JP2006103431A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the vibration-proofing performance of a first vibration-proof member and second vibration-proof members. <P>SOLUTION: A working vehicle is structured so that a flywheel is installed in the output part of an engine and the power of the engine is transmitted to a transmission case through the flywheel and a drive shaft, wherein the first vibration-proof member is installed in a part over the flywheel on the engine side while the second vibration-proof members are installed on the side faces of the engine adjoining to the side face where the flywheel is installed, and the two vibration-proof members are arranged approximately in the diagonal direction of the engine having approximately a quadrangular shape when viewed on the side elevation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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.

  Conventionally, in general, in the tractor or wheel loader described above, an engine is installed in the front part of the traveling machine body, a transmission case is installed in the rear part of the traveling machine body, and the traveling machine body is supported by the front and rear wheels. In this case, the engine is mounted on the front part of the traveling machine body, and the transmission case is arranged on the rear part of the traveling machine body (for example, Patent Document 1).

Further, the traveling airframe is composed of an engine frame and left and right airframe frames, an engine is mounted on a connection portion between the engine frame and the airframe frame, a transmission case is disposed between the left and right airframe frames, and the engine power Is transmitted to the drive shaft via the flywheel (for example, Patent Document 2).
JP-A-11-334395 JP 2003-252236 A

  However, since both sides of the engine and both sides of the flywheel are connected to the traveling machine body via vibration-proof members, and the vibration-proof members are installed near the bottom of the engine, When the rolling force that sways is generated, the rolling force at the upper part of the engine is amplified and transmitted to the lower vibration isolation member, and the vibration at the upper part of the engine is easily transmitted to the traveling machine body as mechanical vibration. There are problems such as simplification of the mounting structure and improvement of the vibration isolation function.

  The invention according to claim 1 is a work vehicle in which a flywheel is arranged at an output portion of an engine, and the power of the engine is transmitted to a transmission case via the flywheel and a drive shaft. A first anti-vibration member is disposed on the upper side of the engine, and second anti-vibration members are disposed on both sides of the engine adjacent to the installation side surface of the flywheel. The first anti-vibration member and the second anti-vibration member are arranged in the above.

  The invention according to claim 2 is characterized in that the first vibration isolation member includes a plurality of vibration isolation bodies, and the vibration isolation bodies are connected to the engine via a single connection body.

  According to a third aspect of the present invention, both ends of the connecting member are connected to the upper surface side of the pair of left and right body frames, the flywheel is disposed below the connecting member, and the first anti-rotation member is provided on the upper surface side of the connecting member. A vibration member is arranged.

  The invention according to claim 1 is a work vehicle in which a flywheel is arranged at an output portion of an engine, and the power of the engine is transmitted to a transmission case via the flywheel and a drive shaft. A first anti-vibration member is disposed on the upper side of the engine, and second anti-vibration members are disposed on both sides of the engine adjacent to the installation side surface of the flywheel. The first vibration isolation member and the second vibration isolation member are disposed in Therefore, the first vibration isolation member and the second vibration isolation member can be arranged close to a diagonal line passing near the position of the center of gravity of the engine in a side view. The vibration isolation performance of the first vibration isolation member and the second vibration isolation member can be improved.

  In the invention according to claim 2, the first vibration isolating member includes a plurality of vibration isolating bodies, and the vibration isolating bodies are coupled to the engine via a single coupling body. Therefore, for example, a plurality of vibration isolators having different vibration attenuation directions can be installed, and the first vibration isolation member can be configured to attenuate vibrations in a plurality of directions (for example, up and down, front and rear, and left and right directions) of the engine. . Vibration transmitted from the engine to the airframe can be reduced, and the vibration isolation performance of the first vibration isolation member can be improved.

  According to a third aspect of the present invention, both ends of the connecting member are connected to the upper surface side of the pair of left and right body frames, the flywheel is disposed below the connecting member, and the first anti-rotation member is provided on the upper surface side of the connecting member. A vibration member was arranged. Therefore, the connecting member can be used both for reinforcing the left and right airframe frames, closing the flywheel upper surface side, and supporting the first vibration isolation member. By installing the first vibration isolating member at a position higher than the flywheel, the vibration isolating performance of the first and second vibration isolating members can be improved.

  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 an explanatory side view thereof, FIG. 4 is a perspective view of the tractor body, and FIG. 5 is a skeleton diagram of power transmission.

  As shown in FIGS. 1 to 4, the tractor 1 supports the 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 the engine 5 mounted on the front part of the traveling machine body 2 uses the rear wheels. By driving the front 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. In addition, 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 installed in the cabin 7. The A step 10 on which the operator gets on and off is provided on the outside of the cabin 7, and a fuel tank 11 for supplying fuel to the engine 5 is provided on the inside of the step 10 and below the bottom of the cabin 7.

  The traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a front axle case 13, and a pair of left and right machine body frames 16 that are detachably fixed to the rear portion of the engine frame 14 with bolts 15. . A mission case 17 is connected to the rear portion of the body frame 16 for transmitting 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 that is 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 the working machine such as the tiller is provided on the rear side surface of the mission case 17 so as to protrude rearward.

  Next, with reference to FIGS. 10 to 23, the rear structure of the traveling machine body 2 that connects the machine body frame 16 and the transmission case 17 will be described. The pair of left and right body frames 16 are manufactured by casting using an iron alloy or aluminum alloy as a material. An upper and lower connecting boss portion 200 is integrally formed at the rear end portion of each body frame 16. As shown in FIGS. 18 and 19, the connecting boss portion 200 is fitted on the cylindrical frame pin 201. Pin fastening members 202 and 203 are fitted on one end side of the frame pin 201 (see FIG. 15). As will be described later, a filter lid 221 is integrally formed on the pin fastening member 203 disposed on the lower rear side of the right body frame 16 in the traveling direction. The frame pin 201 and the pin fastening members 202 and 203 are fixed by welding. The fuselage frame is attached to the side surface of the mission case 17 via the fastening bolts 204 that penetrate the inner holes of the frame pins 201 and the fixing bolts 205 that penetrate the attachment holes of the pin fastening members 202 and 203.

  As shown in FIG. 19, a pin hole 206 for press-fitting the frame pin 201 is formed on the side surface of the mission case 17. On the back side of the pin hole 206, a tightening screw hole 207 for screwing the tightening bolt 204 is formed. A pedestal 208 is integrally formed on the outer surface of the mission case 17 close to the pin hole 206. A fixing screw hole 209 for screwing the fixing bolt 205 is formed in the base 208. The distance L2 between the opening surface 210 of the pin hole 206 and the opening surface 211 of the fixing screw hole 209 is longer than the thickness width dimension L1 of the connecting boss portion 200. The separation dimension L2 that is the protruding length of the pedestal 208 is formed to be, for example, approximately 1 to 3 millimeters longer than the thickness width dimension L1.

  A shaft hole 199 through which the frame pin 201 passes is formed in the connection boss part 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 welded and fixed to the pin fastening members 202 and 203 so that the end surfaces of the frame pins 201 and the outer surfaces of the pin fastening members 202 and 203 are substantially flush with each other (see FIG. 19).

  When the end portion of the frame pin 201 and the pin fastening members 202 and 203 are fixed by welding, the end surface of the frame pin 201 slightly protrudes from the outer surface of the pin fastening members 202 and 203, and the fastening bolt 204 is fastened to the fastening screw hole. When screwed to 207, the head of the fastening bolt 204 may be crimped to the end of the frame pin 201. The end of the frame pin 201 and the pin fastening members 202 and 203 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 holes of the pin fastening members 202 and 203.

  As shown in FIG. 18, the frame pin 201 passes through the shaft hole 199 from the outer surface of the connecting boss portion 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. In this way, a gap 212 is formed between the side surface of the body frame 16 and the mounting side surface of the mission case 17 (see FIG. 18). The frame pin 201 is supported by the mission case 17 and the pin fastening members 202 and 203 in a double-supported structure. By forming the clearance 212, mechanical vibration transmitted from the machine body frame 16 to the mission case 17 can be reduced, and processing (cutting etc.) of the machine frame 16 mounting surface of the mission case 17 can be saved.

  Next, as shown in FIGS. 11, 12, 15, and 17, the mission case 17 is provided with an oil filter 220 for filtering the working oil. The oil filter 220 is disposed on the front side near the bottom in the mission case 17. A pin fastening member 203 is disposed close to one side of the oil filter 220. A filter lid 221 is formed integrally with the pin fastening member 203. A pin fastening member 203 is attached to the mission case 17, and a filter lid 221 is detachably fixed to one side of the oil filter 220.

  An oil outlet pipe 222 that penetrates the pin fastening member 203 and the filter lid 221 is integrally formed. The pin fastening member 203 and the inner and outer surfaces of the filter lid 221 are communicated with each other via an oil discharge pipe 222. The oil supply pipes 223 of the work machine hydraulic pump 94 and the traveling hydraulic pump 95 are communicated with the oil discharge pipe 222 via the oil passage pipe 224. The hydraulic oil in the mission case 17 is configured to be supplied to the working machine hydraulic pump 94 and the traveling hydraulic pump 95 via the oil filter 220 (see FIG. 12).

  Next, the structure of the engine frame 14 will be described with reference to FIGS. 10 to 13, 20, and 23. A pair of left and right front anti-vibration members 230 are arranged on the upper surface side of the middle portion of the left and right engine frame 14 in the front-rear width. Both front sides of the engine 5 are connected to the engine frame 14 via left and right front vibration isolation members 230. A bottom plate frame 231 is disposed on the lower surface side of the middle part in the front-rear width of the left and right engine frames 14. A front axle case 13 and a power steering hydraulic cylinder 93 are installed on the lower surface side of the bottom plate frame 231. The left and right front wheels 3 are configured to be steerable on the left and right sides of the front axle case 13.

  Next, the front structure of the machine body frame 16 connected to the engine frame 14 will be described with reference to FIGS. 10, 13 to 16, 21, and 24. At the front part of the left and right fuselage frame 16, an upper connection member 250 having a front gate shape and a lower connection member 251 having a flat plate shape are disposed. Both ends of the portal shape of the upper connecting member 250 are fastened to the upper surface of the body frame 16 via bolts 252. Both ends of the lower connecting member 251 are fastened to the lower surface of the body frame 16 via bolts 253. A flywheel 25 is disposed between the left and right body frames 16. An upper connecting member 250 is disposed above the flywheel 25. Therefore, the lower connecting member 251 is disposed below the flywheel 25. The left and right airframe frames 16 and the upper and lower connecting members 250 and 251 surround the outer periphery (left and right side portions and upper and lower side portions) of the flywheel 25.

  Next, a connection operation between the body frame 16 and the mission case 17 will be described. The frame pin 201 is passed through the shaft hole 199, and the connecting boss part 200 is fitted on the frame pin 201. The front end side of the frame pin 201 is press-fitted into the pin hole 206, and when the fastening bolt 204 is screwed into the fastening screw hole 207 from the outside of the pin fastening members 202 and 203, the frame pin 201 is press-fitted and fixed to the pin hole 206. When the bolts 204 and 205 are screwed into the screw holes 207 and 209, a gap 212 is formed between the side surface of the body frame 16 and the mounting side surface of the transmission case 17. The frame pin 201 is supported by the transmission case 17 and the pin fastening members 202 and 203 in a double-supported structure, and the rear part of the body frame 16 and the side surface of the transmission case 17 are connected (see FIG. 18).

  After the left and right airframe frame rear portions 16 and the side surfaces of the transmission case 17 are connected, the front portion of the airframe frame 16 is fastened to the outer surface of the rear portion of the engine frame 14 via bolts 15. The gate-shaped both ends of the upper connecting member 250 are fastened to the upper surfaces of the front portions of the left and right body frames 16 via bolts 252. Both end portions of the lower connecting member 251 are fastened to the lower surfaces of the front portions of the left and right airframe frames 16 via bolts 253. The upper and lower surfaces of the front part of the left and right airframe frames 16 are connected via upper and lower connecting members 250 and 251 to assemble the traveling airframe 2 (see FIG. 15).

  Next, when performing, for example, maintenance work of the hydraulic pumps 94 and 95 installed on the front side of the transmission case 17 and removal / removal of components on the front side of the transmission case 17, The fastening members 202 and 203 are removed from the side surfaces of the airframe frame 16 and the transmission case 17, and the rear portion of the airframe frame 16 and the side surface of the transmission case 17 are separated. On the other hand, the front portion of the body frame 16 is separated from the engine frame 14 and the upper and lower connecting members 250 and 251 by the operation of taking out the bolts 15, 252 and 253. One or both of the left and right body frames 16 are removed, and maintenance work and the like of the hydraulic pumps 94 and 95 are performed.

  Next, when the oil filter 220 installed in the mission case 17 is exchanged, the pin fastening member 203 on which the filter lid 221 is formed moves the right body frame 16 and the mission case 17 by the bolt 205 unscrewing operation. It is removed from the right side. When the filter cover 221 is detached from the mission case 17, the dirty oil filter 220 is taken out from the inside of the mission case 17. After the unused oil filter 220 is installed inside the mission case 17, the pin fastening member 203 is fastened to the right body frame 16 and the right side surface of the mission case 17 via bolts 205, and the oil inside the mission case 17 is The work of replacing the filter 220 is completed.

  As apparent from the above description and FIG. 18 and the like, the front part of the pair of left and right body frames 16 is connected to the rear part of the engine frame 14 on which the engine 5 is mounted, and the transmission case 17 is interposed between the rear parts of the pair of left and right body frames 16. In a work vehicle configured to be arranged, a rear part of the body frame 16 is extended on a side surface of the mission case 17, and a frame pin 201 is penetrated from the outside to the rear part of the body frame 16, and the frame pin The tip portion of 201 entered the side surface portion of the mission case 17. Therefore, compared with the conventional bolt fastening, the area of the side of the mission case 17 necessary for the connection of the body frame 16 can be reduced, and the side of the mission case 17 can be utilized for the installation space of the speed change operation mechanism, for example. Since the machine frame 16 and the transmission case 17 are connected via the frame pin 201, the machine frame 16 can be processed with a low material cost and a small design shape, such as casting. Can be manufactured at low cost. For example, a traveling machine body such as the tractor 1 can be simplified or reduced in weight, and the manufacturing cost can be reduced.

  As apparent from the above description and FIG. 25, the flywheel 25 is installed at the rear of the engine 5, and the flywheel 25 is arranged between the left and right body frames 16. Therefore, the left and right sides of the flywheel 25 are closed by the left and right fuselage frame 16, and the left and right fuselage frame 16 can be used as a protective member for the flywheel 25. For example, a traveling machine body such as the tractor 1 can be simplified or reduced in weight, and the manufacturing cost can be reduced.

  As is clear from the above description and FIG. 20 and the like, either one of the left and right airframe frames 16 is connected to the engine frame 14 and the transmission case 17 from the engine frame 14 and the transmission case 17. The other body frame 16 was configured to be removable. Therefore, the engine frame 14 and the left and right airframe frames 16 can perform operations such as processing and assembly separately as three independent parts. For example, the handling property of the traveling machine body 2 can be improved as compared with the conventional case where the engine frame 14 and the left and right machine body frames 16 are integrally connected.

  As apparent from the above description and FIGS. 17 and 18, the front part of the pair of left and right body frames 16 is connected to the rear part of the engine frame 14 on which the engine 5 is mounted, and a transmission case is disposed between the rear parts of the pair of left and right body frames 16. In the work vehicle configured to be arranged 17, a rear part of the machine body frame 16 is extended to a side part of the mission case 17, and a frame pin 201 is penetrated from the outside to the rear part of the machine body frame 16, The distal end portion of the frame pin 201 is inserted into the side surface portion of the transmission case 17, pin fastening members 202 and 203 are disposed at the proximal end portion of the frame pin 201, and the pin fastening members 202 and 203 are connected to the transmission case 17. Fastened to the outside surface. Therefore, the fuselage frame 16 can be supported in the middle of the frame pin 201 in a dual-support structure in which both ends of the frame pin 201 are supported by the mission case 17 and the pin fastening members 202 and 203. The connection strength with the mission case 17 can be secured. Compared to a conventional structure in which the body frame 16 is fastened to the transmission case 17 via bolts, the manufacturing cost of the tractor 1 body or the transmission case 17 can be reduced.

  As apparent from the above description and FIG. 18, the fastening bolts 204 are passed through the frame pins 201 from the outside of the pin fastening members 202 and 203, and the fastening bolts 204 are screwed to the transmission case 17. Therefore, the airframe frame 16 and the transmission case 17 can be connected via a double shaft composed of the frame pin 201 and the fastening bolt 204, and the connection rigidity between the airframe frame 16 and the transmission case 17 can be improved.

  As is clear from the above description and FIGS. 12 and 15, a filter lid 221 for attaching to the oil filter 220 inside the mission case 17 is formed on at least one of the pin fastening members 203. . For this reason, the oil filter 220 can be taken out by detaching the pin fastening member 203 outside the side surface of the mission case 17, and the maintenance workability of the oil filter 220 can be improved.

  As is clear from the above description and FIG. 18, a gap 212 is formed between the side surface of the mission case 17 and the side surface of the body frame 16 facing the mission case 17. Therefore, as compared with the conventional bolt fastening structure in which the side surface of the body frame 16 is crimped to the side surface of the transmission case 17, labor (cutting etc.) of the body frame 16 and the transmission case 17 can be reduced. Further, vibrations of the engine 5 and the like transmitted to the mission case 17 can be reduced.

  Next, as shown in FIGS. 22 to 29, 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 vibration isolation member 254 includes a left and right vibration isolation rubber 255 connected to the upper surface of the upper connection member 250 via a bolt 256, and a pressure receiving frame 257 that connects the vibration isolation rubbers 255. The pressure receiving frame 257 is connected to the upper part of the back surface of the engine 5 via a bolt 258. The upper part of the rear surface of the engine 5 and the upper surface of the upper connecting member 250 are connected via the rear vibration isolating member 254.

  As shown in FIGS. 23 and 25, the left and right front vibration isolation members 230 and the rear vibration isolation members 254 are triangular in plan view (a triangle in which the center of gravity of the engine 5 is located at the approximate center in plan view). It arrange | positions at each vertex (refer FIG. 23). The front vibration isolation member 230 and the rear vibration isolation member 254 are disposed on a straight line (a straight line passing through the approximate center of gravity of the engine 5 in a side view) substantially parallel to a diagonal line of the quadrangle in a side view of the engine 5 ( FIG. 25).

  As shown in FIGS. 27 to 29, the lower surface and the upper surface of the vibration isolating rubber 255 are fixed to the lower plate material 301 that contacts the upper surface of the upper coupling member 250 and the upper plate material 302 that contacts the lower surface of the pressure receiving frame 257. . The lower surface of the pressure receiving frame 257 is pressed against the upper surface of the upper connecting member 250 via a vibration isolating rubber 255. Mainly, the vibration in the vertical direction is received by the vibration isolating rubber 255 in response to the weight of the engine 5.

  The front plate side of the lower plate member 301 with the left vibration isolating rubber 255 sandwiched in the direction of the machine body is bent upward, the front plate side of the upper plate member 302 is bent downward, and the bent portions on the front end side of the plate members 301 and 302 are bent. The auxiliary anti-vibration rubber 303 is sandwiched between them and fixed. Mainly, the vibration vibration of the engine 5 and the vibration in the front-rear direction of the engine 5 are attenuated by the vibration isolating rubber 303.

  On the other hand, the rear end side of the lower plate member 304 sandwiching the vibration isolating rubber 255 on the right side in the aircraft traveling direction is bent upward, and the rear end side of the upper plate member 305 is also bent downward. The auxiliary anti-vibration rubber 306 is sandwiched and fixed between the bent portions on the side (see FIG. 29). Mainly, the vibration of the rotation of the engine 5 and the vibration in the front-rear direction of the engine 5 are attenuated by the vibration isolating rubber 306.

  The lower plate members 301 and 304 sandwiching the left and right anti-vibration rubbers 255 are bent upward at the right end side in the direction of machine movement, and the right end sides of the upper plate members 302 and 305 are bent downward. The auxiliary anti-vibration rubber 307 is sandwiched and fixed between the bent portions on the right end side of 305 (see FIG. 27). Mainly, the vibration of the rotation of the engine 5 and the vibration of the engine 5 in the left-right direction are attenuated by the anti-vibration rubber 307. The anti-vibration rubber 255 and the auxiliary anti-vibration rubbers 303, 306, and 307 are bonded and fixed to the plate members 301, 302, 304, and 305 at the time of the molding process.

  As is clear from the above description and FIGS. 23 and 25, the flywheel 25 is disposed at the output portion of the engine 5, and the power of the engine 5 is transmitted via the flywheel 25 and the power transmission shaft 28 which is a drive shaft. In the work vehicle configured to be transmitted to the mission case 17, a rear vibration isolation member 254, which is a first vibration isolation member, is disposed on the side of the engine 5 above the flywheel 25, and the installation side surface of the flywheel 25 is arranged. Front vibration isolation members 230 as second vibration isolation members are respectively arranged on both side surfaces (left and right side surfaces) of the engine 5 adjacent to (the back surface of the engine 5). The rear vibration isolation member 254 and the front vibration isolation member 230 are arranged in a substantially diagonal direction (side view) of the engine 5. Therefore, the rear vibration isolation member 254 and the front vibration isolation member 230 can be arranged close to a diagonal line passing near the position of the center of gravity of the engine 5 in a side view. The vibration isolation performance of the rear vibration isolation member 254 and the front vibration isolation member 230 can be improved.

  As is clear from the above description and FIGS. 15, 21, 22, etc., the rear vibration isolation member 254 is composed of a plurality of vibration isolation rubbers 255, and each of the vibration isolation rubbers 255 is attached to the engine 5. It connected via the pressure receiving frame 257 which is a single connection body. Therefore, for example, a plurality of auxiliary vibration isolation rubbers 303, 306, and 307 different from the vibration attenuation direction of the vibration isolation rubber 255 are installed, and vibrations of the engine 5 in a plurality of directions (for example, up and down, front and rear, and left and right directions) are provided. The rear vibration isolation member 254 can be configured to attenuate. Vibration transmitted from the engine 5 to the airframe can be reduced, and the vibration isolation performance of the rear vibration isolation member 254 can be improved.

  As apparent from the above description and FIGS. 23 and 24, both ends of the upper connecting member 250 are connected to the upper surface side of the pair of left and right body frames 16, and the flywheel 25 is connected to the lower side of the upper connecting member 250. The rear vibration isolating member 254 is disposed on the upper surface side of the upper connecting member 250. Therefore, the upper connecting member 250 can be used for both the reinforcement of the left and right airframe frames 16, the closure of the upper surface side of the flywheel 25, and the support of the rear vibration isolation member 254. By installing the rear vibration isolation member 254 at a higher position than the flywheel 25, the vibration isolation performance of the rear and front vibration isolation members 254, 230 can be improved.

  As shown in FIGS. 21, 22, 23, and 25, left and right bonnet columns 260 are erected on the left and right ends of the upper surface of the upper connecting member 250. The left and right bonnet struts 260 are arranged on both the left and right sides so as to sandwich the rear vibration isolation member 254. A bonnet support frame 262 is connected to the upper end portion of the bonnet support 260 via a bonnet mounting shaft 261. The bonnet 6 is fixed to the bonnet support frame 262 by welding. The bonnet 6 is configured to open and close by rotating around the bonnet mounting shaft 261.

  The transmission structure between the engine 5 and the transmission case 17 will be described with reference to FIGS. The flywheel 25 forms a recess 270 on the back side. The main shaft 26 is provided in the recess 270. A disc-shaped bearing support member 271 is fastened to the back side of the flywheel 25 via bolts 272. The bearing support member 271 is disposed substantially flush with the back surface of the flywheel 25. The recess 270 is closed in a substantially sealed manner by the bearing support member 271. A front end portion of the main driving shaft 26 is pivotally supported on the front side of the flywheel 25 via a ball bearing 273. A spring-type damper 274 for attenuating vibration generated by rotation of the engine output shaft 24 or the like is fitted in the middle of the main drive shaft 26. The flywheel 25 and the main drive shaft 26 are connected via a damper 274. The rear end portion of the main driving shaft 26 is pivotally supported by a bearing support member 271 via a ball bearing 275. The rear end of the main driving shaft 26 protrudes to the rear side of the bearing support member 271. The power transmission shaft 28 is connected to the protrusion at the rear end of the main driving shaft 26 via a universal joint 276.

  A transmission structure between the front axle case 13 and the transmission case 17 will be described with reference to FIGS. 12, 21, 22, 24, and 25. The front wheel drive shaft 85 includes a rear drive shaft 291 connected to the front wheel output shaft 73 via a shaft joint 290 and a front drive shaft 293 connected to the front wheel input shaft 84 via a shaft joint 292. The front end of the rear drive shaft 291 and the rear end of the front drive shaft 293 are connected via a shaft joint 294. The rear end portion of the front drive shaft 293 is pivotally supported on the intermediate bearing body 295 via a ball bearing 296. A mounting plate 296 is fixed to the intermediate bearing body 295 by welding. The mounting plate is fastened to the lower connecting member 251 via bolts 297. The rear drive shaft 291 and the front drive shaft 293 are covered with rear and front shaft covers 298 and 299.

  As apparent from the above description and FIGS. 17 and 24, the front part of the pair of left and right body frames 16 is connected to the rear part of the engine frame 14 on which the engine 5 is mounted, and a transmission case is disposed between the rear parts of the pair of left and right body frames 16. In the work vehicle configured such that 17 is arranged, the pair of left and right body frames 16 are connected via an upper connecting member 250 and a lower connecting member 251, and a flywheel 25 installed at an output portion of the engine 5. Is configured to be surrounded by the pair of left and right body frames 16 and the upper and lower connecting members 250 and 251. Therefore, the left and right airframe frames 16 can be reinforced by the upper connecting member 250 and the lower connecting member 251 at a position close to the engine 5, and the left and right airframe frames 16 are configured by a highly rigid cylindrical member or the like as in the past. There is no need to do. The upper and lower connecting members 250 and 251 can be used to improve the rigidity of the left and right airframe frames 16 and to protect the flywheel 25. For example, a traveling machine body such as the tractor 1 can be simplified or reduced in weight, and the manufacturing cost can be reduced.

  As is clear from the above description and FIGS. 24 and 25, the rear vibration isolation member 254 and the bonnet support 260 which are attachment members of the engine 5 or the bonnet 6 are disposed on the upper surface side of the upper connecting member 250. Therefore, the rear vibration isolating member 254 and the bonnet post 260 can be arranged in the middle of the vertical width of the side of the engine 5. For example, the rear vibration isolating member 254 that is an attachment member of the engine 5 and the bonnet post that is an attachment member of the bonnet 6. 260 (such as a hinge that can be opened and closed) can be installed compactly above the flywheel 25.

  As is clear from the above description and FIGS. 24, 25, etc., as the intermediate bearing member 295 that is an intermediate support member of the front wheel drive shaft 85 that is a drive shaft that transmits power from the transmission case 17 to the front wheel 3, The lower connecting member 251 is also used. Therefore, vibration of the front wheel drive shaft 85 can be prevented by the lower connecting member 251 and, for example, the front wheel drive shaft 85 can be installed close to the lower surface of the engine 5 or the like.

  Further, FIGS. 5 to 7 show the mission case 17. The mission case 17 is partitioned inside and behind by a partition wall 31. A front side wall member 32 is detachably fixed to the front side of the mission case 17 with bolts. A rear side wall member 33 is detachably fixed to the rear side of the mission case 17 with bolts. The mission case 17 is formed in a box shape, and a front chamber 34 and a rear chamber 35 are formed inside the mission case 17. The front chamber 34 and the rear chamber 35 are in communication with each other so that the hydraulic oil (lubricating oil) inside these chambers moves relative to each other.

  As shown in FIG. 5, the front side wall member 32 is provided with a front wheel drive case 69 described later. In the front chamber 34, a travel auxiliary transmission gear mechanism 30 and a PTO transmission gear mechanism 96, which will be described later, are arranged. In the rear chamber 35, a hydraulic continuously variable transmission 29, which is a traveling main transmission mechanism described later, and a differential gear mechanism 58 are arranged.

  An engine output shaft 24 is provided on the rear side surface of the engine 5 so as to protrude rearward. A flywheel 25 is attached to the engine output shaft 24 so as to be directly connected. 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. Connect. The rotation of the engine 5 is transmitted to the main transmission input shaft 27 in the transmission case 17, and then appropriately shifted by the hydraulic continuously variable transmission 29 and the traveling auxiliary transmission gear mechanism 30, via the differential gear mechanism 58. Thus, the driving force is transmitted to the rear wheel 4.

  Further, the rotation of the engine 5 that has been appropriately shifted by the traveling auxiliary transmission gear mechanism 30 is transmitted to the front wheels 3 via the front wheel drive case 69 and the differential gear mechanism 86 of the front axle case 13. Become.

  Next, FIG. 8 and FIG. 9 show an inline hydraulic continuously variable transmission 29 in which a main transmission output shaft 36 is concentrically arranged 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 extends to the rear side wall member 33. 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 by a ball bearing 504.

  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 provided at the front end portion of the main transmission output shaft 36. The input side of the main transmission input shaft 27 protrudes forward from the front end of the main transmission output shaft 36 such that the input side of the main transmission input shaft 27 projects forward from the front end of the main transmission output shaft 36 via the roller bearing 503. (See FIG. 9).

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

  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. The main transmission input shaft 27 and the cylinder block 505 are connected by a spline 525. The hydraulic pump unit 500 is disposed on one side of the main transmission input shaft 27 opposite to the input side with the 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.

  The hydraulic pump unit 500 includes a first holder 510 that is fixed to the inner side surface of the transmission case 17 so as to face the side surface of the cylinder block 505, and a tilt angle that can be changed with respect to the axis of the main transmission input shaft 27. A pump swash plate 509 disposed in the holder 510, a shoe 508 slidably provided on the pump swash plate 509, a pump plunger 506 connected to the shoe 508 through a spherical universal joint, and the pump plunger 506 connected to the cylinder block 505 And a first plunger hole 507 arranged to be freely accessible. One end of the pump plunger 506 protrudes from the side surface of the cylinder block 505 toward the pump swash plate 509 (right side in FIG. 8). 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 radial and thrust load roller bearings 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 coming out.

  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 provided 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. In FIG. 8, the position rotated about 90 degrees with respect to the pump swash plate 509 (the front side of the drawing of FIG. 8) is separated from the side surface of the cylinder block 505 by about 180 degrees (the back side of the drawing of FIG. 8). 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, a motor plunger 515 connected to the shoe 517 via a spherical universal joint, and the motor plunger 515 to be able to enter and exit the cylinder block 505 A second plunger hole 516 is provided. 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. 8). 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.

  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, a radial and thrust load roller bearing 523, Intervenes. A nut 524 is provided to prevent the roller bearing 523 from coming out of the main transmission input shaft 27.

  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 provided 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. In FIG. 8, the cylinder block 505 is on the opposite side (back side in FIG. 8) about 180 degrees so that the position rotated about 90 degrees with respect to the motor swash plate 518 (front side in FIG. 8) is close to the side surface of the cylinder block 505. The second radial bearing 541 is configured to be tilted and supported so as to be separated from the side surface of the first radial bearing.

  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.

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

  A 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 tip of the first spool valve 536 protrudes in the direction of the first holder 510 from the first valve hole 532 with the back pressure spring force, and the tip of the first spool valve 536 abuts the side surface of the outer ring 538 of the first radial bearing 537. Be touched. 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 chamber 531 is configured to communicate with each other alternately.

  A 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. Be touched. 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, and passes through the first oil chamber 530 or the second oil. The chamber 531 is configured to communicate with each other alternately.

  Further, a hydraulic oil supply oil passage 543 is formed in the central portion 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 hydraulic pump 95 described above. 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 are provided.

  And 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 passed through, 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, the 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. 9). The pump swash plate 509 is provided such that its inclination angle is adjustable with respect to the axis of the main transmission input shaft 27. A main transmission hydraulic cylinder 556 for main transmission, 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. 9). The main transmission hydraulic cylinder 556 is fixed to the rear side wall member 33. A main transmission arm 558 is connected to the tip of the piston rod 557 of the main transmission hydraulic cylinder 556 (see FIG. 6). When the piston rod 557 is connected to the tilt angle adjustment fulcrum 555 via the main transmission arm 558 and the piston rod 557 moves forward or backward, the tilt angle of the pump swash plate 509 is changed, and the continuously variable transmission. 29 main shift operations are performed. The first holder 510 is connected to the non-rotating portion of the transmission case 17 via a connecting means (not shown) so that the pump swash plate 509 does not rotate with respect to the main transmission input shaft 27.

  The main transmission operation of the inline hydraulic continuously variable transmission 29 will be described below. The hydraulic cylinder 556 is controlled by a main transmission lever or the like, and the inclination angle of the pump swash plate 509 is changed with respect to the axis line 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 that the pump plunger 506 does not move forward and backward, and 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. The 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, since the hydraulic oil is not drawn into the first plunger hole 507 even during the suction stroke of the pump plunger 506, 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 transmission motor 501 is not driven by the transmission pump unit 500. Therefore, the motor swash plate 518 is fixed to the cylinder block 505 via the motor plunger 515, and the cylinder block 505 and the motor swash plate 518 rotate at the same rotational speed in the same direction. The main transmission output shaft 36 is rotated at substantially the same rotational speed, and the rotational speed of the main transmission input shaft 27 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.

  When the pump swash plate 509 is inclined in one direction (positive inclination angle) with respect to the axis line 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, the shift output (travel speed) from the main shift output gear 37 is proportional to the inclination (positive inclination angle) of the pump swash plate 509 within the range of the rotation speed higher than the rotation speed of the main transmission input shaft 27. As a result, the maximum traveling speed is reached at the maximum inclination (positive inclination angle) of the pump swash plate 509.

  Further, when the pump swash plate 509 is inclined in the other direction (negative inclination angle) with respect to the axis 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, the shift output (travel speed) from the main shift output gear 37 is proportional to the inclination (negative inclination angle) of the pump swash plate 509 within the range of the rotation speed lower than the rotation speed of the main transmission input shaft 27. As a result, the minimum traveling speed is reached at the maximum inclination (negative inclination angle) of the pump swash plate 509.

  Next, as shown in FIGS. 5 and 6, the front chamber 34 of the mission case 17 has a forward gear 41 and a reverse gear 43 for switching between forward and reverse, and a traveling auxiliary gear for switching between low speed and high speed. A transmission gear mechanism 30 is disposed.

  A description will be given of switching between forward and reverse movements through the forward gear 41 and the reverse gear 43. As shown in FIG. 6, a travel counter shaft 38 and a reverse rotation shaft 39 are disposed in the front chamber 34 where the main transmission output gear 37 is disposed. The travel counter shaft 38 is fitted with a forward gear 41 connected by a forward wet multi-plate hydraulic clutch 40 and a reverse gear 43 connected by a reverse wet multi-plate hydraulic clutch 42. Is done. The forward gear 41 is meshed with the main transmission output gear 37. The main transmission output gear 37 is engaged 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.

  Then, by a forward operation of the main shift lever or a forward switch (not shown), the clutch cylinder 47 is operated by the forward hydraulic solenoid valve 46 and the forward hydraulic clutch 40 is continued, and the main shift output gear 37 and the travel counter shaft are continued. 38 is connected by a forward gear 41 (see FIGS. 5 and 6).

  On the other hand, when the main shift lever or reverse switch (not shown) is operated in reverse, the reverse hydraulic solenoid valve 48 operates the clutch cylinder 49 to continue the reverse hydraulic clutch 42, and the main transmission output gear 37 and the travel countershaft. 38 is connected by a reverse gear 43 (see FIGS. 5 and 6).

  When the main transmission lever (not shown) is supported at the neutral position (when both the forward and reverse switches are off), both the forward and reverse wet multi-plate hydraulic clutches 40 and 42 are both used. 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, the switching between the low speed and the high speed performed via the traveling auxiliary transmission gear mechanism 30 will be described. As shown in FIGS. 5 and 6, a traveling auxiliary transmission gear mechanism 30 and an auxiliary transmission shaft 50 are disposed in the front chamber 34 of the transmission case 17. Between the traveling 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 provided. Further, a low speed clutch 56 and a high speed clutch 57 which are continued or disconnected by the auxiliary transmission hydraulic cylinder 55 are provided. Then, 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. Thus, the low speed gear 52 or the high speed gear 54 is connected to the auxiliary transmission shaft 50, and the driving force is output from the auxiliary transmission shaft 50 to the front wheels 3 and the rear wheels 4.

  The rear end of the auxiliary transmission shaft 50 extends through the partition wall 31 and extends into the rear chamber 35 of the transmission case 17 (see FIG. 5). A pinion 59 is provided at the rear end portion of the auxiliary transmission shaft 50. In addition, a differential gear mechanism 58 that transmits traveling driving force to the left and right rear wheels 4 is disposed in the rear chamber 35. The differential gear mechanism 58 includes a ring gear 60 that meshes with a pinion 59 at the rear end of the auxiliary transmission shaft 50, a differential gear case 61 provided in the ring gear 60, and left and right differential output shafts 62. The differential output shaft 62 is connected to the rear axle 64 by a final gear 63 or the like, and is configured to drive the rear wheel 4 provided on the rear axle 64.

  Further, left and right brakes 65 are respectively installed on the left and right differential output shafts 62 so that the left and right brakes 65 are braked by operating the brake pedal 66. On the other hand, when the steering angle of the handle 9 is detected, the brake cylinder 68 is actuated by the autobrake solenoid valve 67, the brake 65 is automatically braked, and a turning travel such as a U-turn is performed. Yes.

  Next, as shown in FIGS. 5 and 6, switching between the two-wheel drive and the four-wheel drive of the front and rear wheels 3, 4 will be described. A front wheel drive case 69 is provided on the front side wall member 32 of the mission case 17. The front wheel drive case 69 is provided with a front wheel input shaft 72 and a front wheel output shaft 73. The front wheel input shaft 72 is connected to the auxiliary transmission shaft 50 by 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 by gears 78 and 79, respectively.

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

  Next, as shown in FIGS. 5 and 6, switching of the double speed drive of the front wheels 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. And the front wheel output shaft 73 are connected by a double speed gear 77 so that the front wheel 3 is driven at a speed approximately twice as high as that when the front wheel 3 is driven by the four-wheel drive gear 75. Configure.

  As shown in FIG. 5, 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 that transmits traveling driving force to the left and right front wheels 3 is disposed inside the front axle case 13.

  The 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 in the ring gear 88, and left and right differential output shafts 90. A front axle 92 is connected to the differential output shaft 90 by a final gear 91 or the like, and the front wheels 3 provided on the front axle 92 are driven (see FIG. 5). A power steering hydraulic cylinder 93 is disposed on the outer side surface of the front axle case 13 to change the traveling direction of the front wheels to the right and left by the steering operation of the steering handle 9 (see FIG. 3).

  As shown in FIGS. 5 and 7, on the front side of the front side wall member 32 of the mission case 17, a working machine hydraulic pump 94 for supplying hydraulic fluid to the working machine lifting mechanism 20, a mission case And a traveling hydraulic pump 95 for supplying hydraulic oil to each of the 17 shift parts and the hydraulic cylinder 93 for power steering. A transmission case 17 is used in combination as an oil tank so that hydraulic oil in the case 17 is supplied to the hydraulic pumps 94 and 95.

  Next, switching of the driving speed of the PTO shaft 23 (four forward rotations and one reverse rotation) will be described with reference to FIGS. The front chamber 34 of the transmission case 17 is provided with a PTO transmission gear mechanism 96 that transmits power from the engine 5 to the PTO shaft 23 and a pump drive shaft 97 that transmits power from the engine 5 to the hydraulic pumps 94 and 95 ( (See FIG. 7).

  As shown in FIG. 7, the PTO transmission gear mechanism 96 described in detail later includes a PTO counter shaft 98 and a PTO transmission output shaft 99. The PTO input gear 101 connected by the PTO hydraulic clutch 100 is fitted on the PTO counter shaft 98. An input side gear 102 provided on the main transmission input shaft 27 and an output side gear 103 of the pump drive shaft 97 are meshed with the PTO input gear 101, and the pump drive shaft 97 is connected to the main transmission input shaft 27.

  When the PTO clutch lever or PTO clutch switch (not shown) is continuously operated, the clutch cylinder 105 is actuated by the PTO clutch hydraulic solenoid valve 104 (see FIG. 5), and the PTO hydraulic clutch 100 is continued. The input shaft 27 and the PTO counter shaft 98 are connected by a PTO input gear 101.

  Further, a first speed gear 106, a second speed gear 107, a third speed gear 108, a fourth speed gear 109, and a reverse gear 110 are fitted on the PTO speed change output shaft 99 for PTO output (FIG. 5, see FIG.

  A shift shifter 111 is pivotally supported on the PTO shift output shaft 99 by a spline. The gears 106, 107, 108, 109, 110 are configured to be alternatively connected to the PTO shift output shaft 99 by a shift shifter 111. A shift arm 112 connected to a PTO shift lever (not shown) is engaged with the shift shifter 111. Then, a shift operation of the PTO shift lever (not shown) causes the shift shifter 111 to move linearly along the axis of the PTO shift output shaft 99 by the shift arm 112, and each gear 106, 107, 108, 109, Any one of 110 is selected and connected to the PTO shift output shaft 99 (see FIGS. 5 and 7). Therefore, 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 gears 113 and 114.

  In FIG. 6, a rotation detection gear 115 provided on the reverse rotation shaft 39 and a main transmission pickup 116 that detects the rotation of the main transmission output gear 37 are installed facing each other, and a hydraulic continuously variable transmission 29 that is a main transmission mechanism. The continuously variable transmission output rotational speed is detected by the main transmission pickup 116. Further, a vehicle speed pickup 117 for detecting the rotation of the gear 78 of the front wheel input shaft 72 is installed, and the traveling speed (vehicle speed) is detected by the vehicle speed pickup 117 based on the rotation of the front wheel input shaft 72 and the auxiliary transmission shaft 50. Configure as follows.

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 tractor. It is a perspective view of a tractor airframe. 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 permission of a mission case. It is a hydraulic circuit diagram of the continuously variable transmission of the transmission case. It is a side view of a traveling body, an engine, and a mission case. It is a top view of a traveling body, an engine, and a mission case. It is a bottom view of a traveling body, an engine, and a mission case. It is a left front perspective view of a traveling body and a mission case. It is a right rear perspective view of a traveling machine body. It is a left rear perspective view of a traveling machine body. It is a side view of a body frame. It is a left front perspective view of a body frame. It is an enlarged view of a body frame and a mission case connection part. It is an exploded view of an airframe frame and a mission case connection part. It is the left rear perspective view which removed the left body frame. It is a front view of a traveling machine body. It is a rear view of a traveling body. It is a plane explanatory view of an engine vibration-proof structure. It is side surface explanatory drawing of the flywheel part of an engine. It is side surface explanatory drawing of an engine and a bonnet part. It is transmission explanatory drawing of an engine and a mission case part. It is a front enlarged view of an engine anti-vibration structure. It is an enlarged side view of an engine vibration-proof structure. It is a diagonally rear perspective view of an engine vibration-proof structure.

Explanation of symbols

5 Engine 16 Airframe frame 17 Mission case 25 Flywheel 28 Power transmission shaft (drive shaft)
230 Front vibration isolation member (second vibration isolation member)
250 Upper connection member 254 Rear vibration isolation member (first vibration isolation member)
255 Anti-vibration rubber (vibration isolator)
257 Pressure receiving frame (connector)

Claims (3)

  In a work vehicle in which a flywheel is disposed at an output portion of an engine and power of the engine is transmitted to a transmission case via a flywheel and a drive shaft, a first side is disposed on an engine side portion above the flywheel. Anti-vibration members are disposed, second anti-vibration members are respectively disposed on both side portions of the engine adjacent to the installation side surface of the flywheel, and the first anti-vibration members are arranged in a substantially diagonal direction of the engine having a substantially square shape in a side view. A work vehicle comprising a second vibration isolation member.   The work vehicle according to claim 1, wherein the first vibration isolation member includes a plurality of vibration isolation bodies, and the vibration isolation bodies are connected to the engine via a single connection body.   Both ends of a connecting member are connected to the upper surface side of the pair of left and right body frames, the flywheel is disposed below the connecting member, and the first vibration isolating member is disposed on the upper surface side of the connecting member. The work vehicle according to claim 1 or 2.

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