JP3940194B2 - Tractor PTO device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention provides a PTO device for a tractor, in particular, an opening is provided on the upper surface of the airframe housing at one end side in the axial direction of the airframe, and a hydraulic lift case is installed on the upper surface of the airframe housing with the opening being closed. A hydraulically operated PTO clutch for turning on and off the PTO shaft extending from the body housing along the axial direction of the body and a PTO brake for braking the PTO shaft when the PTO clutch is disengaged. The present invention relates to a PTO device in a tractor that is installed in an airframe housing so as to face the range of the opening as viewed in the axial direction.
[0002]
[Prior art]
A tractor PTO device as described above is known from, for example, Japanese Utility Model Publication No. 63-23222. The PTO brake quickly stops the inertial rotation of the PTO shaft after the PTO clutch is disengaged, and the hydraulically operated PTO clutch is disengaged. In this state, the PTO shaft can be prevented from rotating due to the drag phenomenon caused by the oil in the clutch.
[0003]
In the above-mentioned publication, the PTO brake is configured in such a structure that the PTO device is disposed at the rear end portion in the body housing, and the brake is operated by a spring and the brake is released by a hydraulic. A single-acting hydraulic actuating cylinder as a brake actuating body for displacing the movable brake member is provided on one side wall of the machine housing. This hydraulic cylinder is placed behind the side wall to avoid interference with the rear axle housing, fittings, linkages, etc. that are mounted on the outer surface of the side wall of the fuselage housing. The PTO brake is also arranged largely rearward in the fuselage housing. Therefore, the PTO clutch or its clutch cylinder that receives the brake by the PTO brake is also arranged greatly rearward in the fuselage housing.
[0004]
[Problems to be solved by the invention]
When the PTO clutch is rearwardly arranged in this way, the rear end surface of the fuselage housing is also positioned rearward, and the distance between the center line of the rear wheel axle and the rear end surface of the housing is increased. The weight balance between the front and rear of the airframe is greatly lost in a state in which a heavy work machine is connected. Therefore, in order to improve the balance, it is necessary to attach a relatively large front weight to the front of the airframe.
[0005]
Therefore, the present invention provides an opening that is closed by a hydraulic lift case on the upper surface of the body housing on one end side in the body axis direction, that is, the rear end side or the front end side, and the PTO clutch faces the range of the opening. Using the structure installed inside, the end face of the PTO clutch and the fuselage housing can be placed as close as possible to the center line of the rear wheel or the front wheel axle, thereby connecting the work equipment to the rear or front of the fuselage. It is intended to provide a novel PTO device for a tractor that is capable of improving the front-rear weight balance of the aircraft in a state.
[0006]
The accompanying object is to provide a PTO device which is extremely easy to assemble.
[0007]
Another attendant object is to provide a PTO device having a simple structure with PTO brakes and other related means.
[0008]
SUMMARY OF THE INVENTION
In the present invention, an opening 57 is provided on the upper surface of the airframe housing 4 on one end side in the axial direction of the airframe, and the hydraulic lift case 13 is installed on the upper surface of the airframe housing 4 with the opening 57 being closed. A hydraulically operated PTO clutch 37 for turning on and off the PTO shaft 36 extending from the body housing 4 along the axial direction and a PTO brake 63 for braking the PTO shaft 36 when the PTO clutch is disengaged. And the tractor PTO device installed in the body housing 4 so as to face the range of the opening 57 when viewed in the direction of the body axis.
[0009]
In the PTO device according to the present invention, a support plate 65 facing the opening 57 is provided to be connected to and supported by the fuselage housing 4, and the movable brake member of the PTO brake 63 is provided. (Brake shoe) A brake actuating body 75 for displacing 74 is supported by the support plate 65.
[0010]
In a structure in which an opening 57 is provided in the fuselage housing 4 above the PTO clutch 37 and the hydraulic lift case 13 is installed on the upper surface of the fuselage housing with the opening closed, the opening is interposed through the opening. The interior of the fuselage housing and the lift case are connected to each other, and there is an internal space that spans the fuselage housing and the lift case. In the present invention, a support plate 65 connected to and supported by the fuselage housing 4 is disposed using such an internal space, and the movable brake member of the PTO brake 63 is disposed on the support plate. (Brake shoe) The brake actuating body 75 for displacing 74 is supported, and the brake actuating body supported by the support plate inside the tractor is arranged by an axle housing, a fitting, a linkage, etc. on the outer surface of the body housing. Since it can be arranged near the axle housing within the fuselage housing without being restricted by the above, the PTO clutch can be arranged in the same manner. Therefore, the distance between the center line of the rear wheel or the front wheel axle and the end face of the body housing can be reduced to improve the front-rear weight balance of the body when the work machine is connected to the rear or front of the body.
[0011]
For example, the support plate 65 can be mounted and supported on the inner wall surface of the machine housing so as to be directly connected to and supported by the machine housing 4. However, in consideration of assembly problems, it is preferable that the support plate is attached to the hydraulic lift case 13 so as to at least partially face the case, and is connected to and supported by the body housing 4 via the hydraulic lift case ( Claim 2). According to this structure, the support plate 65 that supports the brake operating body 75 is supported in advance by the hydraulic lift case 13 and can be assembled at the same time when the case is mounted on the machine body housing 4. In addition, since it is not necessary to form the connecting portion of the support plate 65 in the airframe housing, there is a restriction in incorporating parts such as a transmission member from the opening into the airframe housing while maintaining the area of the opening 57 large. It can be done.
[0012]
The movable brake member is supported on the support plate 65 so as to be able to come into contact with and separate from the outer peripheral surface of the clutch cylinder 41 of the PTO clutch 37, and on the brake shoe 74 engaged with the brake operating body 75 on the free end side. It is preferable to constitute (claim 3). According to this structure, the support plate 65 supports not only the brake operating body 75 but also the brake shoe 74 as a movable brake member, and the movable brake member is provided in a manner that is simple in structure and easy to incorporate. Further, since the brake shoe 74 is engaged with the brake operating body 75 on the free end side, a boosting effect based on the lever principle can be obtained, and the operation force applied to the brake operating body can be reduced. The desired braking force can be obtained.
[0013]
In order to easily obtain the operation of the brake operating body in conjunction with the engagement / disengagement of the hydraulically operated PTO clutch, the brake operating body 75 is operated by hydraulic action. Movable brake member 74 And an oil chamber 78 for applying a hydraulic pressure to the brake operating body is provided in the support plate 65, and the hydraulic pressure of the PTO clutch 37 is provided in the oil chamber. Is preferably derived (claim 4). An oil passage for applying hydraulic pressure to the oil chamber 78 can be formed in the support plate 65. Oil leakage from the oil chamber 78 is permitted because the oil flows back into the machine housing 4 as it is, and the accuracy of the hydraulic seal for the oil chamber is limited to such an extent that the operation of the brake operating body is not harmed. It does not matter.
[0014]
In a PTO device in which a mechanical PTO transmission 38 is disposed between the PTO clutch 37 and the PTO shaft 36, a movable lock member 83 that engages and disengages with respect to the shift member 54 of the PTO transmission 38 in conjunction with turning on and off of the PTO clutch. It is preferable to provide 83A supported by the support plate 65 (Claim 5). According to this structure, the movable lock members 83 and 83A that are engaged with the shift member 54 in the engaged state of the PTO clutch have an interlock function that prevents the mechanical PTO transmission 38 from being disengaged. By providing the movable lock members 83 and 83A as supported by the support plate 65, it is possible to simplify the structure and facilitate the assembly of the entire PTO apparatus.
[0015]
Other features and advantages of the present invention can be clearly understood from the following description with reference to the accompanying drawings.
[0016]
【Example】
FIG. 1 shows a tractor equipped with an embodiment of the present invention. The engine 1 as a drive source is mounted on the front part of the airframe, and the airframe housing has a front housing 2, a transmission case 3, and a rear housing 4 connected in the front-rear direction. A rear axle housing 5 is mounted on the left and right outer surfaces of the rear housing 4 at its base end flange portion 5a, and left and right rear wheel axles 6a extend from the rear housing 4 through the inside. Traveling of the tractor is obtained by always rotating the left and right rear wheels 6 and rotating the left and right front wheels 7 as necessary. A front wheel drive case 8 is attached to the lower surface of the transmission case 3 and A transmission shaft 10 (FIG. 2) for transmission from the case 8 to the front wheel axle case 9 is provided so as to extend into the cover cylinder 11.
[0017]
Similarly, as shown in FIG. 1, a hydraulic lift case 13 equipped with left and right lift arms 12 is installed on the upper surface of the rear housing 4, and left and right hydraulic lift cylinders 14 that move the left and right lift arms 12 up and down. Are arranged on the back side of the rear housing 4 in a left-right manner. The seat 15 is disposed at an upper position of the mission case 3, and a steering wheel 16 is disposed in front of the seat 15 for turning the left and right front wheels 7 to obtain steering of the vehicle.
[0018]
FIG. 2 shows a transmission mechanism provided in the illustrated tractor. A front end portion of the front housing 2 is formed by a separate case portion 2a, and a buffer spring mechanism 19 that buffers the power of the engine 1 to the driving shaft 18 is disposed in the case portion 2a. is there. A forward / reverse rotation device is provided which is provided with a hollow traveling system driving shaft 20 connected to the driving shaft 18 by a coupling, and which transmits power between the traveling system driving shaft 20 and a short hollow output shaft 21 concentrically arranged with the shaft 20. 22 is provided in the rear half of the front housing 2. The output shaft 21 is connected to a concentric hollow drive shaft 23 in the mission case 3, and a main transmission 25 that performs transmission transmission between the drive shaft 23 and a transmission shaft 24 disposed below the drive shaft 23 is connected to the transmission case 23. It is provided in the front half of the case 3. A hollow intermediate shaft 26 concentrically arranged with the drive shaft 23 and a propeller shaft 27 concentrically arranged with the transmission shaft 24 are arranged in the latter half of the transmission case 3, and transmission transmission is performed between the transmission shaft 24 and the propeller shaft 27. An auxiliary transmission 28 is provided. The rear end portion of the propeller shaft 27 faces the rear housing 4 and is equipped with a bevel pinion 30 that meshes with a large-diameter input bevel gear 29 of a rear wheel differential (not shown).
[0019]
Similarly, as shown in FIG. 2, a PTO system drive shaft 31 coupled to the drive shaft 18 by coupling is provided through the hollow travel system drive shaft 20, and a PTO system transmission coupled to the shaft 31 is provided. The shaft 32 extends through the hollow traveling system drive shaft 23 and the intermediate shaft 26 into the rear housing 4. In the rear housing 4, a transmission shaft 34 connected to the transmission shaft 32 by a coupling 33, a drive shaft 35 concentrically arranged with the transmission shaft 34, and a lower portion of the drive shaft 35 are extended to the rear of the machine body. A PTO shaft 36 is provided. A hydraulically operated PTO clutch 37 is disposed between the transmission shaft 34 and the drive shaft 35, and a mechanical PTO transmission 38 is disposed between the drive shaft 35 and the PTO shaft 36. It is set up. As shown in FIGS. 2 and 3, the rear housing 4 is formed to have a front wall 4 a, a midway branch wall portion 4 b rising from the inner bottom surface, and a rear lid 4 c that closes the rear end opening, The rear end portion of the transmission shaft 32 is supported on the front wall 4a, and the rear end portion of the transmission shaft 34 is supported on the support wall portion 4b. The drive shaft 35 is supported at the front and rear ends by a bearing hole formed at the rear end portion of the transmission shaft 34 and the rear lid 4c, and the PTO shaft 36 is supported at the front and rear ends by the support wall portion 4b and the rear lid 4c. Supported by the department.
[0020]
As clearly shown in FIG. 3, a plurality of PTO clutches 37 are provided on each of the rotary support metal 40 fixedly installed on the rear end portion of the transmission shaft 34 and the clutch cylinder 41 fixedly installed on the vicinity of the front end of the drive shaft 35. A friction multi-plate type hydraulic clutch that supports the addressed friction element slidably and moves the piston 43 retreated by the return spring 42 forward by hydraulic action to obtain engagement between the friction elements. Has been. In the drive shaft 35, there is a hydraulic oil passage 44 for applying hydraulic pressure from the rear lid 4 c to the oil chamber behind the piston 43, and similarly from the rear lid 4 c to the friction element portion and the bearing portion at the front end of the drive shaft 35. A lubricating oil passage 45 for guiding the lubricating oil is provided.
[0021]
As shown in FIGS. 2 and 3, the PTO transmission 38 has two gears 46 and 47 fixedly installed on the drive shaft 35 and two gears 48 and 49 installed loosely on the PTO shaft 36. Corresponding gears are meshed with each other, and a shifter sleeve 50 that rotates integrally with the PTO shaft 36 is provided on the PTO shaft 36 between the gears 48 and 49, and the gears 48 and 49 are selectively made PTO by the shifter sleeve 50. It is configured to be coupled to the shaft 36 to obtain a two-stage shift. As shown in FIGS. 4 and 5, the shift fork 51 engaged with the sleeve 50 for shifting the shifter sleeve 50 on the PTO shaft 36 is fixedly supported at both ends on the support wall 4b and the rear cover 4c. The fork shaft 52 is supported so as to be slidable back and forth. An operating shaft 53 that passes through one side wall of the rear housing 4 and is rotatably supported on the side wall is provided, and an operating arm 54 attached to the inner end of the operating shaft 53 is engaged with the upper end portion of the shift fork 51. Accordingly, the sliding displacement of the shifter sleeve 50 on the PTO shaft 36 is obtained by the rotational displacement of the operation shaft 53. The operation shaft 53 is connected to the PTO speed change lever 55 shown in FIG. 1, and a detent mechanism 56 is provided between the shift fork 51 and the fork shaft 52 as shown in FIG.
[0022]
As shown in FIG. 3-6, the hydraulic lift case 13 is formed in a substantially portal shape, and closes the opening 57 formed on the top wall of the rear housing 4 above the PTO clutch 37. It arrange | positions on the upper surface of the housing 4, and is mounted | worn with the rear housing 4 with the volt | bolt 58 from the upper side. The opening 57 is used for assembling a component such as a gear into the rear housing 4. The hydraulic lift case 13 rotatably supports a lift arm shaft 59 extending in the left-right direction, and the lift arm 12 is attached to both ends of the arm shaft 59 outside the lift case 13.
[0023]
As shown in FIG. 3, a power take-off mechanism having gears 60, 61, 62 for taking out power from the transmission shaft 34, and the clutch 37 driven side in the disengaged state of the PTO clutch 37 as clearly shown in FIG. PTO brake 63 that brakes PTO shaft 36 and an interlock mechanism 64 for preventing gear disengagement of PTO transmission 38 when PTO clutch 37 is engaged as shown in FIGS. , In relation to the PTO device. As a main support means for that purpose, the following support plate 65 is provided across the inside of the rear housing 4 and the hydraulic lift case 13 through the opening 57.
[0024]
That is, as shown in FIG. 7-10, the support plate 65 is formed in a substantially rectangular shape provided with appropriate support portions, and has an appropriate number of positioning knock pin holes 66A and bolt insertion holes 66B. , 4, 6 are attached to the hydraulic lift case 13 by bolts 67 that are inserted into the bolt insertion holes 66 </ b> B from the lower surface side and screwed into the screw holes of the hydraulic lift case 13.
[0025]
As shown in FIGS. 3 and 6, the gear train of the power take-out mechanism described above is disposed in a gear 60 fixedly installed on the transmission shaft 34 and a forward-facing opening 13 a provided in the hydraulic lift case 13 and supported by the case 13. A fixed installation gear 62 is meshed with the power take-off shaft 68 through an intermediate gear 61, and the support plate 65 has a pair of bearing portions 69a and a gap between them as shown in FIGS. An intermediate gear support portion 69 having a gear passage hole 69b is provided. As shown in FIG. 3, the intermediate gear 61 is fixed to a short and long intermediate shaft 70 rotatably supported by both bearing portions 69a via a pair of ball bearings, and is positioned in the gear passage hole 69b. ing. The power take-off shaft 68 extends through the cover plate 13b which closes the open end of the opening 13a to the front of the hydraulic lift case 13, and is driven by the power take-off shaft 68 on the front surface of the hydraulic lift case 13. The individual hydraulic pumps 71 and 72 (FIGS. 1 and 2) are mounted inside a common casing 73.
[0026]
As shown in FIG. 5, the PTO brake 63 includes a brake shoe 74 provided to the clutch cylinder 41 of the PTO clutch 37, and a piston 75 as a brake operating body for displacing the shoe 74. However, in order to support the pin 74a that rotatably supports the brake shoe 74 at one end thereof, a shoe support portion 76 having a pin support hole 76a as shown in FIGS. Is provided. Further, as shown in FIG. 7-10, a brake operating body support portion 77 having a support hole 77a with an open upper end for fitting the piston 75 is provided on the support plate 65 on one side of the rear upper surface of the support plate 65. is there. A small-diameter hole 77b reaching the lower surface of the support plate 65 is formed at the center of the inner bottom surface of the support hole 77a, and the piston 75 has a rod portion 75a inserted into the hole 77b on the lower surface as shown in FIG. An oil chamber 78 is formed between the lower surface of the piston 75 and the bottom surface of the support hole 77a. A cap 77e is fitted and attached to the upper surface side of the support hole 77a by a bolt 77d using a screw hole 77c (FIGS. 7 and 9) of the operating body support 77, and a plurality of coils are interposed between the cap 77e and the piston 75. A spring 79 is provided to urge the piston 75 to move downward.
[0027]
The brake shoe 74 is urged to rotate away from the clutch cylinder 41 with a relatively weak force by a torque spring 80 on the pin 74a, and the shoe 74 is urged by the torque spring 80 at its free end. Thus, the engagement with the rod portion 75a of the piston 75 is maintained. The hydraulic pressure of the PTO clutch 37 is guided to the oil chamber 78, the PTO brake 63 is interlocked with the on / off of the PTO clutch 37, and the piston 75 is moved upward in the clutch-engaged state where the hydraulic pressure acts on the oil chamber 78. In the clutch disengaged state in which the brake is not performed by the brake shoe 74 and the hydraulic pressure is removed from the oil chamber 78, the piston 75 moves downward by the force of the coil spring 79, and the brake shoe 74 resists the force of the torque spring 80. The cylinder 41, and thus the PTO shaft 36 is braked by rotating and pressing the shoe 74 against the outer peripheral surface of the clutch cylinder 41. As shown in FIG. 7-10, in order to guide the clutch operating oil pressure to the oil chamber 78, one end 81a opens to the upper surface on one side of the front portion of the support plate 65, and the other end 81b opens to the inner bottom surface of the support hole 77a. An opening oil passage 81 is formed in the support plate 65, and the oil passage 81 communicates with a hydraulic oil passage 82 in the hydraulic lift case 13 as shown in FIG. 6. As shown in FIG. 5, the piston 75 and its rod portion 75a are formed with a passage 75b for obtaining a breath from the installation space of the coil spring 79.
[0028]
The interlock mechanism 64 is configured to operate in conjunction with the PTO brake 63, and has a movable lock member 83 shown in FIGS. In order to support the lock member 83, the support plate 65 is provided with an interlock support portion 84 that rises in a cylindrical shape on one side of the rear upper surface, as shown in FIGS. The lock member 83 is slidably fitted to the support portion 84 that is slightly inclined with the conical lock protrusion 83a at the lower end protruding from the lower surface of the support plate 65. 4 and 5, a screw cap 84a is attached to the upper end of the interlock support portion 84, and an oil chamber 85 is formed in the support portion 84 below the cap 84a. The lock member 83 is moved and urged by a coil spring 86 disposed in the support portion 84 so as to move backward in the support portion 84. The operating arm 54 for shift shifting is integrally formed with an obliquely upward lock portion 54a, and at the upper end of the lock portion 54a is a neutral position of the shifter sleeve 50 on the PTO shaft 36 and two shift action positions. Are provided with three lock grooves 54N, 54I, 54II. As shown in FIGS. 7, 9, and 10, the support plate 65 has an oil passage 87 that opens at one end 87a in the bottom surface of the support hole 77a of the brake actuating body support 77 and opens into the interlock support 84 at the other end 87b. The oil passage 87 communicates with the oil chamber 85 as shown in FIG.
[0029]
As described above, in the interlock mechanism 64, the movable lock member 83 is protruded by the clutch operating hydraulic pressure acting on the oil chamber 85 via the oil passage 87 in the engaged state of the PTO clutch 37 in which the PTO brake 63 is in an inoperative state. The protrusion 83a faces one of the lock grooves 54N, 54I, 54II at the upper end of the lock portion 54a and restrains the operating arm 54 so as not to rotate, so that the sleeve 50 is brought into the speed change operation position at the neutral position. It prevents the gear 50 from moving out and prevents the sleeve 50 from moving in the neutral position direction at the speed change position. In the disengaged state of the PTO clutch 37 in which the PTO brake 63 is in an operating state, the hydraulic lock is removed from the oil chamber 85, so that the movable lock member 83 is retracted by the action of the coil spring 86 and the interlock is released.
[0030]
FIG. 11 shows simplified hydraulic circuits for various hydraulic operating devices including the hydraulic operating devices described above. Of the two hydraulic pumps 71, 72 driven by the power take-off shaft 68, the hydraulic pump 71 controls the horizontal posture of the hydraulic lift cylinder 14 and other hydraulic operating devices such as a working machine connected to the rear part of the machine body. These hydraulically operated devices are collectively shown as a block 89 in FIG. 11 that is used to supply hydraulic oil to the attitude control cylinder that performs. Hydraulic fluid is supplied to the PTO clutch 37, the PTO brake 63, and the interlock mechanism 64 by a hydraulic pump 72. The hydraulic pumps 71 and 72 suck oil from an oil tank 90 provided at a lower portion in the rear housing 4 through a filter 91 and a line filter 92 in the tank 90. In preparation for a case where the line filter 92 is clogged, a bypass valve 93 that performs a relief operation by increasing the oil pressure on the primary side of the filter 92 and continues supplying oil to the hydraulic pumps 71 and 72 is connected in parallel with the line filter 92. It is provided.
[0031]
A main relief valve 94 and a secondary relief valve 95 for setting a lubricating oil pressure are connected to a discharge oil passage 93 of the hydraulic pump 72. From the primary side of the main relief valve 94, a PTO clutch 37, a PTO brake 63, and an interlock A hydraulic oil passage 96 guided in the direction of the mechanism 64 is led out, and a lubricating oil passage 97 is led out between the relief valves 94 and 95. An electromagnetic direction switching valve 98 is connected to the hydraulic oil passage 96, and the switching valve 98 has a neutral position N and an action position I. An oil passage 99 connected to the PTO clutch 37 and an oil passage 100 connected to the PTO brake 63 and the interlock mechanism 64 are connected to the secondary side of the direction switching valve 98. The latter oil passage 100 is further relieved at a relatively low hydraulic pressure. Is connected to the former oil passage 99 through a resistance valve 101. A well-known modulation relief valve 102 for gradually increasing the hydraulic pressure acting on the PTO clutch 37 from the time of displacement of the direction switching valve 98 to the operating position I is provided connected to the oil passage 99, and this relief is provided. The relief oil from the valve 102 is joined to the lubricating oil passage 97.
[0032]
As described above, at the neutral position N of the electromagnetic direction switching valve 98, oil is discharged from the oil chambers 78 and 85 of the PTO clutch 37, the PTO brake 63 and the interlock mechanism 64, the PTO clutch 37 is in a disconnected state, and the PTO brake 63 is braked. The operating state and the interlock mechanism 64 are in the interlock release state. Further, at the operation position I of the electromagnetic direction switching valve 98, oil is supplied to the PTO clutch 37 under a state in which the resistance valve 101 is in a relief operation, and the oil chamber 78 of the PTO clutch 37, the PTO brake 63 and the interlock mechanism 64 Oil is supplied to 85, the PTO clutch 37 is engaged, the PTO brake 63 is released, and the interlock mechanism 64 is in the interlock operation state. The final portion of the oil passage 99 is provided by the hydraulic oil passage 44 in the drive shaft 35 described above with reference to FIG. 3, and the final portion of the lubricating oil passage 97 is likewise the lubricating oil passage in the drive shaft 35 described above with reference to FIG. 45. The hydraulic pump 72 is also used for taking out the front wheel driving force, and an electromagnetic direction switching valve 146 described later is provided for this purpose, which will be described later.
[0033]
As shown in FIG. 3, the hydraulic lift case 13 is integrally formed with a plate-like abutment portion 13 c that extends to the front end position of the rear housing 4. A valve block 105 is fixedly installed on the front end portion of the abutment portion 13c, and the electromagnetic direction switching valves 98 and 146 described above with reference to FIG. The relief valves 94 and 95, the resistance valve 101, and the modulation relief valve 102 described above with reference to FIG. 11 are unitized as a valve unit 103 together with an oil passage therebetween, as shown in FIG. . That is, for example, as shown in FIG. 3, the secondary relief valve 95 is provided between the valve block 105 and the abutment 13c so as to discharge relief oil directly into the rear housing 4.
[0034]
The hydraulic pumps 71 and 72 have a common oil suction port, and an oil suction pipe 109 led from the lower part in the rear housing 4 that functions as the oil tank 90 shown in FIG. 11 is connected to the oil suction port. It is. Three oil supply pipes 112 and 114 shown in FIGS. 3 and 4 are led from the valve block 105 to the rear lid 4c of the rear housing 4, and these oil supply pipes 112 and 114 are oils in the rear cover 4c, respectively. The hydraulic oil passage 44 and the lubricating oil passage 45 in the drive shaft 35 are connected via the passage. An oil supply pipe 113 shown in FIG. 6 is also led out from the valve block 105 and connected to the hydraulic oil passage 82 in the hydraulic lift case 13.
[0035]
When supplementary explanation is given to the transmission mechanism of the illustrated tractor with respect to FIG. 2, the forward / reverse rotation device 22 arranged in the rear half of the front housing 2 connects the traveling system drive shaft 20 and the output shaft 21 with a reverse gear train. An intermediate shaft 131, a forward hydraulic clutch 132F for directly connecting the driving shaft 20 and the output shaft 21, and a reverse hydraulic clutch 132R for operating a reverse gear train. An integral shaft support partition wall 2b is provided in the middle of the front housing 2, and a bearing plate 133 attached to the rear end surface of the front housing 2 is provided in the rear end portion. A hydraulic pump 134 for supplying hydraulic oil to the hydraulic clutches 132F and 132R is mounted on the front surface of the partition wall 2b and is driven by the driving shaft 20. As shown in FIGS. 1 and 2, the control valve device 135 for controlling the operation of the hydraulic clutches 132F and 132R is provided on one side wall of the front housing 2 so as to straddle the inside and outside of the housing 2. .
[0036]
The main transmission 25 arranged in the first half of the transmission case 3 has four transmission gear trains arranged between the drive shaft 23 and the transmission shaft 24, and two double synchronizations on the transmission shaft 24. It is configured to perform a four-speed shift by selectively operating the clutches 136 and 137. The auxiliary transmission 28 arranged in the rear half of the transmission case 3 includes three drive-side gears on the intermediate shaft 26 connected to the transmission shaft 24 at a reduced speed and outside the intermediate shaft 26. Three gears including a shift gear 138 for shifting and rotating the propeller shaft 27 through each gear and a shift clutch 139 are provided on the propeller shaft 27, and the shift clutch 139 is provided between the transmission shaft 24 and the propeller shaft 27. Can be directly connected to each other, and is configured to perform a four-speed shift between the transmission shaft 24 and the propeller shaft 27. 2, 140 is a pulley fixedly installed on the propeller shaft 27 as a braked body of a parking brake (not shown).
[0037]
Similarly, as shown in FIG. 2, a front wheel driving force extraction gear 141 is fixedly installed on the propeller shaft 27, and a synchronous driving gear 142 driven by the gear 141 and the front wheel driving case 8 are provided. A speed increasing drive gear 143 is loosely fitted to the transmission shaft 10. A synchronous driving hydraulic clutch 144 and a speed increasing driving hydraulic clutch 145 are arranged on the transmission shaft 10 so that the gears 142 and 143 can be selectively coupled to the transmission shaft 10. As shown in FIG. 11, the hydraulic pump 72 is also connected to the hydraulic clutches 144 and 145 via the electromagnetic direction switching valve 146, and the direction switching valve 146 selectively selects the neutral position N and the hydraulic clutches 144 and 145. A synchronous drive position A and a speed-up drive position B that are actuated at the same time. At the synchronous drive position A, the transmission shaft 10 is driven at a rotational speed that rotates the front wheel 7 at a speed synchronized with the rear wheel 6 by the operation of the hydraulic clutch 144. At the acceleration drive position B, the transmission shaft 10 is operated by the operation of the hydraulic clutch 145. However, it is driven at a rotational speed that rotates the front wheel 7 at a speed larger than the speed synchronized with the rear wheel 6. The electromagnetic direction switching valve 146 is displaced in conjunction with the operation of the steering wheel 16 of FIG. 1 and is moved to the speed increasing drive position B to obtain quick vehicle turning.
[0038]
12 and 13 show a second embodiment relating to a modification of the interlock mechanism 64. In this embodiment, instead of the movable lock member 83 shown in FIGS. 4 and 5, a movable lock member 83 </ b> A is provided using a brake shoe 74 of the PTO brake 63. That is, an arm portion protruding in a direction opposite to the clutch cylinder 41 is integrally formed with the brake shoe 74, and this arm portion is configured as a movable lock member 83A. Lock grooves 54N, 54I, and 54II are formed in the lock portion 54a of the shift shift operation arm 54 in the same manner as described above, and the protruding shape of the movable lock member 83A that rotates and displaces integrally with the brake shoe 74. The distal end portion is fitted and engaged with each of the lock grooves 54N, 54I, 54II, and the operating arm 54 is restrained so as not to rotate.
[0039]
Therefore, according to the second embodiment of FIGS. 12 and 13, the movable lock member 83 </ b> A is under the bias of the torque spring 80 for biasing the brake shoe 74 in the engaged state of the PTO clutch 37 in which the PTO brake 63 releases the braking action. Thus, the operating arm 54 is restrained so as not to rotate, and the PTO transmission 38 is prevented from being disengaged. The structure of the other parts of the second embodiment is substantially the same as that of the first embodiment except that the support plate 65 is not provided with the interlock support portion 84.
[0040]
According to the structure in which the hydraulic lift cylinder 14 for moving the lift arm 12 up and down is provided outside the hydraulic lift case 13 as in the above-described embodiment, there is a margin in the hydraulic lift case, which is advantageous in installing the support plate 65. However, the hydraulic lift cylinder provided outside the hydraulic lift case is arranged outside the fuselage housing as in the embodiment. 3,405,766 or Japanese Utility Model Laid-Open No. 58-70921 can also be arranged inside the fuselage housing. Needless to say, the present invention can be similarly applied to a structure in which the layout of each part of the illustrated tractor is reversed and the PTO device and the hydraulic lift mechanism are arranged on the front side of the body.
[Brief description of the drawings]
FIG. 1 is a partially cutaway schematic side view of a tractor equipped with an embodiment of the present invention.
FIG. 2 is a partially developed schematic longitudinal side view for showing a transmission mechanism provided in the illustrated tractor.
FIG. 3 is a longitudinal side view of a rear end portion of a tractor.
4 is a longitudinal side view along another longitudinal section of the rear end portion of the tractor, which is enlarged than FIG. 3. FIG.
FIG. 5 is a longitudinal front view of a rear end portion of a tractor.
6 is a cross-sectional view substantially along the line VI-VI in FIG. 4;
7 is a perspective view of the support plate shown in FIGS. 3-6. FIG.
8 is a cross-sectional view substantially along the line VIII-VIII in FIG.
FIG. 9 is a plan view of the support plate.
10 is a cross-sectional view taken substantially along the line XX in FIG.
FIG. 11 is a circuit diagram schematically showing a hydraulic circuit.
FIG. 12 is a longitudinal side view similar to FIG. 4, showing a second embodiment.
FIG. 13 is a longitudinal front view similar to FIG. 5, showing a second embodiment.
[Explanation of symbols]
4 Rear housing
12 Lift arm
13 Hydraulic lift case
34 Transmission shaft
35 Drive shaft
36 PTO axis
37 PTO clutch
38 PTO transmission
41 Clutch cylinder
54 Actuating arm
54a Lock part
54N, 54I, 54II Lock groove
57 opening
59 Lift arm shaft
63 PTO brake
64 interlock mechanism
65 Support plate
67 volts
74 (Moving brake member) Brake shoe
74a pin
75 piston (brake actuator)
75a Rod part
76 Shoe support
76 a pin support hole
77 Brake actuator support
77a Bearing hole
78 Oil chamber
79 Coil spring
80 Torque spring
81 Oil passage
83 Movable lock member
83A Movable lock member
84 Interlock support
85 Oil chamber
86 Coil spring
87 Oil passage
98 Electromagnetic Directional Switching Valve

Claims (5)

An opening is provided on the upper surface of the airframe housing at one end side in the axial direction of the airframe, and a hydraulic lift case (13) is installed on the upper surface of the airframe housing with the opening being closed, along the axial direction of the airframe. PTO shaft is extended from within the machine housing (36) hydraulic type PTO clutch performing Nyudan power to (37), to brake the PTO shaft (36) in a disengaged condition of the PTO clutch (37) A support plate (65) facing the opening (57) in the tractor installed in the body housing with the PTO brake (63) for installation facing the opening in the direction of the body axis. Is connected to and supported by the fuselage housing (4), and a brake actuator (75) for displacing the movable brake member (74) of the PTO brake (63) is provided on the support plate (65). PTO device of the tractor, characterized in that by lifting. Wherein said support plate (65) hydraulic lift case (13), at least a portion mounted so as to face within the case, are to be linked supported via a hydraulic lift case (13) machine housing (4) according to Item 1. A tractor PTO device according to item 1. The movable brake member (74) is supported by the support plate (65) so as to be able to come into contact with and separate from the outer peripheral surface of the clutch cylinder (41) of the PTO clutch (37), and the brake actuating body (75) on the free end side. The tractor PTO device according to claim 1 or 2, wherein the brake shoe (74) is engaged with the brake shoe. The brake actuating body (75) is configured to displace the movable brake member (74) to the brake release position by the action of hydraulic pressure, and oil for applying hydraulic pressure to the brake actuating body (75). The tractor PTO device according to claim 1 or 2, wherein a chamber (78) is provided in the support plate (65), and the hydraulic pressure of the PTO clutch (37) is guided to the oil chamber.   A mechanical PTO transmission (38) is disposed between the PTO clutch (37) and the PTO shaft (36). The tractor PTO device according to any one of claims 1 to 4, wherein a movable lock member (83, 83A) to be engaged and disengaged is provided to be supported by the support plate (65).

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