Cab stopper device for work machine, method for fixing the cab stopper and cab of work machine

A cab stopper device 32 is provided between a bracket 23 on a machine frame of a work machine and a cab 25. The cab stopper device 32 restricts relative movement of the cab 25 with respect to the machine frame in the vertical direction. Two through holes 43, 44 are formed in a floor plate 27 of the cab 25. A stopper 48 of the cab stopper device 32 is inserted in the through holes 43, 44 from above. An engaging portion 48a is formed at the lower end of the stopper 48 that projects from the through holes 43, 44 downward of the floor plate 27. The engaging portion 48a is arranged to be engageable with a restricting groove 42 formed in the bracket 23. In this state, a securing portion 48b at the upper end of the stopper 48 is secured to the floor plate 27.

FIELD OF THE INVENTION

The present invention relates to a cab stopper device for a work machine, a method for fixing a cab stopper, and a cab for a work machine. A cab stopper device is located between a bracket on a machine frame and the cab of a work machine such as a bulldozer and a hydraulic shovel. The cab stopper device restricts the cab from excessively moving relative to the machine frame when, for example, the work machine rolls over.

BACKGROUND OF THE INVENTION

One type of a cab stopper device proposed for work machines, for example, is the structure disclosed in Patent Document 1. In this conventional device, a block-like stopper member is fixed to a side portion of the cab. A receiving member is secured to the machine frame and projects from the frame. The receiving member includes an engaging recess, which is engageable with the stopper member. The stopper member faces the inner surface of the engaging recess, and a clearance is formed between the stopper member and the inner surface of the engaging recess. According to this structure, when the cab moves relative to the machine frame, the engagement between the stopper member and the receiving member inhibits the cab from moving relative to the machine frame by an amount more than or equal to a predetermined distance.

DISCLOSURE OF THE INVENTION

Problems that the Invention is to Solve

As described above, in the conventional apparatus of Patent Document 1, the stopper member is secured to the side portion of the cab, and the receiving member, which is engageable with the stopper member, is secured to the machine frame to project from the machine frame. However, the structure for securing the stopper member to the cab is not disclosed in Patent Document 1. In order to secure the block-like stopper member to the side portion of the cab, it is necessary to prevent contact between the stopper member and the receiving member, and to ensure the mounting strength of the stopper member. Thus, the mounting structure of the stopper member is undesirably complicated.

Furthermore, two opening portions are formed at a portion adjacent to the engaging recess in the above-mentioned receiving member. The stopper member is inserted from the opening portions, and faces the inner surface of the engaging recess. That is, in the conventional cab stopper device, the stopper member cannot restrict the movement of the cab in the directions in which the stopper member is disengaged from the two opening portions. Patent Document 1 discloses an example in which the stopper member and the engaging portion are formed into a cross figure and a T-shape. In this case also, one opening portion is formed. Thus, the stopper member cannot restrict the movement of the cab in the direction in which the stopper member is disengaged from the opening portion.

The objective of the present invention is to provide a cab stopper device for work machine, a method for fixing the cab stopper, and a cab for a work machine. The cab stopper device has a simple structure, is easily fixed, and restricts the movement in the vertical, left-right, and front-rear directions.

Means for Solving the Problems

To achieve the above objective, the present invention provides a cab stopper device provided between a restricting portion provided on a machine frame of a work machine and a cab of the work machine. The device is characterized by a through hole and a stopper. The through hole is formed in a floor plate of the cab. The stopper is inserted in the through hole from above. The stopper includes an engaging portion at its lower end that projects downward from the through hole. The engaging portion is engageable with the restricting portion. The relative position of the through hole and the stopper is changeable between an inserting position, at which the stopper is insertable in the through hole with the engaging portion not contacting the restricting portion, and an engaging position, at which the engaging portion is engageable with the restricting portion with the stopper inserted in the through hole.

The cab stopper device of the present invention employs a simple structure in which the engaging portion, which is engageable with the restricting portion of the machine frame, is formed at the lower end portion of the stopper. Thus, the structure of the cab stopper device is simplified. The stopper is fixed by a simple operation. That is, when fixing the stopper, the stopper is inserted in a hole in the floor plate of the cab from above so that the lower end portion of the stopper is engageable with the restricting portion of the bracket. Then, the upper end portion of the stopper is secured to the floor plate. Thus, even if various operation devices are mounted on the machine frame in the vicinity of the cab stopper device, the stopper is easily fixed from above the floor plate of the cab. The description that the engaging portion of the stopper is engageable with the restricting portion means that the engaging portion of the stopper faces the restricting portion through a clearance, and when the cab, that is, when the stopper moves relative to the machine frame, the engaging portion engages with the restricting portion.

Furthermore, the stopper can be arranged between the cab and the machine frame after the cab is mounted on the machine frame. Thus, different stoppers for restricting the movement of the cab in the vertical, left-right, and front-rear directions are easily fixed.

The upper end portion of the stopper is preferably fixed on the upper surface of the floor board in a state where the relative position of the through hole and the stopper corresponds to the engaging position.

When the stopper is rotated about a vertically extending axis after being inserted in the through hole, the relative position between the through hole and the stopper is preferably shifted from the inserting position to the engaging position.

The floor plate preferably has an inhibiting portion for inhibiting the stopper located at the engaging position from moving downward.

The device preferably employs the following structure. The upper end portion of the stopper includes a securing portion, which projects to the side of the stopper. The through hole includes an upper through hole formed in the upper surface of the floor plate and a lower through hole formed in the lower surface of the floor plate. The lower through hole has a smaller dimension than the upper through hole. The inhibiting portion is formed on the periphery of the lower through hole. The inhibiting portion serves as a support surface, which contacts the securing portion of the stopper and supports the stopper.

When the stopper is rotated about the vertically extending axis after being inserted in the through hole, the inhibiting portion desirably inhibits the stopper from moving downward.

The floor plate and the stopper are respectively provided with marks, which match each other when the direction in which the stopper is mounted with respect to the floor plate is correct. Thus, the stopper is prevented from being fixed in an erroneous manner.

It is preferable to form the stopper with plate material in view of the productivity.

A cover plate is preferably provided that is secured to the floor plate in a state where the cover plate covers the upper end portion of the stopper. The cover plate inhibits the movement of the stopper in a state where the relative position between the through hole and the stopper is at the engaging position.

It is desirable to provide shock absorbing means between the stopper and the cover plate in view of, for example, absorbing vibration.

Furthermore, in view of the sealing performance, it is preferable to provide sealing means between the cover plate and the floor plate for sealing between the cover plate and the floor plate.

A cab mounted on a machine frame of work machine. A cab stopper device including a stopper is located between the cab and a restricting portion provided on the machine frame. The cab is characterized by a floor plate arranged at the lower part of the cab, and a through hole formed in the floor plate of the cab. The stopper is inserted downward in the through hole from above the floor plate. The relative position of the through hole and the stopper is changeable between an inserting position, at which the stopper is insertable in the through hole while not contacting the restricting portion, and an engaging position, at which the stopper is engageable with the restricting portion while being inserted in the through hole.

Furthermore, the present invention provides a method for fixing a cab stopper device. The cab stopper device is provided between a restricting portion provided on a machine frame of a work machine and a cab of the work machine. The method is characterized by: mounting the cab on the machine frame; inserting a stopper in a through hole formed in a floor plate of the cab from above with the stopper not contacting the restricting portion; changing the stopper from a state in which the stopper does not contact the restricting portion to a state in which the lower end of the stopper is engageable with the restricting portion after inserting the stopper into the through hole; and securing the upper end portion of the stopper to the floor plate.

In this manner, the structure of the cab stopper device is simplified, and the stopper, which restricts the movement of the cab in the different directions, is fixed on the floor plate of the cab from the upper side easily.

Effects of the Invention

As described above, according to the present invention, the deflection of the cab is inhibited in all directions with a simple structure, and the stopper is easily fixed on the floor plate of the cab from the upper side.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIG. 1, a work machine, which is a bulldozer in the present embodiment, includes a machine frame21. A pair of front brackets22, a pair of middle brackets23, and a pair of rear brackets24are fixed on the upper portion of the machine frame21on both the left and right sections of the machine frame21. The brackets22,23,24are formed of metal, and are arranged on the machine frame21at predetermined intervals in the front-rear direction and the left-right direction. A cab25is supported by the front brackets22and the rear brackets24with dampers26. The dampers26function as anti-vibration mounts. When the bulldozer is travelling, vibrations and impact that act on the machine frame21are damped and moderated by the dampers26.

The cab25includes a floor plate27and a ceiling board28. The cab25is of a type in which the rear part is supported at a higher position. That is, a rear part25aof the floor portion is higher than a front part25b. A pair of front pillars29, a pair of middle pillars30, and a pair of rear pillars31are arranged on the floor plate27on both the left and right sections of the floor plate27. The pillars29,30,31support the ceiling board28. If the bulldozer rolls over, most of the impact load that is applied to the cab25is received by the rear part of the cab25. That is, an excessive impact load tends to be applied to the rear part of the cab25when the bulldozer rolls over.

Since the rear dampers26and the front dampers26have almost the same structure, the rear dampers26and the mounting structure of the rear dampers26will be described in detail, and the explanation of the front dampers26is omitted. As shown inFIGS. 9 and 11, each of the rear dampers26includes a case36. The case36is fixed to the associated rear bracket24on the machine frame21by bolts37. A stud38, which projects in the case36, is secured to the lower surface of the floor plate27of the cab25by a bolt39as shown inFIGS. 9 and 11. A shock absorbing member40formed of elastic material such as rubber is arranged between each case36and the associated stud38. The case36is filled with non-illustrated high-viscosity damping liquid such as silicone oil.

If vibrations or impact are applied to the machine frame21when the bulldozer is travelling, the stud38of each damper26is moved in the vertical, front-rear, and left-right directions relative to the associated case36. The relative movement causes the shock absorbing member40to be elastically deformed between the case36and the stud38. Accordingly, the damping liquid flows in the case36, and flow resistance of the damping liquid is generated. Such elastic deformation and flow resistance operate together, and damp and moderate the vibrations and impact transmitted to the cab25.

As shown inFIGS. 2 and 3, a pair of front cab stopper devices32are provided below the middle pillars30of the cab25on both the left and right sections. The front cab stopper devices32are located between the middle brackets23on the machine frame21and the floor board27of the cab25. When impact load is applied to the cab25, the front cab stopper devices32restrict the movement of the cab25within a predetermined range at the front part of the cab25where the sharing ratio of the impact load is low. Although the front cab stopper devices32restrict the movement of the cab25in the vertical, left-right, and front-rear directions, the front cab stopper devices32mainly restrict the vertical movement of the cab25.

As shown inFIGS. 1 and 3, a pair of rear cab stopper devices33are provided below the rear pillars31of the cab25on both the left and right sections. The rear cab stopper devices33are arranged between the rear brackets24on the machine frame21and the floor plate27of the cab25. When impact load is applied to the cab25, the rear cab stopper devices33restrict the movement of the cab25in the vertical, front-rear, and left-right directions within a predetermined range at the rear part of the cab25where the sharing ratio of the impact load is high.

The rear cab stopper devices33are formed as follows.

A restricted member61is fixed to and hangs down from the lower surface of the floor plate27directly below each rear pillar31as shown inFIGS. 9 and 10. The restricted member61has a through hole61a, which extends in the front-rear direction. A pair of restricting members62,63made of metal plates are secured to the upper rear end of the rear bracket24on the machine frame21at a predetermined interval in the front-rear direction. The restricting members62,63are arranged parallel to each other and face the front surface and the rear surface of the restricted member61. The restricting members62,63respectively have pin through holes62a,63a, which extend in the front-rear direction. A closing plate64is fixed to the restricting member62, and the closing plate64is arranged on the outer side of the clearance between the restricting members62,63.

A metal restricting pin65is inserted in the pin through holes62a,63aof the restricting members62,63and the through hole61aof the restricted member61so as to be fitted to the pin through holes62a,63a. The middle part of the restricting pin65is inserted in the through hole61aof the restricted member61. A stopper plate66is secured to the proximal end of the restricting pin65, and the stopper plate66has a bore66a. The rear restricting member63has a threaded bore63a. A bolt67is inserted in the bore66aof the stopper plate66and screwed to the threaded bore63bof the rear restricting member63. As the bolt67is screwed, the restricting pin65is inhibited from falling out of the pin through holes62a,63aof the restricting members62,63.

As shown inFIGS. 11 and 12, clearances S4a, S4bare formed between the upper and the lower outer circumferences of the restricting pin65and the inner circumferential surface of the through hole61aof the associated restricted member61. Thus, the vertical movement of the cab25is restricted to be within the range of the clearances S4a, S4b. A clearance S5ais formed between the restricted member61and the front restricting member62, and a clearance S5bis formed between the restricted member61and the rear restricting member63. Thus, the movement of the cab25in the front-rear direction is restricted to be within the range of the clearances S5a, S5b. Furthermore, clearances S6a, S6bare formed between the left and the right outer circumferences of the restricting pin65and the inner circumferential surface of the through hole61aof the associated restricted member61. The movement of the cab25in the left-right direction is restricted to be within the range of the clearances S6a, S6b.

The structure of the front cab stopper device32will now be described with reference toFIGS. 2 to 8.

As shown inFIGS. 2 and 4, each of the middle brackets23includes a pair of leg portions23a,23bformed of plate material and a locking plate23c. The middle brackets23form part of the machine frame21. The leg portions23a,23bare arranged side by side in the left-right direction, and the locking plate23cis disposed and secured on the upper ends of the leg portions23a,23b. A restricting portion, which is a restricting groove42in this embodiment, is provided on the upper end of the leg portion23awhich is one of the leg portions23a,23blocated on the inner side in the middle bracket23. The upper end of the restricting groove42is closed by the locking plate23c.

As shown inFIGS. 3 and 5, the floor plate27of the cab25is formed by an upper floor plate27A and a lower floor plate27B, which are stacked on one another. As shown inFIGS. 4,5, and6(a) to6(c), through holes43,44are respectively formed in the upper floor plate27A and the lower floor plate27B at the position corresponding to the restricting groove42of the middle bracket23. The through holes43,44are formed into substantially the same shape. However, the upper through hole43of the upper floor board27A has an inner diameter D2that is greater than an inner diameter D1of the lower through hole44of the lower floor plate27B. That is, the upper through hole43is formed to be larger than the lower through hole44as a whole.

As shown inFIGS. 4,6(a), and6(b), a pair of inserting position restricting surfaces43a, which extend in the front-rear direction, and a pair of rotational position restricting surfaces43b, which extend in the left-right direction, are formed in the upper through hole43. The inserting position restricting surfaces43aand the rotational position restricting surfaces43bare formed alternately in the circumferential direction at intervals of 90 degrees. As shown inFIGS. 4,6(a), and6(c), a pair of insertion cutouts44aare formed in the lower through hole44to correspond to the inserting position restricting surfaces43aof the upper through hole43. An inhibiting portion, which is a pair of support surfaces45, is formed on the upper surface of the periphery of the lower through hole44. The support surfaces45are adjacent to the insertion cutouts44aof the lower through hole44.

As shown inFIGS. 6(a) and8, a pair of threaded bores46are formed in the upper floor plate27A in the vicinity of the outer circumference of the upper through hole43. A pair of bolt insertion holes47are formed in the lower floor plate27B to correspond to the threaded bores46. The bolt insertion holes47communicate with the threaded bores46.

As shown inFIGS. 4andFIG. 5, the front cab stopper device32includes a stopper48formed of plate material. The stopper48is formed such that the upper portion is substantially T-shaped, and the lower portion is substantially L-shaped. The stopper48includes a vertically extending main body portion48c, an engaging portion48a, which is formed at the lower end of the main body portion48c, and a securing portion48b, which is formed at the upper end of the main body portion48c. The engaging portion48aprojects laterally from the main body portion48c. The securing portion48bprojects from the main body portion48cin the same direction as and the direction opposite to the direction in which the engaging portion48aextends. The stopper48is inserted in the through holes43,44of the floor plates27A,27B of the cab25from above to be mounted on the floor plates27A,27B.

In this case, in a state in which the engaging portion48aof the stopper48projects forward of the machine frame21as shown by the chain double-dashed lines inFIGS. 4 and 6(a), the stopper48is inserted along the inserting position restricting surfaces43aof the upper through hole43into the insertion cutouts44aof the lower through hole44. At this time, the securing portion48bis placed on the support surfaces45. Subsequently, the stopper48is rotated 90 degrees about a vertically extending axis toward the rotational position restricting surfaces43bof the upper through hole43such that the engaging portion48aprojects outward of the machine frame21.

Thus, the securing portion48bat the upper end of the stopper48is engaged with the rotational position restricting surfaces43bof the upper through hole43as shown by the solid line inFIG. 6(a). This restricts the position of the stopper48in the front-rear direction. At the same time, the securing portion48bis supported by the support surfaces45on the periphery of the opening of the lower through hole44, and the downward movement of the stopper48is prevented. As the stopper48is rotated in this manner, the engaging portion48aat the lower end of the stopper48is inserted in the restricting groove42of the middle bracket23, and moved to a position where the engaging portion48ais engageable with the inner circumferential surface of the restricting groove42as shown inFIGS. 5 and 7.

As shown inFIG. 6(b), the thickness T of the stopper48is set to be thinner than the width W2of the insertion cutouts44a. The length L1of the securing portion48bof the stopper48is shorter than the inner diameter D2of the upper through hole43, and is longer than the length L4between the insertion cutouts44a(between the inner ends) and the inner diameter D1of the lower through hole44. As shown inFIG. 5, the vertical width W1of the securing portion48bis set such that when the securing portion48bis engaged with the support surfaces45of the upper surface of the lower floor plate27B, the securing portion48bprojects upward from the upper surface of the upper floor plate27A. The length L2of the main body portion48cof the stopper48is set such that when the securing portion48bis engaged with the support surfaces45of the lower floor plate27B, the engaging portion48ais located at the vertically middle portion of the restricting groove42. The length L3of the engaging portion48aof the stopper48is set such that the engaging portion48ais inserted in the restricting groove42of the engaging portion48ain a state where the main body portion48cis inserted in the lower through hole44. Furthermore, the length L3of the engaging portion48ais set shorter than the length L4between the insertion cutouts44aso that the stopper48can vertically pass between the insertion cutouts44afacing each other.

As shown inFIG. 5, a clearance S1ais formed between the upper edge of the engaging portion48aof the stopper48and the upper end portion of the restricting groove42of the middle bracket23. A clearance S1bis formed between the lower edge of the engaging portion48aand the lower end portion of the restricting groove42. A clearance S2is formed between the outer edge of the main body portion48cof the stopper48and the inner edge of the upper end of the middle bracket23. As shown inFIG. 7, a clearance S3ais formed between the front surface of the engaging portion48aof the stopper48and the front end portion of the restricting groove42of the middle bracket23, and a clearance S3bis formed between the rear surface of the engaging portion48aand the rear end portion of the restricting groove42. The movement of the cab25relative to the machine frame21in the vertical, outward, and front-rear direction is restricted within the range of the clearances S1a, S1b, S2, S3a, S3b.

As shown inFIGS. 4 and 6, marks49and50are respectively provided on the upper surface of one end of the securing portion48band the support surface45on the periphery of the opening of the lower through hole44. The marks49,50match with each other when the mounting direction of the engaging portion48aof the stopper48is correct. The stopper48is prevented from being mounted on the floor plates27A,27B in an incorrect direction, that is, the engaging portion48aof the stopper48is prevented from being mounted in the incorrect direction by inserting the stopper48in the through holes43,44so as to match the marks49,50.

As shown inFIGS. 4 to 6, the front cab stopper device32includes a cover plate51made of plate material. The cover plate51is substantially oval in shape. A groove-like cover51a, which opens downward, is formed at the center of the cover plate51. The cap portion51ais formed by press drawing. Shock absorbing means, which is a sheet-like elastic material52in this embodiment, is secured to the inner upper surface of the cap portion51a. Sealing means, which is an annular packing53in this embodiment, is mounted on the periphery of the lower surface of the cover plate51. The packing53seals between the cover plate51and the floor plate27. A pair of bolt through holes54is formed in the cover plate51on both sides of the cap portion51a. The cap portion51aof the cover plate51covers the securing portion48bof the stopper48and is fitted to the securing portion48bin a state where the stopper48is inserted and fixed in the through holes43,44. In this state, bolts55are inserted in the through holes54, and are screwed to the threaded bores46of the upper floor plate27A with a pair of washers56,57. Accordingly, the cover plate51is secured to the upper floor cover27A.

Since the cap portion51aof the cover plate51presses the securing portion48bof the stopper48against the support surfaces45with the elastic material52in between, upward movement of the stopper48is prevented. In this state, the packing53on the periphery of the cover plate51is press-fitted to the upper surface of the upper floor plate27A as shown inFIGS. 5 and 8.

The operation of the bulldozer formed as described above will now be described.

If vibrations or impact are applied to the machine frame21when the bulldozer is travelling, the stud38of each damper26moves relative to the case36in the vertical, front-rear, and left-right directions. The relative movement causes the shock absorbing member40to elastically deform. Accordingly, non-illustrated damping liquid flows, and flow resistance of the damping liquid is generated. Such elastic deformation and flow resistance operate together to damp and moderate the vibrations and impact transmitted to the cab25in advance. This ensures a comfortable ride in the cab25.

If the bulldozer rolls over and excessive impact load is applied to the cab25, the cab25moves relative to the machine frame21. At this time, the impact load is shared and received by the rear cab stopper device33and the front cab stopper device32. More specifically, since the ratio of the impact load borne by the rear part is higher as compared to the front part of the cab25, the rear part of the cab25is moved in the vertical, front-rear, and left-right directions by a larger amount. However, the rear cab stopper device33restricts the movement of the rear part of the cab25in the vertical, front-rear, and left-right directions within a predetermined range. Since the ratio of the impact load borne by the front part of the cab25is low, and the bulldozer rarely rolls over to the front side, only slight vertical impact load is generally applied to the front part of the cab25. The vertical movement of the front part of the cab25is restricted within a predetermined range by the front cab stopper device32. The front cab stopper device32, of course, also functions as to restrict the left-right and front-rear movement of the cab25within a predetermined range.

Thus, the rear cab stopper device33and the front cab stopper device32reduce excessive movement of the cab25with respect to the machine frame21, thereby protecting an operator in the cab25. The dampers26are designed to restrict the movement of the cab25in the vertical, front-rear, and left-right directions by a certain range. However, if the dampers are designed to endure the excessive impact load in those directions, the size of the dampers is undesirably increased. This causes problems in the arrangement and the manufacturing costs of the dampers. Therefore, the dampers26of the present embodiment are not designed to restrict the movement range of the cab25by a level that endures excessive impact load.

Subsequently, a method for fixing the front cab stopper device32, which is the main structure of the present embodiment, will now be described.

When fixing the front cab stopper device32, the stopper48is inserted in the through holes43,44from above the floor plate27of the cab25through the insertion cutouts44awhile the engaging portion48aat the lower end of the stopper48projects forward as shown by the chain double-dashed lines inFIGS. 4 and 6(a) to6(c). At this time, the relative position of the stopper48and the through holes43,44corresponds to an inserting position where the stopper48is insertable in the through holes43,44in a state in which the engaging portion48aof the stopper48does not contact the middle bracket23, which includes the restricting groove42. With the stopper48inserted in the through holes43,44, the stopper48is rotated 90 degrees about the vertically extending axis such that the engaging portion48aof the stopper48projects toward the outside of the machine frame21. Accordingly, the securing portion48bof the stopper48is supported on the support surfaces45on the periphery of the opening of the lower through hole44as shown by the solid line inFIG. 6(a). This prevents the downward movement of the stopper48. Furthermore, when the stopper48is rotated, the engaging portion48aat the lower end of the stopper48is inserted in the restricting groove42of the middle bracket23, and moved to the position where the engaging portion48ais engageable with the inner circumferential surface of the restricting groove42and the locking plate23cat the upper end of the middle bracket23as shown inFIGS. 5 and 7. That is, the relative position of the stopper48and the through holes43,44corresponds to an engaging position where the engaging portion48ais engageable with the restricting groove42.

In this case, the pair of marks49,50is correspondingly provided on the stopper48and one of the support surfaces45as shown inFIGS. 4 and 6. The stopper48is prevented from being mounted in an incorrect direction by inserting and fixing the stopper48in the through holes43,44to match the marks49,50.

Subsequently, the cover plate51is placed on the upper surface of the upper floor plate27A, and the securing portion48bof the stopper48is covered by the cap portion51aof the cover plate51and fitted to the cover51a. In this state, the bolts55are inserted in the bolt through holes54of the cover plate51, and screwed to the threaded bores46of the upper floor plate27A with the washers56,57. Accordingly, the cover plate51is fastened to the upper floor plate27A. As a result, the cap portion51aof the cover plate51presses the securing portion48bof the stopper48against the support surfaces45with the elastic material52in between as shown inFIGS. 5 and 8, and prevents the upward movement of the stopper48. The elastic material52, which functions as a shock absorber, inhibits generation of vibration and noise between the stopper48and the cover plate51. At this time, the packing53at the periphery of the cover plate51is press-fitted to the upper surface of the upper floor plate27A. This inhibits air, noise, or water such as rainwater outside the cab25from entering the cab25through the through holes43,44.

As described above, according to the front cab stopper device32of the present embodiment, the stopper48is fixed by a simple operation. More specifically, the stopper48is inserted and fixed in the through holes43,44of the floor plate27of the cab25from above, and the cover plate51is then mounted on the floor plate27to cover the stopper48. Thus, even if a working space is not easily secured between the machine frame21and the cab25due to various devices that are installed in the vicinity of the front cab stopper device32at the upper part of the machine frame21, the stopper48is easily fixed from above the floor plate27of the cab25.

In the front cab stopper device32of the present embodiment, the restricting groove42is formed in the middle bracket23made of plate material on the machine frame21. The securing portion48band the engaging portion48aare also provided on both vertical ends of the stopper48made of plate material. Therefore, the leg portions23a,23bof the middle bracket23, the locking plate23c, and the stopper48are formed by a simple operation, that is, by thermal cutting a metal plate. The cover plate51is formed by subjecting a metal plate to laser thermal cutting, and forming the cover51aby press drawing. Thus, manufacture of the cab stopper device is easy, and the number of components of the cab stopper device is reduced. The elastic material52is located between the cover plate51and the stopper48, and the packing53is located between the cover plate51and the floor plate27. Thus, even if a slight dimensional error occurs during processing of the stopper48and the cover plate51, the dimensional error is absorbed by the deformation of the elastic material52and the packing53. This further facilitates processing of the stopper48and the cover plate51.

As described above, the device of the present invention is easy to form and fix, and has small number of components, which significantly reduces the manufacturing costs.

Modified Embodiment

The present embodiment may be modified as follows.

In the above embodiment, the stopper48is arranged at the engaging position by being rotated 90 degrees about the vertically extending axis from the position where the stopper48is inserted in the through holes43,44of the floor plate27of the cab25. However, the stopper48may be moved laterally after being inserted in the through holes43,44to be arranged at the engaging position. As another embodiment, the through holes43,44may have a rectangular cross-section. In this case, the stopper48is inserted in the through holes43,44from one end such that the stopper48does not contact the restricting portion, and then engageable with the restricting groove42on the other end of the through holes43,44.

In the above embodiment, the middle brackets23, which are engageable with the stoppers48, are provided. However, the middle brackets23may be omitted, and the stoppers48may be directly engaged with the machine frame21.

In the above embodiment, the present invention is embodied in the front cab stopper device of the bulldozer, but may be applied to other cab stopper devices for work machines such as the rear cab stopper device of the bulldozer, a hydraulic shovel, a loader, and an off-road dump truck.

In the above embodiment, the elastic material52is arranged between the stopper48and the cover plate51. For example, the elastic material52may be omitted when vibration and noise generated between the stopper48and the cover plate51can be ignored.

In the above embodiment, the sealing means, which is the annular packing53, is located between the cover plate51and the floor plate27. For example, the sealing means may be omitted when the amount of air or rainwater that enters the cab25via the through holes43,44is negligible.

In the above embodiment, the marks49,50for preventing the stopper48from being mounted in an incorrect direction are provided. For example, the marks49,50may be omitted when the possibility of mounting the stopper48in an incorrect direction is very low.