Crawler type traveling apparatus and pivot shaft

The crawler type traveling apparatus 5 includes a pivot shaft 6 provided on a vehicle body having a hydraulic source in a protruding state, a track frame 51 rocking around and pivotably supported against this pivot shaft 6, a final reduction gear 53 including a sprocket 531 engaged by a crawler 56 and provided at an end part of this track frame 51, and a hydraulic motor 57 for driving the sprocket 531 of the final reduction gear 53 for rotation, in which the hydraulic motor 57 is provided on a vehicle inner side with respect to the final reduction gear 53.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a crawler type traveling apparatus and a pivot shaft used in a bulldozer, a hydraulic shovel and the like.

2. Description of Related Art

Generally crawler type traveling apparatuses are provided in both right and left sides of a work vehicle such as a bulldozer, a hydraulic shovel, and a crawler crane.

In the work vehicle as described above, the crawler type traveling apparatus has the configuration in which a track frame is provided on a main body of the vehicle and a final reduction gear including a sprocket and a hydraulic motor for driving are provided at an end part of this track frame. A hydraulic source and the hydraulic motor provided on the main body of the vehicle are connected to each other through a hydraulic piping arrangement, and when a hydraulic oil is fed from the hydraulic source, the hydraulic motor starts rotation, and in association with rotation of the hydraulic motor, the sprocket rotates to drive a crawler engaged with the sprocket, and thus the work vehicle starts running. With the configuration as described above, a compact crawler type traveling apparatus can be realized.

Further in a vehicle such as a bulldozer in which a traction is made much of, sometimes pivot shafts are provided in both right and left sides of the vehicle for pivotably supporting crawler type traveling apparatuses respectively, and with this configuration, the crawler type traveling apparatuses in the right and left sides can be contacted to the ground surface having three-dimensional undulations and a large traction can be obtained.

In the crawler type traveling apparatus as described above, by providing pivot shafts in both sides of a main body of the vehicle for pivotably supporting the crawler type traveling apparatuses and also providing a final reduction gear and a hydraulic motor at an end part of the track frame, a compact crawler type traveling apparatus capable of generating a large traction can be realized.

With the configuration, however, as a hydraulic motor is provided on a track frame rocking up and down and further a hydraulic source is provided on a main body of the vehicle, the hydraulic motor and the hydraulic source must be coupled to each other with a piping arrangement such as a hydraulic hose and the like having a predetermined length and high flexibility. In this case, the piping arrangement likely contacts sand, rocks, stones and the like during a work and is likely damaged.

For solving the problem as described above, there has been proposed a structure having a hydraulic frame and a final reduction gear each provided on a track frame rocking up and down, in which a hydraulic passage with the piping arrangement connected thereto is formed in a pivot shaft for making configuration of the piping arrangement compact and also for protecting the piping arrangement from earth and sand, rocks and the like (Refer to, for instance, reference 1: LIEBHERR A. G. “Operation and Maintenance Manual PR712 Litronic”, Germany, P.O. Box 54, CH-5415 Nussbaumen, Manual No. IRM-710-06 (pages 2 to 6)).

Further there has been a method of protecting the piping arrangement from earth and sand and rocks by inserting a hydraulic piping connecting a hydraulic motor provided on a track frame rocking up and down to a hydraulic source provided on a main body of the vehicle into a hollow pivot shaft (Refer to, for instance, reference2: Japanese Utility Model Laid-Open No. HEI 2-113585, pages 3 to 5,FIG. 1)).

The technology disclosed in reference numeral1will be described as a related art with reference to the related drawings. It is to be noted that theFIG. 6is a side view showing a bulldozer having a crawler type traveling apparatus according to the related art, andFIG. 7is a sectional view showing a principle portion of the crawler type traveling apparatus.

A bulldozer100includes a main frame101elongated in the longitudinal direction provided at a center thereof, and pivot shafts102are provided in the right and left side of this main frame101so as to protrude from the main frame101. Further, a crawler type traveling apparatus110is pivotably provided to the pivot shaft102, in a manner that it can oscillate around the pivot shaft axis P2.

The crawler type traveling apparatus110includes a track frame111, an idler112, a sprocket113, a track roller114, a carrier roller115, and a crawler116.

The track frame111includes a steel-made frame long in the longitudinal direction like the main frame101, and is pivotably supported on the pivot shaft102.

The idler112is an idle wheel rotatably provided at a front end part of the track frame111, and the sprocket113is a portion of a final reduction gear (not shown) provided at a rear end part of the track frame111, and is a driving wheel driven by a hydraulic motor described hereinafter.

The plurality of track rollers114are rotatably provided under the track frame111respectively, while the carrier roller115is rotatably provided above the track frame111.

The crawler116is wound around the idler112, sprocket113, track roller114, and carrier roller115, and engages the sprocket113.

When the sprocket113is rotated by a hydraulic motor for driving, the crawler116moves along an orbit outer from the idler112, track roller114, and carrier roller115and kicks the ground with a grounding surface to move forward and backward.

A boss portion121is provided on the rear side of the track frame111as shown inFIG. 7, and the boss portion121is rotatably inserted to the pivot shaft102.

Further a bracket portion122extending toward a rear edge side of the track frame111is monolithically formed on the boss portion121, and a final reduction gear123including the sprocket113is attached to an inner side surface of the bracket portion122, while a hydraulic motor124for driving is attached to an outer side surface of the bracket portion122.

The pivot shaft102is tightened to a side plate103of the main frame101with a bolt104so as to penetrate the main frame101from the inside to the outside thereof.

A plurality of hydraulic passages125,126,127,128each extending from inside of the vehicle to the outside thereof along the shaft center P2are formed at a axial center portion of the pivot shaft102, and a gallery block129is attached to an outer end face of the pivot shaft102.

Connected to this gallery block129are a pair of hydraulic hoses130,131extending in parallel to each other. Tips of these hydraulic hoses130,131are connected to a suction port and a discharge port not shown of the hydraulic motor124, and the base end is connected to the gallery block129.

The suction port and discharge port of the hydraulic motor124are communicated via the hydraulic hoses130,131and gallery block129to the hydraulic passages125,126inside the pivot shaft102, and the hydraulic hoses105,106connected to a suction port and an discharge port of a hydraulic pump disposed inside the main frame101and not shown are connected to the hydraulic passages125,126.

Further connected to the gallery block129are hydraulic hoses132,133with a tip of the hydraulic hose132connected to a speed control port (not shown) of the hydraulic motor124and the hydraulic hose133connected to a brake release port (not shown) of a parking brake123A of the final reduction gear123. These hydraulic houses132,133are communicated via the gallery block129to the hydraulic passages127,128in the pivot shaft102, and further the hydraulic hoses107,108connected to an operation valve (not shown) provided inside the main frame101are connected to the hydraulic passages127,128.

An outer side of the bracket portion122is covered with a cover134, and the hydraulic hoses130to133and the gallery block129are protected by this cover134.

In the configuration of the crawler type traveling apparatus110as described above, the hydraulic motor124is first provided outside the vehicle in the bracket portion122at a rear edge of the track frame111. On the other hand, required ports of hydraulic appliances such as a hydraulic pump inside the main frame101are communicated via the hydraulic passages125to128in the pivot shaft102to the gallery block129attached to an outer end face of the pivot shaft102, and further the gallery block129and the hydraulic motor124are connected to each other with short hydraulic hoses130to133, so that configuration of the crawler type traveling apparatus is compact.

The crawler type traveling apparatus110described in reference document1has, however, the problems as described below because the hydraulic motor124is on the more outer side of the vehicle body as compared to the final reduction gear123including the sprocket113.(1) An outer side surface of the crawler type traveling apparatus110often contacts obstacles such as surrounding ground or pavement when moving forward and backward or turning, and further often impinges against rolling rocks from a mucking mound and/or rolling rocks from a wall surface of a bench-cut. For this reason, the hydraulic motor124, hydraulic hoses130to133provided on an outer side surface of the crawler type traveling apparatus110are often damaged even when the components are covered with the cover134.(2) The depth of each of the hydraulic passages125to128formed in the pivot shaft102must be great so as to reach the inside of a side plate103from the outer end face of the pivot shaft102to. Therefore, specific machines such as, a gun drill and extended machining time are necessary for forming the hydraulic passages125to128.

SUMMARY OF THE INVENTION

An object of the present invention is to provide compact crawler type traveling apparatus and a pivot shaft which can be produced with low cost and insure high reliability in operations.

A crawler type traveling apparatus according to a first invention includes:

a pivot shaft provided on a vehicle body having a hydraulic source in a protruding manner;

a track frame pivotably supported on this pivot shaft;

a final reduction gear having a sprocket engaged by a crawler and provided at an end part of the track frame; and

a hydraulic motor provided on the track frame for driving the sprocket of the final reduction gear for rotation,

in which the hydraulic motor is provided at a position closer to the main frame constituting a main body of the vehicle as compared to the final reduction gear.

The crawler type traveling apparatus according to a second invention includes in addition to the components in the crawler type traveling apparatus according to the first invention;

a hydraulic passage including a passage formed in an axial direction of the pivot shaft for communicating inside and outside of the vehicle body with inside of the vehicle body coupled thereto via the hydraulic source and a piping arrangement and also with outside of the vehicle body coupled thereto via the hydraulic motor and the piping arrangement, in which an outer connection port that communicates to the passage extending along the axial direction and opens on a peripheral surface around the shaft outside the vehicle body with a piping arrangement for coupling the hydraulic motor connected thereto is connected to the pivot shaft.

The crawler type traveling apparatus according to a third invention includes, in addition to the components in the second invention, an inner connection port that communicates to the passage along the axial direction, opens on a peripheral surface around the shaft inside the vehicle body with the piping arrangement for coupling the hydraulic source connected thereto is formed in the pivot shaft.

A pivot shaft according to a fourth invention is a pivot shaft for pivotably supporting a track frame constituting a crawler type traveling apparatus against the vehicle body, the pivot shaft including:

a passage formed in the axial direction of the shaft so that inside and outside of the vehicle body are communicated to each other when set in the vehicle body; and

a first connection port that communicates to the passage extending along the axial direction and opens on a peripheral surface around the shaft outside the vehicle body when set on an auxiliary vehicle carrier belt with a piping arrangement to a hydraulic motor provided on the track frame connected thereto.

The pivot shaft according to a fifth invention includes: in addition to the components in the fourth invention,

a flange section fixed to the main frame constituting the vehicle body; and

a supporting section for pivotably supporting the track frame,

in which the first connection port is provided between the flange section and the supporting section.

The pivot shaft according to a sixth invention includes: in addition to the components in the fourth invention or in the fifth invention,

a second connection port that communicates to the passage extending along the axial direction and formed so that the port opens on a peripheral surface around the shaft inside the vehicle body when set on the vehicle body with a piping arrangement to a hydraulic motor provided on the vehicle body connected thereto.

In the pivot shaft according to a seventh invention, in addition to the features according to the fourth invention to the sixth invention, a peripheral surface around the pivot shat with the first connection port and/or the second connection port formed thereon is a flat surface normal to the connecting direction of the piping arrangement.

With the first invention, a rigid final reduction gear is provided on an outer side surface of the crawler type traveling apparatus, and a hydraulic motor and a piping arrangement connected to the hydraulic motor for supplying a hydraulic pressure are provided at a position closer to the main frame as compared to the final reduction gear, so that the hydraulic motor and the piping arrangement do not contact the ground or pavements while the crawler type traveling apparatus is operating, and further stones falling from a mucking mound and/or a wall surface of a bench-cut never collide with the hydraulic motor nor the piping arrangement. Therefore the crawler type traveling apparatus has high reliability in operation.

With the second invention, in addition to the effects and advantages provided by the first invention, by forming the passage along the axial direction in the pivot shaft and also forming an external connection port on a side face around the shaft, the hydraulic passage extending along the axial direction of the pivot shaft can be shortened, to connected with the short hydraulic passage, which allows realization of a compact crawler type traveling apparatus.

With the third invention, as the hydraulic passage can further be shortened by forming an inner connection port on a side face around the shaft, the pipe length can be made further shorter, which allows further size reduction of the crawler type traveling apparatus.

With the fourth to sixth inventions, by applying the pivot shaft according to the invention to a crawler shaft, the effects and advantages similar to those provided by the first invention can be provided. Also when forming a passage extending along the axial direction in the pivot shaft, precise machining as that described in the cited reference1is not required, so that the pivot shaft can be manufactured with the low production cost.

With the seventh invention, the piping arrangement having simple configuration can tightly be connected to a connection port by making the surface around the pivot shaft with the connection port formed thereon flat and normal to the connecting direction of the piping arrangement, which allows further size reduction of a crawler type traveling apparatus and makes it difficult for the piping arrangement to be off from the connection port, and therefore the reliability in operation is further improved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

An embodiment of the present invention is described with reference to the related drawings.

(1) General Configuration

FIG. 1shows a bulldozer1according to an embodiment of the present invention, and this bulldozer1include a main frame2, a cabin3, a blade4, and a crawler type traveling apparatus5.

The main frame2includes a steel-made frame body extending in the longitudinal direction along the running direction, and includes an engine as a driving power source, a hydraulic pump driven by the engine and the like although not shown.

The cabin3is provided in the rear upper section of the main frame2with a seat31and an operation lever32provided inside thereof, and an operator operates the bulldozer1climbing into the cabin3and sitting on the seat31by operating the operation lever32and the like.

In the present invention, the vehicle body including the main frame2, cabin3, the not-shown engine, hydraulic pump and the like.

The blade4is provided in the front section of the bulldozer1in its running direction, and includes a blade body41, a frame42, and a cylinder43.

The blade body41includes a steel plate sheet having a curved concave surface, and by pushing earth with this blade body41, such works as digging and banking can be carried out, and further such work as leveling the ground can be carried out with a lower surface of the blade body41.

The frame42is used for coupling the blade body41to the main frame2, and is rotatably attached to the main frame2with the blade body41attached to a tip thereof so that the blade body41can freely be rotated up and down and in the horizontal direction.

The cylinder43is attached to an upper section of the main frame2with the tip side coupled to an upper section of the blade body41. This cylinder43is extended or shrunk by a hydraulic oil fed from the hydraulic pump in the pressurized state, and can change an elevation angle of the blade body41thereby.

[2] Structure of Crawler Type Traveling Apparatus 5

The crawler type traveling apparatuses5are provided on both sides under the main frame2so that the crawler type traveling apparatuses5can freely rotate around a shaft center P1against the main frame2via a pivot shaft6provided at a substantially central position of the main frame2in a protruding manner.

This crawler type traveling apparatus5includes a track frame51, an idler52, a final reduction gear53, a track roller54, a carrier roller55, and a crawler56.

The track frame51includes a steel-made frame extending in the longitudinal direction like the main frame2, and is pivotably supported by the pivot shaft6.

The idler52is rotatably provided at a front end part of the track frame51, and can be moved forward by an idler cushion not shown against the track frame51.

The final reduction gear53is provided at a rear end part of the track frame51, and includes a sprocket531with crawler56engaging therein and exposed in an outer periphery of the reduction gear main body, and a hydraulic motor for driving the final reduction gear53is provided inside the final reduction gear53although the details are described hereinafter.

A plurality of track rollers54are rotatably provided under the track frame51, and each of the track rollers54is arranged along the running direction of the bulldozer1.

The carrier roller55is rotatably provided above the track frame51.

Although not shown, the crawler56has the configuration in which a plurality of shoe plates coupled to each other with pins, and is wound around the idler52, sprocket531, a plurality of track rollers54, and carrier roller55, and further engages the sprocket531.

(2-2) Internal Structure

FIG. 2is a sectional view taken along he line A-A inFIG. 1, and to describe more in detail the internal structure of the crawler type traveling apparatus5having the appearance as described above, the pivot shaft6penetrates a side plate21of the main frame2and is fixed to the side plate21with a plurality of bolts61, and further the track frame51is pivotably provided on the outer protruding section.

The track frame51includes a boss portion511formed at a position close to the rear end part, and a bracket portion512formed at a position further close to the rear end part as compared to the boss portion511.

The boss portion511has a substantially cylindrical hole extending in the direction orthogonal to the extending direction of the track frame51, and the outer protruding section of the pivot shaft6is inserted into this portion. Provided in the boss portion511are bushes511A,511B, and the crawler type traveling apparatus5is pivotably supported on the pivot shaft6with the bushes511A,511B.

A tip section of the pivot shaft6in the protruding direction is covered with a cover member513, and this cover member513is tightly fixed to the track frame51with a bolt514.

Further a seal section515is formed on a base end section at a position outer from the side plate21of the pivot shaft6, and a lubrication oil is included in a clearance in the boss portion511between the cover member513and the seal section515so that the track frame51can pivot against the pivot shaft6.

Although not shown inFIG. 2, the bracket512includes a supporting section for supporting the final reduction gear53and a hydraulic motor57as a driving power source, and a rib surrounding an outer periphery of this supporting member. Provided on an outer side surface of'this bracket512is the final reduction gear53, and also provided on an inner side surface of the bracket512is the hydraulic motor57. The hydraulic motor57is attached to the track frame51and is provided inside the final reduction gear53.

The inner side surface with the hydraulic motor57of the bracket512provided thereon is covered with the cover members516,517up to the position of the boss portion511.

The final reduction gear53includes a casing532and a final reduction gear main body533, and a sprocket513is provided outside a casing532.

The final reduction gear main body533is a portion for driving the sprocket531for rotation by reducing a rotating force generated by the hydraulic motor57, and a brake mechanism534for parking is provided in the final reduction gear main body533.

The hydraulic motor57has a rotating shaft driven with a hydraulic oil pressure-fed via an operation valve by a hydraulic pump (not shown) provided inside the main frame2, and the rotating shaft of the hydraulic motor57penetrates the bracket512and is connected to gears of the final reduction gear main body533.

[3] Structure of Pivot Shaft 6

The pivot shaft6has a steel-made shaft-like body and includes a supporting section62, a flange section63, and piping connecting sections64,65as shown inFIG. 3.

The supporting section62is a section into which the boss portion511of the track frame51is inserted, a tip section621of the supporting section having a cylindrical form and a base end section622of the supporting section, and a frustum section623formed between the tip section621of the supporting section and the base end section622of the supporting section with the diameter gradually reduced toward the tip end side.

The flange section63is provided around the center of the pivot shaft6at a position closer to the base end side as compared to the supporting section62in a manner protruding toward the outside, and a plurality of holes631are formed on a protruding surface of the flange section63, and further the bolt61for fixing to the side plate21of the main frame2is inserted into each of the holes631.

Piping connecting sections64,65are formed at inner and outer sides of the flange section63, and a piping arrangement for feeding and discharging a hydraulic oil is connected to the section. The piping connecting section64is a section to which the piping arrangement leading to the final reduction gear53and the hydraulic motor57are connected, while the piping connecting section65is a section to which the piping arrangement leading to the operation valve, the hydraulic pump and a hydraulic tank are connected.

The piping connecting sections64,65are square poles formed around the center of the pivot shaft6and having flat surfaces, and the piping connecting section64has side faces641,642, an upper surface643, and a lower surface now shown inFIG. 3, while the piping connecting section65has side faces651,652, an upper surface653, a lower surface not shown inFIG. 3, and an end face654in the base end side of the pivot shaft6in the axial direction.

A plurality of hydraulic passages71,72,73,74, and75for feeding and discharging hydraulic oil to and from the hydraulic motor57or the final reduction gear53are formed inside the pivot shaft6having the form as described above.

The hydraulic passage71includes an axially extending passage711, a first connection port712, and a second connection port713.

The axially extending passage711is a hole extending along a center of the pivot shaft6and is formed with a drill or the like from an end face654in the base end side of the piping connecting section65, and extends up to a substantial center of the piping connecting section64provided at an outer position.

The first connection port712is formed as a hole extending in the direction orthogonal to the axially extending passage711and is opened on a side face641of the piping connecting section64with the hole tip communicated to the axially extending passage711.

The second connection port713is formed as a hole extending in a direction orthogonal to the axially extending passage711like the first connection port712and is opened on the upper surface653of the piping connecting section65with the hole tip communicated to the axially extending passage711.

The first connection port712and the second connection port713are formed from a side face641of the piping connection section64and an upper surface653of the piping connecting section65with a drill or the like.

The hydraulic passage72includes an axially extending passage721, a first connection port722, and a second connection port723each engraved like the hydraulic passage71. The second connection port723of the hydraulic passage72is different from the second connection port713of the hydraulic passage71in that it is opened on a side face of the piping connecting section65.

A plurality of male screw holes76are formed surrounding an opening section of each of the connection ports712,713,722,723of the hydraulic passages71,72, and the piping arrangement is attached thereto with bolts screwed into the male screw holes76respectively.

The hydraulic passage73includes an axially extending path731formed substantially in the same manner as hydraulic passage71described above a first connection port732, and a second connection port733. Of these, the first connection port732of the hydraulic passage73is different from the first connection port712of the hydraulic passage71in that it is opened on an upper surface643of the piping connecting section64.

The hydraulic passages74,75include the axially extending paths741,751formed substantially like the hydraulic passage71described above, first connection ports742,752, and second connection port743,753respectively. Of these, the first ports742,752are different from the first connection port712of the hydraulic passage71in the point that the ports742,752are opened on a side face642of the piping connecting section64. Namely the first connection ports742,752are opened on the side face642opposite to the side face641on which the first connection port712of the hydraulic passage71is opened.

(4-1) Outer Piping Structure

FIG. 4shows the outer piping structure of the main frame2viewed from an arrow indicated by the line B-B inFIG. 2, whileFIG. 5is a general perspective view showing the outer piping structure.

Various types of piping arrangements are connected to the hydraulic passages71to75formed inside the pivot shaft6. The piping arrangement connected to the piping connecting section64is connected to the hydraulic motor57and the final reduction gear53each provided in the track frame51, while the piping arrangement connected to the piping connecting section65is connected to the operation value, the hydraulic oil tank and the like provided inside the main frame2.

More specifically, as shown inFIG. 4, the pivot shat6is provided so that the face with the first connection port712of the hydraulic passage71and the first connection port722of the hydraulic passage72opened thereon opposes the opposite side of the hydraulic motor57, and a gallery block81is connected to the first connection ports712,722respectively.

The gallery block81has flow paths811,812communicating to the first connection: ports712,722respectively, and the flow path811is opened on the upper section, while the flow path812is opened on the lower section.

A flexible hydraulic hose82is connected to the flow path811, and a flexible hydraulic hose83is connected to the flow path812.

The hydraulic hose82is installed along the inner periphery of the upper side of the bracket512, while the hydraulic hose83is installed along the inner periphery of the lower side of the bracket512, and are connected to an inlet port and an discharge port of the hydraulic motor57although not shown.

The flexible hydraulic hose84is connected to the first connection port732of the hydraulic passage73, and flexible hydraulic hoses85,86are connected to the first connection ports742,752of the hydraulic passages74,75. The hydraulic hose84extends in the horizontal direction via an elbow841provided on an upper surface643of the piping connecting section64, and bends in the sigmoid form at an intermediate portion thereof. The hydraulic hoses85,86extend in the substantially horizontal direction from the side face642of the piping connecting section64opposite to the hydraulic motor57.

Tips of the hydraulic hoses84,85,86are respectively connected to a drain port or a speed control port of the hydraulic motor57and a brake release port of a brake mechanism534provided inside the final reduction gear53each not shown for speed control and braking control and the like for the crawler type traveling apparatus5.

(4-2) Inner Piping Structure

The piping structure inside the main frame2includes, as shown inFIG. 2, a plurality of flexible hydraulic hoses connected to the second connection ports formed in the piping connecting section65provided on inner side of the side plate of the main frame2.

A hydraulic hose87is connected to the second connection port713of the hydraulic passage71opened on the upper surface653of the piping connecting section65, and a hydraulic hose88is connected to the second connection port723(not shown inFIG. 2) of the hydraulic passage72opened on the side face651of the piping connecting section65.

Tips of the hydraulic hoses87,88are connected to a discharge port and an inlet port of a hydraulic pump not shown.

A hydraulic hose89is connected to the second connection port733(not shown inFIG. 2) of the hydraulic passage73opening on the upper surface653of the piping -connecting section65, and a tip of this hydraulic hose89is connected to a hydraulic oil tank not shown, the hydraulic hose89forming a drain conduit.

Hydraulic hoses90,91are connected to the second connection ports743,753(not shown inFIG. 2) opening on the upper surface653of the piping connecting section65, and tips of the hydraulic hoses90,91are connected to operation vales not shown.

Openings on end faces in the base end side of the piping connecting sections65for the axially extending passages711,721,731,741, and751(not shown inFIG. 2) are sealed with seal members respectively with bolts92screwed therein respectively to prevent leakage of the hydraulic oil from the axially extending passages711,721,731,741, and751.

[5] Effects and advantages of embodiment

The crawler type traveling apparatus5according to this embodiment has the configuration as described above, and therefore can provide the effects and advantages as described below.(5-1) The hydraulic motor57is arranged at the inner side with respect to the final reduction gear53, so that the final reduction gear53covered with the rigid casing532is arranged at the outer side of the crawler type traveling apparatus5. While the crawler type traveling apparatus5operates, the hydraulic motor57, gallery block81, and hydraulic hoses82,83,84,85,86arranged at the inner side do not come into contact pavement, and are free from impingement with rolling stones from a the mucking mound and/or from the wall surface of a bench cut.(5-2) The hydraulic passages71to75communicating with the hydraulic motor57, etc are defined inside the pivot shaft6. Therefore, piping arrangements that are so disposed as to extend from hydraulic appliances arranged inside the side plate21of the main frame2such as a hydraulic pump toward the hydraulic motor57and the like of the crawler type traveling apparatus5can be arranged to a position close to the hydraulic motor57without being exposed to the outside. Accordingly, the piping configuration that is hardly damaged from the outside can be acquired.(5-3) As the first connection ports712,722,732,742, and752are formed and opened on an outer peripheral surface around the center of the pivot shaft6, connection with the hydraulic motor57can be realized with short hydraulic hoses82to86. Therefore, extremely compact piping structure can be obtained.(5-4) The first connection ports712to752are provided and opened on the side faces641,642as well as the top surface643of the piping connecting section64around a center of the pivot shaft6, and further the second connection ports713,723,733,743,753are provided and opened on the side faces651,652as well as on the top surface653of the piping connecting section65, so that it is required only to form the axially extending passages711,721,731,741, and751in the section L1shown inFIG. 3. Therefore, unlike the pivot shaft disclosed in the reference1as the related art, it is not necessary to form the hydraulic passage over the full length thereof in the axial direction. Consequently, the axially extending passages711to751can be easily extended by an ordinary drill and the like, which enables substantial reduction in machining cost for manufacturing the pivot shaft6as well as in production cost for the crawler type traveling apparatus5.(5-5) The side faces641,642,652and top surfaces643,653of the piping connecting sections64,65are flat surfaces normal to the piping connecting direction, so that the gallery block81or hydraulic hoses82to91are tightly connected to the first connection ports712to752or to the second connection ports713to753with a simple structure with bolts or plates. Therefore, leakage of a hydraulic oil from the connecting sections or separation of the piping arrangements from the specified positions can be prevented, so that reliability in operations can further be improved.
[6] Variants of the Embodiment

The present invention is not limited t the embodiment described above, and changes and improvements in a scope in which objects of the present invention are achievable are included in a scope of the present invention.

In the embodiment, the crawler type traveling apparatus5is employed as a traveling apparatus for the bulldozer1, but the present invention is not limited to this application, and the present invention may be applied to other types of work vehicles such as a hydraulic shovel or a crawler crane.

In the embodiment described above, the piping connecting sections64,65are square poles each arranged around the center of the pivot shaft6and having the flat side faces641,642,651,652, top surfaces643,653, and a lower surface, but the present invention is not limited to this configuration. Namely, the piping connecting section may have a cylindrical form with only a section around a connection port cut and machined to a flat surface.

In addition, other specific structures and forms can be employed for carrying out the present invention within a scope in which objects of the present invention are achievable.