JP4913541B2 - Work vehicle with cabin - Google Patents

Description

  The present invention relates to a cabin-equipped work vehicle on which a cabin such as a tractor used for agricultural work or a wheel loader used for civil engineering work is mounted. More specifically, the present invention relates to a cabin having a control seat for operator sitting and a control handle. The present invention relates to a work vehicle with a cabin that is movably supported.

In a work vehicle such as a tractor or wheel loader, an opening / closing fulcrum shaft is arranged at the rear of the bonnet for covering the engine in order to improve the efficiency of maintenance work of the engine arranged at the front of the traveling machine body. The upper surface of the engine was opened by rotating the hood and lifting the front part of the hood upward (see Patent Document 1). Also, a cabin support body is arranged on the traveling machine body in the front part of the cabin, and the cabin is rotated forward around the cabin support body, so that the upper side of the hydraulic elevating mechanism and the transmission case arranged below the rear part of the cabin Is also known (see Patent Document 2).
JP 2003-237634 A Japanese Patent Application Laid-Open No. 60-50079

  By the way, in a work vehicle such as a tractor, the rear part of the bonnet is arranged close to the front surface of the cabin. Therefore, as in Patent Document 1, by rotating the bonnet around the opening / closing fulcrum shaft at the rear part of the bonnet, the front part and the upper surface side of the engine are largely opened, and the engine maintenance work space can be easily secured. However, as in Patent Document 2, the cabin or bonnet cannot be easily configured with the structure in which the cabin is rotated forward. For example, it is necessary to configure the cabin or bonnet so that the cabin can be rotated forward so that the cabin does not interfere with the bonnet, or to configure the cabin to rotate forward after the hood is removed. That is, since the forward rotation of the cabin is limited by the bonnet and the opening / closing fulcrum shaft, there is a problem that the rear portion of the cabin cannot be easily lifted upward. In the structure where the open / close fulcrum shaft is arranged on the front side of the bonnet and the rear part of the bonnet is lifted upward, even if the cabin is rotated forward, the cabin does not interfere with the bonnet, but the rear part of the bonnet and the cabin There is a problem that a maintenance work space formed between the front part and the front part becomes narrow.

  An object of the present invention is to rotate the cab around the opening / closing fulcrum shaft at the rear part of the bonnet so that the front side and the upper side of the engine can be opened widely, It is an object of the present invention to provide a work vehicle with a cabin that can easily lift the rear part upward.

To achieve the above object, cabin with working vehicle of the invention according to claim 1, a traveling machine body equipped with the engine, the hood covering the engine, and a cabin with a control seat and steering handle for operator Zajo The bonnet is connected to the traveling machine body via an opening / closing fulcrum shaft, the bonnet is rotated around the opening / closing fulcrum shaft, and the front portion of the bonnet is configured to be movable upward, In a work vehicle with a cabin, wherein a cabin support is disposed on a lower end side of a front portion of a cabin, and the cabin is rotated around the cabin support so that a rear portion of the cabin can be moved upward. The opening / closing fulcrum shaft is disposed on a traveling machine body so as to be movable in the front-rear direction, and the opening / closing fulcrum shaft is moved forward so that the rear of the bonnet with respect to the front surface of the cabin. The is obtained by separating configured to be able to forward.

  According to a second aspect of the present invention, in the work vehicle with a cabin according to the first aspect, an engine support frame that supports a rear portion of the engine on the traveling machine body, and a pivotable connection in the front-rear direction to the engine support frame. A bonnet support that supports the bonnet support in an initial position, and the bonnet support is supported in the initial position via the lock mechanism by an operation of returning the bonnet to the initial position. It is configured.

  According to a third aspect of the present invention, in the work vehicle with a cabin according to the first aspect, a front grille covering a front side of the engine is disposed at a front portion of the bonnet, and the bonnet support body is set to an initial position. It is equipped with a return spring that presses in the returning direction.

According to the invention of claim 1, a traveling machine body equipped with the engine, the hood covering the engine, and a cabin with a control seat and steering handle for operator Zajo, the opening and closing fulcrum shaft to the traveling machine body The bonnet is connected to the rear portion of the hood, and the bonnet is rotated about the opening / closing fulcrum shaft so that the front portion of the bonnet can be moved upward, while the cabin is supported on the lower end side of the front portion of the cabin. In a working vehicle with a cabin configured to dispose a body and rotate the cabin around the cabin support so that the rear portion of the cabin can move upward, the opening / closing fulcrum shaft is moved in the front-rear direction The bonnet shaft is moved forward, and the rear end of the bonnet can be moved forward with respect to the front surface of the cabin. Et al., Wherein the rear the hood to the opening and closing fulcrum axis of the hood to pivot, can be opened larger front and upper side of the engine. Further, by moving the hood forward, even if the cabin is rotated forward, the cabin can be prevented from interfering with the bonnet, and the rear portion of the cabin can be easily lifted upward. . That is, by rotating the bonnet around the opening / closing fulcrum shaft at the rear part of the bonnet, the front part and the upper surface side of the engine are largely opened, and a maintenance work space for the engine can be easily secured. Further, by rotating the cabin forward around the cabin support body, the upper side of the hydraulic lifting mechanism and the transmission case disposed below the rear part of the cabin is largely opened, and the hydraulic lifting mechanism and the transmission case are opened. Maintenance work space such as can be easily secured. Therefore, maintenance workability of the engine or the hydraulic lifting mechanism can be easily improved.

  According to invention of Claim 2, the engine support frame which supports the rear part of the said engine to the said traveling body, the bonnet support body connected to the said engine support frame so that rotation in the front-back direction is possible, and the said bonnet support body The bonnet support is supported at the initial position via the lock mechanism by the operation of returning the bonnet to the initial position. Using the support frame, the opening / closing fulcrum shaft movable in the front-rear direction can be supported with high rigidity via the bonnet support having a simple structure. Further, when the bonnet is moved to the closed position for covering the engine, the bonnet support is locked to the initial position by the lock mechanism without special operation of the lock mechanism by an operator. That is, when the bonnet support is moved back to the initial position by the operation of returning the bonnet moved forward, the bonnet support is locked to the initial position by the lock mechanism in conjunction with it. It is possible to prevent the bonnet from being closed when the operator forgets to lock the bonnet support. Therefore, the opening / closing operability of the bonnet can be improved.

  According to a third aspect of the present invention, a front grill that covers the front side of the engine is disposed at a front portion of the bonnet, and a return spring that elastically presses the bonnet support in a direction to return to the initial position. Therefore, the front part of the bonnet and the front grille can be lifted together, and the front of the engine can be opened widely, and maintenance work for engine-equipped parts such as a battery or a radiator disposed on the front side of the engine Can be improved easily. Further, since the backward spring force acts in the direction of moving the bonnet backward, when maintenance work is finished, an operator grasps the front grill on the front side of the traveling machine body and pushes the bonnet backward. However, the pushing operation force of the operator is reduced by the return spring force. That is, the deformation force of the front grille generated by the operator's pushing operation can be reduced. An operator can easily close the bonnet by grasping the front grill.

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings (FIGS. 1 to 21). FIG. 1 is a side view of a farm tractor, FIG. 2 is a perspective view of the tractor as viewed obliquely from the rear, FIG. 3 is a side view of the traveling machine, FIG. 4 is a plan view of the traveling machine, and FIG. 6 is a skeleton diagram of power transmission, FIG. 7 is a hydraulic circuit diagram of a continuously variable transmission, FIG. 8 is a plan view showing a cabin portion of a tractor, and FIG. 9 is an enlarged plan view of FIG.

  As shown in FIGS. 1 and 2, a tractor 1 as a work vehicle with a cabin supports a traveling machine body 2 with a pair of left and right rear wheels 4 as well as a pair of left and right front wheels 3. By driving the rear wheel 4 and the front wheel 3 with the mounted engine 5, the vehicle is configured to travel forward and backward. In this case, a pair of left and right traveling units is configured by a set of front and rear wheels 3 and 4 positioned on the left side in the traveling direction of the traveling machine body 2 and a set of front and rear wheels 3 and 4 positioned on the right side in the traveling direction.

  The engine 5 is covered with a bonnet 6. A cabin 7 is installed on the upper surface of the traveling machine body 2, and a steering seat 8 on which an operator is seated and a steering column 234 positioned in front of the steering seat 8 are mounted in the cabin 7. Yes. A steering handle 9 (round handle) as steering means is provided on the top of the steering column 234. When the operator seated on the control seat 8 rotates the control handle 9, the steering angle (steering angle) of the left and right front wheels 3 changes according to the operation amount (rotation amount). A pair of left and right steps 10 for an operator to get on and off are provided on the left and right outer portions of the cabin 7. Fuel for supplying fuel to the engine 5 on the inner side of the step 10 and below the bottom of the cabin 7. A tank 11 is provided.

  The traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a front axle case 13, and left and right machine body frames 16 that are detachably fixed to the rear portion of the engine frame 14 with bolts 15. A transmission case 17 is connected to the rear part of the machine body frame 16 for transmitting the output from the engine 5 to the rear wheel 4 (front wheel 3) by appropriately shifting the output. In this case, the rear wheel 4 is attached to the transmission case 17 so as to protrude outward from the outer surface of the transmission case 17 and to the outer end of the rear axle case 18. The final gear case 19 is attached.

  A hydraulic working machine lifting mechanism 20 for lifting and lowering a working machine (not shown) such as a tillage machine is detachably attached to the upper surface of the rear portion of the mission case 17. A working machine such as a field cultivator is connected to the rear portion of the mission case 17 via a lower link 21 and a top link 22 so as to be movable up and down. In other words, the lift arm 115 is disposed on the working machine lifting mechanism 20. The lower link 21 is connected to the lift arm 115 via the lift rod 116. Further, a PTO shaft 23 for driving the working machine is provided on the rear side surface of the mission case 17.

  Next, with reference to FIGS. 3, 4, 11, and 12, the rear structure of the traveling aircraft 2 that connects the aircraft frame 16 and the transmission case 17 will be described. Upper and lower connecting boss portions 139 are integrally formed at the rear end portions of the left and right body frames 16 made of iron plate. As shown in FIGS. 11 and 12, the connecting boss portion 139 is fitted on the cylindrical frame pin 140. A pin fastening member 141 is fitted on one end side of the frame pin 140 (see FIG. 12). The frame pin 140 and the pin fastening member 141 are fixed by welding. The fuselage frame 16 is attached to the side surface of the transmission case 17 via one fastening bolt 142 that penetrates the inner hole of the frame pin 140 and two fixing bolts 143 that penetrate the attachment hole of the pin fastening member 141. It is done.

  As shown in FIG. 12, a fixing bolt 143 is screwed onto the side surface of the mission case 17 via a spacer 144. A cylindrical spacer 144 is fitted on the fixing bolt 143 between the side surface of the mission case 17 and the pin fastening member 141. A pin fastening member 141 is fixed to the side surface of the mission case 17 via a fixing bolt 143. Therefore, the body frame 16 is separated from the side surface of the mission case 17 by removing the fastening bolt 142 and the fixing bolt 143 and detaching the pin fastening member 141 from the side surface of the mission case 17.

  FIG. 5 shows a hydraulic circuit 200 of the tractor 1 in this embodiment. The hydraulic circuit 200 of the tractor 1 includes a hydraulic pump 94 for a working machine (elevating mechanism 20) that is operated by the rotational force of the engine 5, and a traveling hydraulic pump 95. The traveling hydraulic pump 95 is connected to a hydraulic cylinder 93 for power steering by the steering handle 9 via a power steering hydraulic mechanism 202, and operates a brake cylinder 68 for a brake 65 for a pair of left and right rear wheels 4 respectively. It is connected to the left and right brake solenoid valves 67a and 67b, which are switching valves.

  Further, the traveling hydraulic pump 95 includes a PTO clutch hydraulic solenoid valve (proportional control valve) 104 for the PTO clutch 100, a proportional control valve 203 for a main transmission hydraulic continuously variable transmission 29 described later, and a main shift operated thereby. The switching valve 204, the high-speed clutch electromagnetic valve 666 with a high-speed switching solenoid 667 that operates the traveling sub-shift hydraulic cylinder 55, the forward switching hydraulic clutch 40 and the reverse switching hydraulic clutch 42 of the traveling machine body 2 are operated. To switch the clutch electromagnetic valve 46 and the reverse clutch electromagnetic valve 48, the four-wheeled hydraulic electromagnetic valve 80 for the four-wheeled hydraulic clutch 74 for simultaneously driving the front wheel 3 and the rear wheel 4, and the front wheel 3 to double speed driving. The double speed hydraulic solenoid valve 82 is connected to the double speed hydraulic clutch 76.

  The work machine hydraulic pump 94 is connected to a lift control electromagnetic valve 201 for supplying hydraulic oil to a single-acting work machine lift hydraulic cylinder 205 in the work machine lift mechanism 20. That is, the lifting / lowering hydraulic cylinder 205 is operated by switching the lifting / lowering control electromagnetic valve 201. The lift arm 115 is rotated by the control of the lifting / lowering hydraulic cylinder 205 for work implement, and the work implement connected to the lower link 21 is raised or lowered. Note that charge oil is supplied to the hydraulic continuously variable transmission 29 from the working machine hydraulic pump 94. The hydraulic circuit 200 includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like.

  FIG. 6 shows a transmission mechanism (mission case 17) from the engine 5 that drives the rear wheels 4, the front wheels 3, and the like. The interior of the mission case 17 is partitioned forward and backward by a partition wall 31. A front side wall member 32 and a rear side wall member 33 are detachably fixed to the front side and the rear side of the mission case 17. The mission case 17 is formed in a substantially square box shape, and a front chamber 34 and a rear chamber 35 are formed inside the mission case 17. The front chamber 34 and the rear chamber 35 are in communication with each other so that the hydraulic oil (lubricating oil) inside these chambers moves relative to each other. The front side wall member 32 is provided with a front wheel drive case 69 described later. In the front chamber 34, a travel auxiliary transmission gear mechanism 30 and a PTO transmission gear mechanism 96, which will be described later, are arranged. In the rear chamber 35, a hydraulic continuously variable transmission 29, which is a traveling main transmission mechanism described later, and a differential gear mechanism 58 are arranged.

  An engine output shaft 24 projects rearward from the rear side of the engine 5, and a flywheel 25 is directly connected to the engine output shaft 24. The main drive shaft 26 projecting backward from the flywheel 25 and the main transmission input shaft 27 projecting forward from the front surface of the transmission case 17 are connected to each other via a power transmission shaft 28 that has universal joints at both ends and can be extended and contracted. Has been. The rotational power of the engine 5 is transmitted to the main transmission input shaft 27, and then is appropriately shifted by the hydraulic continuously variable transmission 29 and the traveling auxiliary transmission gear mechanism 30, and the rear wheel 4 is connected via the differential gear mechanism 58. It is configured to transmit this driving force. Further, the rotation of the engine 5 that has been appropriately shifted by the traveling auxiliary transmission gear mechanism 30 is transmitted to the front wheels 3 via the front wheel drive case 69 and the differential gear mechanism 86 of the front axle case 13. Yes.

  As shown in FIGS. 6 and 7, the in-line hydraulic continuously variable transmission 29 provided in the rear chamber 35 includes a variable displacement type hydraulic pump 500 and a high-pressure operation discharged from the hydraulic pump 500. And a constant displacement type hydraulic motor 501 that operates with oil. A cylindrical main transmission output shaft 36 is concentrically fitted to the main transmission input shaft 27. The rear end side of the main transmission input shaft 27 is rotatably supported on the rear side wall member 33 by a bearing. A cylinder block 505 for the hydraulic pump 500 and the hydraulic motor 501 is fitted on the main transmission input shaft 27 between the partition wall 31 and the rear wall member 33. The hydraulic pump 500 is disposed at the rear of the cylinder block 505 on the side opposite to the input side of the main transmission input shaft 27. The hydraulic motor 501 is disposed in front of the cylinder block 505 on the input side of the main transmission input shaft 27.

  A main transmission output gear 37 for taking out the main transmission output from the hydraulic continuously variable transmission 29 is provided on the main transmission output shaft 36. Note that the front end and the rear end of the main transmission output shaft 36 protrude into the front chamber 34 and the rear chamber 35, respectively. The middle of the main transmission output shaft 36 is rotatably supported on the partition wall 31 by ball bearings. A main transmission output gear 37 is provided at the front end portion of the main transmission output shaft 36. The input side (front end side) of the main transmission input shaft 27 is rotatably supported by the shaft hole of the main transmission output shaft 36 via a roller bearing so as to protrude forward from the front end of the main transmission output shaft 36. .

  As shown in FIG. 4, the hydraulic pump 500 includes a pump swash plate 509 whose inclination angle can be changed with respect to the axis of the main transmission input shaft 27, and a pump plunger 506 connected to the pump swash plate 509. A first plunger hole 507 is formed in the cylinder block 505 for disposing the pump plunger 506 so as to freely enter and exit. The cylinder block 505 is provided with the same number of first spool valves 536 as the pump plungers 506. Further, a first radial bearing 538 for operating the first spool valve 536 is disposed so as to be inclined at a constant inclination angle with respect to the axis of the main transmission input shaft 27.

  On the other hand, the hydraulic motor 501 includes a motor swash plate 518 that maintains a constant inclination angle with respect to the axis of the main transmission input shaft 27, a motor plunger 515 that is coupled to the motor swash plate 518, and a motor plunger 515 that is connected to the cylinder block 505. And a second plunger hole 516 arranged to be freely accessible. The cylinder block 505 is provided with the same number of second spool valves 540 as the motor plungers 515. Further, a second radial bearing 542 for operating the second spool valve 540 is disposed at a constant inclination angle with respect to the axis of the main transmission input shaft 27. The pump plungers 506 and the same number of motor plungers 515 are alternately arranged on the same circumference of the rotation center of the cylinder block 505.

  Further, a ring groove-shaped first oil chamber 530 and a ring groove-shaped second oil chamber 531 are formed in the shaft hole of the cylinder block 505 into which the main transmission input shaft 27 is inserted. The cylinder block 505 is formed with a first valve hole 532 and a second valve hole 533 that are arranged at substantially equal intervals on the same circumference of the rotation center. The first valve hole 532 and the second valve hole 533 communicate with the first oil chamber 530 and the second oil chamber 531, respectively. The first plunger hole 507 communicates with the first valve hole 532 via the first oil passage 535, and the second plunger hole 516 communicates with the second valve hole 533 via the second oil passage 534.

  The first spool valves 536 inserted into the first valve holes 532 are arranged at substantially equal intervals on the same circumference of the rotation center of the cylinder block 505. The front end of the first spool valve 536 that protrudes from the first valve hole 532 by the back pressure spring force is brought into contact with the outer ring side surface of the first radial bearing 538. Then, the first spool valve 536 reciprocates once by one rotation of the cylinder block 505, and the first plunger hole 507 is connected to the first oil chamber 530 or the second oil via the first valve hole 532 and the first oil passage 535. The chamber 531 is configured to communicate with each other alternately.

  Further, the second spool valves 540 inserted into the second valve holes 533 are arranged at substantially equal intervals on the same circumference of the rotation center of the cylinder block 505. The tip end of the second spool valve 540 that protrudes from the second valve hole 533 by the back pressure spring force is brought into contact with the side surface of the outer ring of the second radial bearing 542. Then, the second spool valve 540 reciprocates once by one rotation of the cylinder block 505, and the second plunger hole 516 passes through the second valve hole 533 and the second oil passage 534, and passes through the first oil chamber 530 or the second oil. The chambers 531 are configured to communicate with each other alternately. The first charge valve 544 for supplying the hydraulic oil for the travel hydraulic pump 95 to the first oil chamber 530 and the second charge valve 545 for supplying the hydraulic oil for the travel hydraulic pump 95 to the second oil chamber 531. And are provided.

  Further, the pump swash plate 509 is rotatably disposed on the attachment portion of the rear side wall member 33 via the inclination angle adjustment fulcrum 555. The pump swash plate 509 is configured such that its inclination angle is adjustable with respect to the axis of the main transmission input shaft 27. A main transmission hydraulic cylinder 556 which is an actuator for main transmission operation for changing the inclination angle of the pump swash plate 509 with respect to the axis of the main transmission input shaft 27 is provided (see FIG. 7). The main transmission hydraulic cylinder 556 is configured to change the inclination angle of the pump swash plate 509 so that the main transmission operation of the continuously variable transmission 29 is performed.

  The main transmission operation of the inline hydraulic continuously variable transmission 29 will be described below. The main transmission switching valve 204 is operated by hydraulic oil from a proportional control solenoid valve 203 that operates in proportion to the amount of depression of a forward pedal 232 or a reverse pedal 233 as a transmission ratio operation means (transmission pedal), which will be described later. The cylinder 556 (see FIG. 7) is controlled, and the inclination angle of the pump swash plate 509 provided in the hydraulic pump 500 is changed with respect to the axis line of the main transmission input shaft 27.

  When the inclination angle of the pump swash plate 509 is substantially zero, the hydraulic pressure discharged from the hydraulic pump 500 is maintained at substantially zero, and the hydraulic motor 501 is not driven by the hydraulic pump 500. The fitted cylinder block 505 and the motor swash plate 518 provided in the hydraulic motor 501 rotate at substantially the same rotational speed in the same direction, and the main transmission output shaft 36 rotates at substantially the same rotational speed as the main transmission input shaft 27. Then, the rotational speed of the main transmission input shaft 27 is transmitted to the main transmission output gear 37 without being changed.

  When the pump swash plate 509 is tilted in one direction (positive tilt angle) with respect to the axis of the main transmission input shaft 27, the motor swash plate 518 is driven in the same rotational direction as the cylinder block 505, and the hydraulic motor 501 is driven. The speed change operation is performed, and the main transmission output shaft 36 is rotated at a higher rotational speed than the main transmission input shaft 27. That is, the rotational speed of the hydraulic motor 501 is added to the rotational speed of the main transmission input shaft 27 and transmitted to the main transmission output gear 37. Therefore, the main shift output (travel speed) from the main shift output gear 37 is proportional to the tilt angle (positive tilt angle) of the pump swash plate 509 in the range of the rotation speed higher than the rotation speed of the main transmission input shaft 27. ) Is changed, and the maximum traveling speed (vehicle speed) is obtained at the maximum inclination (positive inclination angle) of the pump swash plate 509.

  Further, when the pump swash plate 509 is inclined in the other direction (negative inclination angle) with respect to the axis line of the main transmission input shaft 27, the motor swash plate 518 is rotated in the direction opposite to the cylinder block 505, and the hydraulic motor The main transmission output shaft 36 is rotated at a lower rotational speed than the main transmission input shaft 27, and the rotational speed of the main transmission input shaft 27 is decelerated and transmitted to the main transmission output gear 37. That is, the rotational speed of the hydraulic motor 501 is subtracted from the rotational speed of the main transmission input shaft 27 and transmitted to the main transmission output gear 37. Therefore, the shift output (traveling speed) from the main shift output gear 37 is proportional to the tilt angle (negative tilt angle) of the pump swash plate 509 within the range of the rotational speed lower than the rotational speed of the main transmission input shaft 27. Is changed to the lowest traveling speed (vehicle speed = 0) at the maximum inclination (negative inclination angle) of the pump swash plate 509. In the embodiment, when the negative inclination angle of the pump swash plate 509 is approximately 11 degrees, the gear ratio is zero (neutral = stopped state). Further, when the positive inclination angle is approximately 11 degrees, the speed ratio is set to be maximum (maximum speed).

  As shown in FIG. 6, in the front chamber 34 of the mission case 17, the forward gear 41 and the reverse gear 43 for switching between the forward and backward travel of the traveling machine body 2 and the low speed and the high speed are switched. A traveling sub-transmission gear mechanism 30 is disposed. A configuration for switching between forward and reverse via the forward gear 41 and the reverse gear 43 will be described. A travel counter shaft 38 and a reverse shaft 39 are disposed in the front chamber 34 where the main transmission output gear 37 is disposed. The travel counter shaft 38 has a forward gear 41 connected by a wet multi-plate hydraulic clutch 40 for forward switching and a reverse gear 43 connected by a wet multi-plate hydraulic clutch 42 for reverse switching. It is fitted. The forward gear 41 is meshed with the main transmission output gear 37. A reverse gear 43 is engaged with the main transmission output gear 37 via a reverse gear 44 provided on the reverse shaft 39. It should be noted that an electromagnetic pickup type main transmission output shaft rotation sensor (not shown) for detecting the rotation of the main transmission output gear 37 is installed facing the rotation detection gear 117 provided on the reverse rotation shaft 39.

  Then, when the forward pedal 232 described later is depressed, the forward clutch cylinder 47 is operated by the forward clutch solenoid valve 46 to continue the forward switching hydraulic clutch 40, and the main transmission output gear 37 and the travel counter shaft 38 are connected to each other. The forward gear 41 is connected. Further, when the reverse pedal 233, which will be described later, is depressed, the reverse clutch cylinder 49 is operated by the reverse clutch solenoid valve 48 to continue the reverse switching hydraulic clutch 42, and the main transmission output gear 37, the travel counter shaft 38, Are connected via a reverse gear 43 and a reverse gear 44 and a reverse output gear 45 provided on the reverse shaft 39 (see FIG. 6). In the neutral position where both the forward pedal 232 and the reverse pedal 233 are not depressed, both the forward and reverse hydraulic clutches 40 and 42 are disconnected and output to the front wheel 3 and the rear wheel 4. The main drive output gear 37 is configured so that the travel driving force is substantially zero (main clutch disengaged).

  Next, a configuration for switching between the low speed and the high speed via the traveling auxiliary transmission gear mechanism 30 will be described. As shown in FIG. 3, a traveling auxiliary transmission gear mechanism 30 and an auxiliary transmission shaft 50 are arranged in the front chamber 34 of the transmission case 17. The travel counter shaft 38 is provided with a low-speed gear 51 and a high-speed gear 53 for auxiliary transmission, while the auxiliary transmission shaft 50 is provided with an output-side low-speed gear 52 that meshes with the input-side low-speed gear 51 of the travel counter shaft 38, and a travel counter. An output side high speed gear 54 that meshes with the input side high speed gear 53 of the shaft 38 is provided. Further, the auxiliary transmission shaft 50 includes a low speed clutch 56 and a high speed clutch 57 that can be connected and disconnected by an auxiliary transmission hydraulic cylinder 55. Then, the low speed clutch 56 or the high speed clutch 57 is continued under the control of the auxiliary transmission hydraulic cylinder 55 by operating an auxiliary transmission changeover switch 222 as an auxiliary transmission operation means, which will be described later, or detecting the rotational speed of the engine 5. A low speed gear 52 or a high speed gear 54 is connected to the shaft 50, and a traveling driving force is output from the auxiliary transmission shaft 50 to the front wheel 3 and the rear wheel 4.

  The rear end portion of the auxiliary transmission shaft 50 extends through the partition wall 31 to the interior of the rear chamber 35 of the transmission case 17 (see FIG. 6). In the rear chamber 35, a differential gear mechanism 58 that transmits a driving force to the left and right rear wheels 4 is disposed. The differential gear mechanism 58 includes a ring gear 60 that meshes with a pinion 59 at the rear end of the auxiliary transmission shaft 50, a differential gear case 61 provided in the ring gear 60, and a differential output shaft 62 that extends in the left-right direction. . The differential output shaft 62 is connected to the rear axle 64 by a final gear 63 or the like, and drives the rear wheel 4 of the rear axle 64 (see FIG. 6). Also, left and right brakes 65 are respectively installed on the left and right differential output shafts 62, and the base end side of one brake pedal 230 on the rear side of the steering column 234 is rotatably connected to the brake pedal shaft 255 (FIG. 4). FIG. 9 and FIG. 10). The brake pedal 230 and the left and right brake 65 are mechanically connected via a pair of left and right brake rods 250, a link mechanism 251 and the like. In addition, the parking lever (illustration omitted) etc. which latch the brake pedal 230 in a braking position is provided, and the left-right brake 65 is operated as a parking brake. On the other hand, when the steering angle of the steering wheel 9 is detected, the brake cylinder 68 is operated by the left and right brake electromagnetic valves 67a and 67b, and the brake 65 inside the turning is automatically braked.

  Next, a description will be given of the switching structure between the two-wheel drive and the four-wheel drive of the front and rear wheels 3 and 4. As shown in FIG. 6, the front wheel drive case 69 provided on the front side wall member 32 of the mission case 17 is provided with a front wheel input shaft 72 and a front wheel output shaft 73. The front wheel input shaft 72 is connected to the auxiliary transmission shaft 50 via the power transmission gears 70 and 71 so as to be able to transmit power. The front wheel output shaft 73 is connected to the front wheel output shaft 73 via a four-wheel drive gear 75 connected to the front wheel output shaft 73 via a four-wheel drive hydraulic clutch 74 and a double speed hydraulic clutch 76. The double speed gear 77 is fitted. The four-wheel drive gear 75 meshes with the input-side four-wheel drive gear 78 of the front wheel input shaft 72, and the double speed gear 77 meshes with the input side double speed gear 79 of the front wheel input shaft 72. Then, by operating a switching lever (not shown) between the 2WD and 4WD to the 4WD side, the 4WD clutch cylinder 81 is operated by the 4WD hydraulic solenoid valve 80 and the 4WD hydraulic clutch 74 is continued. Then, the front wheel input shaft 72 and the front wheel output shaft 73 are connected by a four-wheel drive gear 75, and the front wheel 3 is driven together with the rear wheel 4 (see FIG. 3).

  Next, the switching configuration of the double speed drive of the front wheel 3 will be described. Upon detection of the U-turn (direction change at the headland in the field) operation of the steering handle 9, the double speed clutch cylinder 83 is operated by the double speed hydraulic solenoid valve 82, and the double speed hydraulic clutch 76 is continued. And the front wheel output shaft 73 are connected by a double speed gear 77 so that the front wheel 3 is driven at a speed approximately twice as high as that when the front wheel 3 is driven by the four-wheel drive gear 75. (See FIG. 6). An electromagnetic pickup type vehicle speed sensor (not shown) for detecting the rotation of the gear 78 is installed near the gear 78 of the front wheel input shaft 72.

  Next, the drive structure of the front wheel 3 will be described. As shown in FIG. 6, the front wheel 3 is connected between the front wheel transmission shaft 84 projecting rearward from the front axle case 13 and the front wheel output shaft 73 projecting forward from the front surface of the transmission case 17. It connects via the front wheel drive shaft 85 which transmits motive power to. In addition, a differential gear mechanism 86 that transmits traveling driving force to the left and right front wheels 3 is disposed in the front axle case 13 described above. The differential gear mechanism 86 includes a ring gear 88 that meshes with a pinion 87 at the front end of the front wheel transmission shaft 84, a differential gear case 89 provided on the ring gear 88, and left and right differential output shafts 90. A front axle 92 is connected to the differential output shaft 90 by a final gear 91 or the like, and a front wheel 3 provided on the front axle 92 is driven.

  Next, a configuration for switching the driving speed of the PTO shaft 23 (four forward rotations and one reverse rotation) will be described. As shown in FIG. 6, in the front chamber 34 of the transmission case 17, a PTO transmission gear mechanism 96 for transmitting power from the engine 5 to the PTO shaft 23, and power from the engine 5 to each hydraulic pump 94, A pump drive shaft 97 for transmission to 95 is provided. The PTO transmission gear mechanism 96 includes a PTO counter shaft 98 and a PTO transmission output shaft 99. A PTO input gear 101 is connected to the PTO counter shaft 98 via a hydraulic PTO clutch 100. The input side gear 102 of the main transmission input shaft 27 and the output side gear 103 of the pump drive shaft 97 are meshed with the PTO input gear 101, and the pump drive shaft 97 is connected to the main transmission input shaft 27. Then, the PTO clutch cylinder 105 is operated by the PTO clutch hydraulic solenoid valve 104 (see FIGS. 5 and 6) by the operation of the PTO clutch switch 223 described later or the operation of the PTO clutch lever (not shown), and the hydraulic PTO clutch. 100 is continued, and the main transmission input shaft 27 and the PTO counter shaft 98 are connected by the PTO input gear 101.

  The PTO speed change output shaft 99 is fitted with a PTO first speed gear 106, a PTO second speed gear 107, a PTO third speed gear 108, a PTO fourth speed gear 109, and a PTO reverse gear 110. A speed change arm 112 connected to a PTO speed change lever 224 (see FIG. 8) is engaged with a speed change shifter 111 for selectively connecting the gears 106 to 110 to the PTO speed change output shaft 99. The PTO shift lever 224 is configured to shift the 1st to 4th and reverse PTO shift outputs from the PTO shift output shaft 99 to the PTO shaft 23 via the PTO transmission gears 113 and 114 by the shift operation. (See FIG. 6).

  Next, with reference to FIGS. 6 and 7, the speed change structure of the traveling auxiliary transmission gear mechanism 30 will be described in detail. As shown in FIG. 7, the auxiliary transmission hydraulic cylinder 55 is formed with a first cylinder chamber 662 in which a piston rod 661 on one side of the piston 660 is provided, and a second cylinder chamber 663 on the other side. The low speed clutch 56 or the high speed clutch 57 is continued by the shift arm 664 at the tip of the piston 660, and the auxiliary transmission shaft 50 is driven at a low speed or a high speed. The first cylinder chamber 662 communicates directly with the discharge side of the traveling hydraulic pump 95. The second cylinder chamber 663 communicates with the discharge side of the traveling hydraulic pump 95 via the high speed clutch electromagnetic valve 666. The high speed clutch electromagnetic valve 666 is switched by a speed change solenoid 667, and the high speed clutch 57 is continued to drive the auxiliary speed change shaft 50 at a high speed (see FIG. 5).

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. As shown in FIGS. 8 and 9, a step floor plate 235 is disposed in front of the control seat 8 in the cabin 7. The steering handle 9 is arranged on the upper side of the steering column 234 on the step floor plate 235. On the right side surface of the steering column 234, a throttle lever 206 for adjusting the rotational speed of the engine 5, an accelerator connecting lever 127 for connecting the forward pedal 232 and the reverse pedal 233 to the accelerator mechanism of the engine 5, a forward pedal 232, and a reverse gear A pedal lock lever 128 that maintains the pedal 233 in a substantially constant posture is disposed. Further, below the right side of the steering column 234, a brake pedal 230, a forward pedal 232, and a reverse pedal 233 are arranged in parallel. A PTO speed change lever 224 is disposed on the fender 126 on the left side of the cabin 7 (left side of the control seat 8). A differential lock pedal 225 that locks the differential gear mechanism 58 is disposed on the left side of the control seat 8. A work machine elevating lever 259 for operating the elevating mechanism 20 is disposed on the fender 126 on the right side of the cabin 7 (on the right side of the control seat 8).

  As shown in FIG. 9, a dial installation base 121 is integrally formed on the front end side of the right armrest 8a made of synthetic resin on the right side of the control seat 8 by synthetic resin molding. The dial installation base 121 is provided with a vehicle speed setting dial 211, an auxiliary transmission changeover switch 222, and a PTO clutch switch 223. An operator sitting on the control seat 8 puts his right hand on the right armrest 8a, and the operator operates the vehicle speed setting dial 211, the auxiliary transmission changeover switch 222 or the PTO clutch switch 223 with the right hand.

  As shown in FIG. 7, a work machine attitude controller 122 is disposed inside the right armrest 8 a whose upper surface side is closed with an openable and closable upper surface lid 123. The working machine attitude controller 122 includes an inclination dial 124 for adjusting the horizontal inclination of a rotary tiller (not shown) and a tilling depth dial for adjusting the tilling depth of a tilling claw (not shown) of the rotary tiller. 125 etc. are arranged. The operator sitting on the control seat 8 operates the tilt dial 124 or the tilling depth dial 125 with the right hand. The rotary tiller is connected via the lower link 21 and the top link 22. Further, the right armrest 8a and the left armrest 8b of the control seat 8 are provided so that the front end side can be lifted (shifted from a substantially horizontal posture to a substantially vertical posture) around the rotation support shaft 120 on the rear end side. .

  As shown in FIG. 10, the above-described brake pedal shaft 255 is rotatably supported on a column frame 129 provided on the steering column 234. The base end side of the brake pedal 230 is connected to the brake pedal shaft 255. Further, the base end sides of the forward pedal 232 and the reverse pedal 233 are rotatably fitted to the brake pedal shaft 255. The tread plate of the brake pedal 230 and the tread plates of the forward pedal 232 and the reverse pedal 233 are mounted so as to be able to be depressed diagonally downward from the initial (neutral) position on the upper surface of the step floor plate 235 around the brake pedal shaft 255. ing.

  The column frame 129 includes a shift potentiometer 220 as a shift sensor that detects the amount of depression of the forward pedal 232 and the reverse pedal 233. The transmission potentiometer 220 is connected to the forward pedal 232 and the reverse pedal 233 via a transmission link mechanism 275. When the pedal depression amounts of the forward pedal 232 and the reverse pedal 233 are transmitted to the transmission potentiometer 220 via the transmission link mechanism 275, the proportional control valve 203 is operated based on the detected value of the transmission potentiometer 220. The main transmission switching valve is switched by the proportional control valve 203 to operate the main transmission hydraulic cylinder 556. The main transmission hydraulic cylinder 556 changes the inclination angle of the pump swash plate 509 and switches the rotation speed of the main transmission output shaft 36.

  As shown in FIGS. 3, 4, and 10, left and right brake operation shafts 130 are respectively disposed on the left and right body frames 16 in front of the step floor plate 235. The left and right brake operation boss bodies 131 are rotatably fitted to the outer end portions of the left and right brake operation shafts 130 protruding from the outer surfaces of the left and right machine body frames 16, respectively. The both ends of the link rod 134 as the left and right brake link mechanism 251 are connected to the pedal shaft arm 132 of the brake pedal shaft 255 and the forward arm 133 of the left and right brake operation boss bodies 131 via the connecting shafts 135 and 136, respectively. Link. The front end sides of the left and right brake rods 250 are respectively connected to the downward arms 137 of the left and right brake operation boss bodies 131 via the connecting shaft 138.

  Further, left and right brake levers 252 for operating the left and right brakes 65 are disposed on the left and right outer surfaces of the mission case 17 (see FIG. 12). The rear end sides of the left and right brake rods 250 are connected to the left and right brake levers 252 via a long hole 253 and a pin shaft body 254 as an accommodation mechanism (see FIG. 19). That is, when the brake pedal 230 is depressed, the left and right brake rods 250 are pulled substantially simultaneously via the left and right link rods 134. Accordingly, the left and right brakes 65 are actuated substantially simultaneously via the left and right brake rods 250, and the left and right rear wheels 4 are braked. In addition, when the brake rod 250 is pushed in the opposite direction (the direction moving backward) with respect to the braking direction (the direction moving forward by the pedal 230 operation), in other words, the brake rod 250 at a substantially fixed position. On the other hand, when the brake lever 252 moves forward, the pin shaft body 254 moves in the long hole 253. That is, even if the brake lever 252 moves forward, no forward pushing force is applied to the brake rod 250, so that the brake rod 250 and the like can be prevented from being deformed and damaged by the forward movement of the brake lever 252.

  Next, referring to FIGS. 3, 4, 13 to 18, the mounting structure of the engine 5 and the bonnet 6 will be described in detail. As shown in FIGS. 3, 4, and 16, the left and right ends of the engine support frame 145 are fastened with bolts 146 to the left and right body frames 16 in front of the step floor plate 235. The upper end side of the engine support frame 145 is connected to the rear surface side of the engine 5 via left and right rear vibration isolation rubbers 147. The left and right side portions of the engine frame 14 are connected to the front portions of the left and right side surfaces of the engine 5 via left and right front vibration isolating rubbers 148. The engine 5 is supported on the traveling machine body 1 by the left and right front vibration isolating rubber 148 and the left and right rear vibration isolating rubber 147.

  On the other hand, as shown in FIGS. 13 and 14, a front grill 6 a is integrally connected to the lower side of the front portion of the bonnet 6. The left and right, front, and upper sides of the engine 5 are covered by the left and right engine covers 149 supported by the engine frame 14 and the bonnet 6. A bonnet lock mechanism 151 for removably locking the lower end side of the front grill 6a is provided, and the bonnet lock mechanism 151 is disposed on the engine frame 14 below the front grill 6a. The hood 6 is supported by the hood lock mechanism 151 so as to cover the front and upper sides of the engine 5. Engine-attached parts such as a battery 226 and a radiator 227 disposed in front of the engine 5 are covered with the bonnet 6 and the front grille 6a (see FIGS. 15 and 16). As shown in FIGS. 17 and 18, a bonnet opening / closing fulcrum shaft 150 is disposed inside the rear portion of the bonnet 6. By disengaging the bonnet lock mechanism 151 and lifting the front part of the bonnet 6 upward, the front part of the bonnet 6 is moved upward around the bonnet opening / closing fulcrum shaft 150 at the rear part of the bonnet 6. The front and top of 5 will be greatly opened.

  As shown in FIGS. 14, 17, and 18, the lower end sides of both sides of the portal bonnet support frame 152 are fastened to the upper end side of the engine support frame 145 with bolts 153. A pair of left and right open / close guide frames 154 are integrally raised on the upper surface of the horizontal pipe portion 152 a of the bonnet support frame 152. The lower end side of the open / close guide frame 154 is fixed to the upper surface of the horizontal pipe portion 152a by welding.

  As shown in FIG. 18, the forward / backward fulcrum shaft 155 passes through the lower end side of the open / close guide frame 154. On the upper end side of the open / close guide frame 154, an arcuate guide hole 156 is formed on a circumference centered on the longitudinal movement fulcrum shaft 155. The guide shaft 157 is penetrated through the guide hole 156 so as to be movable. Further, the forward movement restricting shaft 158 passes through the upper end side of the opening / closing guide frame 154.

  As shown in FIGS. 14 and 18, the lower end side of the opening / closing fulcrum frame 159 is rotatably fitted to the longitudinal movement fulcrum shaft 155. The open / close fulcrum frame 159 passes through the longitudinal movement guide shaft 157. The opening / closing fulcrum frame 159 and the longitudinal movement guide shaft 157 are configured to move integrally around the longitudinal movement fulcrum shaft 155. Further, when the opening / closing fulcrum frame 159 moves forward around the longitudinal movement fulcrum shaft 155, the front surface of the opening / closing fulcrum frame 159 comes into contact with the forward movement restriction shaft 158, thereby preventing the opening / closing fulcrum frame 159 from moving forward. It is configured as follows.

  As shown in FIGS. 17 and 18, one end side of a hook lever 160 as a lock mechanism for preventing the bonnet 6 from moving forward is rotatably fitted to the longitudinal guide shaft 157. On the other end side of the hook lever 160, an engagement notch 160a that is detachably fitted to the front movement restriction shaft 158 and a release operation portion 160b that releases the engagement with the front movement restriction shaft 158 are formed. Yes. By engaging the engagement notch 160a with the forward movement restricting shaft 158, the opening / closing fulcrum frame 159 has a substantially upright posture. Further, the opening / closing fulcrum frame 159 is tilted forward by grasping the disengaging operation portion 160b and lifting the hook lever 160 to disengage the engaging notch 160a from the forward movement restricting shaft 158. That is, the opening / closing fulcrum frame 159 is supported by the longitudinal movement fulcrum shaft 155 in a substantially upright posture shown in FIG. 17 or a posture tilted forward shown in FIG.

  Further, when the opening / closing fulcrum frame 159 is tilted forward (FIG. 18), the lower end side of the hook lever 160 abuts on the forward movement restriction shaft 158 so as to be movable by its own gravity. That is, by returning the opening / closing fulcrum frame 159 from the posture inclined forward (FIG. 18) to the substantially upright posture (FIG. 17), the engagement notch 160a is locked to the front movement restriction shaft 158.

  As shown in FIGS. 14, 17, and 18, a bonnet side hinge 171 fixed to the rear end side of the bonnet 6 and a frame side hinge 173 fastened with a bolt 172 to the upper end side of the opening / closing fulcrum frame 159, The bonnet opening / closing fulcrum shaft 150 is pivotally connected. That is, the rear end side of the bonnet 6 is rotatably connected to the upper end side of the opening / closing fulcrum frame 159 via the hinge-shaped hinges 171 and 173 and the bonnet opening / closing fulcrum shaft 150. Therefore, regardless of whether the bonnet 6 is supported in the opened or closed position around the bonnet opening / closing fulcrum shaft 150, the bonnet lock mechanism 151 is unlocked and opened / closed around the bonnet opening / closing fulcrum shaft 150. By moving the bonnet 6 that moves (rotates) around the fulcrum shaft 155, the rear end of the bonnet 6 can be separated from or approached to the front surface of the cabin 7 behind the bonnet 6. .

  As shown in FIGS. 14, 17, and 18, a bonnet base 161 that protrudes forward from the front surface of the opening / closing fulcrum frame 159, a bonnet frame 162 that is fixed to the inner surface side in the middle of the front and rear width of the bonnet 6, and folding A tension base link 164 and a tip link 165 are connected via a shaft 163 so as to be foldable in one direction. That is, the base link 164 and the tip link 165 form a tension mechanism 174 that holds the bonnet 6 in the open position. A base link 164 is rotatably connected to the bonnet base 161 by a base connecting shaft 166. A tip link 165 is connected to the bonnet frame 162 by a tip connecting shaft 167 so as to be rotatable. That is, by lifting the front part of the bonnet 6 upward, the base link 164 and the front end link 165 for stretching are deployed, and the bonnet 6 is supported by the projecting action of the base link 164 and the front end link 165, The upper surface side and the front side of the engine room 54 are opened.

  As shown in FIGS. 14, 17, and 18, the spring receiving arm 168 fixed to the forward movement restricting shaft 158, the spring receiving shaft 169 fixed to the bonnet base 161, and the spring receiving arm 168 and the spring receiving shaft 169 And a tension spring 170 as a return spring that connects both ends. That is, the opening / closing fulcrum frame 159 moves forward by applying the compressive force of the tension spring 170 to the opening / closing fulcrum frame 159 in a direction returning from the posture tilted forward shown in FIG. 18 to the substantially upright posture shown in FIG. The reverse operation force for returning the bonnet 6 to the rear is reduced by the tension spring 170 force. It should be noted that the compression force of the tension spring 170 is made smaller than the load in which the bonnet 6 moved forward is returned to the rear, and the bonnet 6 moved forward is prevented from returning backward only by the tension spring 170 force. .

  With the above configuration, the lower end side of the front grill 6a is locked to the engine frame 14 via the bonnet lock mechanism 151, and the bonnet 6 is supported at the closed position indicated by the solid line in FIG. The top and front are covered. In that case, the engagement notch 160a is locked to the forward movement restricting shaft 158, and the opening / closing fulcrum frame 159 is supported by the hook lever 160 in a substantially upright posture. In this state, the operator unlocks the bonnet lock mechanism 151 and lifts the front part of the bonnet 6, thereby opening the bonnet 6 around the hood opening / closing fulcrum shaft 150, maintenance work of the engine 5, etc. Can be executed. Further, by rotating the opening / closing fulcrum frame 159 around the longitudinal movement fulcrum shaft 155, the bonnet 6 is moved forward or backward, and the rear end of the bonnet 6 is made to face the front surface of the cabin 7 behind the bonnet 6. Can be separated or approached.

  Next, the mounting structure of the cabin 7 and the hydraulic steering device such as the power steering hydraulic mechanism 202 will be described in detail with reference to FIGS. 4, 10, 12, 14, and 17 to 21. As shown in FIG. 19, a handle post 176 is disposed on the steering column 234 via a handle frame 175. A handle shaft 177 is passed through the handle post 176. The steering handle 9 is assembled to the upper end portion of the handle shaft 177. Further, as shown in FIG. 14, a power steering frame 178 is bridged between the left and right body frames 16. The power steering hydraulic mechanism 202 is fastened to the power steering frame 178 with bolts. The power steering input shaft 179 protrudes upward from the upper surface of the power steering hydraulic mechanism 202. A power steering input shaft 179 is connected to the lower end side of the handle shaft 177 via a steering shaft 182 having universal joints 180 and 181.

Accordingly, by an operator seated on the driver's seat 15 is operated to rotate the steering vertical wheel 9, the power steering hydraulic mechanism 202 is actuated in response to the operation amount (rotation amount), the hydraulic cylinder 93 is driven for power steering The steering angle (steering angle) of the left and right front wheels 5 is changed. In addition, a joint shaft 181a (a connecting portion that can be bent between the power steering input shaft 179 and the steering shaft 182) of the universal joint 181 is disposed on the axis of the brake operation shaft 130 provided on the left and right body frames 16. (See FIG. 14). The power steering hydraulic mechanism 202 includes a hydraulic torque generator for power steering. Operation amount OPERA vertical handle 9 hydraulic torque diene Nereta is actuated for power steering in accordance with the (rotation amount) is configured as a steering angle of the left and right front wheels 5 (steering angle) is changed.

  As shown in FIGS. 14 and 17, the left and right brake operation shafts 130 are passed through the left and right body frames 16. The outer ends of the left and right brake operation shafts 130 are projected from the outer surfaces of the left and right body frames 16. The left and right brake operation boss bodies 131 are rotatably fitted to the outer ends of the left and right brake operation shafts 130. On the other hand, the inner ends of the left and right brake operation shafts 130 are projected from the inner side surfaces of the left and right body frames 16. The cabin support 183 is rotatably fitted to the inner ends of the left and right brake operation shafts 130.

  As shown in FIGS. 14 and 17, the cabin rotation bracket 184 is fixed to the front end portion of the step floor plate 235 of the cabin 7 by welding. The bottom surface of the cabin rotation bracket 184 is brought into contact with the upper surface of the cabin support body 183 from above, and the cabin rotation bracket 184 is fastened to the cabin support body 183 with a bolt 185. Therefore, the cabin 7 rotates around the brake operation shaft 130.

  As shown in FIGS. 19 to 21, left and right cabin frames 186 extending in the front-rear direction are disposed at the bottom of the cabin 7. The step floor plate 235 is fixed to the front half of the left and right cabin frames 186 by welding. A cabin bottom plate 187 on which the control seat 8 is placed is fixed to the rear half of the left and right cabin frames 186 by welding. The left and right cabin frames 186, the step floor plate 235, and the cabin bottom plate 187 are integrally configured as a monocoque structure as a single component. The left and right rear support frames 188 are fixed to the rear ends of the left and right cabin frames 186 by welding. A fender 126 is connected to the cabin frame 186 and the upper end side of the rear support frame 188.

  Further, the rear mounting frame 189 is fixed to the cabin frame 186 and the lower end side of the rear support frame 188 by welding. A rear mounting base 190 is fixed to the lower surface of the rear mounting frame 189 by welding. The rear mounting base 190 is brought into contact with the cabin mounting portion 18a on the upper surface of the rear axle case 18 from above, and the rear mounting base 190 is fastened to the cabin mounting portion 18a with a bolt 191. The front and rear portions of the cabin 7 are connected to the traveling machine body 1 by the brake operation shaft 130 and the rear axle case 18, and the upper surface side of the transmission case 17 and the work implement lifting mechanism 20 is covered by the cabin bottom plate 187.

  Next, with reference to FIGS. 12 and 19 to 21, the rotation structure of the cabin 7 that lifts the rear portion of the cabin 7 upward will be described in detail. As shown in FIGS. 12 and 19, a push-up body 192 that is detachably connected to the lift arm 115 is provided. A protruding contact body 193 is disposed on the lower surface of the cabin bottom plate 187. The push-up body 192 has a rear-downward shape formed by a base tube 192a fitted on a connecting shaft 194 detachably penetrating the lift arm 115, a lower surface of the cabin bottom plate 187, and a contact body 193. It has a round bar-shaped tip bar 192b that comes into contact with the recess 195 from below and a round bar-shaped support arm 192c that is integrally fixed to the base tube 192a and the tip bar 192b by welding. That is, one end of the support arm 192c is integrally fixed to the base end tube 192a by welding, and the distal end bar 192b is integrally fixed to the other end of the support arm 192c by welding in a substantially T shape. A raised body 192 will be formed.

  Next, with reference to FIG. 18 to FIG. 21, the rotation structure of the cabin 7 that lifts the rear portion of the cabin 7 upward will be described in detail. When the rear part of the cabin 7 is lifted upward, as shown in FIG. 18, first, the front part of the bonnet 6 is lifted upward to open the bonnet 6, and the hook lever 160 is removed from the longitudinal movement restricting shaft 158. Then, the open / close fulcrum frame 159 is rotated around the longitudinal movement fulcrum shaft 155 to move the bonnet 6 forward, so that the rear end of the bonnet 6 is separated from the front surface of the cabin 7 behind the bonnet 6. On the other hand, the bolt 191 is unscrewed to release the fastening between the cabin mounting portion 18a and the rear mounting base 190. Further, the connecting shaft 194 of the lift arm 115 is pulled out, and the lift rod 116 shown in FIG. Thereafter, the connecting shaft 194 is inserted into the proximal end cylinder 192 a while the connecting shaft 194 is passed through the lift arm 115, and the projecting body 192 is connected to the lift arm 115 via the connecting shaft 194. It should be noted that the push-up body 192 is connected to the cabin bottom plate 187 reinforced by the abutment body 193 by an operation of bringing the push-up body 192 into contact with the cabin bottom plate 187 via the abutment body 193. When the cabin 7 is lifted upward, the lifted body 192 is lifted with the support arm 192c of the lifted body 192 extended in the tangential direction of the rotation locus of the contact body 193 with the cabin support body 183 as the center. Supported by the arm 115.

  Then, the work machine lifting / lowering hydraulic cylinder 205 of the work machine lifting / lowering mechanism 20 is operated, and the lift arm 115 is slightly rotated in the upward direction. The contact body 193 is rotated around the connecting shaft 194, and the tip bar 192b is brought into contact with the contact body 193 as shown in FIG. In this state, the work machine lifting / lowering hydraulic cylinder 205 of the work machine lifting / lowering mechanism 20 is actuated again to further rotate the lift arm 115 in the upward direction. As a result, as shown in FIG. 20, the cabin 7 rotates about the brake operation shaft 130 (cabin support 183) so as to be separated from the upper surface of the work implement lifting mechanism 20, and the rear portion of the cabin 7 is lifted upward. . In such a state that the rear portion of the cabin 7 is lifted upward, the mission case 17 and the work implement lifting mechanism 20 are connected to the machine body frame 16, and the upper side of the mission case 17 and the work implement lifting mechanism 20 is arranged. Maintenance work or repair work is performed.

  Further, when the cabin 7 rotates around the brake operation shaft 130 and the rear portion of the cabin 7 moves up, the brake pedal shaft 255 rotates around the brake operation shaft 130 and moves forward. That is, the brake pedal shaft 255 is rotated by the rotation of the cabin 7, and the brake rod 250 is pushed rearward to move. The pin shaft body 254 moves in the long hole 253 by the rearward movement of the brake rod 250. Therefore, even if the brake rod 250 moves rearward due to the rotation of the cabin 7, the brake lever 252 is held at a substantially constant position, and the rear wheel 4 is not braked by the brake 65. The state where the braking of the rear wheel 4 is released is maintained. For example, the rear wheel 4 can be rolled by a hand pressing operation or the like. When the cabin 7 is rotated, a long hole (not shown) is formed in the fender 126 for allowing the work implement lifting lever 259 and the like to penetrate so that the work implement lifting lever 259 and the like do not interfere with the fender 126. Yes. Therefore, the rear portion of the cabin 7 can be moved upward without removing the work implement lifting lever 259 and the like.

  On the other hand, as shown in FIGS. 20 and 21, a cabin support stand 195 that supports the cabin 7 in a posture in which the rear portion of the cabin 7 is lifted upward, and a cabin between the cabin support 183 and the rear axle case 18. A stand fixture 196 disposed on the frame 186. When the mission case 17 and the work machine lifting mechanism 20 are separated from the machine frame 16 and maintenance or repair thereof is performed, the rear portion of the cabin 7 is moved upward as shown in FIG. In the lifted state, the upper end side of the cabin support stand 195 is locked to the stand fixture 196. Thereafter, the lifting / lowering hydraulic cylinder 205 for the working machine of the working machine lifting / lowering mechanism 20 is controlled to rotate the lift arm 115 in the downward direction, so that the tip bar 192b is separated from the contact body 193. In this state, the fastening bolt 142 and the fixing bolt 143 are screwed off, the pin fastening member is removed, and the transmission case 17 is separated from the body frame 16. Then, while rolling the rear wheel 4, the mission case 17 whose lower surface side is supported by a carriage (not shown) is moved backward to perform maintenance work or repair work for the mission case 17 and the work implement lifting mechanism 20, etc. Execute.

  When the transmission case 17 is moved rearward as described above, the main transmission input shaft 27 is separated from the power transmission shaft 28 by their universal joints. Further, the front wheel output force shaft 73 is separated from the front wheel drive shaft 85 by their universal joints. On the other hand, when assembling the mission case 17 and the work implement elevating mechanism 20 and the like, the work is performed in the reverse procedure to the above, and the mission case 17 is moved forward and connected to the machine body frame 16. The lifting hydraulic cylinder 205 for work implements is controlled to remove the cabin support stand 195, and the rear portion of the cabin 7 is lowered and connected to the rear axle case 18 to complete the assembly of the transmission case 17, the cabin 7, and the like.

  As is clear from the above description and FIGS. 14 to 18, the traveling machine body 2 on which the engine 5 is mounted, the bonnet 6 that covers the engine 5, the cabin 7 that has the operator seat 8, the operator handle 9, etc. The rear part of the bonnet 6 is connected to the traveling machine body 2 via the opening / closing fulcrum shaft 150, and the bonnet 6 is rotated around the opening / closing fulcrum shaft 150 so that the front part of the bonnet 6 can be moved upward. The cabin-equipped working vehicle is configured such that the cabin support 183 is disposed on the lower end side of the front portion of the cabin 7, the cabin 7 is rotated around the cabin support 183, and the rear portion of the cabin 7 is movable upward. 2, the opening / closing fulcrum shaft 150 is disposed on the traveling machine body 2 so as to be movable in the front-rear direction, and the opening / closing fulcrum shaft 150 is moved forward so that the rear end of the bonnet 6 faces the front surface of the cabin 7. Since it is obtained by separating capable constructed towards, it can be a hood 6 in the rear of the switching fulcrum shaft 150 around the hood 6 rotates, releasing large front and upper side of the engine 5. Further, by moving the hood 6 forward, even if the cabin 7 is rotated forward, the cabin 7 can be prevented from interfering with the hood 6 and the rear portion of the cabin 7 can be easily lifted upward. . That is, by rotating the bonnet 6 about the opening / closing fulcrum shaft 150 at the rear part of the bonnet 6, the front part and the upper surface side of the engine 5 are largely opened, and a maintenance work space for the engine 5 can be easily secured. Further, by rotating the cabin 7 forward around the cabin support 183, the upper surfaces of the hydraulic lifting mechanism 20 and the transmission case 17 and the like disposed below the rear portion of the cabin 7 are largely opened, and the hydraulic lifting mechanism 20 and the mission Maintenance work space such as the case 17 can be easily secured. Therefore, the maintenance workability of the engine 5 or the hydraulic lifting mechanism 20 can be easily improved.

  As apparent from the above description and FIGS. 14 to 18, the engine support frame 145 that supports the rear portion of the engine 5 on the traveling machine body 2, and the bonnet support body that is rotatably connected to the engine support frame 145 in the front-back direction The opening / closing fulcrum frame 159 and a hook lever 160 as a lock mechanism for supporting the opening / closing fulcrum frame 159 at the initial position are provided, and the opening / closing fulcrum frame 159 is initialized via the hook lever 160 by the operation of returning the bonnet 6 to the initial position. Since it is configured to be supported at a position, the opening / closing fulcrum shaft 150 movable in the front-rear direction is supported with high rigidity via the opening / closing fulcrum frame 159 having a simple structure by using the engine support frame 145. it can. Further, when the bonnet 6 is moved to the closed position for covering the engine 5, the opening / closing fulcrum frame 159 is locked to the initial position by the hook lever 160 even if the operator does not specially operate the hook lever 160. That is, when the opening / closing fulcrum frame 159 is moved back to the initial position by returning the bonnet 6 moved forward, the opening / closing fulcrum frame 159 is locked to the initial position by the hook lever 160 in conjunction therewith. It is possible to prevent the bonnet 6 from being closed when the operator forgets to lock the opening / closing fulcrum frame 159. Therefore, the opening / closing operability of the bonnet 6 can be improved.

  As is clear from the above description and FIGS. 14 to 18, the front grill 6 a covering the front side of the engine 5 is disposed at the front portion of the bonnet 6, and the opening / closing fulcrum frame 159 is elastically pressed back to the initial position. A battery disposed on the front side of the engine 5 because the front part of the bonnet 6 and the front grille 6a can be lifted integrally so that the front of the engine 5 can be greatly opened because the tension spring 170 as a return spring is provided. Maintenance workability of engine-attached parts such as H.226 or radiator 227 can be easily improved. Further, since the return spring 170 force acts in the direction of moving the bonnet 6 backward, when the maintenance work is finished, the operator holds the front grill 6a on the front side of the traveling machine body 2 and pushes the bonnet 6 backward. In addition, the pushing operation force of the operator is reduced by the return spring 170 force. That is, it is possible to reduce the deformation force of the front grill 6a generated by the operator's pushing operation. An operator can easily close the bonnet 6 by holding the front grill 6a.

It is a side view of the tractor for farm work. It is a diagonally rear perspective view of a tractor. It is side surface explanatory drawing of a traveling body. It is plane explanatory drawing of a traveling body. It is a hydraulic circuit diagram in the whole tractor. It is a skeleton diagram of power transmission. It is a hydraulic circuit diagram of a continuously variable transmission. It is a top view which shows the cabin of a tractor. It is a top view which shows arrangement | positioning of driving | operation operation mechanisms, such as a pedal. It is a side view which shows attachment structures, such as a brake pedal. It is a side view of the appearance of a mission case. It is a top view of the appearance of a mission case. It is a side view which shows the attachment structure of a bonnet and a cabin. It is a rear view which shows the attachment structure of a bonnet and a cabin. It is a side view which shows the attachment structure of a bonnet. It is explanatory drawing which moved the bonnet ahead. FIG. 16 is an enlarged side view of FIG. 15. FIG. 17 is an enlarged side view of FIG. 16. It is a side view which shows the attachment structure of a cabin. It is explanatory drawing which raised the rear part of the cabin. It is explanatory drawing which removed the mission case.

2 traveling machine body 5 engine 6 bonnet 6a front grill 7 cabin 8 control seat 9 control handle 145 engine support frame 150 bonnet open / close fulcrum shaft 159 open / close fulcrum frame (bonnet support)
160 Hook lever (locking mechanism)
170 Tension spring (return spring)
183 cabin support

Claims (3)

A traveling machine body equipped with the engine, the hood covering the engine, and a cabin with a control seat and steering handle for operator Zajo, connecting the rear portion of the hood through the opening and closing fulcrum shaft on the vehicle body, The bonnet is rotated about the opening / closing fulcrum shaft, and the front part of the bonnet is configured to be movable upward, while a cabin support is disposed on the lower end side of the front part of the cabin, In the work vehicle with a cabin configured to rotate the cabin to move the rear part of the cabin upward,
The opening / closing fulcrum shaft is arranged on the traveling machine body so as to be movable in the front-rear direction, and the opening / closing fulcrum shaft is moved forward so that the rear end of the bonnet can be separated forward with respect to the front surface of the cabin. A working vehicle with a cabin.   An engine support frame that supports the rear portion of the engine on the traveling machine body, a bonnet support that is pivotally connected to the engine support frame in the front-rear direction, and a lock mechanism that supports the bonnet support in an initial position. 2. The work vehicle with a cabin according to claim 1, wherein the bonnet support is supported at an initial position through the lock mechanism by an operation of returning the bonnet to an initial position.   The front bonnet is provided with a front spring that covers a front side of the engine and includes a return spring that presses the bonnet support in a direction to return the bonnet support to an initial position. Working vehicle with cabin.

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