetrate in the left-right direction are respectively formed (see Figure 10 ). The cylinder support pin 17D described later is inserted through these two trunnion pin insertion through holes 11N.

[0035] Here, the interval between the left panel 11A and the right panel 11B of the base arm 11 is set smaller on the front end side (one end side in the length direction) of the base arm 11 than on the rear end 11G side (the other end side in the length direction) of the base arm 11 to which the lifting cylinder 17 is attached via the cylinder support pin 17D. Specifically, as Figure 10 shown, the left panel 11A has a left rear panel 11A1 disposed on the rear end 11G side of the base arm 11 and a left front panel 11A2 disposed on the front side of the left rear panel 11A1. The right panel 11B has a right rear panel 11B1 disposed on the rear end 11G side of the base arm 11 and a right front panel 11B2 disposed on the front side of the right rear panel 11B1. And, the interval A2 between the left front panel 11A2 and the right front panel 11B2 is set smaller than the interval A1 between the left rear panel 11A1 and the right rear panel 11B1 (A2 < A1).

[0036] At the inner corner where the bottom panel 11E and the front panel 11F of the base arm 11 intersect, a bending plate 11P is fixed (refer to Figure 5 ). The bending plate 11P has: a horizontal plate 11Q that faces the bottom panel 11E at a certain interval; and a vertical plate 11R that bends at a right angle from the horizontal plate 11Q toward the bottom panel 11E. Thus, at the inner corner where the front upper panel 11C and the front panel 11F of the base arm 11 intersect, a cylinder holding portion 11S surrounded by the left panel 11A, the right panel 11B, the front upper panel 11C, the front panel 11F, and the horizontal plate 11Q of the bending plate 11P is formed. This cylinder holding portion 11S holds the end portion on the bottom side of the lifting cylinder 17 installed inside the base arm 11.

[0037] A reinforcing plate 12 is provided inside the base arm 11 and extends in the length direction of the base arm 11 in a state of connecting the left panel 11A and the right panel 11B. As Figure 5 and Figure 7 shown, the reinforcing plate 12 is composed of a component different from the front upper panel 11C and the rear upper panel 11D of the base arm 11 and is formed of a single plate body having a flat plate portion 12A and an inclined plate portion 12B. The flat plate portion 12A is disposed between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B and extends in the length direction of the base arm 11 while maintaining a certain interval from the rear upper panel 11D and the bottom panel 11E. The inclined plate portion 12B bends backward and upward from the flat plate portion 12A and extends above the upper guide arm connecting pin 13B.

[0038] The front end 12C of the reinforcing plate 12 (flat plate portion 12A) is joined to the rear end of the front upper panel 11C, and the rear end 12D of the reinforcing plate 12 (tilted plate portion 12B) is joined to the rear end side of the rear upper panel 11D. The bent portion 12E, which is the boundary portion between the flat plate portion 12A and the tilted plate portion 12B, is arranged in the longitudinal direction of the base arm 11 between the mounting portion of the swing arm 6 (swing arm connecting pin 11K), the upper guide arm connecting pin 13B, and the lower guide arm connecting pin 14B. Specifically, the bent portion 12E is arranged at a position adjacent to the front side of a cylinder support pin 17D described later.

[0039] In this way, the reinforcing plate 12 is connected between the left side panel 11A and the right side panel 11B of the base arm 11. Thereby, it is possible to prevent the left side panel 11A on which a second lifting pulley 22 etc. described later is mounted and the right side panel 11B on which a second opening / closing pulley 30 etc. described later is mounted from being deformed by an external force. In addition, the bent portion 12E of the reinforcing plate 12 is arranged at a position adjacent to the front side of the cylinder support pin 17D, the tilted plate portion 12B of the reinforcing plate 12 extends upward from the flat plate portion 12A to the upper side of the upper guide arm connecting pin 13B, and the rear end 12D of the reinforcing plate 12 is joined to the rear end side of the rear upper panel 11D. Thereby, on the rear end 11G side of the base arm 11 where the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D are provided, a box-shaped structure portion 11T is formed by the left side panel 11A, the right side panel 11B, the rear upper panel 11D, and the lower panel 11E divided by the tilted plate portion 12B of the reinforcing plate 12 (refer to Figure 7 ).

[0040] The upper guide arm 13 and the lower guide arm 14 are detachably mounted on the rear side of the base arm 11 in a state of being paired in the vertical direction. The upper guide arm 13 and the lower guide arm 14 are each formed as a square tube body having a rectangular cross-sectional shape and extend along the longitudinal direction (front-rear direction) of the base arm 11. As Figure 5 shown, a cylindrical portion 13A extending in the left-right direction is fixed to the front end of the upper guide arm 13, and a cylindrical portion 14A extending in the left-right direction is fixed to the front end of the lower guide arm 14. The upper guide arm connecting pin 13B is inserted through the inner peripheral side of the cylindrical portion 13A of the upper guide arm 13, and both ends of the upper guide arm connecting pin 13B are inserted through the pin insertion holes 11L on the upper side of the base arm 11. The lower guide arm connecting pin 14B is inserted through the inner peripheral side of the cylindrical portion 14A of the lower guide arm 14, and both ends of the lower guide arm connecting pin 14B are inserted through the pin insertion holes 11M on the lower side of the base arm 11. On the other hand, the rear ends of the upper guide arm 13 and the lower guide arm 14 are connected via a connecting member 14C. Thereby, the upper guide arm 13 and the lower guide arm 14 extend rearward from the rear end 11G of the base arm 11 while maintaining a certain interval in the vertical direction.

[0041] The pulley mounting member 15 is movably mounted on the upper guiding arm 13 and the lower guiding arm 14. The pulley mounting member 15 moves in the front-rear direction along the upper guiding arm 13 and the lower guiding arm 14 in a state where a first lifting pulley 18 and a first opening / closing pulley 20, which will be described later, are mounted. The pulley mounting member 15 is formed as a cylindrical body having a rectangular cross-sectional shape equivalent to that of the base arm 11, and surrounds the upper guiding arm 13 and the lower guiding arm 14 from the outside. The pulley mounting member 15 is formed as a short-sized cylindrical body (frame) surrounded by a left side plate 15A, a right side plate 15B, an upper plate 15C, and a lower plate 15D.

[0042] In the front side portions of the left side plate 15A and the right side plate 15B constituting the pulley mounting member 15, pin insertion through-holes 15E penetrating in the left-right direction are respectively formed (see Figure 5 ). A rod mounting pin 17F, which will be described later, is inserted through these two pin insertion through-holes 15E. A first lifting pulley shaft 19, which will be described later, is mounted at the center of the left side plate 15A constituting the pulley mounting member 15. A first opening / closing pulley shaft 21, which will be described later, is mounted at the center of the right side plate 15B constituting the pulley mounting member 15.

[0043] Sliding plates 15F are respectively provided between the inner peripheral surfaces of the left side plate 15A, the right side plate 15B, and the upper plate 15C of the pulley mounting member 15 and the upper guiding arm 13, and the sliding plates 15F are slidably abutted against the upper guiding arm 13. Sliding plates 15G are respectively provided between the inner peripheral surfaces of the left side plate 15A, the right side plate 15B, and the lower plate 15D of the pulley mounting member 15 and the lower guiding arm 14, and the sliding plates 15G are slidably abutted against the lower guiding arm 14. These sliding plates 15F and 15G are fixed to the pulley mounting member 15 using bolts or the like, enabling the pulley mounting member 15 to move (slide) smoothly relative to the upper guiding arm 13 and the lower guiding arm 14.

[0044] The bucket lifting and opening / closing device 16 is provided on the arm 10. The bucket lifting and opening / closing device 16 controls various operations including the lifting operation and the opening / closing operation of the clam shell bucket 9. The bucket lifting and opening / closing device 16 is configured to include a lifting cylinder 17, a first lifting pulley 18, a first opening / closing pulley 20, a second lifting pulley 22, a second opening / closing pulley 30, an opening / closing cylinder 31, an intermediate guiding pulley 37, a lifting rope 38, an opening / closing rope 40, a slack adjustment pulley 47, and a slack adjustment cylinder 48, which will be described later.

[0045] The lifting cylinder 17 is provided inside the base arm 11 and extends along the length direction (front-rear direction) of the base arm 11. The lifting cylinder 17 extends or contracts according to the operation of an operating device provided in the cab 4, thereby lifting the clam shell bucket 9. The lifting cylinder 17 has a tube 17A, a piston (not shown) inserted into the tube 17A, and a rod 17B having a base end mounted on the piston and a front end protruding from the tube 17A.

[0046] An attachment flange 17C is fixed to the pipe 17A of the lifting cylinder 17. Two pin holes (not shown) are formed concentrically on the attachment flange 17C with the pipe 17A interposed therebetween. In these two pin holes, two cylinder support pins 17D inserted through the trunnion pin insertion holes 11N of the base arm 11 (left side panel 11A and right side panel 11B) are fitted. Thus, the pipe 17A of the lifting cylinder 17 is connected to the base arm 11 via the cylinder support pins 17D.

[0047] On the other hand, an attachment ring 17E is provided at the front end of the rod 17B of the lifting cylinder 17. A rod attachment pin 17F is inserted through the pin insertion hole 15E of the attachment ring 17E and the pulley attachment member 15. Thus, the rod 17B of the lifting cylinder 17 is connected to the pulley attachment member 15 via the rod attachment pin 17F. In this way, the pipe 17A of the lifting cylinder 17 is attached to the base arm 11 via the cylinder support pins 17D, and the rod 17B is attached to the pulley attachment member 15 via the rod attachment pin 17F. Therefore, by expanding and contracting the lifting cylinder 17, the pulley attachment member 15 moves in the front-rear direction along the upper guide arm 13 and the lower guide arm 14.

[0048] As Figure 5 shown Figure 6 A quadrilateral frame body 17G is fixed to the bottom end portion of the lifting cylinder 17 (pipe 17A). The bottom end portion of the pipe 17A and the frame body 17G are disposed together within the cylinder holding portion 11S of the base arm 11. The frame body 17G is composed of two U-shaped frame members that sandwich the pipe 17A in the radial direction, and has a cross-sectional shape that is one size smaller than the cylinder holding portion 11S of the base arm 11. A plurality of plate-shaped spacers 17H are mounted on the outer side surface of the frame body 17G. These plurality of spacers 17H are disposed between the left side panel 11A, the right side panel 11B, the front upper panel 11C, and the bent plate 11P (horizontal plate 11Q) that constitute the cylinder holding portion 11S of the base arm 11 and the frame body 17G. In this way, the bottom end portion of the lifting cylinder 17 is received within the cylinder holding portion 11S of the base arm 11 via the frame body 17G and the spacers 17H. Thereby, the swing of the lifting cylinder 17 centered on the cylinder support pins 17D is restricted, and the buckling strength of the lifting cylinder 17 can be improved.

[0049] The first lifting pulley 18 is mounted on the outer side surface of the left side plate 15A that constitutes the pulley attachment member 15 via the first lifting pulley shaft 19. The first lifting pulley shaft 19 is fixed to the central portion of the left side plate 15A that constitutes the pulley attachment member 15. A plurality of (for example, five) first lifting pulleys 18 are arranged in the axial direction of the first lifting pulley shaft 19, and are supported so as to be rotatable about the first lifting pulley shaft 19 with respect to the pulley attachment member 15.

[0050] The first opening and closing pulley 20 is mounted on the outer side surface of the right side plate 15B constituting the pulley mounting member 15 via the first opening and closing pulley shaft 21. The first opening and closing pulley shaft 21 is fixed to the central portion of the right side plate 15B constituting the pulley mounting member 15. A plurality of (for example, 5) first opening and closing pulleys 20 are arranged in the axial direction of the first opening and closing pulley shaft 21 and are supported so as to be rotatable about the first opening and closing pulley shaft 21 with respect to the pulley mounting member 15.

[0051] The second lifting pulley 22 is provided on the base arm 11 separately from the first lifting pulley 18. The second lifting pulley 22 is mounted on the outer side surface of the left side panel 11A (left front side panel 11A2) constituting the base arm 11 via the second lifting pulley bracket 23. As Figure 7 and Figure 8 shown, the second lifting pulley bracket 23 includes a base plate 23A, a plurality of first rib plates 23B, and a pulley cover 23C. The base plate 23A extends in the front-rear direction with a certain interval between the base plate 23A and the left side panel 11A of the base arm 11. A plurality of (for example, 2) first rib plates 23B are arranged in a state of straddling the second lifting pulley shaft 24 in the up-down direction and maintaining a certain interval from each other, and connect between the left side panel 11A of the base arm 11 and the base plate 23A. The upper first rib plate 23B among the two first rib plates 23B is welded to the left side panel 11A at a position overlapping the flat plate portion 12A of the reinforcing plate 12 in the direction (left-right direction) orthogonal to the length direction of the base arm 11. The pulley cover 23C is formed in a frame shape that covers the plurality of second lifting pulleys 22 from the outside and is mounted on the base plate 23A.

[0052] The second lifting pulley shaft 24 is fixed to the base plate 23A of the second lifting pulley bracket 23 and is arranged between the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B in the up-down direction of the base arm 11. The second lifting pulley shaft 24 supports the second lifting pulley 22 in a state of being orthogonal to the length direction of the base arm 11 and protruding in the direction away from the base arm 11 (left side). A plurality of (for example, 4) second lifting pulleys 22 are arranged in the axial direction of the second lifting pulley shaft 24 and are supported so as to be rotatable about the second lifting pulley shaft 24 with respect to the base arm 11. Therefore, the pulley mounting member 15 moves according to the telescopic movement of the lifting cylinder 17, so that the first lifting pulley 18 mounted on the pulley mounting member 15 approaches and separates from the second lifting pulley 22. A lifting rope 38 is wound around the first lifting pulley 18 and the second lifting pulley 22.

[0053] The opening and closing pulley moving mechanism 25 is located at the middle portion in the front-rear direction of the base arm 11 and is provided on the right side panel 11B (right front side panel 11B2). The opening and closing pulley moving mechanism 25 supports the second opening and closing pulley 30 so as to be movable in the front-rear direction. AsFigure 3 , Figure 4 , Figure 11 As shown in Figure 3 , Figure 4 , Figure 11 , etc., the opening / closing pulley moving mechanism 25 is configured to include a guide rail 26, a sliding member 27, a second opening / closing pulley bracket 28, and a second opening / closing pulley shaft 29.

[0054] The guide rail 26 is formed of a rectangular flat plate extending along the length direction of the base arm 11, and is attached to the right side panel 11B of the base arm 11 via a plurality of (e.g., two) second rib plates 26A. The second rib plates 26A are arranged in a state of straddling the second opening / closing pulley shaft 29 in the vertical direction and maintaining a certain interval from each other, and are connected between the right side panel 11B of the base arm 11 and the guide rail 26. As shown in Figure 8 , the upper second rib plate 26A among the two second rib plates 26A is welded to the right side panel 11B at a position overlapping with the flat plate portion 12A of the reinforcing plate 12 in the direction (left-right direction) orthogonal to the length direction of the base arm 11. In addition, a front end plate 26B for reinforcement is welded between the front ends of the guide rail 26 and the second rib plates 26A and the right side panel 11B. A rear end plate 26C for reinforcement is welded between the rear ends of the guide rail 26 and the second rib plates 26A and the right side panel 11B.

[0055] The front and rear sliding members 27 are respectively engaged with the guide rail 26 so as to be slidable along the length direction. The second opening / closing pulley bracket 28 is attached to the front and rear sliding members 27 using bolts or the like, and can move along the guide rail 26 in the length direction of the base arm 11. A rod 31B of an opening / closing cylinder 31 described later is attached to the rear sliding member 27. The second opening / closing pulley shaft 29 is fixed to the second opening / closing pulley bracket 28, and is arranged between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11. The second opening / closing pulley shaft 29 supports the second opening / closing pulley 30 in a state of being orthogonal to the length direction of the base arm 11 and protruding in the direction away from the base arm 11 (right side).

[0056] The second opening / closing pulley 30 is rotatably attached to the second opening / closing pulley shaft 29 of the opening / closing pulley moving mechanism 25. That is, the second opening / closing pulley 30 is provided on the outer side surface of the right side panel 11B constituting the base arm 11 so as to be movable in the front-rear direction via the opening / closing pulley moving mechanism 25. A plurality of (e.g., four) second opening / closing pulleys 30 are arranged in the axial direction of the second opening / closing pulley shaft 29 provided on the opening / closing pulley moving mechanism 25, and are supported so as to be rotatable about the second opening / closing pulley shaft 29 with respect to the base arm 11.

[0057] ​​The opening / closing cylinder 31 is provided between the base arm 11 and the second opening / closing pulley 30. The opening / closing cylinder 31 extends along the length direction of the base arm 11, causing the second opening / closing pulley 30 to approach and depart from the first opening / closing pulley 20. The opening / closing cylinder 31 has a tube 31A, a piston (not shown) inserted into the tube 31A, and a rod 31B with its base end mounted on the piston and its front end protruding from the tube 31A. One end side (bottom side) of the opening / closing cylinder 31 is mounted via an opening / closing cylinder bracket 31C on the rear end side of the right side panel 11B constituting the base arm 11. The front end of the rod 31B is connected to the sliding member 27 of the opening / closing pulley moving mechanism 25 and is mounted on the second opening / closing pulley 30 via the opening / closing pulley moving mechanism 25. The second opening / closing pulley 30 moves in the front-rear direction according to the telescopic action of the opening / closing cylinder 31 and approaches and departs from the first opening / closing pulley 20.

[0058] As Figure 9 shown, the opening / closing cylinder bracket 31C is composed of two plate bodies opposed in the vertical direction and is arranged between the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D in the length direction of the base arm 11. Here, one end 31D side (rear side) in the length direction of the opening / closing cylinder bracket 31C extends between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B while maintaining a certain interval in the vertical direction. On the other hand, the other end 31E side (front side) in the length direction of the opening / closing cylinder bracket 31C has a shape in which the interval in the vertical direction gradually expands toward the cylinder support pin 17D. Thus, the other end 31E of the opening / closing cylinder bracket 31C and the cylinder support pin 17D are arranged adjacent to each other in the vertical direction, and the periphery of the mounting portion (trunnion pin insertion through-hole 11N) of the cylinder support pin 17D of the base arm 11 is strengthened.

[0059] The guide pulley support shaft 32 is provided on the front end side of the base arm 11. One end of the guide pulley support shaft 32 is fixed to the front end side of the left side panel 11A to which the front panel 11F is fixed, and the other end of the guide pulley support shaft 32 protrudes from the left side panel 11A toward the left side. The guide pulley support shaft 32 rotatably supports the lifting guide pulley 33 and the opening / closing guide pulley 34.

[0060] The lifting guide pulley 33 and the opening / closing guide pulley 34 are provided on the left side panel 11A of the base arm 11 via the guide pulley support shaft 32. The lifting guide pulley 33 guides the lifting rope 38 wound around the first lifting pulley 18 and the second lifting pulley 22 to the clam shell bucket 9. The opening / closing guide pulley 34 guides the opening / closing rope 40 wound around the first opening / closing pulley 20, the second opening / closing pulley 30, and the intermediate guide pulley 37 and the slack adjusting pulley 47 described later to the clam shell bucket 9. Thus, as Figure 1As shown, for example, in a state where the arm 10 is held horizontal with respect to the ground, the clamshell bucket 9 can be lifted and lowered in the vertical direction by the lifting rope 38 wound around the lifting guide pulley 33 disposed at the front end of the arm 10.

[0061] The lifting guide pulley 33 and the opening / closing guide pulley 34 are disposed at the front end side of the left panel 11A in the base arm 11, which has high visibility for the operator sitting on the driver's seat 4A. Thus, the operator can operate the bucket lifting / opening / closing device 16 while visually confirming the states of the lifting rope 38 and the opening / closing rope 40 attached to the clamshell bucket 9.

[0062] The intermediate guide pulley shaft 35 is provided at the rear side of the front upper panel 11C constituting the base arm 11. A frame member 36 bent into a U-shaped cross section is fixed to the front upper panel 11C of the base arm 11. One end (lower end) of the intermediate guide pulley shaft 35 is attached to the front upper panel 11C, and the other end (upper end) is attached to the frame member 36, thereby being slightly inclined rearward and extending upward from the front upper panel 11C.

[0063] The intermediate guide pulley 37 is rotatably provided on the front upper panel 11C of the base arm 11 via the intermediate guide pulley shaft 35. The intermediate guide pulley 37 is interposed between the opening / closing guide pulley 34 provided on the left panel 11A of the base arm 11 and the slack adjustment pulley 47 provided on the right panel 11B of the base arm 11. The intermediate guide pulley 37 guides the opening / closing rope 40 to the opening / closing guide pulley 34 by winding the opening / closing rope 40 extending from the slack adjustment pulley 47.

[0064] The lifting rope 38 is provided between the arm 10 and the clamshell bucket 9 and supports the clamshell bucket 9 so as to be liftable. The lifting rope 38 is composed of a steel wire rope. One end 38A of the lifting rope 38 is attached to the lifting rope mounting bracket 39 provided on the left panel 11A of the base arm 11. The other end 38B of the lifting rope 38 is attached to the bucket support portion 9A of the clamshell bucket 9 to support the clamshell bucket 9 (see Figure 1 ). The intermediate portion of the lifting rope 38 is alternately wound around a plurality of first lifting pulleys 18 and a plurality of second lifting pulleys 22.

[0065] As Figure 7 To Figure 10As shown, the lifting rope mounting bracket 39 is disposed adjacent to the rear side of the second lifting pulley bracket 23 on the left side panel 11A of the base arm 11 and extends in the front-rear direction. The lifting rope mounting bracket 39 has two plate bodies 39A opposed to each other in the up-down direction at a certain interval, and an extension portion 39B extending leftward from the left side panel 11A is provided on the front side of the plate body 39A. A joint 39D that can swing in the up-down direction about a pin 39C is mounted on the extension portion 39B. The joint 39D forms a part of the lifting rope mounting bracket 39 and is connected to one end 38A of the lifting rope 38.

[0066] Here, the front side portion of the lifting rope mounting bracket 39 is welded to the base plate 23A of the second lifting pulley bracket 23, and the rear side portion is welded to the left side panel 11A of the base arm 11. Thus, the lifting rope mounting bracket 39 is integrally fixed to the second lifting pulley bracket 23. Thereby, a structure is formed in which the load acting on the lifting rope 38 is efficiently transmitted from the lifting rope mounting bracket 39 to the second lifting pulley bracket 23 and the base arm 11.

[0067] An opening / closing rope 40 is provided between the dipper arm 10 and the clamshell bucket 9 to open and close a pair of buckets 9B of the clamshell bucket 9. The opening / closing rope 40 is composed of a wire rope. One end 40A of the opening / closing rope 40 is mounted on an opening / closing rope mounting bracket 41 provided on the right side panel 11B of the base arm 11. The other end 40B of the opening / closing rope 40 is mounted on a bucket support portion 9A of the clamshell bucket 9 (see Figure 1 ). The middle portion of the opening / closing rope 40 is alternately wound around a plurality of first opening / closing pulleys 20 and a plurality of second opening / closing pulleys 30. In addition, the other end 40B side of the opening / closing rope 40 is alternately wound around a plurality of upper pulleys 9E and a plurality of lower pulleys 9F constituting the clamshell bucket 9.

[0068] As Figure 9 and Figure 10 shown, the opening / closing rope mounting bracket 41 is disposed adjacent to the rear side of the opening / closing pulley moving mechanism 25 on the right side panel 11B of the base arm 11 and extends in the front-rear direction. The opening / closing rope mounting bracket 41 is composed of an upper plate 41A and a lower plate 41B opposed to each other in the up-down direction at a certain interval. The front side portion of the opening / closing rope mounting bracket 41 is welded to the rear end plate 26C of a guide rail 26 constituting the opening / closing pulley moving mechanism 25. An extension portion 41C extending rightward from the right side panel 11B is provided on the front side of the opening / closing rope mounting bracket 41, and a joint 41E that can swing in the up-down direction about a pin 41D is mounted on the extension portion 41C. The joint 41E forms a part of the opening / closing rope mounting bracket 41 and is connected to one end 40A of the opening / closing rope 40. An opening / closing cylinder 31 is disposed between the upper plate 41A and the lower plate 41B of the opening / closing rope mounting bracket 41 to protect the opening / closing cylinder 31.

[0069] The clam shell bucket 9 descends by the lifting cylinder 17 contracting so that the first lifting pulley 18 approaches the second lifting pulley 22, and ascends by the lifting cylinder 17 extending so that the first lifting pulley 18 moves away from the second lifting pulley 22. On the other hand, the clam shell bucket 9 opens by the opening and closing cylinder 31 contracting and the second opening and closing pulley 30 approaching the first opening and closing pulley 20, and closes by the opening and closing cylinder 31 extending and the second opening and closing pulley 30 moving away from the first opening and closing pulley 20.

[0070] The slack adjustment pulley moving mechanism 42 is located on the front end side of the base arm 11 and is provided on the right side panel 11B. The slack adjustment pulley moving mechanism 42 supports the slack adjustment pulley 47 so as to be movable in the front-rear direction. As Figure 3 shown Figure 4 The slack adjustment pulley moving mechanism 42 is configured to include a guide rail 43, a sliding member 44, a slack adjustment pulley bracket 45, and a slack adjustment pulley shaft 46.

[0071] The guide rail 43 is fixed to the right side panel 11B of the base arm 11. The sliding member 44 engages with the guide rail 43 so as to be slidable in the longitudinal direction. The slack adjustment pulley bracket 45 is mounted on the sliding member 44 using bolts or the like. A rod 48B of a slack adjustment cylinder 48 described later is mounted on the slack adjustment pulley bracket 45. In addition, the slack adjustment pulley shaft 46 is fixed to the slack adjustment pulley bracket 45.

[0072] The slack adjustment pulley 47 is rotatably mounted on the second slack adjustment pulley shaft 46 of the slack adjustment pulley moving mechanism 42. That is, the slack adjustment pulley 47 is provided on the right side panel 11B of the base arm 11 so as to be movable in the front-rear direction via the slack adjustment pulley moving mechanism 42. The slack adjustment pulley 47 is composed of a single pulley and is supported so as to be rotatable about the slack adjustment pulley shaft 46 with respect to the base arm 11.

[0073] The opening and closing rope 40 wound around the plurality of first opening and closing pulleys 20 and the plurality of second opening and closing pulleys 30 is successively wound around the slack adjustment pulley 47, the intermediate guide pulley 37, and the opening and closing guide pulley 34. And after the other end 40B side of the opening and closing rope 40 wound around the opening and closing guide pulley 34 is wound around the upper pulley 9E and the lower pulley 9F of the clam shell bucket 9, the other end 40B of the opening and closing rope 40 is mounted on the bucket support portion 9A.

[0074] The slack adjustment cylinder 48 is located on the front side of the opening / closing pulley moving mechanism 25 and is provided on the right side panel 11B of the base arm 11. The slack adjustment cylinder 48 extends in the front-rear direction, causing the slack adjustment pulley 47 to approach and depart from the second opening / closing pulley 30. The slack adjustment cylinder 48 includes: a tube 48A; a piston (not shown) inserted into the tube 48A; and a rod 48B having its base end mounted on the piston and its front end protruding from the tube 48A.

[0075] One end side (bottom side) of the slack adjustment cylinder 48 is mounted on the right side panel 11B of the base arm 11 via the slack adjustment cylinder bracket 48C. The slack adjustment cylinder bracket 48C is welded to the front end plate 26B of the guide rail 26 constituting the opening / closing pulley moving mechanism 25 and is integrally fixed to the guide rail 26. Thus, a structure is formed in which the load acting on the slack adjustment pulley 47 is efficiently transmitted to the base arm 11 via the slack adjustment cylinder 48, the slack adjustment cylinder bracket 48C, the guide rail 26, the reinforcement plate 12, etc. The front end of the rod 48B is mounted on the slack adjustment pulley bracket 45 of the slack adjustment pulley moving mechanism 42.

[0076] Therefore, the slack adjustment opening / closing pulley 47 mounted on the slack adjustment pulley moving mechanism 42 moves in the front-rear direction according to the telescopic movement of the slack adjustment cylinder 48, approaching and departing from the second opening / closing pulley 30. For example, during the excavation operation of a deep pit using the deep-base excavator 1, when the clamshell bucket 9 touches the ground and the opening / closing rope 40 is slack, the slack adjustment cylinder 48 is extended. Thereby, the slack adjustment pulley 47 departs from the second opening / closing pulley 30, and thus the slack of the opening / closing rope 40 can be removed.

[0077] The electric deep-base excavator 1 of the present embodiment has the above-described structure. Hereinafter, the operation of the electric deep-base excavator 1 will be described.

[0078] The operator riding in the cab 4, for example, as Figure 1 shown, operates the boom cylinder 7 to lift the front end of the boom 6 upward, and operates the stick cylinder 8 to hold the stick 10 in a horizontal posture with respect to the ground. Next, after the clamshell bucket 9 is disposed above the ground to be excavated, the lift cylinder 17 is contracted. As a result, the pulley mounting member 15 moves forward along the upper guide stick 13 and the lower guide stick 14, the first lift pulley 18 approaches the second lift pulley 22, and the first opening / closing pulley 20 approaches the second opening / closing pulley 30. As a result, the lift rope 38 and the opening / closing rope 40 are fed out from the stick 10, and the clamshell bucket 9 descends.

[0079] When the clam shell bucket 9 approaches the ground, the operator contracts the opening / closing cylinder 31. As a result, the second opening / closing pulley 30 mounted on the opening / closing pulley moving mechanism 25 approaches the first opening / closing pulley 20, the opening / closing rope 40 is sent out from the boom 10, and the pair of buckets 9B of the clam shell bucket 9 becomes fully open. In a state where the clam shell bucket 9 is fully open, the operator contracts the lifting cylinder 17, causing the pair of buckets 9B of the clam shell bucket 9 to penetrate into the ground by their own weight.

[0080] Next, before closing the clam shell bucket 9, the operator extends the slack adjustment cylinder 48, causing the slack adjustment pulley 47 mounted on the slack adjustment pulley moving mechanism 42 to move away from the second opening / closing pulley 30. As a result, only the slack of the opening / closing rope 40 is eliminated in a state where the lifting rope 38 is slack. In this state, the operator extends the opening / closing cylinder 31, causing the second opening / closing pulley 30 mounted on the opening / closing pulley moving mechanism 25 to move away from the first opening / closing pulley 20, thereby pulling the opening / closing rope 40 toward the boom 10 side. As a result, the clam shell bucket 9 closes while diving into the ground due to its own weight, and a large amount of sand and soil can be scooped up.

[0081] After closing the clam shell bucket 9 and scooping up the sand and soil, the operator extends the lifting cylinder 17. At this time, when the lifting rope 38 is slack after scooping up the sand and soil, the slack adjustment cylinder 48 is contracted while the lifting cylinder 17 is extended. As a result, the first lifting pulley 18 mounted on the pulley mounting member 15 moves away from the second lifting pulley 22, the lifting rope 38 is lifted toward the boom 10 side, and the first opening / closing pulley 20 moves away from the second opening / closing pulley 30, and the opening / closing rope 40 is lifted toward the boom 10 side. As a result, the lifting rope 38 and the opening / closing rope 40 are lifted toward the boom 10 side together, and the clam shell bucket 9 is lifted and rises while holding the sand and soil by the lifting rope 38 and the opening / closing rope 40.

[0082] After lifting the clam shell bucket 9 to the outside of the deep pit, for example, the upper rotating body 3 is rotated to move the clam shell bucket 9 above the loading platform of a dump truck (not shown). In this state, the operator contracts the opening / closing cylinder 31, causing the second opening / closing pulley 30 mounted on the opening / closing pulley moving mechanism 25 to approach the first opening / closing pulley 20. As a result, the opening / closing rope 40 is pulled out from the boom 10, and the clam shell bucket 9 opens, so that the excavated sand and soil can be discharged into the cargo box of the dump truck.

[0083] In this way, after discharging the sand and soil into the cargo box of the dump truck, the upper rotating body 3 is rotated to move the clam shell bucket 9 above the deep pit, and by repeating the above-mentioned operations, the deep pit can be excavated.

[0084] Here, in the deep foundation excavator 1 of this embodiment, by providing a reinforcing plate 12 inside the base arm 11 to connect the left panel 11A and the right panel 11B, deformation of the left panel 11A and the right panel 11B caused by external forces can be suppressed. Moreover, by disposing a part of the reinforcing plate 12 between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B, sufficient strength can be ensured for the base arm 11 against external forces acting on the connecting portions of the upper guide arm 13 and the lower guide arm 14 with the base arm 11. As a result, the strength of the base arm 11 can be increased and its lifespan can be extended.

[0085] In addition, the front end 12C of the reinforcing plate 12 (flat plate portion 12A) is joined to the rear end of the front upper panel 11C, and the rear end 12D of the reinforcing plate 12 (inclined plate portion 12B) is joined to the rear end side of the rear upper panel 11D. A bent portion 12E that is the boundary between the flat plate portion 12A and the inclined plate portion 12B is disposed in the longitudinal direction of the base arm 11 between the mounting portion of the boom 6 (boom connecting pin 11K), the upper guide arm connecting pin 13B, and the lower guide arm connecting pin 14B. Thereby, on the rear end 11G side of the base arm 11, a box-structured portion 11T can be formed that is delimited by the left panel 11A, the right panel 11B, the rear upper panel 11D, and the lower panel 11E by the inclined plate portion 12B of the reinforcing plate 12. As a result, the strength of the rear end 11G side of the base arm 11 where the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D are provided can be increased.

[0086] On the other hand, the reinforcing plate 12 has a flat plate portion 12A extending in the longitudinal direction of the base arm 11 and an inclined plate portion 12B that bends from the flat plate portion 12A toward the rear upper panel 11D, thereby improving workability when mounting the lifting cylinder 17 inside the base arm 11. Specifically, in a state where the lower panel 11E of the base arm 11 faces upward, when inserting the lifting cylinder 17 from the rear end 11G of the base arm 11 that is the open end, the bottom side of the lifting cylinder 17 can be smoothly guided along the inclined plate portion 12B toward the flat plate portion 12A. Then, the lifting cylinder 17 is inserted into the base arm 11 along the flat plate portion 12A of the reinforcing plate 12. Thereby, the frame 17G fixed to the end portion on the bottom side of the lifting cylinder 17 (pipe 17A) and the spacer 17H can be housed together in the cylinder holding portion 11S of the base arm 11.

[0087] In addition, the spacing between the left panel 11A and the right panel 11B that constitute the base arm 11 is set smaller on the front end side (one end side) of the base arm 11 where the front panel 11F is provided, as compared to the rear end 11G side (the other end side) of the base arm 11 to which the lifting cylinder 17 is mounted via the cylinder support pin 17D. As a result, on the rear end 11G side of the base arm 11, it is possible to ensure the width dimension (the spacing A1 between the left rear panel 11A1 and the right rear panel 11B1) required for mounting the lifting cylinder 17. Consequently, it is possible to reduce the width dimension (the spacing A2 between the left front panel 11A2 and the right front panel 11B2) of the portion on the front side of the mounting portion of the lifting cylinder 17, and thus it is possible to achieve weight reduction of the base arm 11.

[0088] In addition, on the lower panel 11E of the base arm 11, an arm mounting bracket 11H composed of two plate bodies opposed to each other in the left-right direction is fixed. The left arm mounting bracket 11H is arranged at a position vertically aligned with the left panel 11A of the base arm 11. The right arm mounting bracket 11H is arranged at a position vertically aligned with the right panel 11B of the base arm 11. As a result, the external force transmitted from the boom 6 to the base arm 11 via the arm mounting bracket 11H can be efficiently transmitted to the left panel 11A and the right panel 11B. Consequently, stress concentration at the joint portion between the arm mounting bracket 11H and the base arm 11 and the like can be reduced. In addition, even if the left panel 11A and the right panel 11B of the base arm 11 do not coincide with the arm mounting bracket 11H, by arranging the left panel 11A and the right panel 11B within a range close to each other (within a range not exceeding twice the plate thickness of the thicker one of the two), the external force can also be efficiently transmitted to the left panel 11A and the right panel 11B of the base arm 11.

[0089] In addition, at the inner corner where the front upper panel 11C of the base arm 11 intersects with the front panel 11F, a cylinder holding portion 11S surrounded by the left panel 11A, the right panel 11B, the front upper panel 11C, the front panel 11F, and the horizontal plate 11Q of the bent plate 11P is formed. As a result, the bottom end portion of the lifting cylinder 17 mounted in the base arm 11 via the cylinder support pin 17D can be accommodated in the cylinder holding portion 11S. As a result, the swing of the lifting cylinder 17 centered on the cylinder support pin 17D is restricted, and the buckling strength of the lifting cylinder 17 can be improved. Moreover, as long as the dimensional accuracy of the cylinder holding portion 11S for accommodating the bottom end portion of the lifting cylinder 17 is ensured, the dimensional tolerance of the other portions can be set larger, the assembly man-hours of the base arm 11 can be reduced, and it can also contribute to cost reduction in manufacturing.

[0090] In addition, the arm 10 is configured to be divisible into a base arm 11, an upper guide arm 13, a lower guide arm 14, and a pulley mounting member 15. Therefore, even in a narrow work site such as an indoor site where there is not enough space to move in the deep foundation excavator 1, for example, the arm 10 can be removed from the boom 6, the removed arm 10 can be divided and loaded onto a relatively small transport vehicle and then moved into the work site, and the arm 10 can be assembled at the work site. Moreover, by changing the lengths of the upper guide arm 13 and the lower guide arm 14, the overall length of the arm 10 can be appropriately set. Thus, when the lengths of the upper guide arm 13 and the lower guide arm 14 are increased to increase the overall length of the arm 10, the digging depth against standing of the deep foundation excavator 1 can be increased. On the other hand, when the lengths of the upper guide arm 13 and the lower guide arm 14 are reduced to reduce the overall length of the arm 10, the arm 10 can be lightened, and the transportability can be improved.

[0091] In addition, as Figure 8 shown, a first rib plate 23B of the second lifting pulley bracket 23 is fixed to the left side panel 11A of the base arm 11, and a second lifting pulley shaft 24 for supporting the second lifting pulley 22 is installed on the second lifting pulley bracket 23. The upper first rib plate 23B of the two first rib plates 23B is welded to the left side panel 11A at a position where it coincides with the flat plate portion 12A of the reinforcing plate 12 in a direction orthogonal to the longitudinal direction of the base arm 11. Thus, the external force acting on the left side panel 11A of the base arm 11 from the second lifting pulley 22 is transmitted to the reinforcing plate 12 via the first rib plate 23B, so that deformation of the left side panel 11A can be suppressed. In addition, even if the first rib plate 23B does not coincide with the reinforcing plate 12 (flat plate portion 12A), by arranging the first rib plate 23B and the reinforcing plate 12 within a range where they are close to each other (the interval between the two is within a range of not more than twice the plate thickness of the first rib plate 23B with a larger plate thickness), the external force can be transmitted to the reinforcing plate 12 via the first rib plate 23B. In other words, for example, it is sufficient for the second lifting pulley bracket 23 to have a plurality of first rib plates 23B, and it is sufficient for the second lifting pulley shaft 24 to be installed on the second lifting pulley bracket 23 where the first rib plate 23B is fixed to the left side panel 11A.

[0092] In addition, on the right panel 11B of the base arm 11, a guide rail 26 of a moving mechanism 25 for the opening / closing pulley is installed via a second rib plate 26A to move the second opening / closing pulley 30 in the longitudinal direction of the base arm 11. The upper second rib plate 26A of the two second rib plates 26A is welded to the right panel 11B at a position overlapping with the flat portion 12A of the reinforcing plate 12 in a direction orthogonal to the longitudinal direction of the base arm 11. Thus, the external force acting on the right panel 11B of the base arm 11 from the second opening / closing pulley 30 is transmitted to the reinforcing plate 12 via the second rib plate 26A, so that deformation of the right panel 11B can be suppressed. In addition, even if the second rib plate 26A does not overlap with the reinforcing plate 12 (flat portion 12A), by arranging the second rib plate 26A and the reinforcing plate 12 within a range close to each other (the interval between the two is within a range of not more than twice the plate thickness of the second rib plate 26A with a larger plate thickness), the external force can be transmitted to the reinforcing plate 12 via the second rib plate 26A. In other words, for example, the guide rail 26 only needs to be installed on a plurality of second rib plates 26A fixed to the right panel 11B.

[0093] Here, the flat portion 12A of the reinforcing plate 12 is arranged between an upper guide arm connecting pin 13B and a lower guide arm connecting pin 14B provided at the rear end 11G of the base arm 11. Therefore, the upper first rib plate 23B and the upper second rib plate 26A are also arranged between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. On the other hand, a second lifting pulley shaft 24 for supporting the second lifting pulley 22 and a second opening / closing pulley shaft 29 for supporting the second opening / closing pulley 30 are arranged between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11. Thus, the load acting on the second lifting pulley 22 and the load acting on the second opening / closing pulley 30 can be efficiently transmitted to the reinforcing plate 12 via the first rib plate 23B and the second rib plate 26A. As a result, stress concentration on the base arm 11 can be reduced, and by reducing the plate thickness of each plate material constituting the base arm 11, the overall weight of the base arm 11 can be reduced.

[0094] In addition, as Figure 10 shown, a lifting rope mounting bracket 39 for mounting one end 38A of a lifting rope 38 is integrally fixed to the base plate 23A of the second lifting pulley bracket 23. Thus, the load acting on the lifting rope 38 can be efficiently transmitted from the lifting rope mounting bracket 39 via the second lifting pulley bracket 23 to the base arm 11. As a result, stress concentration at the joint between the lifting rope mounting bracket 39 and the base arm 11 and the like can be reduced. Moreover, compared with the case where the lifting rope mounting bracket 39 is arranged at a position away from the base plate 23A of the second lifting pulley bracket 23, for example, the length dimension on the rear end 11G side of the base arm 11 (the length dimension from the moving arm connecting pin 11K to the rear end 11G) can be shortened.

[0095] In addition, as Figure 9 shown, the opening / closing cylinder bracket 31C that supports the bottom side of the opening / closing cylinder 31 is arranged between the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D in the longitudinal direction of the base arm 11. Thereby, compared with the case where the opening / closing cylinder bracket 31C is installed on the front side of the cylinder support pin 17D, for example, the length dimension on the rear end 11G side of the base arm 11 can be shortened. Moreover, by fixing the opening / closing cylinder bracket 31C around the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D, the strength of the rear end 11G side of the base arm 11, which is the open end, can be improved.

[0096] In this case, the other end 31E side (front side) in the longitudinal direction of the opening / closing cylinder bracket 31C has a shape in which the vertical interval gradually expands toward the cylinder support pin 17D. Thereby, the other end 31E of the opening / closing cylinder bracket 31C can be arranged adjacent to the cylinder support pin 17D in the vertical direction, and the periphery of the mounting portion of the cylinder support pin 17D in the base arm 11 can be strengthened.

[0097] In addition, behind the opening / closing pulley moving mechanism 25, an opening / closing rope mounting bracket 41 having an upper plate 41A and a lower plate 41B opposed to each other in the vertical direction is provided, and the opening / closing cylinder 31 is arranged between the upper plate 41A and the lower plate 41B of the opening / closing rope mounting bracket 41. Thereby, the opening / closing cylinder 31 can be protected by the opening / closing rope mounting bracket 41 from interference caused by vibration of the opening / closing rope 40 or the like.

[0098] In addition, as Figure 3 and Figure 4 shown, one end side (bottom side) of the slack adjustment cylinder bracket 48C on which the slack adjustment cylinder 48 is mounted is integrally fixed to the guide rail 26 constituting the opening / closing pulley moving mechanism 25. Thereby, the load acting on the slack adjustment pulley 47 can be efficiently transmitted to the base arm 11 via the slack adjustment cylinder 48, the slack adjustment cylinder bracket 48C, the guide rail 26, the reinforcing plate 12, etc. As a result, stress concentration at the joint portion between the slack adjustment cylinder bracket 48C and the base arm 11 can be reduced. In addition, for example, compared with the case where the slack adjustment cylinder bracket 48C is arranged on the front side of the guide rail 26, the length dimension on the rear end 11G side of the base arm 11 can be shortened.

[0099] Thus, in the embodiment, the working device 5 of the deep foundation excavator 1 includes: a basic arm 11 having a clam shell bucket 9 disposed at one end side in the longitudinal direction; an upper guide boom 13 and a lower guide boom 14 connected to the other end side of the basic arm 11 via an upper guide boom connecting pin 13B and a lower guide boom connecting pin 14B; a first lifting pulley 18 and a first opening / closing pulley 20; a lifting cylinder 17; a second lifting pulley 22 and a second opening / closing pulley 30; a lifting rope 38; and an opening / closing rope 40. The basic arm 11 is formed as a cylindrical body having a left side panel 11A and a right side panel 11B opposed to each other at intervals in a direction orthogonal to the longitudinal direction. A second lifting pulley shaft 24 and a second opening / closing pulley shaft 29 are disposed between the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B in the vertical direction of the basic arm 11. A reinforcing plate 12 extending in the longitudinal direction of the basic arm 11 is provided on the basic arm 11 in a state where the left side panel 11A and the right side panel 11B are connected, and a part of the reinforcing plate 12 is disposed between the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B in the vertical direction of the basic arm 11.

[0100] According to this structure, by disposing a part of the reinforcing plate 12 connected between the left side panel 11A and the right side panel 11B between the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B, deformation of the left side panel 11A and the right side panel 11B caused by external forces can be suppressed. As a result, the basic arm 11 can ensure sufficient strength against external forces acting on the connecting portions of the upper guide boom 13 and the lower guide boom 14 with the basic arm 11, and its service life can be extended.

[0101] In the embodiment, the basic arm 11 is rotatably mounted at the front end of a boom 6 mounted on the upper rotating body 3. The reinforcing plate 12 has: a flat plate portion 12A disposed between the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B and extending in the longitudinal direction of the basic arm 11; and an inclined plate portion 12B bent from the flat plate portion 12A and extending upward of the upper guide boom connecting pin 13B. A bent portion 12E that is a boundary portion between the flat plate portion 12A and the inclined plate portion 12B is disposed in the longitudinal direction of the basic arm 11 between the mounting portion (boom connecting pin 11K) of the boom 6 and the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B. According to this structure, on the rear end 11G side of the basic arm 11, a box structure portion 11T defined by the inclined plate portion 12B of the reinforcing plate 12 can be formed. As a result, the strength of the rear end 11G side of the basic arm 11 where the upper guide boom connecting pin 13B, the lower guide boom connecting pin 14B, and the cylinder support pin 17D are provided can be improved.

[0102] In an embodiment, the lifting cylinder 17 is located on the other end (rear end 11G) side in the longitudinal direction of the base arm 11, and is mounted on the left side panel 11A and the right side panel 11B constituting the base arm 11 via the cylinder support pin 17D. The interval between the left side panel 11A and the right side panel 11B of the base arm 11 is set smaller with respect to the other end side of the base arm 11 where the lifting cylinder 17 is mounted (the interval between the left rear side panel 11A1 and the right rear side panel 11B1) than the one end side of the base arm 11 (the interval between the left front side panel 11A2 and the right front side panel 11B2). According to this structure, the width dimension of the portion of the base arm 11 that is forward of the mounting portion (cylinder support pin 17D) of the lifting cylinder 17 can be reduced, and the weight reduction of the base arm 11 can be achieved.

[0103] In an embodiment, the base arm 11 has a boom mounting bracket 11H, and the boom mounting bracket 11H is rotatably mounted on the front end of the boom 6 mounted on the upper rotating body 3. The boom mounting bracket 11H is disposed at a position that coincides with the left side panel 11A and the right side panel 11B constituting the base arm 11 in the vertical direction. According to this structure, the external force transmitted from the boom 6 to the base arm 11 via the boom mounting bracket 11H can be efficiently transmitted to the left side panel 11A and the right side panel 11B. As a result, the stress concentration on the joint portion between the boom mounting bracket 11H and the base arm 11 and the like can be reduced.

[0104] In an embodiment, on the other end side in the longitudinal direction of the base arm 11, a lifting cylinder 17 is rotatably mounted via a cylinder support pin 17D, and on the one end side in the longitudinal direction of the base arm 11, a cylinder holding portion 11S is provided to hold the bottom end portion of the lifting cylinder 17 in a constrained state. According to this structure, by housing the bottom end portion of the lifting cylinder 17 in the cylinder holding portion 11S, the swing of the lifting cylinder 17 centered on the cylinder support pin 17D can be restricted, and the buckling strength of the lifting cylinder 17 can be improved.

[0105] In an embodiment, the second lifting pulley shaft 24 is mounted on the second lifting pulley bracket 23, and the second lifting pulley bracket 23 has a plurality of first rib plates 23B fixed to the left side panel 11A constituting the base arm 11. According to this structure, the deformation of the left side panel 11A can be suppressed.

[0106] In an embodiment, the second opening and closing pulley shaft 29 is mounted on the second opening and closing pulley bracket 28 that moves along a guide rail 26 extending in the longitudinal direction of the base arm 11, and the guide rail 26 is mounted on a plurality of second rib plates 26A fixed to the right side panel 11B constituting the base arm 11. According to this structure, the deformation of the right side panel 11B can be suppressed.

[0107] In an embodiment, a lifting rope mounting bracket 39 for mounting one end 38A of a lifting rope 38 is provided on a base arm 11, and the lifting rope mounting bracket 39 is integrally fixed to a second lifting pulley bracket 23. According to this structure, the load acting on the lifting rope 38 can be efficiently transmitted from the lifting rope mounting bracket 39 to the base arm 11 via the second lifting pulley bracket 23. As a result, stress concentration at joints such as the joint between the lifting rope mounting bracket 39 and the base arm 11 can be reduced.

[0108] In an embodiment, a lifting cylinder 17 is mounted on the other end side in the longitudinal direction of the base arm 11 via a cylinder support pin 17D, and an opening / closing cylinder 31 is provided between the base arm 11 and a second opening / closing pulley 30. One end of the opening / closing cylinder 31 is connected to the base arm 11 via an opening / closing cylinder bracket 31C, and the other end is connected to the second opening / closing pulley 30, causing the second opening / closing pulley 30 to approach and separate from a first opening / closing pulley 20. The opening / closing cylinder bracket 31C is arranged between an upper guide arm connecting pin 13B, a lower guide arm connecting pin 14B, and the cylinder support pin 17D in the longitudinal direction of the base arm 11. According to this structure, the strength of the other end side in the longitudinal direction of the base arm 11 can be increased by the opening / closing cylinder bracket 31C fixed around the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D.

[0109] In an embodiment, the opening / closing cylinder bracket 31C is composed of two plate bodies opposed in the vertical direction. One end 31D side in the longitudinal direction extends between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B while maintaining a certain interval in the vertical direction, and the interval in the vertical direction expands toward the cylinder support pin 17D on the other end 31E side in the longitudinal direction. According to this structure, the other end 31E of the opening / closing cylinder bracket 31C and the cylinder support pin 17D can be arranged adjacent to each other vertically, and the periphery of the mounting portion of the cylinder support pin 17D in the base arm 11 can be strengthened.

[0110] In an embodiment, an opening / closing rope mounting bracket 41 is provided on the base arm 11. The opening / closing rope mounting bracket 41 has an upper plate 41A and a lower plate 41B opposed in the vertical direction, and one end 40A of an opening / closing rope 40 is mounted. The opening / closing cylinder 31 is arranged between the upper plate 41A and the lower plate 41B of the opening / closing rope mounting bracket 41. According to this structure, the opening / closing cylinder 31 can be protected by the opening / closing rope mounting bracket 41 from interference caused by vibration of the opening / closing rope 40 or the like.

[0111] In an embodiment, on the base arm 11, there are provided: a slack adjustment pulley 47 around which an opening / closing rope 40 is wound and which is movable in a direction approaching and departing from the second opening / closing pulley 30; and a slack adjustment cylinder 48 that moves the slack adjustment pulley 47. The second opening / closing pulley shaft 29 is mounted on a second opening / closing pulley bracket 28 that moves along a guide rail 26 extending in the longitudinal direction of the base arm 11, and a slack adjustment cylinder bracket 48C that supports one end of the slack adjustment cylinder 48 is integrally fixed to the guide rail 26. According to this structure, the load acting on the slack adjustment pulley 47 can be efficiently transmitted to the base arm 11 via the slack adjustment cylinder 48, the slack adjustment cylinder bracket 48C, the guide rail 26, the reinforcement plate 12, etc. As a result, stress concentration at the joint between the slack adjustment cylinder bracket 48C and the base arm 11 can be reduced.

[0112] In addition, in the embodiment, as the reinforcement plate connecting the left side panel 11A and the right side panel 11B of the base arm 11, the reinforcement plate 12 composed of components different from the front upper panel 11C and the rear upper panel 11D of the base arm 11 is exemplified. However, the present invention is not limited thereto. For example, as in Figure 12 and Figure 13 In the deformation example shown, the upper panel 52 of the base arm 51 is formed by the reinforcement plate. That is, the base arm 51 of the deformation example is formed as a square tube body having a left side panel 51A, a right side panel 51B, a lower panel 51C, a front panel 51D, etc., and the upper panel 52 connecting the upper ends of the left side panel 51A and the right side panel 51B as a pair of side panels constitutes the reinforcement plate of the deformation example.

[0113] The upper panel 52 of the base arm 51 is disposed between the upper guide boom connecting pin 13B and the lower guide boom connecting pin 14B. The upper panel 52 has: a flat plate portion 52A that extends in the longitudinal direction of the base arm 51 while maintaining a certain interval between the lower panel 51C; and an inclined plate portion 52B that bends backward and upward from the flat plate portion 52A and extends above the upper guide boom connecting pin 13B. The bent portion 52C that is the boundary between the flat plate portion 52A and the inclined plate portion 52B is disposed in the longitudinal direction of the base arm 51 between the mounting portion of the boom 6 (boom connecting pin 11K), the upper guide boom connecting pin 13B, and the lower guide boom connecting pin 14B. The upper first rib plate 23B fixed to the base plate 23A of the second lifting pulley bracket 23 is fixed to the left side panel 51A of the base arm 51 at a position overlapping the upper panel 52 in the left-right direction orthogonal to the longitudinal direction of the base arm 51. In addition, the upper second rib plate 26A fixed to the guide rail 26 of the opening / closing pulley moving mechanism 25 is fixed to the right side panel 51B of the base arm 51 at a position overlapping the upper panel 52 (flat plate portion 52A) in the left-right direction.

[0114] The base arm 51 of the modified example includes an upper panel 52 as a reinforcing plate that connects the left side panel 51A and the right side panel 51B. Regarding its basic function, there is no particular difference from the base arm 11 of the embodiment including the reinforcing plate 12. However, by forming the upper panel 52 with a reinforcing plate, the base arm 51 of the modified example can suppress the size in the vertical direction to achieve elongation, and can achieve weight reduction and cost reduction.

[0115] In addition, in the embodiment, an example is shown in which the reinforcing plate 12 is formed of a single plate body fixed to the left side panel 11A and the right side panel 11B of the base arm 11. However, the present invention is not limited thereto. For example, it may be configured to connect two plate bodies, one fixed to the left side panel 11A of the base arm 11 and the other fixed to the right side panel 11B, at the middle portion in the left-right direction of the base arm 11. That is, for example, the base arm 11 may have a reinforcing plate 12 that is configured to be fixed to at least one of the left side panel 11A and the right side panel 11B and extends along the length direction of the base arm 11.

[0116] In addition, in the embodiment, an example is shown in which the base arm 11 is formed of a square cylindrical body having a quadrilateral cross-sectional shape. However, the present invention is not limited thereto. For example, a cylindrical body having a cross-sectional shape of a polygon other than a quadrilateral may be used to form the base arm, and the polygon has a pair of opposed side plates.

[0117] Reference Signs

[0118] 1: Deep Excavator

[0119] 2: Lower Traveling Body (Vehicle Body)

[0120] 3: Upper Swing Body (Vehicle Body)

[0121] 5: Working Device

[0122] 6: Boom

[0123] 9: Clamshell Bucket

[0124] 10: Arm

[0125] 11, 51: Base Arm

[0126] 11A, 51A: Left Side Panel (Side Plate)

[0127] 11B, 51B: Right Side Panel (Side Plate)

[0128] 11H: Boom Mounting Bracket

[0129] 11K: Boom Connecting Pin (Mounting Port with Boom)

[0130] 11S: Cylinder Holding Port

[0131] 12: Reinforcement plate

[0132] 12A, 52A: Flat plate part

[0133] 12B, 52B: Inclined plate part

[0134] 12E, 52C: Bending part

[0135] 13: Upper guide arm

[0136] 13B: Upper guide arm connecting pin

[0137] 14: Lower guide arm

[0138] 14B: Lower guide arm connecting pin

[0139] 17: Lifting cylinder

[0140] 17D: Cylinder support pin

[0141] 18: First lifting pulley

[0142] 20: First opening and closing pulley

[0143] 22: Second lifting pulley

[0144] 23: Second lifting pulley bracket

[0145] 23B: First rib plate

[0146] 24: Second lifting pulley shaft (pulley shaft)

[0147] 26: Guide rail

[0148] 26A: Second rib plate

[0149] 28: Second opening and closing pulley bracket

[0150] 29: Second opening and closing pulley shaft (pulley shaft)

[0151] 30: Second opening and closing pulley

[0152] 31: Opening and closing cylinder

[0153] 31C: Opening and closing cylinder bracket

[0154] 38: Lifting rope

[0155] 38A: One end

[0156] 39: Lifting rope mounting bracket

[0157] 40: Opening and closing rope

[0158] 41: Opening and closing rope mounting bracket

[0159] 41A: Upper plate

[0160] 41B: Lower plate

[0161] 47: Slack adjustment pulley

[0162] 48: Slack adjustment cylinder

[0163] 48C: Slack adjustment cylinder bracket

[0164] 52: Upper panel (Reinforcement panel)

Claims

1. A deep foundation excavator is composed of a vehicle body capable of autonomous driving and a working device provided on the vehicle body. The working device includes: A base arm, which is rotatably provided relative to the vehicle body, and a clam shell bucket is arranged at one end side in the length direction in a liftable manner; An upper guide boom and a lower guide boom, which are connected to the other end side of the base arm at a certain interval in the vertical direction via an upper guide boom connecting pin and a lower guide boom connecting pin, and extend along the length direction of the base arm; A first lifting pulley and a first opening / closing pulley, which are arranged to be movable along the upper guide boom and the lower guide boom; A lifting cylinder, which is installed on the base arm and moves the first lifting pulley and the first opening / closing pulley; A second lifting pulley and a second opening / closing pulley, which are separated from the first lifting pulley and the first opening / closing pulley, and are rotatably arranged on the base arm respectively with a pulley shaft as the center; A lifting rope, which is wound around the first lifting pulley and the second lifting pulley to lift the clam shell bucket; and An opening / closing rope, which is wound around the first opening / closing pulley and the second opening / closing pulley to open and close the clam shell bucket, The deep foundation excavator is characterized in that, The base arm is formed as a cylinder, and the cylinder is provided with a pair of side plates facing each other at intervals in a direction orthogonal to the length direction, The pulley shafts of the second lifting pulley and the second opening / closing pulley are arranged between the upper guide boom connecting pin and the lower guide boom connecting pin in the vertical direction of the base arm, A reinforcing plate fixed to at least one of the pair of side plates of the base arm and extending along the length direction of the base arm is provided on the base arm, and a part of the reinforcing plate is arranged between the upper guide boom connecting pin and the lower guide boom connecting pin in the vertical direction of the base arm.

2. The deep foundation excavator according to claim 1, characterized in that, The base arm is rotatably installed at the front end of a boom installed on the vehicle body, The reinforcing plate has: a flat plate portion, which is arranged between the upper guide boom connecting pin and the lower guide boom connecting pin and extends along the length direction of the base arm; and an inclined plate portion, which bends from the flat plate portion and extends toward the upper side of the upper guide boom connecting pin, The bending portion that becomes the boundary portion between the flat plate portion and the inclined plate portion is arranged in the length direction of the base arm between the mounting portion of the boom and the upper guide boom connecting pin and the lower guide boom connecting pin.

3. The deep foundation excavator according to claim 1, characterized in that, The lifting cylinder is installed via a cylinder support pin on the pair of side plates that are located at the other end side in the length direction of the base arm and constitute the base arm, The interval between the pair of side plates of the base arm is set smaller at one end side of the base arm than at the other end side of the base arm where the lifting cylinder is installed.

4. The deep foundation excavator according to claim 1, characterized in that, The base arm has a boom mounting bracket, and the boom mounting bracket is rotatably installed at the front end of a boom installed on the vehicle body. The boom mounting bracket is arranged at a position vertically aligned with the pair of side plates constituting the base arm.

5. The deep foundation excavator according to claim 1, wherein at the other end side in the longitudinal direction of the base arm, the lifting cylinder is rotatably mounted via a cylinder support pin, at one end side in the longitudinal direction of the base arm, a cylinder holding portion is provided for holding the bottom end portion of the lifting cylinder in a constrained state.

6. The deep foundation excavator according to claim 1, wherein the pulley shaft of the second lifting pulley is mounted on a second lifting pulley bracket, and the second lifting pulley bracket has a plurality of first rib plates fixed to one of the pair of side plates constituting the base arm.

7. The deep foundation excavator according to claim 6, wherein the pulley shaft of the second opening and closing pulley is mounted on a second opening and closing pulley bracket that moves along a guide rail extending in the longitudinal direction of the base arm, the guide rail is mounted on a plurality of second rib plates fixed to the other side plate of the pair of side plates constituting the base arm.

8. The deep foundation excavator according to claim 6, wherein a lifting rope mounting bracket for mounting one end of the lifting rope is provided on the base arm, the lifting rope mounting bracket is integrally fixed to the second lifting pulley bracket.

9. The deep foundation excavator according to claim 1, wherein at the other end side in the longitudinal direction of the base arm, the lifting cylinder is mounted via a cylinder support pin, an opening and closing cylinder is provided between the base arm and the second opening and closing pulley. One end of the opening and closing cylinder is connected to the base arm via an opening and closing cylinder bracket, and the other end is connected to the second opening and closing pulley, so that the second opening and closing pulley approaches and separates from the first opening and closing pulley. The opening and closing cylinder bracket is arranged between the upper guide arm connecting pin, the lower guide arm connecting pin and the cylinder support pin in the longitudinal direction of the base arm.

10. The deep foundation excavator according to claim 9, wherein the opening and closing cylinder bracket is composed of two plate bodies opposed in the vertical direction. One end side in the longitudinal direction extends between the upper guide arm connecting pin and the lower guide arm connecting pin while maintaining a certain interval in the vertical direction, and the interval in the vertical direction expands toward the cylinder support pin at the other end side in the longitudinal direction.

11. The deep foundation excavator according to claim 9, wherein an opening and closing rope mounting bracket is provided on the base arm. The opening and closing rope mounting bracket has an upper plate and a lower plate opposed in the vertical direction and mounts one end of the opening and closing rope. The opening and closing cylinder is arranged between the upper plate and the lower plate of the opening and closing rope mounting bracket.

12. The deep foundation excavator according to claim 1, wherein on the base arm, there are provided a slack adjustment pulley around which the opening and closing rope is wound and which can move in a direction approaching and separating from the second opening and closing pulley, and a slack adjustment cylinder for moving the slack adjustment pulley. The pulley shaft of the second opening / closing pulley is mounted on a second opening / closing pulley bracket that moves along a guide rail extending in the longitudinal direction of the base arm. A slack adjustment cylinder bracket that supports one end of the slack adjustment cylinder is integrally fixed to the guide rail.

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