`Suwabe et al.
`
`US006065799A
`Patent Number:
`11
`(45) Date of Patent:
`
`6,065,799
`May 23, 2000
`
`NINSAINTUCTURE FOR
`(54)
`75 Inventors: Tohru Suwabe, Shinji Iguchi, both of
`Niigate-ken, Japan
`
`73 Assignees: Komatsu EST Corporation,
`Niigata-ken; Komatsu Limited, Tokyo,
`both of Japan
`
`21 Appl. No.: 09/167,976
`22 Filed:
`Oct. 8, 1998
`30
`Foreign Application Priority Data
`Oct. 9, 1997
`JP
`Japan .................................... 9-276989
`(51) Int. Cl." ....................................................... HO1R 4/60
`52 U.S. C. ...
`... 296/190.04; 296/190.08;
`180/89.12; 180/89.18
`58 Field of Search ......................... 296/190.01, 190.04,
`296/190.08, 190.06, 26.05, 26.04, 35.3;
`180/89.12, 89.13, 89.18
`
`56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,252,546 5/1966 Allin, Jr. ........................ 296/190.04 X
`4.556,117 12/1985 Frey et al. ........................... 180/89.13
`
`5. O. STS". 180/89.12
`
`FOREIGN PATENT DOCUMENTS
`61-18519
`1/1986 Japan.
`4-125921 11/1992 Japan.
`Primary Examiner D. Glenn Dayoan
`Assistant Examiner Patricia Engle
`Attorney, Agent, or Firm-Hill & Simpson
`57
`ABSTRACT
`A cabin is movable along the Outer Side Surfaces of an
`operator cab floor by a vertical drive means. Specifically,
`pinions fixed to left and right end portions of a shaft are
`driven and rotated by motors installed on the operator cab
`floor. Rack gears engaged with the pinions are fixed to the
`cabin. Even when the cabin is moved and Situated at its
`lowermost position, where the lower edges of the cabin
`project downwards below the operator cab floor, by the rack
`gears by rotations of the pinions, a Single door which is
`continuous in the Vertical direction can be installed on a side
`plate. Therefore, even when the whole height of the cabin is
`lowered to its limit, the door can be opened and closed
`without troubles. The shaft also functions to synchronize the
`rotations of the left and right pinions mechanically, thereby
`preventing torsion of the cabin.
`
`8 Claims, 23 Drawing Sheets
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`CATERPILLAR EXHIBIT 1015
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`F. G. 3
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`FG.
`FIG.||
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`O8
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`{20
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`FG. 3
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`' FIG. I4
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`1
`CABIN-INSTALLATION STRUCTURE FOR
`CONSTRUCTION MACHINE
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates to a structure for installing
`a cabin to a construction machine Such as a motor grader, a
`hydraulic shovel, a wheel loader, and So on.
`2. Description of the Related Art
`When a construction machine is transported by being
`mounted on a loading space of a truck, with its cabin
`installed on the body of the machine, the whole height of the
`truck may exceed a height limit for transportation due to an
`existence of the cabin.
`In particular, when a motor grader which is So constructed
`as to have a tall cabin So that an operator can Stand in the
`cabin during operation is transported on a loading Space of
`a truck, the whole height of the truck exceeds a height limit
`for transportation.
`In this case, the motor grader is transported after remov
`ing the cabin, which is installed on the body of the motor
`grader at a construction site. Such installation and removing
`Works are complicated and troublesome.
`There has been a known installation Structure in which a
`lower housing and an upper housing are engaged with each
`other to form a cabin Such that the housings are movable in
`the Vertical direction and the lower housing is attached to a
`machine body, as is disclosed in Japanese Utility Model
`Laid-open Publication No. 4-125921.
`According to the installation Structure described above,
`the height of the cabin is decreased by moving downwards
`the upper housing, and the height of the cabin is increased
`by moving upwards the upper housing. Therefore, the height
`of the cabin can be increased when an operator rides in and
`operates the machine, and the height can be decreased
`during transportation of the machine So that the machine
`does not exceed the height limit for transportation.
`Thus, according to the installation Structure of the cabin
`as described above, the stroke of vertical movement of the
`upper housing is Substantially half of a maximum height of
`the cabin, and therefore, the cabin can only be lowered
`substantially to the half of the maximum height of the cabin
`obtained when the upper housing is moved to the uppermost
`limit.
`Therefore, in case where the height of the cabin (or the
`maximum cabin height) is large like a large-sized motor
`grader, the height Sometimes exceeds a height limit for
`transportation even if the upper housing is moved to its
`lowermost position.
`Further, in this Structure, a door for opening and closing
`an entrance/exit of the cabin is divided into upper and lower
`parts and the upper door part is connected to the lower door
`part Such that the upper door is movable in the Vertical
`direction. Therefore, when the upper housing is moved
`downwards, the door cannot be opened or closed because the
`door parts are layered inside and outside. If the door can be
`opened or closed, the inside and outside door parts must be
`opened or closed one after another, and the Structure of the
`door parts and the installation Structure of the cabin are thus
`complicated.
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`SUMMARY OF THE INVENTION
`Hence, the present invention has an object of providing a
`cabin installation Structure for a construction machine,
`which solves the problems as described above.
`According to a first aspect of the present invention, there
`is provided a cabin-installation Structure for a construction
`machine, for installing a box-like cabin of which lower
`Surface is opened, on a body of a construction machine
`having an operator cab floor, comprising: the cabin having
`a lateral-cross-sectional Surface Shape Substantially similar
`to and Slightly larger than a plane shape of the operator cab
`floor, and an inner Surface positioned outside outer Side
`Surfaces of the operator cab floor and is movable in a
`direction vertical to the operator cab floor;
`a guide mechanism for moving and guiding the cabin in
`Said vertical direction; and a vertical-drive means for verti
`cally moving the cabin between an upper position where a
`lower edge of the cabin is positioned at a height Substantially
`equal to the operation cab floor and a lower position where
`the lower edge of the cabin projects downwards below the
`operator cab floor.
`According to the first aspect as described above, Since the
`cabin can be moved downwards below the operator cab
`floor, a vertical length of the cabin is much reduced So that
`the whole height of the machine transported by a truck or the
`like can not exceed a height limit for transportation. On the
`other hand, the vertical length of the cabin can be enlarged
`by moving the cabin to its uppermost position, which
`facilitates the operation by an operator.
`According to a second aspect of the present invention, in
`addition to the above-described Structure,
`the cabin further has at least one door-installation opening
`portion in a side Surface of the cabin, Said door-installation
`portion being continuous in Said vertical direction So that a
`door installed on the door-installation opening portion can
`be opened and closed.
`According to the Second aspect as described above, Since
`the door-installation opening portion of the cabin is con
`tinuous in the vertical direction, one Single door can be
`installed and the door can always be opened and closed
`easily regardless of the movements of the cabin in the
`Vertical direction. Also, the door itself can have a simple
`Structure, So that a simple installation-structure can be
`adopted.
`According to a third aspect of the present invention, the
`cabin-installation Structure further comprises an urging
`means between the cabin and the operator cab floor for
`elastically urging the cabin upwards.
`According to the third aspect as described above, the
`urging means for elastically urging the cabin upwards
`always acts to push up the cabin. Therefore, when the cabin
`is moved downwards, the urging means Serves to buff
`impact so that the durability of the cabin and the body is
`improved. Further, when the cabin is moved upwards, the
`urging means Subsidiarily drives up the cabin, So that only
`a Small power of the drive motor is required, So the drive
`motor can be downsized. A gas Spring or a compression
`Spring may be used as the urging means.
`According to a fourth aspect of the present invention, the
`Vertical drive means according to one of the first to third
`aspects operates the cabin by Supporting left and right Side
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`plates of the cabin and includes torsion-prevention means
`for preventing torsion of the cabin.
`According to the fourth aspect as described above, when
`the cabin is vertically driven, it is possible to prevent the
`cabin from being damaged and Stopped by torsion between
`the left and right Side walls and the guide mechanism.
`According to a fifth aspect of the present invention, the
`torsion-prevention means of the cabin is a connection mem
`ber of a rigid body connecting respective portions of left and
`right side wall of the operator cab floor.
`According to the fifth aspect as described above, Since the
`respective portions of the left and right side walls of the
`operator cab floor are connected by a connection member of
`a rigid body, the elevation distances in the left and right Sides
`are always equalized to each other. Therefore, Smooth ver
`tical movement can be performed without causing torsion
`between the left and right side walls.
`According to a sixth aspect of the present invention, the
`torsion-prevention means of the cabin has a vertical
`movement-distance-detector means and a comparison cal
`culation circuit for controlling movement amounts of the left
`and right Side plates of the cabin to be equalized to each
`other, based on comparison calculation results thereof.
`According to the Sixth aspect as described above, the
`Vertical movement amounts of the left and right Side plates
`are equalized to each other by controlling the vertical
`movements of the Side plates. In this manner, Smooth
`Vertical movements can be achieved without causing torsion
`between the left and right Side plates.
`In this case, the connecting member is not needed, So that
`the lower Space can therefore be widened.
`The control means may be those for electrically detecting
`and controlling the rotation Speed of a drive motor, control
`means for controlling and Synchronizing expansion amounts
`of hydraulic cylinders used as a drive means, or means for
`detecting and controlling lengths of left and right wires
`wound up or extracted.
`According to a Seventh aspect of the present invention,
`there is provided a cabin-installation Structure for a con
`Struction machine, for installing a box-like cabin of which
`lower Surface is opened, on a body of a construction
`machine having an operator cab floor, comprising: the cabin
`having a lateral-cross-sectional Surface shape Substantially
`Similar to and slightly larger than a plane shape of the
`operator cab floor, an inner Surface positioned outside outer
`Side Surfaces of the operator cab floor and is movable in a
`direction vertical to the operator cab floor, and at least one
`door-installation opening portion on a side Surface of the
`cabin, the door-installation opening portion being continu
`ous in a direction vertical to the operator cab floor So that a
`door installed on the door-installation opening portion can
`be opened and closed; a guide mechanism for moving and
`guiding the cabin in Said vertical direction; and a lock
`mechanism for locking the cabin at an upper position where
`a lower edge of the cabin is positioned at a height Substan
`tially equal to the operation cab floor and at a lower position
`where the lower edge of the cabin projects downwards
`below the operator cab floor.
`According to the Seventh aspect as described above, the
`cabin can be Suspended by a machine Such as a crane having
`a Suspension ability to be moved between its upper and
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`lower positions. At the positions, the cabin can be locked by
`a lock mechanism Such as a pin.
`According to an eighth aspect of the present invention, a
`Side Surface of the cabin has a step-like Shape Such that a
`front portion of a lower edge of the Side Surface forms a
`lower Step and a rear portion of a lower edge of the Side
`Surface forms an upper Step and Such that the door
`installation opening portion is formed at the front portion of
`the Side Surface, and when the cabin is positioned at the
`lower position, the front portion of the lower edge of the Side
`Surface projects downwards below the operator cab floor and
`the rear portion of the lower edge of the Side Surface is
`positioned to be slightly higher than the operator cab floor.
`According to the eighth aspect as described above, when
`the cabin is at the lowermost position, the rear portion of the
`lower edge of the Side Surface of the cabin does not project
`downwards below the operator cab floor. Therefore, the rear
`portion of the Side edge of the Side Surface of the cabin does
`not interfere with rear wheels Such as of a motor grader.
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWING
`FIG. 1 is an exploded perspective View showing a first
`embodiment of the present invention;
`FIG. 2 is a side view of an operator cab floor;
`FIG. 3 is a side view of a cabin;
`FIG. 4 is a side view showing a state in which the cabin
`is installed;
`FIG. 5 is an exploded perspective view showing a Second
`embodiment of the present invention;
`FIG. 6 is an exploded perspective view showing a third
`embodiment of the present invention;
`FIGS. 7A and 7B are exploded perspective views respec
`tively showing an operator cab floor and a cabin according
`to a fourth embodiment of the present invention;
`FIG. 8 is a side view of a lower window-installation
`portion of a cabin;
`FIG. 9 is a croSS-Sectional view taken along a line A-A
`in FIG. 7B;
`FIG. 10 is an exploded perspective view showing a fifth
`embodiment of the present invention;
`FIG. 11 is a plan View explaining the Sealing-member
`installation portion;
`FIG. 12 is a plan view of the operator cab floor;
`FIG. 13 is a perspective view where the cabin is situated
`at an upper position;
`FIG. 14 is a perspective view where the cabin is situated
`at a lower position;
`FIG. 15 is an exploded perspective view showing a sixth
`embodiment of the present invention;
`FIG. 16 is a perspective view where the cabin is situated
`at an upper position;
`FIG. 17 is a perspective view where the cabin is situated
`at a lower position;
`FIG. 18 is an exploded perspective view showing an
`operator cab floor and a cabin according to a Seventh
`embodiment of the present invention;
`FIG. 19 is a block diagram showing an example of a
`control circuit for vertical driving of the seventh embodi
`ment,
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`FIG. 20 is an exploded perspective view showing an
`operator cab floor and a cabin according to a modification of
`the Second embodiment;
`FIG. 21 is an exploded perspective view showing an
`operator cab floor and a cabin according to an eighth
`embodiment of the present invention;
`FIG. 22 is a circuit diagram showing an example of a
`hydraulic circuit adopted in the fourth embodiment; and
`FIG. 23 is a circuit diagram showing another example of
`a hydraulic circuit.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`In the following, preferred embodiments of the present
`invention will be described in detail with reference to the
`appended drawings.
`FIG. 1 shows a motor grader. A frame 2 is installed on a
`body 1 and is oriented forward. Front wheels 3 are equipped
`on the frame 2, and rear wheels 4 are equipped on the body
`1. A draw bar 6 provided with a blade 5 is equipped on the
`frame 2 such that the draw bar 6 can pivotally move in the
`vertical direction by an elevation cylinder 7.
`An operator cab floor 10 is installed on the body 1 at a
`portion toward the front side thereof. The operator cab floor
`10 comprises a floor plate 11 of the body 1, a substantially
`ring-like plate 12 fastened by bolts to a periphery of the floor
`plate 11, a front lower window 13 Standing along a front
`edge of the ring-like plate 12, a rear wall 14 Standing along
`a rear edge of the ring-like plate 12, and left and right walls
`15 Standing respectively at the left and Side edges of the
`ring-like plate 12 in the rear Side thereof. An outer periphery
`of the floor plate 11 projects sidewards over the installation
`portion of the body 1, and the outer periphery of the ring-like
`plate 12 projects sidewards over the floor plate 11.
`The front lower window 13 is a glass window in which a
`glass 17 is fitted in a rectangular frame 16. This window
`helps an operator to watch end portions of the blade 5 and
`the like without difficulty in case of a motor grader.
`A cabin 20 has a substantially box-like shape surrounded
`by a front plate 21, left and right Side plates 22, a rear plate
`23, and a roof 24, and is opened in its lower Side. A lateral
`croSS-Sectional shape or an inner shape of the cabin 20 is
`Similar to and slightly larger than a plane shape of the
`operator cab floor 10.
`A lower portion of the front plate 21 forms an opening
`portion 25, while an upper portion thereof forms a window.
`The opening portion 25 is to be overlapped on the outer sides
`of the front lower window 13 of the operator cab floor 10.
`The rear plate 23 and rear portions 22a of the left and right
`side plates 22 of the cabin 20 are shorter than the front plate
`21 and front portions 22b of the side plates 22. Door
`installation opening portions 26 are formed continuously in
`the vertical direction in the front portions 22b of the side
`plates 22, and doors are attached to the door-installation
`opening portions 26 Such that the doors can be freely opened
`and closed.
`Upper and lower ends of guide rods 27 are installed on the
`cabin 20 through brackets 27a. The guide rods 27 are
`adapted to be engaged with guides 28 Standing on the left
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`and right walls 15. A plurality of gas SpringS 29 are provided
`between the cabin 20 and the operator cab floor 10 for urging
`the cabin 20 upwards. The gas SpringS 29 are elastic urging
`means in the present invention, but normal compression
`Springs can be used in place of the gas Springs.
`A pair of rear guide rollers 30 are fitted by brackets 31 to
`the rear wall 14 respectively at portions toward the left and
`right sides thereof. The rear guide rollers 30 are located so
`as to slightly project over the outer Surface of the rear wall
`14 Such that they can contact with an inner Surface of the rear
`plate 23 of the cabin 20.
`Further, two pairs of front guide rollers 32 are rotatably
`attached to upper and lower portions of the rectangular
`frame 16 of the front lower window 13, each pair being
`attached respectively to left and right Sides of the rectangular
`frame 16. Each of the front guide rollers 32 is located so as
`to project forwardly of the rectangular frame 16 and contact
`each inner Surface of the left and right Sides of the front plate
`21 of the cabin 20.
`Rack gears 33 are respectively attached to the inner
`surfaces of the left and right side plates 22 of the cabin 20.
`The rack gears 33 project downwards below the lower end
`Surfaces of the rear portions 22a of the Side plates 22 and are
`respectively opposed to the inner Surfaces of the left and
`right side walls 15.
`A shaft 34 is rotatably attached between lower portions of
`the left and right side walls 15 of the operator cab floor 10.
`The shaft 34 is equipped at its opposite ends with pinions 35
`which are respectively engaged with the rack gears 33. The
`shaft 34 guarantees smooth vertical movement of the cabin
`20 by mechanically preventing the left and right side walls
`15 from being twisted by torsion due to a difference between
`elevation distances of the left and right rack gears 33 when
`the left and right pinions 35 are driven and rotated so as to
`elevate up and down the rack gears 33.
`In the present invention, if the pinions 35 equipped on
`both ends of the shaft 34 are separated from a drive source
`and are Simply engaged with the left and right rack gears 33,
`the torsion prevention function as described above can be
`performed. In this case, the left and right rack gears 33 are
`engaged with pinions optionally connected to a drive Source.
`According to the present embodiment, a motor 36
`equipped with a decelerator is installed on a lower Surface of
`the ring-like plate 12 of the operator cab floor 10, and a
`pinion 37 is engaged with one of the pinions 35 equipped on
`the shaft 34 through a hole 12a in the plate 12, to rotate and
`drive the shaft 34. This constructs a vertical drive means for
`the cabin 20.
`A front Sealing member 39 is attached on an upper edge
`portion of the rectangular frame 16. The sealing member 39
`is pressed against an inner Surface of an intermediate portion
`21 of the front plate 21.
`Further, a rear Sealing member 39 is attached on an upper
`edge portion of the rear wall 14. The rear sealing member 39
`is pressed against an inner Surface of the rear plate 23.
`Side sealing members 40 are respectively attached on the
`left and right side walls 15 in the rear side. The side sealing
`members 40 are to be respectively pressed against the inner
`Surfaces of the rear portions 22a of the left and right Side
`plates 22.
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`An uppermost position of the cabin 20 raised most is
`illustrated by continuous lines in FIG. 4. In this state, the
`front lower window 13 of the operator cab floor 10 and the
`opening portion 25 of the cabin 20 are fitted on each other,
`and the front Sealing member 39 is arranged So as to be
`pressed into contact with an inner Surface of the intermediate
`portion 21a of the front plate 21. Respective upper edge
`portions of the rear wall 14 and the left and right rear side
`walls 15 of the operator cab floor 10 are overlapped on or
`come into contact with respective lower edge portions of the
`rear plate 23 and the rear portions 22a of the left and right
`side plates 22 of the cabin 20, and the regions thus over
`lapped or contacted are Sealed by a rear Sealing member 39
`and a side Sealing members 40.
`When the motor 36 is driven to rotate the shaft 34 in the
`state described above, the pinions 35 are rotated in one
`direction thereby moving the cabin 20 downwards by the
`rack gears 33 to the lowermost position indicated by dash
`and-dotted lines in FIG. 4, which is the lowermost position
`of the cabin 20. In this manner, the whole height of the cabin
`20 is decreased. Recessed portions (not shown) are formed
`in the operator cab floor 10 so that the rack gears 33 might
`not interfere with the operator cab floor 10.
`When the motor 36 is driven to rotate the shaft 34 and the
`pinions 35 in the opposite direction in the state described
`above, the cabin 20 is moved upwards in a similar manner.
`When the cabin 20 is moved up or down, the cabin 20 is
`guided by the front guide roller 32 and the rear guide roller
`30, the guide rods 27, and the guide 28, so that the cabin 20
`can be Smoothly moved up or down in cooperation with the
`shafts 34.
`Further, Since the cabin 20 is urged upwards by the gas
`springs 29, a heavy body of the cabin 20 can be moved
`upwards by even a Small force. Also, Since a cushioning
`effect is obtained when the cabin 20 is moved downwards,
`impact is small when the cabin 20 reaches a lower limit
`position, and a durability of the cabin 20 and the body 1 can
`be improved.
`FIG. 5 shows a second embodiment of this invention. The
`operator cab floor 10 has a plurality of guide rails 50
`Standing on the ring-like plate 12, while the cabin 20 is
`provided with a plurality of guide columns 51. The guide
`columns 51 are adapted to be engaged with the guide rails
`50 so that the cabin 20 is vertically movable. Rack gears 33
`are provided, which also serve as guide columns. A shaft 34
`is rotatably attached between left and right guide rails 50 to
`be engaged with the rack gears 33, and pinions 35 on the
`shaft 34 are engaged with the rack gears 33. The other
`constructions of this Second embodiment are Substantially
`identical with those of the first embodiment.
`Upper holes 52 and lower holes 53 are formed in the guide
`rails 50 engaged with the rack gears 33. The cabin 20 is fixed
`to a uppermost position by inserting lock pins 54 from the
`upper holes 52 into pin holes not shown, which are formed
`in the guide columns 51. The cabin 20 is fixed to a
`lowermost position by inserting the lock pins 54 from the
`lower holes 53 into the pin holes. A lock mechanism is thus
`constructed.
`If Such a lock mechanism is provided, it is possible to
`hang up the cabin by a crane or the like without providing
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`rack gears and pinion gears, and the cabin can then be locked
`at its upper or lower position.
`FIG. 6 shows a third embodiment in which a standing
`member 60 is fixed to a front edge of the ring-like plate 12
`and a front Sealing member 39 is attached on the Standing
`member 60.
`A front plate 21 of the cabin 20 has a lower window 61
`and an upper window 62 which are Separated by an inter
`mediate portion 21a. A concave portion 63 oriented down
`wards to be engaged with the standing member 60 is formed
`at a lower edge of the lower window 61, such that the front
`sealing member 39 is pressed into contact therewith when
`the cabin 20 is at the uppermost position.
`The side plates 22 and the rear plate 23 of the cabin 20
`have the same length as the front plate 21, So that four
`peripheral edges of the lower end surface of the cabin 20 are
`continuous in one plane.
`In this case, an outer edge portion of the operator cab floor
`10 is positioned higher than the upper surface of the body 1,
`so that the lower peripheral edge portions of the cabin 20 do
`not interfere with the body 1 when moved below the outer
`edge portion of the operator cab floor 10.
`FIGS. 7A and 7B show a fourth embodiment in which a
`lower window 70 is attached on an opening portion 25 of the
`front plate 21 of the cabin 20 such that the lower window 70
`can be moved obliquely forwards and backwards by a link
`mechanism 71. Specifically, as shown in FIG. 8, each one of
`end portions of upper links 72 and lower links 73 is attached
`respectively on left and right longitudinal edges of the lower
`window 70 such that the window 70 can pivotally move up
`and down. The other end portions of the upper links 72 and
`the lower links 73 are respectively attached on upper brack
`ets 74 and lower brackets 75 on the left and right longitu
`dinal edges of the opening portion 25, for pivotal movement.
`Gas springs 76 are provided between the left and right
`longitudinal edge portions of the opening portion 25 and the
`upper links 72.
`Based on Such a structure as described above, the lower
`window 70 can be moved parallel between a closed position
`where the lower window 70 is in contact with the outer
`Surface of the edges of the opening portion 25 to close the
`opening portion 25 and an opened position where the lower
`window 70 is distant from the outer surface of the edges of
`the opening portion 25 and is above the closed position.
`The lower edge of the lower window 70 at the closed
`position is arranged to be brought into contact with an upper
`surface of an front end portion of the floor plate 11 when the
`cabin 20 is at its uppermost position. When the cabin 20 is
`moved downwards, the lower window 70 is set at the opened
`position so that the window 70 is positioned forward of the
`front end portion of the floor plate 11 thereby to avoid
`interference.
`As shown in FIG. 7A, the operator cab floor 10 comprises
`a floor plate 11, a rear wall 14 Standing along a rear edge of
`the floor plate 11, and left and right side walls 15 standing
`from the left and right side edges of the floor plate 11 in the
`rear side thereof. Expansion cylinders 77 are respectively
`provided at the left and right side edges of the floor plate 11
`in the front side thereof, and at a laterally-middle portion of
`the floor plate 11 in the rear side thereof.
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`Guides 78 are respectively fixed to middle portions and
`rear end portions of the left and right Side edges of the floor
`plate 11, while guide members 79 are respectively attached
`at corresponding middle portions and rear end portions of
`the inner surfaces of the left and right sides of the cabin 20,
`as shown in FIG. 9. The guide members 79 are engaged with
`the guides 78 so as to be movable vertically along the guides
`78.
`In case of the present embodiment, the expansion cylin
`ders 77 expand and contract to move the cabin 20 vertically.
`However, the cabin 20 may be moved vertically by using
`pinions and rack gears as described in the previous embodi
`mentS.
`Now, a fi