JP4860271B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as a tractor used for agricultural work or a wheel loader used for civil engineering work, and more specifically, to a transmission case for shifting power from an engine to drive a working unit such as a tillage work machine. It is related with the work vehicle which has arrange | positioned this PTO axis | shaft.

  In a work vehicle such as a tractor or a wheel loader, a working unit such as a tillage work machine is connected to a traveling machine body equipped with an engine. For example, Patent Document 1 discloses a drive wheel such as a rear wheel via a hydrostatic continuously variable transmission (HST) in the transmission case and a gear-type auxiliary transmission mechanism (switching between low speed, high speed, and reverse). A configuration is disclosed in which power from the engine is transmitted to a PTO shaft for driving a working unit such as a tillage work machine while transmitting power from the engine.

Further, in Patent Document 1, since the hydraulic pump of the hydrostatic continuously variable transmission is disposed on the transmission input shaft, and the hydraulic motor of the hydrostatic continuously variable transmission is disposed on the transmission output shaft, There was a limit to downsizing the case or reducing the manufacturing cost of the hydrostatic continuously variable transmission. Therefore, in order to reduce the size of the transmission case and reduce the manufacturing cost of the hydrostatic continuously variable transmission, Patent Document 2 discloses a shift input for transmitting power from an engine instead of the hydrostatic continuously variable transmission. A shaft and a speed change output shaft for transmitting a hydraulic speed change output to the left and right wheels are concentrically arranged, and a hydraulic pump part and a hydraulic motor part are arranged on both sides of a cylinder block constituting the hydraulic continuously variable transmission, It is disclosed to employ a so-called inline hydraulic continuously variable transmission in which a shaft and an output shaft are configured as a double shaft. As shown in Patent Document 3, it is also known to dispose the hydrostatic continuously variable transmission shown in Patent Document 1 at the rear of the transmission case.
JP 2003-226165 A Japanese Patent No. 3526674 JP 2004-255918 A

  By the way, in a work vehicle such as a tractor, for example, while pulling various working machines such as field cultivation, leveling work, uprighting work, and multi-laying work, the engine is moved from the engine to the various working machines via the PTO shaft. It is necessary to convey the power of constant speed rotation. Therefore, the power from the engine is branched on the input side of the hydraulic continuously variable transmission and transmitted to the PTO shaft. However, since it is necessary to arrange the PTO shaft on the center line in the front-rear direction of the traveling machine body, the hydraulic continuously variable transmission is installed at the front of the transmission case, and the PTO transmission gear is installed at the rear of the transmission case. When a mechanism is built in, the power from the engine cannot be easily branched on the input side of the hydraulic continuously variable transmission. On the other hand, when the PTO transmission gear mechanism is built in the front part of the transmission case and the hydraulic continuously variable transmission is installed in the rear part of the transmission case, the power from the engine is input to the hydraulic continuously variable transmission. However, there is a problem that the mounting height of the PTO shaft is limited by the hydraulic continuously variable transmission and the PTO shaft is assembled at a low position of the transmission case.

  An object of the present invention is to allow the power from the engine to be easily transmitted to the PTO shaft via the PTO transmission gear mechanism, while assembling the PTO shaft at a high position of the transmission case. A work vehicle is provided that can be configured to have a compact vertical dimension.

In order to achieve the above object, a work vehicle according to a first aspect of the present invention includes a hydraulic continuously variable transmission (29) for shifting power from an engine (5) mounted on a traveling machine body (2), and a traveling driving force. A transmission differential gear mechanism (58); and a transmission case (17) incorporating the hydraulic continuously variable transmission (29) and the differential gear mechanism (58); and after the transmission case (17) In a work vehicle (1) formed by projecting a PTO shaft (23) laterally, a PTO output gear (114) for transmitting power from a PTO transmission gear mechanism (96) is disposed on the PTO shaft (23), The uppermost part of the PTO output gear (114) is formed higher than the lowermost part of the side opposite to the input side of the hydraulic continuously variable transmission (29), and the axial center line direction of the hydraulic continuously variable transmission (29) In view, the hydraulic continuously variable transmission (29) and the P O output gear (114) and with overlapping, the inside front chamber of the transmission case (17) (34) and the rear chamber (35) and is formed, in the interior of the rear chamber (35), the hydraulic stepless The transmission (29) and the differential gear mechanism (58) are arranged such that the hydraulic continuously variable transmission (29) is positioned higher than the differential output shaft (62) of the differential gear mechanism (58). The PTO shaft (23) is disposed between the hydraulic continuously variable transmission (29) and the differential gear mechanism (58) in plan view.

According to the first aspect of the present invention, the hydraulic continuously variable transmission (29) for shifting the power from the engine (5) mounted on the traveling machine body (2) and the differential gear mechanism for transmitting the traveling driving force ( 58) and a transmission case (17) incorporating the hydraulic continuously variable transmission (29) and the differential gear mechanism (58) , and a PTO shaft (23) on the rear side of the transmission case (17). In the work vehicle (1) that protrudes, a PTO output gear (114) that transmits power from the PTO transmission gear mechanism (96) is disposed on the PTO shaft (23), and the hydraulic continuously variable transmission (29 ), The uppermost part of the PTO output gear (114) is formed higher than the lowermost part of the side opposite to the input side, and the hydraulic continuously variable transmission is viewed in the axial direction of the hydraulic continuously variable transmission (29). Machine (29) and the PTO output gear (114) Since is obtained by, the mounting height of the PTO shaft is not limited by the hydraulic stepless transmission. Accordingly, since the PTO shaft can be easily arranged at a high position of the mission case, the vertical width dimension of the mission case can be made compact. Further, the height of the ground such as the PTO shaft or a transmission shaft with a universal joint connected to the PTO shaft can be increased to reduce the winding of the grass.
Moreover, a front chamber (34) and a rear chamber (35) are formed in the mission case (17), and the hydraulic continuously variable transmission (29) and the differential are formed in the rear chamber (35). Since the gear mechanism (58) is arranged so that the hydraulic continuously variable transmission (29) is positioned higher than the differential output shaft (62) of the differential gear mechanism (58), The hydraulic continuously variable transmission can be arranged at a position higher than the oil level of the hydraulic oil in the mission case, and the hydraulic oil in the mission case is hardly agitated by the rotation of the hydraulic continuously variable transmission. Therefore, the power transmission loss of the hydraulic continuously variable transmission can be reduced, and the temperature rise of the hydraulic oil in the transmission case can be prevented. Further, for example, even if the differential gear mechanism, the PTO transmission gear mechanism, and the like are installed inside the transmission case, such as a transmission structure of a tractor, the hydraulic stepless is provided at the rear part of the transmission case. The installation space for the transmission can be easily secured. In addition, the attaching / detaching operation of the hydraulic continuously variable transmission can be executed in a state where the differential gear mechanism is incorporated in the rear part of the transmission case. In addition, it is possible to secure an installation space for the PTO transmission gear mechanism or the traveling auxiliary transmission gear mechanism in the front part of the transmission case which is the input side of the hydraulic continuously variable transmission, for example, downsizing the transmission case of the tractor Alternatively, the weight can be reduced and the manufacturing cost can be reduced.

  Further, since the PTO shaft (23) is disposed between the hydraulic continuously variable transmission (29) and the differential gear mechanism (58) in plan view, Above, a space necessary for installing the hydraulic continuously variable transmission can be secured without being limited by the differential gear mechanism. In other words, since the space in the transmission case opposite to the differential gear mechanism across the PTO shaft is effectively used, the hydraulic continuously variable transmission can be easily arranged at a high position in the transmission case. Therefore, the PTO shaft can also be easily arranged at a high position of the mission case.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, drawings when an embodiment of the present invention is applied to a farm tractor as a work vehicle will be described. 1 is a side view of the tractor, FIG. 2 is a rear perspective view thereof, FIG. 3 is a side view of the tractor body, FIG. 4 is a plan view of the tractor body, FIG. 5 is a side view of the tractor mission case, and FIG. It is a skeleton diagram of power transmission.

  As shown in FIGS. 1 to 4, the tractor 1 supports a traveling machine body 2 with a pair of left and right front wheels 3 and a pair of left and right rear wheels 4, and is rear-mounted by an engine 5 mounted on the front part of the traveling machine body 2. By driving the wheel 4 and the front wheel 3, the vehicle is configured to travel forward and backward. 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 and a steering handle 9 that moves the front wheel 3 to the left and right by steering are disposed in the cabin 7. . A step 10 on which the operator gets on and off is arranged outside the cabin 7, and a fuel tank 11 that supplies fuel to the engine 5 is arranged inside the step 10 and below the bottom of the cabin 7.

  As shown in FIGS. 2 to 5, the traveling aircraft body 2 includes a pair of left and right aircraft bodies that are detachably fixed to the engine frame 14 having a front bumper 12 and a front axle case 13 and bolts 15 at the rear of the engine frame 14. Frame 16. A transmission case 17 is connected to the rear part of the body frame 16 to transmit the rotation of the engine 5 to the rear wheels 4 and the front wheels 3 with appropriate speed change. In this case, the rear wheel 4 is rearwardly 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. It is attached via a gear case 19 mounted so as to extend. A hydraulic working machine lifting mechanism 20 for lifting and lowering a working machine (not shown) such as a tiller is detachably attached to the upper surface of the rear portion of the mission case 17. The working machine such as a tiller is connected to the rear part of the mission case 17 via a lower link 21 and a top link 22. Further, a PTO shaft 23 for a working machine such as a tiller is projected rearward on the rear side surface of the mission case 17.

  Next, with reference to FIGS. 3 to 5 and FIGS. 13 to 15, the rear structure of the traveling machine body 2 that connects the machine frame 16 and the transmission case 17 will be described. Upper and lower connecting boss portions 200 are integrally formed at the rear end portions of the left and right body frames 16 made of iron plates. As shown in FIGS. 14 and 15, the connecting boss portion 200 is fitted on the cylindrical frame pin 201. A pin fastening member 202 is fitted on one end side of the frame pin 201 (see FIG. 15). The frame pin 201 and the pin fastening member 202 are fixed by welding. The fuselage frame 16 is attached to the side surface of the mission case 17 via one fastening bolt 204 that penetrates the inner hole of the frame pin 201 and three fixing bolts 205 that penetrate the attachment hole of the pin fastening member 202. Will be.

  As shown in FIG. 15, a pin hole 206 into which the frame pin 201 is press-fitted is formed on the side surface of the mission case 17. A tightening screw hole 207 for screwing the tightening bolt 204 is formed on the back side of the pin hole 206. A fixing screw hole 209 for screwing the fixing bolt 205 is formed on the side surface of the mission case 17. A cylindrical spacer 208 is fitted on the fixing bolt 205. The fixing bolt 205 is screwed to the side surface of the mission case 17 via the spacer 208, and the pin fastening member 202 is fixed to the mission case 17 via the fixing bolt 205.

  A shaft hole 199 for penetrating the frame pin 201 is formed in the connection boss portion 200. The inner diameter of the shaft hole 199, the outer diameter of the frame pin 201, and the inner diameter of the pin hole 206 are formed to have substantially the same dimensions. The end of the frame pin 201 is fixed to the pin fastening member 202 by welding so that one end surface of the frame pin 201 and the outer surface of the pin fastening member 202 are substantially flush with each other (see FIG. 15). ).

  When the end of the frame pin 201 and the pin fastening member 202 are fixed, the end surface of the frame pin 201 slightly protrudes from the outer surface of the pin fastening member 202, and the fastening bolt 204 is screwed into the fastening screw hole 207. When worn, the head of the fastening bolt 204 may be configured to be crimped to the end of the frame pin 201. The end of the frame pin 201 and the pin fastening member 202 may be fixed by a fixing method other than welding, for example, a fixing method in which the end of the frame pin 201 is press-fitted into the opening of the pin fastening member 202.

  As shown in FIG. 14, the frame pin 201 passes through the shaft hole 199 from the outer surface of the connecting boss part 200. Next, the frame pin 201 is press-fitted into the pin hole 206. The bolts 204 and 205 are screwed into the screw holes 207 and 209, respectively. If it does in this way, the frame pin 201 will be supported by the mission case 17 and the pin fastening member 202 by a double-sided structure.

  On the other hand, as shown in FIG. 5, a rearward open positioning groove 210 is formed in the middle of the vertical width of the rear end surface of the machine body frame 16. On the side surface of the mission case 17, a guide pin 211 that fits in the positioning groove 210 protrudes sideways. That is, when the rear part of the body frame 16 is fixed to the side surface of the mission case 17, first, the connection boss part 200 on the lower side of the body frame 16 is loosely stopped on the mission case 17 via the pin fastening member 202. Then, the rear portion of the mission case 17 is slightly lifted, and the guide pin 211 is fitted into the positioning groove 210. Next, the upper connection boss part 200 of the machine frame 16 is firmly fixed to the mission case 17 via the pin fastening member 202, and the lower connection boss part 200 is also firmly fixed.

  That is, after the lower pin fastening member 202 is assembled using the frame pin 201 and the bolts 204 and 205, the fuselage frame 16 is connected to the side surface of the transmission case 17 via the positioning groove 210 and the guide pin 211. Thus, the above-described operation of assembling the upper pin fastening member 202 using the frame pin 201 and the bolts 204 and 205 can be executed, and the body frame 16 can be supported at the attachment position on the side surface of the mission case 17. Therefore, when the connection boss part 200 of the airframe frame 16 is fixed to the transmission case 17 via the pin fastening member 202, the relative positioning work of the airframe frame 16 and the transmission case 17 can be easily performed. Assembly workability can be improved. Although one end side of the guide pin 211 is embedded in the mission case 17, the guide pin 211 may be integrally formed on the mission case 17 by casting.

  As shown in FIGS. 5 and 13, a transmission case 17 for shifting the power from the engine 5 mounted on the traveling machine body 2 and left and right machine body frames 16 connected to the left and right outer surfaces of the mission case 17 are provided. In this work vehicle, a guide pin 211 protrudes from either the outer surface of the mission case 17 or the left and right body frames 16, and a positioning groove 210 is formed as a guide notch on the other side. Accordingly, since the forward movement of the mission case 17 with respect to the left and right airframe frames 16 can be blocked, when the left and right airframe frames 16 are connected to the outer surface of the mission case 17, positioning grooves are formed in the guide pins 211. 210 can be engaged to determine the assembly position of the mission case 17, and the left and right aircraft The fastening position of the frame 16 can hold the transmission case 17 easily, it is possible to improve the assembling workability of the running vehicle body 2.

  As shown in FIGS. 5 and 13, a guide pin 211 protrudes from the outer surface of the mission case 17, and a rearward open positioning groove 210 is formed in the middle of the vertical width on the rear end side of the body frame 16. Therefore, when the traveling machine body 2 is assembled, the positioning case 17 is approached from the rear of the machine frame 16 with the front end sides of the left and right machine frame 16 fixed to the rear end side of the engine frame 14 in advance. The guide pin 211 can be easily engaged with 210, and the fastening workability between the body frame 16 and the transmission case 17 can be improved. In the present embodiment, the guide pin 211 is disposed in the mission case 17 and the positioning groove 210 is formed in the airframe frame 16. However, the guide pin 211 is disposed in the airframe frame 16 and the positioning groove 210 (mission A stopper for forward movement of the case 17) may be formed.

  As shown in FIGS. 5, 13, and 14, the upper and lower frame pins 201 are penetrated from the outside to the upper and lower portions of the bifurcated shape on the rear end side of the left and right aircraft frames 16, respectively. One end side of the upper and lower frame pins 201 is inserted, a pin fastening member 202 as an upper and lower coupling body is fixed to the other end side of the upper and lower frame pins 201, and the upper and lower pin fastening members 202 are fixed to the outer surface of the transmission case 17. Therefore, even if the fuselage frame 16 is not directly fastened to the transmission case 17, the connection strength between the fuselage frame 16 and the transmission case 17 can be sufficiently secured, and the connection of the fuselage frame 16 can be ensured. The area of the outer surface of the mission case 17 required for the above can be reduced. Therefore, the side surface of the mission case 17 for connecting the body frame 16 can be utilized for installation of a speed change operation mechanism, for example.

  Next, the structure of the engine frame 14 will be described with reference to FIGS. 3 and 4. A pair of left and right front anti-vibration members 230 are disposed on the upper surface side of the middle portion of the left and right engine frame 14 in the front-rear width. Both sides of the front portion of the engine 5 are connected to the engine frame 14 via left and right front vibration isolation members 230. A front axle case 13 and a power steering hydraulic cylinder 93 are disposed on the lower surface side of the front and rear width intermediate portion of the left and right engine frames 14. The left and right front wheels 3 are disposed on the left and right sides of the front axle case 13 so as to be steerable.

  As shown in FIG. 3 and FIG. 4, an upper connection member 250 having a front view and a lower connection member 251 having a flat plate shape are disposed in front portions of the left and right body frames 16. The gate-shaped both ends of the upper connecting member 250 are fastened to the upper surfaces of the left and right body frames 16 with bolts. Both ends of the lower connecting member 251 are fastened to the lower surface of the body frame 16 with bolts. A flywheel 25 on the rear side of the engine 5 is disposed between the left and right body frames 16. An upper connecting member 250 is disposed above the flywheel 25, and a lower connecting member 251 is disposed below the flywheel 25. That is, the flywheel 25 is disposed in a space surrounded by the left and right body frames 16 and the upper and lower connecting members 250 and 251.

  Next, the assembly work of the traveling machine body 2 will be described. First, the front part of the body frame 16 is fastened to the outer side surface of the rear part of the engine frame 14 via bolts 15. Fastened to the upper surface of the front part of the left and right fuselage frame 16 are both gate-shaped ends of the upper connecting member 250 with bolts. Both ends of the lower connecting member 251 are fastened to the lower surfaces of the front parts of the left and right body frames 16 with bolts. The upper and lower surfaces of the front parts of the left and right body frames 16 are connected by the upper and lower connecting members 250 and 251. Thereafter, the guide pin 211 of the mission case 17 is fitted into the positioning groove 210 of the fuselage frame 16, and the rear portion of the fuselage frame 16 is connected to the mounting position on the side surface of the mission case 17.

  As described above, the frame pin 201 is inserted into the shaft hole 199 of the connecting boss 200 and the frame is inserted into the pin hole 206 in a state where the body frame 16 is connected to the side surface of the transmission case 17 via the positioning groove 210 and the guide pin 211. The front end side of the pin 201 is press-fitted, and the fastening bolt 204 is screwed into the fastening screw hole 207 from the outside of the pin fastening member 202. Further, the bolts 204 and 205 are screwed into the screw holes 207 and 209, the frame pin 201 is assembled to the transmission case 17 and the pin fastening member 202 in a double-supported structure, and the rear part of the body frame 16 and the transmission case 17 are assembled. And the assembly work of the traveling machine body 2 is completed (see FIGS. 3 and 4).

  In the assembly work of the traveling machine body 2, the front part of the machine body frame 16 is fastened to the outer side surface of the rear part of the engine frame 14, and then the rear parts 16 of the left and right machine body frames are connected to the side surfaces of the transmission case 17. After connecting the rear portion 16 of the aircraft frame and the side surface of the transmission case 17, the front portion of the aircraft frame 16 may be fastened to the outer side surface of the rear portion of the engine frame 14.

  On the other hand, for example, when carrying out the detaching operation of the components on the front side of the mission case 17 such as the maintenance work of the hydraulic pumps 94 and 95 installed on the front side of the mission case 17, the bolts 204 and 205 are removed. The pin fastening member 202 is removed, the airframe frame 16 is removed from the side surface of the mission case 17, and the airframe frame 16 and the mission case 17 are separated. Further, the front portion of the machine body frame 16 is separated from the engine frame 14 and the upper and lower connecting members 250 and 251 by the operation of removing the bolts 15 and the like. That is, only one of the left and right body frames 16 is removed, and maintenance work and the like of the hydraulic pumps 94 and 95 are performed from the side from which the body frame 16 is removed.

  Accordingly, since the maintenance work or the like on the front side of the mission case 17 can be performed in a state in which either the left or right body frame 16 is connected to the side surfaces of the engine frame 14 and the mission case 17, when the maintenance work or the like is completed, The removed body frame 16 can be reassembled by a simple operation, and workability such as maintenance can be improved.

  As shown in FIG. 14, the rear part of the fuselage frame 16 is extended to the side surface of the mission case 17, and the frame pin 201 is penetrated from the outside to the rear part of the fuselage frame 16. 17, the area of the side of the mission case 17 necessary for connecting the fuselage frame 16 can be reduced as compared with the conventional connection structure such as bolt fastening. It can be used for the installation space of the speed change mechanism. Since the fuselage frame 16 and the transmission case 17 are connected via the frame pin 201, the fuselage frame 16 can be manufactured by processing with low material cost and few restrictions on the design shape. For example, a traveling machine body such as the tractor 1 can be simplified, and the manufacturing cost can be reduced.

  In addition, since either one of the left and right body frames 16 is connected to the engine frame 14 and the transmission case 17, the other body frame 16 can be removed from the engine frame 14 and the transmission case 17. The frame 14 and the left and right body frames 16 can be processed as independent parts. For example, the traveling machine body 2 can be configured in a low cost structure as compared with a conventional monocoque machine body structure in which the engine frame 14 and the left and right machine body frames 16 are integrally connected.

  As shown in FIGS. 3 and 4, a rear vibration isolating member 254 is installed in the middle of the left and right widths of the upper surface of the upper connecting member 250. The rear surface of the engine 5 is coupled to the upper surface of the upper coupling member 250 via the rear vibration isolation member 254. Note that the left and right front vibration isolation members 230 and the rear vibration isolation members 254 are disposed at respective apex corners of a plan view triangle (a triangle in which the center of gravity of the engine 5 is located at the approximate center in plan view). (See FIG. 4). The front vibration isolation member 230 and the rear vibration isolation member 254 are arranged on a straight line (a straight line passing through the center of gravity of the engine 5 in a side view) that is substantially parallel to a diagonal line of the quadrangle in a side view of the engine 5 ( (See FIG. 3).

  FIG. 11 shows a hydraulic circuit 300 of the tractor 1 according to this embodiment, which includes a working machine hydraulic pump 94 and a traveling hydraulic pump 95 that are operated by the rotational force of the engine 5. The traveling hydraulic pump 95 is connected to a hydraulic cylinder 93 for power steering by the steering handle 9 via a control valve 302 for power steering. On the other hand, the left and right autobrake solenoid valves 67a and 67b, which are switching valves for actuating the brake cylinder 68 for the pair of left and right autobrakes 65, are connected.

  As shown in FIG. 11, the traveling hydraulic pump 95 includes a PTO clutch hydraulic solenoid valve (proportional control valve) 104 for the PTO hydraulic clutch 100 and each transmission portion of the transmission case 17, that is, a main shift described later. The main transmission proportional control valve 303 connected to the main transmission hydraulic cylinder 556 of the hydraulic continuously variable transmission 29, the main transmission switching valve 304 operated by the main transmission hydraulic control cylinder 303, and the traveling subtransmission hydraulic cylinder 55 by the excitation of the high speed side switching solenoid 306. A sub-transmission solenoid valve 307 for switching to a high speed side, a forward clutch solenoid valve 46 for operating hydraulic clutches 40 and 42 for switching between forward and reverse travel, a reverse clutch solenoid valve 48, the front wheel 3 and the rear wheel For switching the four-wheel drive hydraulic solenoid valve 80 for the four-wheel drive hydraulic clutch 74 for simultaneously driving the four and the front wheels 3 to the double speed drive It is connected to the double speed hydraulic electromagnetic valve 82 for the hydraulic clutch 76 for speed.

  As shown in FIG. 11, the work machine hydraulic pump 94 is connected to a lift control electromagnetic valve 301 for supplying hydraulic oil to a single-acting lift hydraulic cylinder 305 in the work machine lifting mechanism 20. The hydraulic circuit 300 includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like.

  Next, the internal structure of the mission case 17 will be described with reference to FIGS. 7 to 9 and FIG. The mission case 17 includes a mission case main body 17a that is divided into a front and a rear by a partition wall 31, a front side wall member 32 and a front wheel drive case 69 as a front lid, and a rear side wall member 33 as a rear lid. And have. A front wheel drive case 69 is detachably fastened to the front side of the transmission case body 17a with a bolt via a front side wall member 32. A rear side wall member 33 is detachably fastened to the rear side of the transmission case main body 17a with a bolt. That is, the mission case 17 is formed in a square box shape, and a front chamber 34 and a rear chamber 35 are formed inside the mission case body 17a. The front chamber 34 and the rear chamber 35 communicate with each other by cutting out a part of the partition wall 31 in the vicinity of the bottom of the transmission case body 17a so that the hydraulic oil (lubricating oil) in the interior moves relative to each other. is doing.

  As shown in FIGS. 6 and 7, a traveling auxiliary transmission gear mechanism 30 and a PTO transmission gear mechanism 96 described later are disposed in the front chamber 34. In the rear chamber 35, a hydrostatic continuously variable transmission 29, which is a traveling main transmission mechanism described later, and a differential gear mechanism 58 for rear wheels are arranged. As shown in FIG. 12, the above-described suction filter 220 and the hydraulic pumps 94 and 95 are arranged outside the front surface of the front wheel drive case 69.

  As shown in FIG. 6, an engine output shaft 24 is provided on the rear side surface of the engine 5 so as to protrude rearward. A flywheel 25 is directly connected to the engine output shaft 24. A telescopic power transmission shaft 28 having a universal shaft joint at both ends is provided between a main drive shaft 26 projecting rearward from the flywheel 25 and a main transmission input shaft 27 projecting forward from the front surface of the transmission case 17. Are connected. The rotation of the engine 5 is transmitted to the main transmission input shaft 27, and the speed is appropriately changed by the continuously variable transmission 29 and the traveling auxiliary transmission gear mechanism 30, and the transmission output is transmitted to the differential gear mechanism 58 for the rear wheels. The left and right rear wheels 4 are driven. Further, the rotation of the engine 5 appropriately shifted by the traveling auxiliary transmission gear mechanism 30 is transmitted from the front wheel drive case 69 to the front wheel side differential gear mechanism 86 of the front axle case 13 to drive the left and right front wheels 3. It is configured.

  Next, FIG. 9 shows an in-line hydraulic continuously variable transmission 29 in which a main transmission output shaft 36 is concentrically disposed on the main transmission input shaft 27. A hydraulic continuously variable transmission 29 is installed in the rear chamber 35 via a main transmission input shaft 27. The rear end side of the main transmission input shaft 27 opposite to the input side (front end side) of the main transmission input shaft 27 is rotatably supported by the rear side wall member 33 via the rear ball bearing 504. Yes.

  As shown in FIG. 9, a cylindrical main transmission output shaft 36 is fitted on the front side of the hydraulic continuously variable transmission 29, that is, 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. The middle of the main transmission output shaft 36 is penetrated by the partition wall 31, and the front end and the rear end 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 two sets of ball bearings 502. A main transmission output gear 37 is disposed at the front end portion of the main transmission output shaft 36. The input side of the main transmission input shaft 27 is rotatably supported in the shaft hole of the main transmission output shaft 36 via a roller bearing 503 (see FIG. 9). The input side (front end side) of the main transmission input shaft 27 projects forward from the front end of the main transmission output shaft 36.

  As will be described below, the continuously variable transmission 29 includes a variable displacement shift hydraulic pump unit 500 and a constant displacement shift hydraulic motor that operates with high-pressure hydraulic fluid discharged from the hydraulic pump unit 500. Part 501.

  As shown in FIG. 9, a cylinder block 505 for the hydraulic pump unit 500 and the hydraulic motor unit 501 is fitted on the main transmission input shaft 27 substantially in the middle between the partition wall 31 and the rear side wall member 33. ing. The main transmission input shaft 27 and the cylinder block 505 are connected by a spline 525. A hydraulic pump unit 500 is arranged on one side of the main transmission input shaft 27 opposite to the input side with a cylinder block 505 interposed therebetween. A hydraulic motor unit 501 is disposed on the other side of the cylinder block 505 that is the input side of the main transmission input shaft 27.

  As shown in FIG. 9, the hydraulic pump unit 500 includes a first holder 510 that is fixed to the inner surface of the transmission case 17 so as to face the side surface of the cylinder block 505, and the axis of the main transmission input shaft 27. The pump swash plate 509 disposed in the first holder 510 so that the tilt angle can be changed, the shoe 508 slidably provided on the pump swash plate 509, and the pump plunger 506 connected to the shoe 508 via a spherical universal joint And are provided. The cylinder block 505 is formed with a first plunger hole 507 in which the pump plunger 506 is detachably disposed. One end of the pump plunger 506 protrudes from the side surface of the cylinder block 505 in the direction of the pump swash plate 509 (right side in FIG. 8). That is, the hydraulic pump unit 500 includes a cylinder block 505, a pump plunger 506, a shoe 508, a pump swash plate 509, and a first holder 510.

  A sleeve 511 fitted to the main transmission input shaft 27, a roller bearing 512, and a radial and thrust load roller bearing 513 are interposed between the main transmission input shaft 27 and the first holder 510. . A nut 514 is provided behind the main transmission input shaft 27 to prevent the roller bearing 513 from slipping out.

  As shown in FIG. 9, the cylinder block 505 is provided with the same number of first spool valves 536 as the pump plungers 506. In addition, a first radial bearing 537 is disposed in the first holder 510. The first radial bearing 537 is disposed in the first holder 510 so as to be inclined at a constant inclination angle with respect to the axis of the main transmission input shaft 27. 9, about 180 degrees opposite side (back side of the drawing of FIG. 9) so that the position rotated about 90 degrees with respect to the pump swash plate 509 (the front side of the drawing of FIG. 9) is separated from the side surface of the cylinder block 505. The first radial bearing 537 is inclined and supported such that the first radial bearing 537 is close to the side surface of the cylinder block 505.

  On the other hand, the hydraulic motor unit 501 includes a second holder 519 arranged to face the side surface of the cylinder block 505, and a second holder 519 so as to maintain a constant inclination angle with respect to the axis of the main transmission input shaft 27. A motor swash plate 518 to be fixed, a shoe 517 slidably provided on the motor swash plate 518, and a motor plunger 515 connected to the shoe 517 via a spherical universal joint are provided. The cylinder block 505 is formed with a second plunger hole 516 for allowing the motor plunger 515 to be freely inserted and removed. One end of the motor plunger 515 protrudes from the side surface of the cylinder block 505 in the direction of the motor swash plate 518 (left side in FIG. 9).

  That is, the hydraulic motor unit 501 includes a cylinder block 505, a motor plunger 515, a shoe 517, a motor swash plate 518, and a second holder 519. A joint member 526 is fixed to the second holder 519 with a bolt 527. The output shaft 36 and the joint member 525 are connected by a spline 528.

  As shown in FIG. 9, between the main transmission input shaft 27 and the second holder 519, radial load roller bearings 520 and 521, a sleeve 522 fitted to the main transmission input shaft 27, the radial and A thrust load roller bearing 523 is interposed. A nut 524 is provided to prevent the roller bearing 523 from coming out of the main transmission input shaft 27.

  As shown in FIG. 9, the cylinder block 505 is provided with the same number of second spool valves 540 as the motor plungers 515. In addition, a second radial bearing 541 is disposed in the second holder 519. The second radial bearing 541 is disposed in the second holder 519 so as to be inclined at a constant inclination angle with respect to the axis of the main transmission input shaft 27. The opposite side (back side in FIG. 9) is separated from the side surface of the cylinder block 505 so that the position rotated about 90 degrees with respect to the motor swash plate 518 (front side in FIG. 9) is close to the side surface of the cylinder block 505. Thus, the second radial bearing 541 is configured to be inclined and supported.

  The pump plungers 506 and the same number of motor plungers 515 as the pump plungers 506 are alternately arranged on the same circumference of the rotation center of the cylinder block 505.

  As shown in FIG. 9, an annular groove-shaped first oil chamber 530 and an annular 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. Has been. The cylinder block 505 is formed with a first valve hole 532 and a second valve hole 533 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 through the first oil passage 534. The second plunger hole 516 communicates with the second valve hole 533 through the second oil chamber 531.

  As shown in FIG. 9, the first spool valve 536 is inserted into the first valve hole 532. The first spool valves 536 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 protrudes from the first valve hole 532 toward the first holder 510 by the elastic pressure of the back pressure spring force, and the front end of the first spool valve 536 is formed on the side surface of the outer ring 538 of the first radial bearing 537. It is in contact. Then, the first spool valve 536 reciprocates once in 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 534. The chambers 531 are configured to communicate with each other alternately.

  On the other hand, the second spool valve 540 is inserted into the second valve hole 533. The second spool valves 540 are arranged at substantially equal intervals on the same circumference of the rotation center of the cylinder block 505. The tip of the second spool valve 540 protrudes in the direction of the second holder 519 from the second valve hole 533 due to the back pressure spring force, and the tip of the second spool valve 540 contacts the side surface of the outer ring 542 of the second radial bearing 541. It touches. 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 535, or the first oil chamber 530 or second The oil chambers 531 are configured to alternately communicate with each other.

  As shown in FIG. 9, a charging hydraulic oil supply oil passage 543 is formed in the center of the main transmission input shaft 27 in the axial direction. The supply oil passage 543 is opened at the rear end face of the main transmission input shaft 27 and communicates with the discharge port of the traveling charge hydraulic pump 95 described above via an oil passage pipe (not shown). Further, the first charge valve 544 for supplying hydraulic oil in the hydraulic oil supply oil passage 543 to the first oil chamber 530 and the second charge valve 545 for supplying hydraulic oil in the hydraulic oil supply oil passage 543 to the second oil chamber 531. And.

  That is, with respect to the hydraulic closed circuit formed between the first and second plunger holes 507 and 516 and the first and second oil chambers 530 and 531, the first and second charge valves 544 and 545 are connected. The hydraulic oil is supplied from the hydraulic oil supply oil passage 543. It should be noted that hydraulic oil is supplied from the hydraulic oil supply oil passage 543 to the rotating portions of the hydraulic pump unit 500 and the motor unit 501 as lubricating oil via check valves.

  Further, a pump swash plate 509 is disposed on the outer periphery of the small diameter portion of the first holder 510 via an inclination angle adjustment fulcrum 555 (see FIG. 10). The pump swash plate 509 is arranged so that its inclination angle is adjustable with respect to the axis of the main transmission input shaft 27. A main transmission hydraulic cylinder 556 for main transmission operation, which is a transmission actuator 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. 10). The main transmission hydraulic cylinder 556 is disposed on the rear side wall member 33. A main transmission arm 558 is connected to a piston rod 557 of the main transmission hydraulic cylinder 556 (see FIG. 7). A piston rod 557 is connected to the tilt angle adjustment fulcrum 555 via a main transmission arm 558. That is, when the piston rod 557 is operated, the inclination angle of the pump swash plate 509 is changed, and the main transmission operation of the continuously variable transmission 29 is performed. The first holder 510 is attached to the rear side wall member 33 of the transmission case 17 via a connecting means such as a vibration isolator 605 described later so that the pump swash plate 509 does not rotate with respect to the main transmission input shaft 27. It is connected.

  The main transmission operation of the above-described inline hydraulic continuously variable transmission 29 will be described below. The hydraulic cylinder 556 is controlled by depressing the forward pedal 232 or the reverse pedal 233 (see FIG. 2) as the main transmission operation tool, and the inclination angle of the pump swash plate 509 is changed with respect to the axis of the main transmission input shaft 27. .

  First, even if the cylinder block 505 is rotated when the tilt angle of the pump swash plate 509 is kept substantially zero so that the pump swash plate 509 is substantially orthogonal to the axis of the main transmission input shaft 27, the first plunger hole The pump plunger 506 is supported in a substantially constant posture at 507 so as not to move forward and backward. That is, the hydraulic oil in the first plunger hole 507 is not discharged from the first oil passage 534 toward the first valve hole 532 in the discharge stroke of the pump plunger 506. Therefore, hydraulic oil is not supplied from the first plunger hole 507 to the second plunger hole 516, and the motor plunger 515 does not advance. Further, even during the suction stroke of the pump plunger 506, the hydraulic oil is not drawn into the first plunger hole 507, so the hydraulic oil is not discharged from the second plunger hole 516 into the first plunger hole 507 and the motor plunger 515 does not retract.

  That is, when the tilt angle of the pump swash plate 509 is substantially zero, the speed change motor 501 is not driven by the speed change pump portion 500, so that the motor swash plate 518 is fixed to the cylinder block 505 via the motor plunger 515. Maintained. Accordingly, the cylinder block 505 and the motor swash plate 518 rotate at substantially the same rotational speed in the same direction, and the main transmission input shaft 27 and the main transmission output shaft 36 are rotated at approximately the same rotational speed. The rotation speed is transmitted to the main transmission output gear 37 without being changed.

  Next, when the pump swash plate 509 is tilted with respect to the axis of the main transmission input shaft 27, the rotation of the cylinder block 505 that rotates integrally with the main transmission input shaft 27 causes the outer ring 538 of the first radial bearing 537 to be The 1-spool valve 536 slides back and forth, and the first oil chamber 530 or the second oil chamber 531 communicates with the first plunger hole 507 alternately every half rotation of the cylinder block 505. Further, the second spool valve 540 slides back and forth at the outer ring 542 of the second radial bearing 541, and the first oil chamber 530 or the second oil chamber 531 alternates with the second plunger hole 5016 every half rotation of the cylinder block 505. Communicated with

  A closed hydraulic circuit is formed between the first plunger hole 507 and the second plunger hole 516, and hydraulic oil is pumped from the first plunger hole 507 to the second plunger hole 516 in the discharge stroke of the pump plunger 506, The hydraulic fluid is returned from the second plunger hole 516 to the first plunger hole 507 during the suction stroke of the pump plunger 506, and the operation of the axial piston pump and the motor is performed.

  Therefore, when the pump swash plate 509 is inclined in one direction (positive inclination angle) with respect to the axis of the main transmission input shaft 27, the motor swash plate 518 is rotated in the same direction as the cylinder block 505, and the transmission motor 501 is rotated. The main transmission output shaft 36 is rotated at a higher rotational speed than the main transmission input shaft 27, and the rotational speed of the main transmission input shaft 27 is increased and transmitted to the main transmission output gear 37. . That is, the rotation speed of the transmission motor 501 driven by the transmission pump 500 is added to the rotation speed of the main transmission input shaft 27 and transmitted to the main transmission output gear 37. Therefore, in tillage work (high load work) that moves at high speed, etc., in the range of the rotational speed higher than the rotational speed of the main transmission input shaft 27, it is proportional to the inclination (positive inclination angle) of the pump swash plate 509, The speed change output (travel speed) from the main speed change output gear 37 is changed, and the maximum travel speed is reached at the maximum inclination (positive inclination angle) of the pump swash plate 509.

  On the other hand, when the pump swash plate 509 is inclined in the other direction (negative inclination angle) with respect to the axis 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 transmission 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 rotation speed of the transmission motor 501 driven by the transmission pump 500 is subtracted from the rotation speed of the main transmission input shaft 27 and transmitted to the main transmission output gear 37. Therefore, in tillage work (low load work) that moves at low speed, etc., in the range of the rotational speed lower than the rotational speed of the main transmission input shaft 27, in proportion to the inclination (negative inclination angle) of the pump swash plate 509, The speed change output (travel speed) from the main speed change output gear 37 is changed, and the minimum travel speed is reached at the maximum inclination (negative inclination angle) of the pump swash plate 509.

  With reference to FIGS. 6 and 7, a forward / backward switching structure performed via the forward gear 41 and the reverse gear 43 will be described. In the front chamber 34 of the transmission case 17, a forward gear 41 and a reverse gear 43 for switching between forward and reverse, and a traveling auxiliary transmission gear mechanism 30 for switching between a low speed and a high speed are arranged. A travel counter shaft 38 and a reverse rotation shaft 39 are disposed inside the front chamber 34 where the main transmission output gear 37 is disposed.

  As shown in FIG. 7, the travel counter shaft 38 is connected by a forward gear 41 connected by a forward wet multi-plate hydraulic clutch 40 and a reverse wet multi-plate hydraulic clutch 42. The reverse gear 43 is fitted. The forward gear 41 is meshed with the main transmission output gear 37. The main transmission output gear 37 meshes with a reverse gear 44 provided on the reverse shaft 39. The reverse gear 43 meshes with a reverse output gear 45 provided on the reverse shaft 39.

  Accordingly, when the forward pedal 232 or the forward switch (not shown) is operated forward, the forward hydraulic solenoid valve 46 operates the clutch cylinder 47 to continue the forward hydraulic clutch 40 and travel with the main transmission output gear 37. The counter shaft 38 is connected to the forward gear 41 (see FIGS. 6 and 7).

  On the other hand, when the reverse pedal 233 or the reverse switch (not shown) is operated reversely, the reverse hydraulic solenoid valve 48 operates the clutch cylinder 49 to continue the reverse hydraulic clutch 42 and travel with the main transmission output gear 37. The counter shaft 38 is connected to the reverse gear 43 (see FIGS. 6 and 7).

  When the forward pedal 232 and the reverse pedal 233 are maintained at the initial (neutral) position (when both the forward and reverse switches are off), the forward and reverse wet multi-plate hydraulic clutches 40, Both 42 are cut off, and the driving force from the main transmission output gear 37 output to the front wheels 3 and the rear wheels 4 is substantially zero (main clutch disengaged).

  Next, a switching structure between the low speed and the high speed performed through the traveling auxiliary transmission gear mechanism 30 will be described. As shown in FIGS. 6 and 7, 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. Between the travel counter shaft 38 and the auxiliary transmission shaft 50, low-speed gears 51 and 52 for auxiliary transmission and high-speed gears 53 and 54 for auxiliary transmission are arranged. Further, a low speed clutch 56 and a high speed clutch 57 that are continued or disconnected by the auxiliary transmission hydraulic cylinder 55 are provided.

  Accordingly, the low-speed clutch 56 or the high-speed clutch 57 is continued in the auxiliary transmission hydraulic cylinder 55 by operating the auxiliary transmission lever (not shown) or the low-speed and high-speed auxiliary transmission switch (not shown) or detecting the rotational speed of the engine 5. In this case, the low-speed gear 52 or the high-speed gear 54 is connected to the auxiliary transmission shaft 50, and traveling driving force is output from the auxiliary transmission shaft 50 to the front wheels 3 and the rear wheels 4.

  As shown in FIGS. 6 and 7, the auxiliary transmission shaft 50 has a rear end portion that extends through the inner partition wall 31 and extends into the rear chamber 35 of the transmission case 17 (see FIG. 6). A pinion 59 is provided at the rear end of the auxiliary transmission shaft 50. In addition, a rear wheel differential gear mechanism 58 for transmitting a driving force to the left and right rear wheels 4 is disposed inside the rear chamber 35. The rear wheel 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 on the ring gear 60, and left and right differential output shafts 62. ing. A differential output shaft 62 is connected to the rear axle 64 via a final gear 63 and the like, and the rear wheel 4 provided on the rear axle 64 is driven.

  As shown in FIG. 6, left and right brakes 65 are arranged on the left and right differential output shafts 62, and when the brake pedal 66 is depressed, the left and right brakes 65 are actuated to brake the rear wheels 4. become. The brake cylinder 68 is actuated by the autobrake solenoid valve 67 by detecting the steering angle of the steering handle 9 and the like so that the brake 65 is automatically brake controlled to perform a turning run such as a U-turn. .

  Next, with reference to FIGS. 6 and 7, the drive switching structure between the left and right front wheels 3 and the left and right rear wheels 4 will be described. A front wheel drive case 69 is fixed to the front side wall member 32 of the mission case 17. The front wheel drive case 69 includes 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 gears 70 and 71. The front wheel output shaft 73 is fitted with a four-wheel drive gear 75 connected by a four-wheel drive hydraulic clutch 74 and a double speed gear 77 connected by a double speed hydraulic clutch 76. The four-wheel drive gear 75 and the double speed gear 77 are connected to the front wheel input shaft 72 via gears 78 and 79.

  Therefore, when the two-wheel drive and four-wheel drive switching lever (not shown) is operated four-wheel drive, the clutch cylinder 81 is operated by the four-wheel drive hydraulic solenoid valve 80 and the four-wheel drive hydraulic clutch 74 is continued. That is, the front wheel input shaft 72 and the front wheel output shaft 73 are connected by the four-wheel drive gear 75, and the front wheel 3 is driven together with the rear wheel 4.

  Next, the switching operation 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 clutch cylinder 83 is operated by the double speed hydraulic solenoid valve 82, and the double speed hydraulic clutch 76 is continued. That is, the front wheel input shaft 72 and the front wheel output shaft 73 are connected by the double speed gear 77 and the front wheel 3 is driven at a high speed about twice as high as the speed when the front wheel 3 is driven by the four-wheel drive gear 75. The wheel 3 is driven.

  As shown in FIG. 6, the front wheel 3 is powered between a front wheel input shaft 84 projecting rearward from the front axle case 13 and a front wheel output shaft 73 projecting forward from the front surface of the transmission case 17. Are connected via a front wheel drive shaft 85 that transmits In addition, a differential gear mechanism 86 for the front wheels that transmits the driving force to the left and right front wheels 3 is disposed inside the front axle case 13.

  The front wheel differential gear mechanism 86 includes a ring gear 88 that meshes with a pinion 87 at the front end of the front wheel input 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 via a final gear 91 or the like, and the front wheels 3 provided on the front axle 92 are driven (see FIG. 6). Further, a hydraulic cylinder 93 for power steering that changes the traveling direction of the front wheel 3 to the left and right by the steering operation of the steering handle 9 is disposed on the outer surface of the front axle case 13 (see FIG. 3).

  As shown in FIGS. 6 and 8, on the front side of the front side wall member 32 of the mission case 17, a work machine hydraulic pump 94 for supplying hydraulic fluid to the work machine lifting mechanism 20, the mission case 17. And a traveling charge hydraulic pump 95 for supplying hydraulic oil to the hydraulic cylinder 93 for power steering. A mission case 17 is used in combination as an oil tank so that hydraulic oil in the mission case 17 is supplied to the hydraulic pumps 94 and 95.

  Next, referring to FIGS. 6, 8, and 12, the structure of switching the driving speed of the PTO shaft 23 (four forward rotations and one reverse rotation) will be described. A PTO transmission gear mechanism 96 for transmitting power from the engine 5 to the PTO shaft 23 is disposed in the front chamber 34 of the mission case 17 (see FIG. 8). A pump drive shaft 97 for transmitting power from the engine 5 to the hydraulic pumps 94 and 95 is disposed in the front wheel drive case 69 (see FIG. 12).

  As shown in FIG. 8, the PTO transmission gear mechanism 96 includes a PTO counter shaft 98 and a PTO transmission output shaft 99. A PTO input gear 101 connected via a PTO hydraulic clutch 100 is fitted on the PTO counter shaft 98. The PTO input gear 101 meshes with the input side gear 102 provided on the main transmission input shaft 27 and the output side gear 103 of the pump drive shaft 97, and the pump drive shaft 97 is connected to the main transmission input shaft 27. .

  Therefore, when the PTO clutch lever or the PTO clutch switch (not shown) is continuously operated, the clutch cylinder 105 is operated by the PTO clutch hydraulic solenoid valve 104 (see FIG. 6) to continue the PTO hydraulic clutch 100. Then, the main transmission input shaft 27 and the PTO counter shaft 98 are connected via the PTO input gear 101.

  Further, the first-speed gear 106, the second-speed gear 107, the third-speed gear 108, the fourth-speed gear 109, and the reverse gear 110 are fitted on the PTO transmission output shaft 99 for PTO output ( (See FIGS. 6 and 8).

  As shown in FIGS. 6 and 8, a shift shifter 111 is pivotally supported on the PTO shift output shaft 99 so as to be movable by a spline. Each gear 106, 107, 108, 109, 110 is selectively connected to the PTO shift output shaft 99 via the shift shifter 111. A shift arm 112 connected to a PTO shift lever (not shown) is engaged with the shift shifter 111.

  Therefore, when the PTO shift lever is operated to shift, the shift shifter 111 moves linearly along the axis of the PTO shift output shaft 99 via the shift arm 112, and the gears 106, 107, 108, 109, 110 Any one of these is selected and connected to the PTO speed change output shaft 99 (see FIGS. 6 and 8). That is, the first, second, third, fourth, and reverse PTO shift outputs are transmitted from the PTO shift output shaft 99 to the PTO shaft 23 via the PTO transmission gear 113 and the PTO output gear 114. .

  In FIG. 7, a hydraulic continuously variable transmission, which is a main transmission mechanism, is provided with a rotation detection gear 115 provided on the reverse shaft 39 and a main transmission pickup 116 that detects the number of rotations of the main transmission output gear 37 facing each other. 29 continuously variable transmission output rotation speeds are detected by the main transmission pickup 116. Further, a vehicle speed pickup 117 for detecting the rotational speed of the gear 78 of the front wheel input shaft 72 is installed, and the traveling speed (vehicle speed) is determined based on the rotational speeds of the front wheel input shaft 72 and the auxiliary transmission shaft 50. It is comprised so that it may detect by.

  Next, referring to FIGS. 5, 12, 13, and 16, a mounting structure of the working machine hydraulic pump 94, the traveling charge hydraulic pump 95, and the suction filter 220 will be described. A suction filter 220 as a low pressure hydraulic filter, a working machine hydraulic pump 94 and a steering charge hydraulic pump 95 as a working hydraulic pump are arranged on the outer surface of the front portion of the mission case 17.

  As shown in FIGS. 5 and 12, a suction filter 220 for filtering hydraulic oil is fixed to the front surface of the mission case 17 via a filter bracket 221. That is, the filter pedestal 69 a is formed on the front wheel drive case 69 at the front of the mission case 17, the filter bracket 221 is fastened to the outer surface of the filter pedestal 69 a, and the suction filter 220 is fixed to the filter bracket 221. The suction filter 220 protrudes in front of the mission case 17 at the lower part of the front surface of the mission case 17.

  As shown in FIG. 12, a front pipe receiving portion 69b is formed on the inner surface of the filter pedestal 69a, one end side of the oil supply pipe 222 is fitted into the connection hole 69c of the front pipe receiving portion 69b, and the suction hole 221a of the filter bracket 221 The connection hole 69c is communicated, and the suction filter 220 is communicated with one end side of the oil supply pipe 222 via the filter bracket 221. The middle of the oil supply pipe 222 passes through the wall hole 32 a of the front side wall member 32 of the mission case 17. A rear pipe receiving portion 31a is formed in the partition wall 31 of the transmission case 17, the other end side of the oil supply pipe 222 is fitted into the rear pipe receiving portion 31a, and the other end side of the oil supply pipe 222 is inserted into the rear chamber 35 of the transmission case 17. Is communicated. That is, the other end side of the oil supply pipe 222 is communicated with the lower position inside the rear chamber 35 via the communication hole 31b of the rear pipe receiving portion 31a, and the rear chamber 35 is connected to the suction filter 220 via the oil supply pipe 222. The bottom hydraulic fluid will be supplied.

  As shown in FIGS. 12 and 16, a pump base 69d is formed on the front wheel drive case 69 at the front of the mission case 17, and a steering charge hydraulic pump 95 is fastened to the outer surface of the pump base 69d. The work machine hydraulic pump 94 is fixed to the front side surface of the charge hydraulic pump 95, and the work machine hydraulic pump 94 and the steering charge hydraulic pump 95 are fixed substantially in series on the pump base 69d. The working machine hydraulic pump 94 and the steering charge hydraulic pump 95 project from the front of the transmission case 17 at the lower part of the front surface of the transmission case 17.

  As shown in FIGS. 12 and 16, one end side of the suction hose 224 is connected to the oil outlet 221 b of the filter bracket 221, and is connected to the suction port of the work machine hydraulic pump 94 and the travel charge hydraulic pump 95. The other end of the bifurcated shape of the suction hose 224 is connected. That is, the work machine hydraulic pump 94 and the travel charge hydraulic pump 95 are communicated with the suction filter 220 via the suction hose 224. Therefore, the working hydraulic pump 94 and the traveling hydraulic pump 95 are supplied with the hydraulic fluid at the bottom of the rear chamber 35 of the transmission case 17 via the suction filter 220 (see FIG. 12).

  As shown in FIG. 16, the suction hose 224 is bent in a mountain shape when viewed from the front, and is formed so that the middle portion of the suction hose 224 is higher than both ends of the suction hose 224. An intermediate portion of the suction hose 224 is disposed substantially directly above the front wheel output shaft 73 described above, and a suction filter 220 is disposed on the right side of the front wheel output shaft 73 in the traveling direction. Further, a work machine hydraulic pump 94 and a travel hydraulic pump 95 are arranged on the left side of the front wheel output shaft 73 in the traveling direction. The suction filter 220, the working machine hydraulic pump 94, and the traveling hydraulic pump 95 are installed separately on the left and right sides of the front wheel output shaft 73. That is, the suction filter 220, the working machine hydraulic pump 94, and the traveling hydraulic pump 95 are arranged in a substantially horizontal line at a low position on the front side of the transmission case 17 between the left and right machine body frames 16. .

  Therefore, the driving force to the front wheel 3 can be taken out from the low position on the front surface of the mission case 17 via the front wheel output shaft 73. In addition, the height difference between the bottom of the rear chamber 35, the oil supply pipe 222, the suction filter 220, the working machine hydraulic pump 94 and the traveling hydraulic pump 95 is reduced, and the working machine hydraulic pump 94 and The suction negative pressure of the traveling hydraulic pump 95 can be reduced. Further, for example, compared to a structure in which the suction filter 220 is disposed inside or outside of the mission case 17, the oil outlet on the side of the suction filter 220, the suction port of the working machine hydraulic pump 94 and the traveling hydraulic pump 95 The suction hose 224 can be formed in a short length, and the suction negative pressure of the working machine hydraulic pump 94 and the traveling hydraulic pump 95 can be reduced. That is, the front wheel output shaft 73, the suction filter 220, the working machine hydraulic pump 94, and the traveling hydraulic pump 95 are incorporated in a compact and functional manner by effectively using the front side of the mission case 17. .

  As shown in FIGS. 6, 11, 12, and 16, a transmission case 17 for shifting power from the engine 5 mounted on the traveling machine body 2, and left and right aircrafts connected to the left and right outer surfaces of the transmission case 17. In a work vehicle comprising a frame 16, a work machine hydraulic pump 94 and a travel hydraulic pump 95 as work hydraulic pumps driven by power from the engine 5 are provided on the outer surface of the front portion of the transmission case 17, Since the working machine hydraulic pump 94 and the traveling hydraulic pump 95 are provided with a suction filter 220 connected via a suction hose 224, the working machine hydraulic pump 94 and the traveling hydraulic pump 95 are arranged. And the suction filter 220 can be brought close to each other so that the suction hose 224 can be formed short. Intake negative pressure of the travel hydraulic pump 95 can be reduced. Since the working machine hydraulic pump 94 and the traveling hydraulic pump 95 or the suction filter 220 are not projected outwardly from the left and right sides of the transmission case 17, the working machine hydraulic pump 94 and the working machine hydraulic pump 94 by plowing are used in, for example, tilling work using a plow or the like. Damage to the traveling hydraulic pump 95 or the suction filter 220 can be prevented. Since the working machine hydraulic pump 94, the traveling hydraulic pump 95, and the suction filter 220 can be configured as a part of the mechanism of the transmission case 17, the working machine hydraulic pump 94, the traveling hydraulic pump 95, and the suction filter 220 are added to the transmission case 17. The mission case 17 can be attached to and detached from the fuselage frame 16 in a state where is assembled.

  As shown in FIG. 12, one end side of the oil supply pipe 222 is connected to the suction filter 220, and the other end side of the oil supply pipe 222 is connected to the rear chamber 35 as a rear axle chamber in the rear part of the transmission case 17. Since the hydraulic oil in the rear chamber 35 can be supplied to 220, the transmission gear (sub-transmission gear mechanism) is connected to the working machine hydraulic pump 94 and the traveling hydraulic pump 95 via the suction filter 220. The hydraulic oil at the bottom of the rear chamber 35 with less air mixing than in the vicinity of the vicinity 30 or the like) can be supplied, and a reduction in efficiency due to air suction of the working machine hydraulic pump 94 and the traveling hydraulic pump 95 can be easily prevented.

  As shown in FIG. 12, a partition wall as a partition in the mission case 17 that connects one end side of the oil supply pipe 222 to a front wheel drive case 69 as a front lid body of the mission case 17 and forms a rear chamber 35. 31, the other end of the oil supply pipe 222 is connected to the oil supply pipe 222. Therefore, the oil supply pipe 222 is provided in the mission case 17 using the front wheel drive case 69 and the partition wall 31 that are part of the mission case 17. Can be assembled easily. Therefore, a special part for fixing the oil supply pipe 222 to the transmission case 17 becomes unnecessary. Further, since the suction filter 220 can be attached to and detached from the mission case 17 regardless of the oil supply pipe 222, it is possible to improve the assembly workability and maintenance workability of the suction filter 220 that needs to be replaced at regular intervals.

  As shown in FIGS. 7 and 12, the auxiliary transmission gear mechanism 30 and the PTO transmission gear mechanism 96 are arranged in the transmission case 17 in front of the partition wall 31, and the rear wheel differential is arranged in the rear chamber 35. Since the gear mechanism 58 and the hydraulic continuously variable transmission 29 are disposed, the differential gear mechanism 58 for the rear wheel and the hydraulic continuously variable transmission 29 are disposed on the high side in the rear chamber 35, and The suction side of the oil supply pipe 222 can communicate with a large space on the bottom side in the rear chamber 35. Therefore, hydraulic fluid with less air in the mission case 17 can be supplied to the working machine hydraulic pump 94 and the traveling hydraulic pump 95 via the oil supply pipe 222.

  As shown in FIGS. 13 and 16, between the left and right airframe frames 16, a work machine hydraulic pump 94 and a traveling gear are provided on both left and right sides of the front wheel output shaft 73 protruding forward from the front surface of the transmission case 17. Since the hydraulic pump 95 and the suction filter 220 are arranged, the space in front of the transmission case 17 formed between the left and right machine body frames 16 is effectively used to The traveling hydraulic pump 95 and the suction filter 220 can be installed in a compact manner. Since the working machine hydraulic pump 94 and the traveling hydraulic pump 95 can be installed at a low position in front of the transmission case 17, the suction negative pressure of the working machine hydraulic pump 94 and the traveling hydraulic pump 95 can be reduced, and the working machine hydraulic pressure can be reduced. The hydraulic oil in the transmission case 17 can be sufficiently supplied to the pump 94, the traveling hydraulic pump 95, and the suction filter 220, and the efficiency reduction of the working machine hydraulic pump 94 and the traveling hydraulic pump 95 due to the suction of air can be prevented.

  Next, with reference to FIG. 9, FIG. 12, FIG. 17 to FIG. 19, the vibration isolating structure of the hydraulic continuously variable transmission 29 will be described. As shown in FIGS. 9, 12, and 17, the power input side from the engine 5 of the main transmission input shaft 27 in the hydraulic continuously variable transmission 29 is divided into a partition of the transmission case 17 a via the front ball bearing 502. It is pivotally supported on the wall 31. Further, the rear end side of the main transmission input shaft 27 opposite to the power input side from the engine 5 is freely rotatable to a rear side wall member 33 as a rear cover body of the transmission case 17 via a rear ball bearing 504. It is pivotally supported.

  As shown in FIGS. 17 to 19, the rear side wall member 33 described above is arranged in the extending direction of the axis of the main transmission input shaft 27 by the bolt 601 and the positioning pin 602 on the outer surface of the transmission case main body 17 a on the rear side. Fasten detachably. Further, a screw hole 603 is formed on the rear surface of the first holder 510 in the hydraulic continuously variable transmission 29 described above. A substantially cylindrical vibration isolator 605 is detachably fitted to a vibration isolating bolt 604 that is screwed into the screw hole 603 from the rear of the first holder 510. The vibration isolator 605 includes an inner cylinder 605a that fits on the vibration isolating bolt 604, an outer cylinder 605b that is removably fitted into a front opening-shaped bag hole-shaped fitting hole 606 of the rear side wall member 33, and an inner cylinder 605b. It consists of a vibration-proof rubber 605c that is sintered and fixed between the cylinder 605a and the outer cylinder 605b. That is, a plurality of vibration isolator 605 is disposed on the rear surface of the first holder 510, and the rear surface of the first holder 510 is connected to the inner surface of the rear side wall member 33 via the plurality of vibration isolator 605.

  As shown in FIG. 17, the anti-vibration bolts 604 are arranged substantially parallel to the axis of the main transmission input shaft 27 fitted with the first holder 510. As shown in FIG. 18, two sets of four vibration isolators on the same circumference centered on the axis of the main transmission input shaft 27 at a substantially symmetrical position across the axis of the main transmission input shaft 27. 605 is arranged. The two sets of vibration isolators 605 are disposed at substantially symmetrical positions across a straight line connecting the axis of the main transmission input shaft 27 and the axis of the PTO shaft 23. That is, the vibration isolator 605 is fitted into the plurality of fitting holes 606 opened on the inner surface (front surface) of the rear side wall member 33 so as to be detachable in the extending direction of the axis of the main transmission input shaft 27. Accordingly, the input side of the hydraulic continuously variable transmission 29 and the opposite side thereof are pivotally supported by the transmission case 17 via the front ball bearing 502 and the rear ball bearing 504, and the weight of the hydraulic continuously variable transmission 29 is determined by each ball. Since it is supported by the transmission case 17 via the bearings 502 and 504, the vibration isolator 605 receives only the rotational moment of the hydraulic continuously variable transmission 29 and the rotational vibration of the hydraulic continuously variable transmission 29 is applied to the transmission case 17. Propagation is prevented (see FIG. 19).

  Next, with reference to FIGS. 17 and 19, an assembly operation for connecting the transmission case 17 and the hydraulic continuously variable transmission 29 with the vibration isolator 605 will be described below. First, the hydraulic continuously variable transmission 29 is assembled to the main transmission input shaft 27, and the anti-vibration bolts 604 fitted with the anti-vibration bodies 605 are screwed into the first holder 510, and the anti-vibration bodies 605 are attached to the first holder 510. Is fastened (see FIG. 19). Then, the main transmission input shaft 27 fitted with the hydraulic continuously variable transmission 29 is assembled in the transmission case body 17a, and the rear side wall member 33 is connected to the rear surface of the transmission case body 17a via the positioning pins 602. The rear side wall member 33 is fastened to the rear surface of the main body 17a with a bolt 601, and the assembly work for connecting the transmission case 17 and the hydraulic continuously variable transmission 29 with the vibration isolator 605 is completed (see FIG. 17).

  As shown in FIGS. 8, 12, and 17, a hydraulic continuously variable transmission 29 that shifts power from the engine 5 mounted on the traveling machine body 2, and a mission case 17 that incorporates the hydraulic continuously variable transmission 29. In a work vehicle in which a hydraulic continuously variable transmission 29 is disposed on a main transmission input shaft 27 that transmits power from the engine 5, the transmission case 17 is provided with a front ball bearing 502 and a rear ball bearing 504. Thus, the power input side of the main transmission input shaft 27 and the opposite side thereof are respectively supported, and the transmission case 17 receives only the rotational moment of the hydraulic continuously variable transmission 29 via the vibration isolator 605. Since the hydraulic continuously variable transmission 29 is connected, propagation of the rotational moment of the hydraulic continuously variable transmission 29 to the transmission case 17 can be reduced, and mechanical vibration of the transmission case 17 can be easily prevented. Can, it is possible to improve the anti-vibration and acoustic insulation of the transmission case 17. Further, since the weight of the hydraulic continuously variable transmission 29 is received by the front ball bearing 502 and the rear ball bearing 504, it is not necessary to receive the weight of the hydraulic continuously variable transmission 29 by the vibration isolator 605. Can be made compact.

  As shown in FIGS. 17, 18, and 19, a vibration isolator 605 is disposed in the hydraulic continuously variable transmission 29, and the main transmission input shaft 27 is inserted into a fitting hole 606 as a fitting portion of the transmission case 17. Since the vibration isolator 605 is fitted so as to be detachable in the axial direction, the hydraulic continuously variable transmission 29 and the vibration isolator 605 are assembled to the main transmission input shaft 27 as a single unit structure. The assembly and disassembly workability of the transmission case 17 and the hydraulic continuously variable transmission 29 can be improved.

  As shown in FIGS. 7, 8, and 12, the hydraulic continuously variable transmission 29 includes a hydraulic pump unit 500 and a hydraulic motor unit 501, and the second holder 519 serving as a swash plate holder of the hydraulic motor unit 501 is mainly used. A transmission output shaft 36 is connected, and a rear side wall member 33 as a rear cover body of the transmission case 17 and a first holder 510 as a swash plate holder of the hydraulic pump unit 500 are connected by a vibration isolator 605. Therefore, for example, the auxiliary transmission gear mechanism 30, the PTO transmission gear mechanism 96, the four-wheel drive gear 75 and the double speed gear 77 as the front wheel drive gear mechanism, etc. are built in the front portion of the transmission case 17, and the transmission case. The hydraulic continuously variable transmission 29, the differential gear mechanism for the rear wheels, and the like can be built in the rear portion of 17. Therefore, a space for the hydraulic continuously variable transmission 29 can be easily secured at the rear portion in the mission case 17, and the hydraulic continuously variable transmission 29 can be assembled from the rear side of the mission case 17 with a simple work procedure. Maintenance workability of the hydraulic continuously variable transmission 29 and the vibration isolator 605 can be improved.

  Next, with reference to FIG. 5, FIG. 12, FIG. 13, FIG. 17 and FIG. 18, the mounting structure of the PTO shaft 23 and the PTO output gear 114 described above will be described. As shown in FIGS. 12 and 17, a PTO bearing wall 615 is erected on the bottom surface of the rear part in the mission case 17, and the front end side of the PTO shaft 23 is pivotally supported on the PTO bearing wall 615 via a ball bearing 616. The intermediate portion of the PTO shaft 23 is pivotally supported on the rear side wall member 33 via the ball bearing 617, and the PTO output gear 114 is fitted on the PTO shaft 23 between the ball bearings 616 and 617 via the spline 23a. . That is, the PTO shaft 23 is passed through the shaft hole of the PTO output gear 114, the intermediate portion of the PTO shaft 23 is pivotally supported on the rear side wall member 33 via the ball bearing 617, and then the bolt 601 is mounted on the rear portion of the transmission case 17. , The rear side wall member 33 is fastened, the PTO shaft 23 is rotatably supported on the rear side wall member 33 and the PTO bearing wall 615, and the rear end side of the PTO shaft 23 protrudes to the rear side of the transmission case 17. .

  As shown in FIGS. 12 and 17, the rear end side of the PTO speed change output shaft 99 is pivotally supported by the rear side wall member 33 and the PTO bearing wall 615 via ball bearings 618 and 619. The PTO transmission gear 113 is fitted on the PTO speed change output shaft 99 between the ball bearings 618 and 619 via the spline 99a. The PTO shaft 23 is connected to the PTO transmission output shaft 99 via the PTO transmission gear 113 and the PTO output gear 114. Therefore, the power from the engine 5 is transmitted to the PTO shaft 23 via the front PTO transmission gear mechanism 96 and the PTO transmission output shaft 99 in the transmission case 17.

  As shown in FIGS. 17 and 18, the first holder 510 of the hydraulic continuously variable transmission 29 and the rear lid body of the transmission case 17 in the state where the PTO output gear 114 is always meshed with the PTO transmission gear 113. A PTO output gear 114 is disposed between the rear side wall member 33 and the rear side wall member 33. That is, a part of the PTO output gear 114 is inserted between the hydraulic continuously variable transmission 29 and the rear side wall member 33, and the hydraulic continuously variable transmission 29 and the PTO output gear 114 are overlapped by a constant width dimension Dr. Accordingly, the uppermost part of the PTO output gear 114 is formed higher than the lowermost part of the rear part of the hydraulic continuously variable transmission 29, and the front side of the PTO output gear 114 is placed on the rear side of the hydraulic continuously variable transmission 29. The transmission 29 is wrapped by a certain width dimension Dr as viewed in the axial direction of the axial line.

  With the configuration described above, the PTO output gear 114 is arranged below the hydraulic continuously variable transmission 29 (outside the outer diameter of the hydraulic continuously variable transmission 29) so as to avoid interference with the hydraulic continuously variable transmission 29. As compared with the conventional structure in which the PTO shaft 23 is disposed, the mounting height of the PTO shaft 23 is not limited by the hydraulic continuously variable transmission 29. That is, the vertical inter-axis distance between the hydraulic continuously variable transmission 29 and the PTO shaft 23 is shortened while maintaining the horizontal width of the hydraulic continuously variable transmission 29 and the PTO output gear 114 substantially constant. The installation height of the PTO shaft 23 can be increased with respect to the bottom of the mission case 17. Therefore, the PTO shaft 23 can be arranged at a high position in the rear portion of the transmission case 17 in which the hydraulic continuously variable transmission 29 and the differential gear mechanism 58 are built in without increasing the width in the left-right direction of the transmission case 17.

  On the other hand, as shown in FIG. 5, the hydraulic continuously variable transmission 29 is arranged at a position higher than the differential output shaft 62 of the differential gear mechanism 58 built in the mission case 17. That is, the hydraulic continuously variable transmission 29 is arranged at a position higher than the oil level of the hydraulic oil in the mission case 17. Further, as shown in FIG. 13, the PTO shaft 23 is disposed between the hydraulic continuously variable transmission 29 and the differential gear mechanism 58 in plan view. That is, a space necessary for installing the hydraulic continuously variable transmission 29 can be formed above the rear portion in the mission case 17 without being limited by the differential gear mechanism 58.

  As is apparent from the above description and FIGS. 12, 17, and 18, a hydraulic continuously variable transmission 29 that shifts the power from the engine 5 mounted on the traveling machine body 2 and the hydraulic continuously variable transmission 29 are incorporated. In a work vehicle having a PTO shaft 23 protruding from the rear side of the mission case 17, a PTO output gear 114 for transmitting power from the PTO transmission gear mechanism 96 is disposed on the PTO shaft 23. The uppermost part of the PTO output gear 114 is formed higher than the lowermost part of the side opposite to the input side of the hydraulic continuously variable transmission 29, and the hydraulic continuously variable transmission 29 is viewed in the axial direction of the hydraulic continuously variable transmission 29. 29 and the PTO output gear 114 are overlapped, so that the mounting height of the PTO shaft 23 is not limited by the hydraulic continuously variable transmission 29. Therefore, since the PTO shaft 23 can be easily arranged at a high position of the mission case 17, the vertical width dimension of the mission case 17 can be made compact. Further, the height of the ground such as the PTO shaft 23 or a transmission shaft with a universal joint (not shown) connected to the PTO shaft 23 can be increased to reduce the winding of the grass.

  As apparent from the above description and FIGS. 12, 17, and 18, the rear side wall member 33 as the rear cover body of the transmission case 17 and the rear end side opposite to the input side of the hydraulic continuously variable transmission 29. Since the PTO output gear 114 is disposed therebetween, a space for installing the PTO output gear 114 can be easily secured between the hydraulic continuously variable transmission 29 and the rear side wall member 33. When the PTO shaft 23 is disposed on the rear side wall member 33, the hydraulic continuously variable transmission 29 and the PTO shaft 23 can be detached from the rear side of the transmission case 17 by detaching the rear side wall member 33. Therefore, the assembly workability of the transmission case 17 and the maintenance workability of the hydraulic continuously variable transmission 29 can be improved.

  As apparent from the above description and FIG. 13, the PTO shaft 23 is disposed between the hydraulic continuously variable transmission 29 and the differential gear mechanism 58 in a plan view. A space necessary for installation of the hydraulic continuously variable transmission 29 can be secured above the rear portion of the inside without being limited by the differential gear mechanism 58. That is, since the space in the transmission case 17 on the opposite side of the differential gear mechanism 58 across the PTO shaft 23 is effectively used, the hydraulic continuously variable transmission 29 can be easily arranged at a high position in the transmission case 17. Therefore, the PTO shaft 23 can also be easily arranged at a high position of the mission case 17.

  As apparent from the above description and FIG. 5, the hydraulic continuously variable transmission 29 is disposed at a position higher than the differential output shaft 62 of the differential gear mechanism 58 built in the mission case 17. The hydraulic continuously variable transmission 29 can be arranged at a position higher than the oil level of the hydraulic oil in the mission case 17, and the hydraulic oil in the mission case 17 is hardly agitated by the rotation of the hydraulic continuously variable transmission 29. Therefore, the power transmission loss of the hydraulic continuously variable transmission 29 can be reduced, and the temperature rise of the hydraulic oil in the transmission case 17 can be prevented. Further, for example, even in the case where the traveling auxiliary transmission gear mechanism 30, the differential gear mechanism 58, the PTO transmission gear mechanism 96, and the like are installed inside the transmission case 17, as in the transmission structure of the tractor 1, the transmission case The installation space of the hydraulic continuously variable transmission 29 can be easily secured at the rear portion of the 17. Further, the attaching / detaching operation of the hydraulic continuously variable transmission 29 can be executed in a state where the differential gear mechanism 58 is incorporated in the rear portion of the transmission case 17. Further, an installation space for the PTO transmission gear mechanism 96 or the traveling auxiliary transmission gear mechanism 30 or the like can be secured in the front portion of the transmission case 17 on the input side of the hydraulic continuously variable transmission 29. For example, the transmission case 17 of the tractor 1 can be reduced in size. Or weight reduction, and the manufacturing cost can be reduced.

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 explanatory drawing side surface explanatory drawing of a mission case. It is a skeleton diagram of power transmission. It is explanatory drawing of the travel transmission part of a mission case. It is explanatory drawing of the PTO transmission part of a mission case. It is explanatory drawing of the transmission without a transmission of a transmission case. It is a hydraulic circuit diagram of a continuously variable transmission. It is a hydraulic circuit diagram in the whole tractor. It is a section explanatory view of a mission case. It is an external plane explanatory drawing of a mission case. It is an expansion plane explanatory view of the connection part of a body frame and a mission case. It is decomposition | disassembly explanatory drawing of FIG. It is front explanatory drawing of a mission case. It is sectional side surface explanatory drawing to which a part of mission case which attached the vibration isolator was expanded. It is a back surface explanatory view of the mission case which attached the vibration isolator. It is decomposition | disassembly explanatory drawing of the mission case which attached the vibration isolator.

2 traveling machine body 5 engine 17 mission case 23 PTO shaft 29 hydraulic continuously variable transmission 33 rear side wall member (rear cover body)
58 Differential gear mechanism for rear wheels 62 Differential output shaft 96 PTO transmission gear mechanism 114 PTO output gear

Claims (1)

A hydraulic continuously variable transmission (29) for shifting the power from the engine (5) mounted on the traveling machine body (2), a differential gear mechanism (58) for transmitting traveling driving force, and the hydraulic continuously variable transmission (29) and a transmission case (17) including the differential gear mechanism (58) , and a work vehicle (1) having a PTO shaft (23) protruding rearward of the transmission case (17). ,
A PTO output gear (114) for transmitting power from the PTO transmission gear mechanism (96) is disposed on the PTO shaft (23),
The uppermost part of the PTO output gear (114) is formed higher than the lowermost part of the side opposite to the input side of the hydraulic continuously variable transmission (29), and the axial center line direction of the hydraulic continuously variable transmission (29) Visually, the hydraulic continuously variable transmission (29) and the PTO output gear (114) are overlapped,
A front chamber (34) and a rear chamber (35) are formed inside the mission case (17),
In the rear chamber (35), the hydraulic continuously variable transmission (29) and the differential gear mechanism (58) are disposed, and the hydraulic continuously variable transmission (29) is disposed in the differential gear mechanism (58). Arranged to be higher than the differential output shaft (62),
A work vehicle in which the PTO shaft (23) is disposed between the hydraulic continuously variable transmission (29) and the differential gear mechanism (58) in a plan view.

Images