JP4693730B2 - Circulation type drilling rig - Google Patents

Description

The present invention relates to a forward circulation excavation method for rotating a drilling pipe having a drilling tool at a tip and supplying a stable liquid through the drilling pipe, and a circulation excavation apparatus used for a reverse circulation excavation method for sucking the stable liquid through the drilling pipe. about the.

  In the circulation type excavation method, the drilling pipe provided with a drilling tool at the lower end is rotated, and the stable liquid is supplied into the drilling pipe from above by the supply pump, while the soil and sand are planted together with the stable liquid from the vertical hole excavated by the suction pump. The normal circulation excavation method that sucks up and discharges the soil, and the reverse circulation method that sucks up the earth and sand together with the stable liquid through the drilling pipe by the suction pump while sending the stable liquid into the vertical hole excavated by the supply pump from the plant There is an excavation method. Patent Documents 1 and 2 disclose a swivel joint that can be applied to any of these circulation excavators.

  On the other hand, as the circulation type excavator, the excavator for carrying out the normal circulation excavation method and the excavator for carrying out the reverse circulation excavation method are separately configured.

  In the swivel joint, a drive device for rotating the drilling pipe is mounted, and a drive cylinder that is rotationally driven by the drive device is rotatably mounted in the housing via a bearing. This drive cylinder is connected to a non-rotating water conduit provided in the upper part of the housing of the swivel joint, and the formation of a gap between the water conduit and the drive cylinder makes the drive cylinder rotatable. Therefore, there is a risk of water leaking from the gap to the bearing side, damaging the bearing and shortening its life. For this reason, a packing for preventing water leakage to the bearing is provided between the housing and the drive cylinder.

  Patent Document 1 discloses a swivel joint that can be applied to any excavation method of forward and reverse circulation, in which line packing is provided in the packing. Patent Document 2 discloses a technique in which grease is pressurized and supplied to a bearing using a water supply pressure in a normal circulation excavation method. In Patent Document 3, as a means for supplying grease to the bearing, a through hole connected to the bearing is provided on one side of the housing, a grease nipple is attached to the through hole, and a through hole connected to the bearing is provided on the other side of the housing. The thing which attached the stopper to the through-hole is disclosed.

JP 2004-339819 A (FIG. 2) JP-A-8-189281 (FIG. 5) JP-A-9-14274 (FIG. 3)

  In the conventional circulation drilling rig, the circulation system of the stable liquid is separately used for the excavation device for the normal circulation excavation method that discharges the stable liquid from the excavation part through the drilling pipe and the excavation device for the reverse circulation excavation method. It is configured. For this reason, in a drilling rig that implements the reverse circulation excavation method, when gravel is clogged in the additional drilling pipe, the drilling pipe is pulled up, and the drilling pipe clogged with gravel is separated and replaced with a new one. The work is continued by eliminating the clogging by adding drilling pipes. For this reason, there is a problem that it takes a lot of time and labor to recover the work.

  On the other hand, considering the swivel joint, the swivel joint described in Patent Document 1 is provided with line packing as packing, but the application target of this swivel joint is basically a normal circulation excavation method, Since the passing stable liquid is the stable liquid excluding the earth and sand in the plant, the amount of earth and sand mixed in the stable liquid is small, and even if water leaks to the bearing, the problem of damage does not occur so much. However, in the case of the reverse circulation excavation method, the stable liquid that passes through the drive cylinder is a mixture of earth and sand, and the line packing alone cannot prevent the intrusion of mud containing this earth and sand into the bearing. There is a risk of shortening the life.

  In addition, as described in Patent Document 2, in the case of supplying grease to the bearing using the positive pressure of the stabilizing liquid in the forward circulation excavation method, it cannot be used in the reverse circulation excavation method. There is a drawback of narrowing.

  In addition, as described in Patent Document 3, in the case where a grease nipple is provided on one side of the housing and a plug is provided on the other side, the plug is removed when grease is supplied, and grease is supplied from the grease nipple to the bearing. However, when this is applied to the reverse circulation excavation method, the inside of the drive cylinder becomes negative pressure, and the bearing also becomes negative pressure, so the stable liquid containing earth and sand enters the bearing, There is a problem that earth and sand damage the bearings and impair the life.

In view of the above problems, the present invention is suitable for a circulation excavator that can easily switch between forward and reverse circulation systems, can reliably prevent water leakage to the bearing, and extend the life of the bearing. An object of the present invention is to provide a circulating excavator having a swivel joint with a possible structure.

The circulating excavator of claim 1 includes a drilling pipe having a drilling tool attached to the tip,
A swivel joint having a driving device for connecting and rotating the drilling pipe to the lower part and having a water guide pipe for passing the stabilizing liquid at the upper part;
A plant for storing the stabilizing liquid and separating earth and sand in the stabilizing liquid;
A supply pump for supplying a stable liquid from the plant to a vertical hole excavated by the excavator;
A suction pump for sucking up the stable liquid that has passed through the excavation part by the excavator into the plant ;
The discharge port of the supply pump is switched and connected between the conduit pipe and the pipe installed in the vertical hole, and the suction port of the suction pump is connected between the pipe and the conduit pipe installed in the vertical hole. In the circulation type excavator provided with a switching valve for switching connection at
The swivel joint is
A housing in which the water conduit is provided in an upper part and the driving device is provided;
A drive cylinder provided with a chuck device that communicates with the water conduit and is rotatably mounted in the housing via a bearing, and is connected to the drilling pipe at a lower portion;
A packing provided between the housing and the drive cylinder to prevent water leakage to the bearing;
A first through hole provided in the housing and communicating with the bearing from the outside of the housing;
A grease nipple attached to the first through hole;
A second through hole provided on the opposite side of the first through hole in the housing and communicating with the bearing from the outside of the housing;
It is provided with a blind with a hole which is attached to the second through-hole and has a pore which allows the bearing and the outside of the housing to communicate with each other.

Circulating drilling device according to claim 2, in circulating drilling device according to claim 1,
The packing is provided in two stages with a vertical gap,
Providing a third through hole for communicating between these packings and the outside of the housing;
On the opposite side of the third through hole from the location where the third through hole is provided, a fourth through hole is provided for communicating between the two-stage packing and the outside of the housing;
A grease nipple is attached to the third through hole, and a blinded hole is attached to the fourth through hole.

  According to the first aspect of the present invention, when the drilling apparatus is operated by the reverse circulation excavation method, when the drilling pipe is clogged with gravel, etc., the circulation system is operated by operating the switching valve. By switching to a circulating flow path configuration, it is possible to extrude gravel with positive pressure inside the drilling pipe, which can eliminate clogging of the drilling pipe and continue drilling, and remove the drilling pipe The excavation work can be quickly recovered without any trouble. In addition, when the regular circulation excavation method is preferable, excavation by the regular circulation excavation method can be easily performed only by the switching operation of the switching valve, and the response to the site can be performed quickly.

Further, when excavation by the normal circulation excavation method is performed, that is, when the hydraulic pressure in the drive cylinder is positive, water leakage from the drive cylinder to the bearing is well prevented by the packing and grease. On the other hand, during excavation by the reverse circulation excavation method, the hydraulic pressure in the drive cylinder becomes negative, but since outside air enters the bearing side from the perforations with holes, the negative pressure in the bearing is prevented. Thus, drainage containing muddy water is prevented from entering the bearing, and the bearing is prevented from being damaged by small sand in the earth and sand. Accordingly, when any of the normal circulation excavation method and the reverse circulation excavation method is applied, adverse effects such as damage to the bearing due to water leakage to the bearing can be prevented.

The circulating excavator of the present invention can be applied to the bearing in either excavation method when constructing the excavation method by selecting either the normal circulation excavation method or the reverse circulation excavation method according to the ground conditions at the site. Since the intrusion of muddy water is prevented, the life extension of the swivel joint can be achieved in the excavation device for pile driving configured to be able to select both excavation methods.

  In addition, since the grease nipple is provided on one side of the housing and the blinds with holes are provided on the other side, when injecting grease from the grease nipple, it is not necessary to attach and detach the stopper one by one, and the grease injecting work becomes easy. By frequently injecting grease, the bearing can be always filled with fresh grease, and the life extension of the bearing is promoted. Further, whether or not the bearing is filled with grease can be easily determined based on whether or not the grease from the perforated blind has leaked, facilitating the filling operation, and eliminating the insufficient filling of the grease. Moreover, since the hole provided in the blind with a hole is a fine hole, there is no worry of dust entering the bearing.

According to the invention of claim 2 , since the packing is provided in two upper and lower stages and the grease is supplied between the upper and lower packings, the water leakage prevention function can be enhanced.

  FIG. 1 is a block diagram showing an embodiment of an excavator of the present invention. 1 is a drilling pipe with a drilling tool 2 attached to the tip, 3 is a drilled vertical hole, 4 is a stabilizing liquid supplied to the vertical hole 3, 5 is a swivel joint provided with a drive device for driving the drilling pipe 1, and 27 is this A reader 8 having an elevating device 7 that guides the swivel joint 5 up and down and moves it up and down is a plant installed on the ground (including ground such as tunnels and underground). It has the function of separating earth and sand from the liquid.

  Reference numeral 9 denotes a supply pump for supplying a stable liquid from the plant 8 to the excavation part, and reference numeral 10 denotes a suction pump which is supplied to the excavation part and returns the stable liquid 4 in the vertical hole 3 to the plant 8.

  11 is a switching valve for switching the circulation system of the stable liquid forward and backward, and the discharge port 9a of the supply pump 9 is connected between the water conduit 12 above the swivel joint 5 and the pipe 13 installed in the vertical hole 3. In addition to switching connection, the suction port 10a of the suction pump 10 is switched and connected between the pipe 13 installed in the vertical hole 3 and the water conduit 12. Reference numerals 14 and 15 respectively denote a suction pipe and a discharge pipe of the supply pump 9, and reference numerals 16 and 17 denote a suction pipe and a discharge pipe of the suction pump 10, respectively.

  In this example, the switching valve 11 is constituted by a single valve, but it may be constituted by a plurality of valves. One or both of the pipes connected to the water conduit 12 and the pipes 13 installed in the vertical holes 3 may be provided in correspondence with the pumps 9 and 10, respectively.

  In FIG. 1, when excavating by the normal circulation excavation method, the switching valve 11 connects the discharge pipe 15 connected to the discharge port 9 a of the supply pump 9 to the water conduit 12 at the upper part of the swivel joint 5, and A suction pipe 16 connected to the suction port 10 a of the suction pump 10 is connected to the pipe 13 installed in the vertical hole 3.

  When this regular circulation excavation method is adopted, the stabilizing liquid 4 in the plant 8 is supplied from a suction pipe 14, a supply pump 9, a discharge pipe 15, a switching valve 11, a water guide pipe 12, and a drive cylinder described later in the swivel joint 5. 19 (see FIG. 3) and the drilling pipe 1 are supplied to the excavation part from the tip of the excavator 2. On the other hand, the drilling pipe 1 is driven to rotate by a driving device provided at the swivel joint 5 and is rotated together with the excavating tool 2 while being pushed down by the lifting device 7 as required.

  Thus, the earth and sand excavated by the excavating tool 2 rises in the vertical hole 3 together with the stabilizing liquid 4, and by the suction force of the suction pump 10, the pipe 13, the switching valve 11, the suction pipe 16, and the suction pump together with the earth and sand. 10. Return to the plant 8 through the discharge pipe 17. When such a regular circulation excavation method is adopted, the specific gravity is usually 1.2 or more in order to increase the buoyancy applied to the earth and sand in the vertical hole 3 as much as possible during the earth removal. Use a stabilizing solution.

  On the other hand, when the reverse circulation excavation method is adopted, the discharge pipe 15 connected to the discharge port 9 a of the supply pump 9 is connected to the pipe 13 installed in the vertical hole 3 and is connected to the suction port 10 a of the suction pump 10. The suction pipe 16 to be connected is connected to the water conduit 12 at the upper part of the swivel joint 5.

  When this reverse circulation excavation method is adopted, the stabilizing liquid 4 from the plant 8 passes through the suction pipe 14, the supply pump 9, the discharge pipe 15, the switching valve 11, and the pipe 13 installed in the vertical hole 3 into the vertical hole 3. Supplied. Then, the earth and sand excavated by the rotation of the excavating tool 2 passes through the drilling pipe 1 together with the stabilizing liquid 4 by the suction force of the suction pump 10, and the drive cylinder 19, the water guide pipe 12, the switching valve 11, and the suction pipe 16. The suction pump 10 and the discharge pipe 17 are returned to the plant 8. Since the drilling pipe 1 has an outer diameter of 20 cm, for example, and the flow passage cross-sectional area is smaller than the flow passage cross-sectional area of the vertical hole 3, when the reverse circulation excavation method is adopted, Since the suction force of the stabilizing liquid and earth and sand applied in 1 is increased, it is not necessary to use the stabilizing liquid 4 having a large specific gravity, and a specific gravity of 1.05 or less is usually used.

  Now, the excavator 2 is used when the earth and sand are sucked up and discharged through the drilling pipe 1 while supplying the stable liquid into the vertical hole 3 from the pipe 13 installed in the vertical hole 3 by the reverse circulation excavation method. When the gravel or the like excavated by the clogging is clogged in the drilling pipe 1, the operation is temporarily stopped, and the switching valve 11 is switched to the side for performing the normal circulation excavation method. That is, the discharge pipe 15 of the supply pump 9 is connected to the water conduit 12, the pipe 13 installed in the vertical hole 3 is connected to the suction pipe 16 of the suction pump 10, and the pumps 9 and 10 are operated. Then, the inside of the drilling pipe 1 becomes a positive pressure, and gravel and the like clogged in the drilling pipe 1 can be pushed out from the lower end of the drilling pipe 1. Then, after performing processing such as finely crushing the gravel clogged by the rotation of the excavator 2, the operation can be quickly recovered by returning the switching valve 11 to the original state and restarting the operation. Accordingly, it is possible to prevent a reduction in work efficiency due to clogging of the drilling pipe 1 when the reverse circulation excavation method is adopted, and to improve the work efficiency.

  In addition, when the normal circulation excavation method is preferable, excavation by the normal circulation excavation method can be easily performed only by the switching operation of the switching valve 11, and it is possible to respond to the site without changing the piping connection. Can be done quickly.

  FIG. 2 is a side view showing an example of an excavator (pile driver) that performs excavation work for such pile driving. A main body (base machine) 21 of this excavator has a swivel body 24 installed on a traveling body 22 via a swivel device 23, and a power unit 25 that serves as a hydraulic pressure source, a cab 26 and the like are mounted on the swivel body 24. Configured. Reference numeral 28 denotes a front / rear extension / contraction frame that is attached to the revolving body 24 and mounts a leader (extension leader in the present embodiment) 27. The extendable leader 27 is configured such that a movable leader 27b is mounted on a fixed leader 27a so as to be movable up and down by extension and contraction of a hydraulic cylinder 29. The expansion / contraction leader 27 is attached to the revolving body 24 so that it can be raised and lowered so that it can be tilted backward by a hydraulic cylinder 32 around a shaft 31.

  Reference numeral 30 denotes an outrigger attached to the left and right of the rear portion of the revolving structure 24 and to the left and right of the front and rear telescopic frame 28. The outrigger 30 lands during work and receives an excavation reaction force.

  The movable leader 27b has a structure with an open front surface, and accommodates two hydraulic cylinders 33 and 34 of the same size for constituting the lifting device 7 therein. These hydraulic cylinders 33 and 34 connect the tubes, respectively, so that the piston rods face downward and upward, respectively. The piston rod of one hydraulic cylinder 33 is connected to the movable leader 27 b, and the piston rod of the other hydraulic cylinder 34 is connected to the bracket 36. The swivel joint 5 is attached to the bracket 36.

  Guide brackets 38 are provided on the left and right sides of the bracket 36, and these guide gibs 38 are slidably fitted to guide rails 39 provided on the left and right sides of the movable leader 27b so that the swivel joint 5 is raised and lowered along the movable leader 27b. Install as possible.

  The swivel joint 5 includes a drive device including a drive motor 40 for rotating the drilling pipe 1, an output gear 53 described later, an external gear 54 (see FIG. 3), and the like. Further, a chuck device 42 for fixing to the drive cylinder 19 is provided. FIG. 2 shows a state in which the hydraulic cylinders 33 and 34 are contracted and the swivel joint 5 is lowered.

  43 is a winch installed on the revolving body 24 in order to add and separate the drilling pipe 1 and the like, and to lift various tools and materials for pile construction, and 44 is a revolving mechanism 45 on a frame juxtaposed to the telescopic leader 27. It is the expansion-contraction frame installed through. A lifting rope 46 wound around the winch 43 is hooked on a sheave 47 at the proximal end of the telescopic frame 44 and a sheave 48 at the distal end, and is connected to a hook 49.

  FIG. 3 is a cross-sectional view showing details of the swivel joint 5 shown in FIG. The configuration shown in FIG. 3 may be used in an excavator that does not have the switching valve 11 shown in FIG. As shown in FIG. 3, a drive cylinder 19 is rotatably incorporated in a housing 50 of the swivel joint 5 supported by upper and lower bearings 51 and 52. A chuck device 42 for connecting the drilling pipe 1 is provided below the drive cylinder 19.

  The motor 40 is mounted on the housing 50. An external gear 54 is attached to the outside of the drive cylinder 19, and the output gear 53 of the motor 40 is engaged with the external gear 54. As a result, the drive cylinder 19 and the drilling pipe 1 connected to the drive cylinder 19 via the chuck device 42 can be rotated by the rotation of the motor 40.

  4 and 5 are enlarged cross-sectional views of the right and left portions of FIG. 3 to 5, 55 is a packing for preventing muddy water from entering the bearing 51 from the gap 56 between the drive cylinder 19 and the water conduit 12, and is made of rubber. Reference numeral 57 denotes a first through hole provided in the housing 50, and this hole 57 is for communicating the outside of the housing 50 with the bearing 51. Reference numeral 60 denotes a grease nipple attached to the first through hole 57.

  A second through hole 59 is provided on the opposite side of the housing 50 from the first through hole 57 and communicates the outside of the housing 50 with the bearing 51. Reference numeral 61 denotes a blind with a hole which is attached to the second through hole 59 and has a pore 61a which allows the bearing 51 and the outside of the housing 50 to communicate with each other. Reference numeral 62 denotes an oil seal that prevents grease from leaking out of the housing portion of the bearing 51.

  In the present embodiment, the packing 55 is provided in two stages with a vertical gap, and a third through-hole 63 is provided for communicating between the packings 55 and 55 and the outside of the housing 50. Reference numeral 65 denotes a grease nipple attached to the third through hole 63.

  Reference numeral 64 denotes a fourth through hole. The hole 64 communicates between the two-stage packing 55 and 55 and the outside of the housing 50 on the opposite side of the housing 50 where the third through hole 63 is provided. It is something to be made. Reference numeral 66 denotes a blind with a hole having a small hole 66 a attached to the fourth through hole 64.

  Furthermore, in the present embodiment, between the thick wall portion 12a for attachment to the housing 50 in the water conduit 12 and the housing 50, in order from the bottom, a packing 67 made of rubber, a metal O-ring 68, A dust seal 69 for preventing entry of dust is attached. In the present embodiment, a fifth through hole 70 is provided to communicate between the gap between the housing 50 and the thick portion 12a of the water conduit 12 and the outside of the housing 50, and the grease nipple is provided in the through hole 70. 72 is attached. In addition, on the opposite side of the through hole 70 in the housing 50, a sixth through hole 71 is provided that allows communication between the gap between the housing 50 and the thick portion 12 a of the water conduit 12 and the outside of the housing 50. A through hole 73 having a hole 73a is attached to the through hole 71.

  3 to 5, when excavation by the normal circulation excavation method is performed, that is, when the hydraulic pressure in the drive cylinder 19 is positive, the grease nipple 60 through the first through hole 57. Through the grease filled in the bearing 51 through, water leakage from the drive cylinder 19 to the bearing 51 is satisfactorily prevented.

  On the other hand, at the time of excavation by the reverse circulation excavation method, the hydraulic pressure in the drive cylinder 19 becomes negative, but outside air enters the bearing 51 side from the pore 61a of the holed blind 61, so It is prevented that the negative pressure is generated, thereby preventing the drainage containing muddy water from entering the bearing 51 and preventing the bearing 51 from being damaged by small sand or the like in the earth and sand. Therefore, when any of the normal circulation excavation method and the reverse circulation excavation method is applied, adverse effects such as damage to the bearing due to water leakage to the bearing 51 can be prevented. Therefore, the life extension of the swivel joint 5 can be achieved.

  In the present embodiment, since the packing 55 is provided in two upper and lower stages and grease is supplied between the upper and lower packings 55 and 55, the function of preventing water leakage to the bearing 51 can be enhanced.

  Further, in the present embodiment, the gap between the packing 67 and the O-ring 68 between the thick wall portion 12a of the water conduit 12 and the housing 50 is communicated with the outside of the housing 50 through the through holes 70 and 71. Since the grease nipple 72 and the holed blind 73 are provided in each of the through holes 70, 71, the gap between the packing 67 and the O-ring 68 can be filled with grease, and water leakage to the outside of the housing 50 Can be prevented well.

  Further, since the grease nipples 60, 65, 72 are provided on one side of the housing 50 and the blind dice 61, 66, 73 are provided on the other side, each time the grease is injected from the grease nipples 60, 65, 72, each time. It is not necessary to attach or detach the stopper, and the grease injection work is facilitated. Further, since the grease injection can be easily performed, the grease injection is promoted, the bearing 51 can be always filled with fresh grease, and the life extension of the bearing 51 is promoted.

  Further, whether or not the bearing 51 is filled with grease can be easily determined based on whether or not the grease from the perforated blind 61 has leaked, facilitating a filling operation, and eliminating insufficient filling of the grease. . In addition, since the holes provided in the holed blinds 61, 66, 73 are the pores 61a, 66a, 73a, there is no fear of dust entering the bearings. Although the diameter of the pores 61a, 66a, 73a is 0.8 mm in the embodiment, the diameter is preferably 0.5 mm or more in the sense of fulfilling the function of introducing outside air by negative pressure. On the other hand, it is preferably 2 mm or less in the sense of preventing dust from entering.

It is a lineblock diagram showing one embodiment of an excavation device of the present invention. 1 is a side view showing an embodiment of an excavator to which the present invention is applied. It is side surface sectional drawing which shows one Embodiment of the swivel joint of this invention. It is sectional drawing which expands and shows the principal part of the right side part of FIG. It is sectional drawing which expands and shows the principal part of the left side part of FIG.

1: drilling pipe, 2: drilling tool, 3: vertical hole, 4: stabilizing liquid, 5: swivel joint, 7: lifting device, 8: plant, 9: supply pump, 10: suction pump, 11: switching valve, 12 : Water guide pipe, 13: piping, 16, 16: suction pipe, 15, 17: discharge pipe, 19: drive cylinder, 21: excavator body, 22: traveling body, 23: turning device, 24: turning body, 25: Power unit, 26: cab, 27: reader, 27a: fixed reader, 27b: movable reader, 28: front / rear telescopic frame, 29: hydraulic cylinder, 30: outrigger, 31: shaft, 32: hydraulic cylinder, 33, 34 : Hydraulic cylinder, 36: bracket, 38: guide rail, 39: guide rail, 40: motor, 42: chuck device, 43: winch, 44: telescopic frame, 45: turning mechanism, 46: lifting cylinder 47, 48: sheave, 49: hook, 50: housing, 51, 52: bearing, 53: output gear, 54: external gear, 55, 67: packing, 56: clearance, 57: first through hole , 59: second through hole, 60, 65, 72: grease nipple, 61, 66, 73: dizziness with holes, 61a, 66a, 73a: pore, 62: oil seal, 68: O-ring, 69: Dust seal, 63: third through hole, 64: fourth through hole, 70: fifth through hole, 71: sixth through hole

Claims (2)

A drilling pipe with a drilling tool attached to the tip;
A swivel joint having a driving device for connecting and rotating the drilling pipe to the lower part and having a water guide pipe for passing the stabilizing liquid at the upper part;
A plant for storing the stabilizing liquid and separating earth and sand in the stabilizing liquid;
A supply pump for supplying a stable liquid from the plant to a vertical hole excavated by the excavator;
A suction pump for sucking up the stable liquid that has passed through the excavation part by the excavator into the plant ;
The discharge port of the supply pump is switched and connected between the conduit pipe and the pipe installed in the vertical hole, and the suction port of the suction pump is connected between the pipe and the conduit pipe installed in the vertical hole. In the circulation type excavator provided with a switching valve for switching connection at
The swivel joint is
A housing in which the water conduit is provided in an upper part and the driving device is provided;
A drive cylinder provided with a chuck device that communicates with the water conduit and is rotatably mounted in the housing via a bearing, and is connected to the drilling pipe at a lower portion;
A packing provided between the housing and the drive cylinder to prevent water leakage to the bearing;
A first through hole provided in the housing and communicating with the bearing from the outside of the housing;
A grease nipple attached to the first through hole;
A second through hole provided on the opposite side of the first through hole in the housing and communicating with the bearing from the outside of the housing;
A circulation type excavator, comprising: a blind with a hole attached to the second through hole and having a pore for communicating the bearing and the outside of the housing . The circulating excavator according to claim 1 ,
The packing is provided in two stages with a vertical gap,
Providing a third through hole for communicating between these packings and the outside of the housing;
On the opposite side of the third through hole from the location where the third through hole is provided, a fourth through hole is provided for communicating between the two-stage packing and the outside of the housing;
A circulation type excavator characterized in that a grease nipple is attached to the third through hole and a blind with a hole is attached to the fourth through hole.

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