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BACKGROUND OF THE INVENTION  
       [0001]     1. Field of The Invention  
         [0002]     This invention relates to a backhoe having a ground working implement connected to the front of a swivel deck.  
         [0003]     2. Description of the Related Art  
         [0004]     In this type of conventional technique, a support frame bifurcated in plan view has a right and left longitudinal ribs and a front swing bearing member on the swivel slide. The swing bearing member of the support frame supports the ground working implement through a swing shaft. A hydraulic oil tank and a fuel tank are arranged at the right-hand side on the swivel slide, and a swing cylinder for swinging the ground working implement is disposed below these tanks. An engine and a counter weight are arranged on a rear portion of the swivel deck (see Japanese Unexamined Patent Publication No. 2005-232795, for example).  
         [0005]     In the above conventional technique, the forward ends of the right and left longitudinal ribs are welded to right and left rear positions of the swing bearing member. The welds are short, and stress tends to concentrate on the welds. The right and left longitudinal ribs are not connected to each other, and it is therefore difficult to improve their mounting strength.  
       SUMMARY OF THE INVENTION  
       [0006]     This invention intends to provide a backhoe that overcomes the disadvantages of the prior art noted above.  
         [0007]     An object of this invention, therefore, is to provide a backhoe with improved mutual assembly strength between a swing bearing member and right and left longitudinal ribs, and with a reduced stress concentration occurring at welds.  
         [0008]     The above object is fulfilled, according to this invention, by a backhoe comprising:  
         [0009]     a swivel deck;  
         [0010]     a first longitudinal rib disposed on the swivel deck, the first longitudinal rib extending in a fore and aft direction, and having a front portion extending in a transverse direction;  
         [0011]     a second longitudinal rib disposed on the swivel deck, the second longitudinal rib extending in the fore and aft direction, and having a front end thereof connected to the front portion of the first longitudinal rib; and  
         [0012]     a swing bearing member attached to a front surface of the front portion of the first longitudinal rib for supporting a ground working implement through a swing shaft.  
         [0013]     This construction realizes an improvement in mutual assembly strength between the front portion of the first longitudinal rib, the front portion of the second longitudinal rib and the swing bearing member. Welds between these parts are subjected to a reduced stress concentration.  
         [0014]     The first longitudinal rib may include an inclined portion extending rearward and outward from the front portion, and a rear portion extending from a rear end of the inclined portion transversely away from the second longitudinal rib.  
         [0015]     Then, the first longitudinal rib forms an approximately S-shape in plan view. This shape can distribute stress applied thereto, and can improve strength in the transverse direction of the swivel deck.  
         [0016]     The second longitudinal rib may extend from front to rear of the swivel deck, and support an engine.  
         [0017]     Then, the second longitudinal rib can be used not only for supporting a swing cylinder on the swivel deck, but also for mounting structures such as the engine.  
         [0018]     Preferably, the backhoe further comprises a rear longitudinal rib extending rearward from the backward portion, and a connecting member for connecting a rear end of the second longitudinal rib and a rear end of the rear longitudinal rib.  
         [0019]     This construction allows the two longitudinal ribs to reinforce each other, and distribute stress between each other.  
         [0020]     According to this invention, an improvement is realized in mutual assembly strength between the front portion of the first longitudinal rib, the front portion of the second longitudinal rib and the swing bearing member, and welds between these parts are subjected to a reduced stress concentration. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a side elevation of a backhoe according to this invention;  
         [0022]      FIG. 2  is a perspective view of the backhoe seen from a right forward direction;  
         [0023]      FIG. 3  is a perspective view of the backhoe seen from a left rearward direction;  
         [0024]      FIG. 4  is a side view of an upper structure;  
         [0025]      FIG. 5  is a front view of the upper structure;  
         [0026]      FIG. 6  is a plan view of an interior of the upper structure;  
         [0027]      FIG. 7  is a perspective view of the interior of the upper structure;  
         [0028]      FIG. 8  is a plan view of a swivel deck;  
         [0029]      FIG. 9  is a perspective view of the swivel deck;  
         [0030]      FIG. 10  is a side view of the swivel deck;  
         [0031]      FIG. 11  is a schematic plan view of the upper structure.  
         [0032]      FIG. 12  is a plan view of a platform;  
         [0033]      FIG. 13  is a front view, partly in section, of the upper structure; and  
         [0034]      FIG. 14  is an enlarged sectional view of a portion between an engine room and a cab apparatus.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0035]     An embodiment of this invention will be described hereinafter with reference to the drawings.  
         [0036]     In  FIGS. 1-14 , a backhoe  1  of the rear small revolution type (swivel type working vehicle), includes a traveling device  2  disposed below, an upper structure  3  disposed above, a dozer apparatus  4  attached to the front of the traveling device  2 , and a ground working implement  5  attached to the upper structure  3 .  
         [0037]     The traveling device  2  has crawler traveling means  7  arranged at right and left side of a track frame  6  to be driven by hydraulic motors. The track frame  6  supports thereon a swivel deck  10  which is a base of the upper structure  3 , to be swivelable through a swivel bearing  11  about a swivel center (vertical axis) X. The swivel deck  10  is driven by a swivel motor  8  mounted thereon. The dozer apparatus  4  has a blade vertically movable in front of the track frame  6 .  
         [0038]     The track frame  6  has a swivel joint  12  disposed centrally of the swivel bearing  11 . The swivel joint  12  projects into the swivel deck  10 .  
         [0039]     The track frame  6  has the swivel bearing  11  disposed on an upper surface of a top plate thereof for swivelably supporting the swivel deck  10 , and a swivel gear disposed in an inner peripheral position of the swivel bearing  11 . A mounting member is attached to a lower surface of the top plate. An attachment part of the swivel joint  12  is fixed to a lower surface of the mounting member. The swivel joint  12  is disposed centrally of a center opening of the top plate.  
         [0040]     Referring to  FIGS. 2-7 , the upper structure  3  includes, arranged on the swivel deck  10  and with reference to the swivel center X where the swivel joint  12  is located, an engine  15  at one side (right-hand side), a platform  16  at the other side (left-hand side), and a hydraulic oil tank  17  and a fuel tank  18  at the rear. A driver&#39;s seat  26  on the platform  16  is disposed adjacent the center of the swivel deck  10  and above the hydraulic oil tank  17  and fuel tank  18 .  
         [0041]     The platform  16  may have, mounted thereon, a rollover protection structure of the four strut type or two strut type, or a cab body  27 A forming a cab apparatus  27 .  
         [0042]     On the swivel deck  10  a support frame  21  bifurcated in plan view is provided, which includes right and left longitudinal ribs  19 R and  19 L and a swing bearing member  20  at the front. The ground working implement  5  is supported by the swing bearing member  20  of the support frame  21  through a swing shaft  22 . A swing cylinder  23  is disposed at the left-hand side on the swivel deck  10  for swinging the ground working implement  5 .  
         [0043]     The swing shaft  22  is displaced to one side (right-hand side) from the swivel center X. The center of the driver&#39;s seat  26  is displaced to the other side (left-hand side) for enabling the driver to observe operating states of the ground working implement  5 .  
         [0044]     The engine  15  is disposed on the swivel deck  10  further rightward than the longitudinal rib  19 R at the right-hand side, with a crankshaft  15 A extending in the fore and aft direction. A radiator  57  and an oil cooler  58  are arranged forwardly of the engine  15 , and a hydraulic pump  59  rearwardly of the engine  15 .  
         [0045]     As shown in detail in  FIGS. 6-10 , the support frame  21  has the right longitudinal rib  19 R (corresponding to the second longitudinal rib of this invention) extending substantially in the fore and aft direction and substantially parallel to the engine  15 . The left longitudinal rib  19 L (corresponding to the first longitudinal rib of this invention) has a front portion  19 La extending in a right and left direction and connected to the front of the right longitudinal rib  19 R. The swing bearing member  20  is attached to the front portion  19 La.  
         [0046]     The front portion  19 La has a front surface of substantially the same vertical dimension as a rear surface of the swing bearing member  20 , and slightly longer in the right and left direction than the rear surface. Parts thereof protruding right and left serve as welds to the swing bearing member  20 . The lower surface of the front portion  19 La is welded to the swivel deck  10 . The upper surface of the front portion  19 La defines a mounting surface in combination with an upper rear part of the swing bearing member  20  for supporting the platform  16  through a cushion material  76 .  
         [0047]     The left longitudinal rib  19 L includes the front portion  19 La, an inclined portion  19 Lb extending rearward and outward from the front portion  19 La, a rear portion  19 Lc extending leftward from the rear end of the inclined portion  19 Lb and supporting the swing cylinder  23 , and a tail portion  19 Ld bent rearward from rear portion  19 Lc. The rear portion  19 Lc also extends in the right and left direction and substantially parallel to the front portion  19 La.  
         [0048]     A connecting part between the forward portion l 9 La and right longitudinal rib  19 R is reinforced with a coupling member  86 . A coupling member similar to the coupling member  86  may be provided for a bend between the front portion  19 La and inclined portion  19 Lb.  
         [0049]     A pair of upper and lower brackets  23  are formed on a front surface of the rear portion  19 Lc for pivotally supporting a proximal portion of the swing cylinder  23  through a pin. The upper bracket  23   a  is welded also to the inclined portion  19 Lb to reinforce the bend between the inclined portion  19 Lb and rear portion  19 Lc.  
         [0050]     A rear longitudinal rib  24  extends from the rear portion  19 Lc of left longitudinal rib  19 L to the rear of the swivel deck  10 . The rear longitudinal rib  24  is connected to the rear end of the right longitudinal rib  19 R by a connecting member  25 . The support frame  21 , including the rear longitudinal rib  24  and connecting member  25 , has a closed frame configuration approximately in the shape of a trapezoid. This support frame  21  is strong particularly against loads acting in the fore and aft direction.  
         [0051]     The left longitudinal rib  19 L curved to form an approximately S-shape in plan view has high strength for attaching to the swivel deck  10 , serves to increase strength in the right and left direction of the swivel deck  10 , and also increases mounting strength of the rear longitudinal rib  24  and connecting member  25 .  
         [0052]     The right longitudinal rib  19 R adjacent the engine  15  extends from front to rear of the swivel deck  10  to serve as a lower partition of an engine room  14  and define a space for arranging the engine room  14 , hydraulic oil tank  17  and fuel tank  18 . A longitudinal frame  61  of the engine room  14  extends upward from the right longitudinal rib  19 R.  
         [0053]     Mounting members l 9 Ra and l 9 Rb are provided in forward and rearward positions of the right longitudinal rib  19 R. The engine  15  is mounted on the mounting members l 9 Ra and l 9 Rb and forward and rearward mounting bases  63  arranged at the right end of the swivel deck  10 . An accessory frame  65  extends between the mounting members l 9 Ra and l 9 Rb and mounting bases  63 , straddling the engine  15 , for supporting engine accessories such as an air cleaner. The engine  15  is mounted using the right longitudinal rib  19 R, and is connected to the right longitudinal rib  19 R, thereby reinforcing the right longitudinal rib  19 R. The accessory frame  65  also reinforces the right longitudinal rib  19 R.  
         [0054]     Referring to  FIGS. 2, 7 ,  13  and  14 , the longitudinal frame  61  has a square frame  61 A, a front partition plate  61 B, a rear partition plate (not shown) and a cover frame  66  arranged between the engine room  14  and platform  16  (or cab apparatus  27 ), and is fixed to the accessory frame  65  and right longitudinal rib  19 R.  
         [0055]     The square frame  61 A is formed of an angle pipe looped into a square to serve as a reinforcing member. The front partition plate  61 B is disposed at the front of the square frame  61 A to cover the left-hand plane of the engine room  14 . The rear partition plate is disposed at the rear of the square frame  61 A to form a tank arranging space, and serve as a member for supporting an oil filter  88 . The front partition plate  61 B and rear partition plate are fixed to the right longitudinal rib  19 R.  
         [0056]     The cover frame  66  covers upper edges of the square frame  61 A and front partition plate  61 B, and has a cover portion  66 A covering an upper surface and a right-hand side surface of the radiator  57 .  
         [0057]     The front partition plate  61 B may extend to the rear partition plate to cover the entire surface of the square frame  61 A, i.e. to cover the entire left-hand side plane of the engine room  14 .  
         [0058]     The accessory frame  65  has a band plate between the square frame  61 A and the right end of the swivel deck  10 , and a band plate between the square frame  61 A and right longitudinal rib  19 R, and is located an intermediate position in the fore and aft direction of the engine room  14 .  
         [0059]     The longitudinal frame  61  and/or accessory frame  65  pivotally support a hood  35  covering the engine room  14 , to be openable about an axis extending in the fore and aft direction. When the cab apparatus  27  is mounted, an upper part of the side wall adjacent the engine of the cab apparatus  27  is disposed to overlap the top of the longitudinal frame  61 .  
         [0060]     Referring to  FIGS. 4, 6  and  7 , a mounting frame  30  is provided to extend between the rear longitudinal rib  24  and a rear portion of the right longitudinal rib  19 R (or the rear partition plate), straddling the hydraulic oil tank  17  and fuel tank  18 . The mounting frame  30  reinforces the rear portion of the support frame  21 , and supports a control valve  13 .  
         [0061]     The hydraulic oil tank  17  and fuel tank  18  are elongated vertically and in the fore and aft direction to have necessary and sufficient capacities. These tanks  17  and  18  are arranged in the right and left direction together with an air-conditioner  31  also elongated vertically and in the fore and aft direction.  
         [0062]     The hydraulic oil tank  17  is formed of sheet metal, and fixed to the upper surface of the swivel deck  10 . The fuel tank  18  is formed of a synthetic resin, and attached to the hydraulic oil tank  17  with a fork clip  18 A. It is also possible to form the hydraulic oil tank  17  with a synthetic resin, and the fuel tank  18  with sheet metal. The fuel tank  18  may be fixed to the swivel deck  10  independently of the hydraulic oil tank  17 .  
         [0063]     The fuel tank  18  is disposed in the a middle position little influenced by a sideways tilt, so that the fuel may be fetched even when the fuel decreases in quantity and the swivel deck  10  inclines right and left.  
         [0064]     A counter weight  73  is mounted at rear of swivel deck  10  and connecting member  25 . A battery  74  is mounted at the left side of the swivel deck  10 . The counter weight  73  has an opening  73 A in an upper middle position for exposing a filling hole  18 B of the fuel tank  18 . A door  39  is provided to open and close this opening  73 A.  
         [0065]     The platform  16  extends from above the swing cylinder  23  and battery  74  on the swivel deck  10  to above the hydraulic oil tank  17 , fuel tank  18  and counter weight  73 . The platform  16  has a front portion thereof detachably attached through cushion material  76  to supporting legs  75  and swing bearing member  20  at the front of the swivel deck  10 , and a rear portion to the counter weight  73  (or mounting frame  30 ).  
         [0066]     Referring to  FIGS. 4, 5 ,  12  and  13 , the platform  16  is formed of sheet metal or synthetic resin as a unit. The platform  16  has a step portion  16 A defining a step surface above the swing cylinder  23  and battery  74 , a vertical portion  16 B extending upward from the rear end of the step portion  16 A and located forwardly of the hydraulic oil tank  17  and fuel tank  18 , a mounting portion extending from the upper end of the vertical portion  16 B above the hydraulic oil tank  17  and fuel tank  18  and defining a driver&#39;s seat mounting surface, a rear connecting portion  16 D from the rear end of the mounting portion  16 C rearward and upward above the counter weight  73 , and a side wall  16 E extending upward from side edges adjacent the engine of these step portion  16 A, vertical portion  16 B, mounting portion  16 C and rear connecting portion  16 D.  
         [0067]     A driver&#39;s seat mounting base  42  is supported through a suspension  41  on the mounting portion  16 C of the platform  16 . The driver&#39;s seat  26  and a control device  29  are arranged on the driver&#39;s seat mounting base  42 . When the driver&#39;s seat  26  is rocked a great deal up and down, the control device  29  is rocked with the driver&#39;s seat  26 . The mounting portion  16 C is disposed below the top of the engine  15 , and at least an upper part of the engine room  14 . The mounting portion  16 C disposed at a low level allows use of the suspension  41  even if the driver&#39;s seat  26  is at the same height as in the prior art.  
         [0068]     Thus, the driver&#39;s seat  26  is disposed at a proper height and in a proper fore and aft position without being obstructed by the engine which is the bulkiest object on the swivel deck  10 , and by the hydraulic oil tank  17  and fuel tank  18 . The hydraulic oil tank  17 , fuel tank  18  and air-conditioner  31  below the driver&#39;s seat  26  are similar in shape as noted hereinbefore, which is used to arrange these components compactly on the swivel deck  10 .  
         [0069]     The platform  16  has also travel controls  28  arranged thereon, and can serve as a bottom plate of the cab apparatus  27 . The cab apparatus  27  has a cab main body  27 A mounted on the platform  16  and enclosing the driver&#39;s seat  26 , controls  28  and control device  29 .  
         [0070]     Referring to  FIGS. 1-3  and  11 - 14 , the cab main body  27 A is formed of a front portion  27   a  having a windshield, a rear portion  27   b  having a glass window, an upper side wall  27   c  having a side window adjacent the engine, and a left side portion having a ceiling  27   d  and a door  67 . A lower right side of the cab main body  27 A is formed of the side wall  16 E of the platform  16 . The side wall  16 E can also serve as a side wall of engine room  14 .  
         [0071]     The upper side wall  27   c  overhangs the longitudinal frame  61  and an elastic seal element  69  is disposed therebetween. Thus, rain water does not enter the cab apparatus  27  even when the cab apparatus  27  vibrates vertically relative to the swivel deck  10 .  
         [0072]     The controls  28  on the platform  16  include propelling control means  43  of the pedal-lever interlock type disposed forwardly of the driver&#39;s seat  26 , swing cylinder control means  44  operable by the right foot, a foot-operated change switch  45  operable one of the right and left feet to switch between two, high and low speeds of the traveling device  2 , and a hand-operated change switch  46  arranged at the same side as the foot-operated change switch  45  and operable by hand.  
         [0073]     The foot-operated change switch  45  for switching between two, high and low speeds of the traveling device  2 , and hand-operated change switch  46 , are arranged in positions operable by the right foot and right hand of the driver seated on the driver&#39;s seat  26 .  
         [0074]     A foot pedal  77  is disposed in a left forward position on the platform  16  to be operable by the left foot for supplying hydraulic fluid to hydraulic equipment associated with the ground working implement  5 .  
         [0075]     The control device  29  has two grip type work control means  43 R and  43 L arranged at the right and left sides of the driver&#39;s seat  26 , with two grips  32  sharing a plurality of operations of the ground working implement  5 . The driver can swing the left grip type work control means  43 L upwards in time of boarding or alighting.  
         [0076]     Each of the grips  32 R and  32 L of the two grip type work control means  43 R and  43 L has a pilot valve assigned thereto for pilot operation of the hydraulic equipment constituting the ground working implement  5 , such as the motor  8 , a boom cylinder  52 , an arm cylinder  54  and a working tool cylinder  56 . Each grip has also, assigned thereto, a switch for supplying hydraulic fluid to other hydraulic equipment, if any, constituting the ground working implement  5 , and/or hydraulic equipment such as a breaker, if any, associated with the ground working implements  5 .  
         [0077]     The right (i.e. one) grip  32 R, for example, has a volume switch  80  and a horn switch  83  for supplying hydraulic fluid to the hydraulic equipment associated with the ground working implement  5 . The left (i.e. the other) grip  32 L has a control switch  81  and a change switch  82  for selectively operating the two types of hydraulic equipment.  
         [0078]     When the ground working implement  5  includes a boom  51  having two members for flexion, the control switch  81  may be a two-piece switch for supplying hydraulic fluid to a flexion cylinder for flexing the second boom relative to the first boom. When the hydraulic equipment associated with the ground working implement  5  has two hydraulic drivers, the control switch  81  may be a second implement switch for supplying hydraulic fluid to the second hydraulic driver. When the two types of hydraulic equipment are used, only one control switch  81  may be provided, and the change switch  82  may be operated for selectively using the two types of hydraulic equipment. The change switch  82  may be adapted to turn the control switch  81  on and off.  
         [0079]     Numeral  85  denotes a monitor disposed in an upper right position of the platform  16  for displays running and working states. The monitor  85  is attached to the side wall  16 E (or on a strut erected on the step  16 A).  
         [0080]     Referring to  FIGS. 2, 3 ,  5  and  11 , the upper structure  3  has, provided to be openable and closable, the hood  35  for covering the upper plane and outer plane of the engine room  14 , a front cover  36  for covering the front plane of the engine room  14  at the front of the cover portion  66 A, and a lower side cover  37  for covering the space where the swing cylinder  23  and battery  74  are arranged, in a position between the swivel deck  10  and the front of the platform  16 . The swivel deck  10  has outer edges protruding laterally outward to minimize the chance of the hood  35 ; front cover  36  and lower side cover  37  contacting obstacles.  
         [0081]     A pivotal support pivotally supporting the upper end of the hood  35  It has an axis extending in the fore and aft direction. A pivotal support pivotally supporting the lower end of the front cover  36  has an axis extending horizontally (or vertically). A pivotal support pivotally supporting the front end of the lower side cover  37  has an axis extending vertically.  
         [0082]     The control valve  13  is disposed between the swivel deck  10  and the rear of the platform  16  and laterally outwardly of the hydraulic oil tank  17 . The control valve  13  is covered by an openable rear side cover  38 . A pivotal support pivotally supporting the rear end of the rear side cover  38  has an axis extending vertically. The rear side cover  38  may have a pivotal support in a lower front position thereof to be openable about a transverse axis.  
         [0083]     The control valve  13  is mounted in a rear side position of the swivel deck  10  adjacent the oil tank  17  through the mounting frame  30 . A relay junction  70  is mounted in a position of the platform  16  adjacent the control valve  13 .  
         [0084]     The relay junction  70  has a hose connected thereto and communicating with the controls  28  and control device  29  on the platform  16 . These are attached to the swivel deck  10  after being assembled, and the relay junction  70  and control valve  13  are connected to each other through the hose. Thus, piping of the swivel deck  10  and piping of the platform  16  made into assemblies, respectively, to be connected easily.  
         [0085]     Referring to  FIG. 1 , the ground working implement  5  includes a swing bracket  50  pivotally supported by swing bearing member  20  of the support frame  21  to be swingable through a swing shaft  22 , the boom  51  connected to the swing bracket  50  to be vertically movable by the boom cylinder  52 , an arm  53  connected to the boom  51  to be pivotable about a transverse axis by the arm cylinder  54 , and a working tool (bucket)  55  connected to the arm  53  and driven by the working tool cylinder  56  to perform scoop operations. The boom  51  may be a two-piece boom having two flexible members. The arm  53  or working tool  55  may have, associated therewith, one or two hydraulic devices having one or two hydraulic drivers.  
         [0086]     According to this invention, the shape of each member in the described embodiment and the positional relationship in the fore and aft, right and left, and vertical directions are optimal when arranged as shown in  FIGS. 1-14 . However, their arrangement is not limited to the above embodiment. The members and constructions may be modified in various ways, or the combinations may be changed.  
         [0087]     For example, the radiator  57  may be disposed rearwardly of the engine  15 , and the hydraulic pump  59  forwardly of the engine  15 . It is possible to reverse the right and left arrangement of the engine  15 , platform  16  and cab apparatus  27  on the swivel deck  10 , and the right and left configuration of the support frame  21 .  
         [0088]     Instead of the cab main body  27 A, a driver&#39;s seat protection frame of the two strut type may be erected on the rear of the platform  16  rearwardly of the driver&#39;s seat  26 . A driver&#39;s seat protection frame of the four strut type may be erected, which has rear struts at the rear of the platform  16 , front struts at the front of the swivel deck  10 , and a shading roof.

Summary:
An improvement is realized in mutual assembly strength between a swing bearing member and right and left longitudinal ribs, and welds are subjected to a reduced stress concentration. A backhoe comprises a swivel deck ( 10 ); a first longitudinal rib ( 19 L) disposed on the swivel deck, the first longitudinal rib extending in a fore and aft direction, and having a front portion ( 19 La) extending in a transverse direction; a second longitudinal rib ( 19 R) disposed on said swivel deck, the second longitudinal rib extending in the fore and aft direction, and having a front end thereof connected to the front portion of the first longitudinal rib; and a swing bearing member ( 20 ) attached to a front surface of the front portion of the first longitudinal rib for supporting a ground working implement through a swing shaft.