JP2008309284A - Drive shift gear transmission system of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive shift gear transmission system of a working vehicle capable of enhancing operability with a wide vehicle speed range covered using an advantage by not only improving operability of a vehicle speed zone switch through a subshifting gear unit but also applying to a multi-stage shifting gear through a main shifting gear unit with improved operability. <P>SOLUTION: The drive shift gear transmission system of the working vehicle includes the subshifting gear unit C for outputting power to a running main clutch and a running axle side so as to allow gear shifting, and also transmitting a forward/backward traveling switching unit D between both of these, a plural-stage main shifting gear unit A and at least two-stage additional shifting gear unit B in series any of which includes a switching clutch, wherein the additional shifting gear unit B is located in a power input position of the subshifting gear unit C and also configured so as to allow termination operation of the switching clutch 76 of any of the additional shifting gear unit B when shifting the gear of the subshifting gear unit C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a travel shift for a work vehicle comprising a main clutch for traveling that receives engine power, a sub-transmission unit that outputs shift power to a traveling axle, and a forward / reverse switching unit, a main transmission unit, and an additional transmission unit therebetween. It relates to a transmission device.

  As shown in Patent Document 1 described below, a work vehicle is known that includes a traveling transmission device that includes a forward / reverse switching unit, a main transmission unit, and a sub-transmission unit in series between an engine and a traveling axle. The forward / reverse switching unit and the main transmission unit can select and change the transmission system by selecting a transmission system by a multi-plate clutch corresponding to a gear train having a different transmission direction, and the sub-transmission unit can select a gear by a gear shift operation. The speed band can be switched by switching the transmission series having different ratios by the sliding operation of the gear.

The gear transmission of this work vehicle selects a speed band of the sub-transmission unit according to the work content by gear shift operation, starts running by clutch adjustment of the forward / reverse switching unit, and performs multi-stage speed adjustment by the main transmission unit. Thus, it is possible to select a traveling speed in the speed band and to perform work traveling at an appropriate vehicle speed.
JP 2006-97743 A

However, when the gear of the sub-transmission unit is switched, if there is a difference in rotational speed between the input side and the sub-transmission unit, gear shift cannot be performed, so the main transmission unit on the input side of the sub-transmission unit acting as rotational inertia is There is a problem that it takes time until the rotation of the rotating portion of the advance switching portion is settled and the gear can be shifted, which hinders quick operation.
This problem also applies to the case where the main transmission unit is configured to be capable of multi-stage switching by a hydraulic control clutch so that travel adjustment can be performed by operating the switch. Since the operability of the transmission unit is deteriorated, the problem of operability in the auxiliary transmission unit has caused a problem that the operability improvement effect by the switch operation cannot be fully utilized for the main transmission unit. .

  The problem to be solved by the invention is not only to improve the operability of the vehicle speed band switching by the sub-transmission unit, but also to apply it to multi-stage shifts by the main transmission unit for improved operability, thereby taking advantage of the wide vehicle speed range. An object of the present invention is to provide a traveling speed change transmission device for a work vehicle that can improve operability while covering the above.

The invention according to claim 1 includes a traveling main clutch that receives the power output from the motor and controls the rotational transmission thereof, and a sub-transmission unit that outputs power to the traveling axle so that the gear can be shifted. Switching clutch that switches a plurality of transmission trains having different gear ratios in series with a forward / reverse switching unit that switches between, a main transmission unit that performs transmission in multiple stages, and an additional transmission unit that performs transmission in at least two stages The additional transmission unit is disposed at a power input position of the sub-transmission unit, and at the time of shifting of the sub-transmission unit, any switching clutch of the additional transmission unit is provided. It is configured to be capable of cutting operation.
By the transmission interruption in the additional transmission section, the rotational inertia on the input side of the nearest sub transmission section can be kept small.

According to a second aspect of the present invention, in the configuration of the first aspect, the sub-transmission unit is provided with neutral detection means for detecting a neutral state of non-transmission, and the side of the additional transmission unit near the sub-transmission unit. For the switching clutch, transmission cut-off control is performed according to the detection operation of the neutral detection means.
When the sub-transmission unit is in a neutral state, the transmission of the switching clutch on the output side of the additional transmission unit is cut off via the neutral detection means for detecting this, and the rotational inertia on the input side of the nearest sub-transmission unit is minimized. It can be suppressed.

  Since the rotational inertia on the input side of the sub-transmission unit is suppressed to be small by the transmission interruption in the additional transmission unit, the travel-speed transmission device for the work vehicle having the configuration according to claim 1 can reduce the input side rotation difference during the shift of the sub-transmission unit. Therefore, the shift switching of the auxiliary transmission unit becomes smooth. Therefore, not only improvement in the operability of the vehicle speed band switching by the sub-transmission unit, but also the application of this together with the multi-stage shift of the main transmission unit by hydraulic control etc., can cover the wide range of vehicle speeds. The operability can be improved.

  In the traveling speed change transmission device for a work vehicle having the configuration according to claim 2, since the transmission is cut off by the switching clutch on the output side of the additional speed change portion when the sub speed change portion becomes neutral, the input side rotational inertia of the sub speed change portion is reduced. Since the speed can be reduced to the minimum, the sub-transmission unit can be switched quickly and smoothly, and the transmission interruption corresponds to the neutral operation of the sub-transmission unit. Power cutting can be prevented.

Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings.
An agricultural tractor as an example of a work vehicle according to the present invention has an engine as a prime mover in a hood at the front part of a machine body having front wheels 61 and 61 and rear wheels 63 and 63 as shown in FIG. 62, and the rotational power of the engine 62 is transmitted to a transmission which is a transmission transmission T, and the power appropriately shifted by the transmission transmission T is transmitted to the front wheels 61 and 61 and the rear wheels 63 and 63. The output is made to a working machine (not shown) through the rear PTO shaft 14. Further, for operation by an operator, a control unit H is configured at the upper part of the transmission device T, and operation units such as a forward / reverse switching lever and a clutch pedal (not shown) are arranged so that the control unit can control the shift. The

  The speed change transmission device T is a mechanism that controls the speed of the traveling power and work machine power, and as shown in the transmission system development view of FIG. 2, the traveling system is a forward / reverse switching section D that receives power from the engine 62, and the main transmission section. A, additional transmission B and sub-transmission C are transmitted to the rear wheels 63 and 63 via the differential mechanism 45, and also equipped with a front wheel transmission clutch (two-wheel drive and four-wheel drive switching clutch) 67 to switch between two and four wheel drive The power for the front wheels 61 and 61 is divided through the differential mechanism 47 so as to be controllable. The work machine system includes a PTO clutch 66, a PTO transmission unit 32, and the like that branch work machine power from the engine 62 and control transmission to the rear PTO shaft 18.

  The forward / reverse switching section D is configured to switch forward / reverse by two switching clutches 60, the main transmission section A is configured to be switchable in four stages by four switching clutches 76, 76, and the additional transmission section B is switched to two switches. The clutch 76 switches between low speed and high speed. The transmission configuration of the transmission device T and its hydraulic control configuration including these transmission units will be described in detail separately.

(Sub transmission)
The sub-transmission unit C is provided with a gear shift driving unit by hydraulic control or electromagnetic actuator Ca as shown in FIGS. 3 and 4 in plan and front views of the gear shift driving unit. The transmission of each gear 35 for high-speed synchromesh connection switching and ultra-low-speed creep is configured to be shift-switchable. In addition to the "high", "low", and "creep" speed bands for these work runs, the "neutral", which is a neutral state without power transmission, can be switched, and the shift position including the neutral state can be detected. A possible sensor S is provided.

  The sensor S is a neutral detection means for detecting a neutral state that is a transmission cutoff position of the sub-transmission unit C. When the sub-transmission unit C is switched to “neutral” by a shift operation using a lever, a push button switch, or the like, Control is configured to control transmission interruption of the additional transmission unit B according to the detection operation of the neutral detection means, and to switch the forward / reverse switching unit D to the neutral position if necessary.

  The travel transmission device configured as described above is configured such that the additional transmission unit B is disposed at the power input position of the sub-transmission unit C, and that the gear transmission is preferably cut off at any time, preferably on the shift output side. Further, the auxiliary transmission unit C is provided with neutral detection means S for detecting a neutral state of transmission interruption, and the auxiliary transmission unit C is in the neutral state by performing transmission interruption control of the additional transmission unit B according to the neutral detection. , Transmission is cut off on the output side of the additional transmission B.

Accordingly, the rotational inertia on the input side of the sub-transmission unit C at the nearest position is suppressed to be small, and the adjustment of the input-side rotation difference at the time of the shift of the sub-transmission unit C is facilitated. Not only the operability improvement of the vehicle speed band switching by the part C, but also the operability improvement covering a wide vehicle speed range can be taken advantage of by applying it together with the multi-stage shift of the main transmission part by hydraulic control etc. It becomes possible.
In this case, by causing the transmission interruption of the additional transmission portion B to correspond to the neutral operation of the auxiliary transmission portion C, inadvertent power disconnection during traveling transmission can be prevented.

(Shifting operation part)
As for the configuration of the speed change operation unit, when operating the sub-transmission unit C with a lever, as shown in FIG. 5A, an H pattern lever guide P is used, and the operation system configuration diagram of FIG. By connecting with a guide cable Cc that switches between high and low speeds by tilting the switching lever L provided with increase / decrease switches B1 and B2 in the grip portion G, the number of operating levers can be reduced and the operation can be simplified.

  Specifically, the main transmission A is operated by the increase / decrease button switches B1 and B2, the additional transmission B is operated by the switch, the sub-transmission C is switched by lever operation, and the sub-transmission C is operated by the lever. When switching from "low speed" to "high speed" at L, first, the main transmission section A is automatically shifted from the current position to the highest speed 8-speed position, and then the sub-transmission section C is switched by actuator drive. When switching to a low speed, the main transmission section A is automatically shifted from the current position to the first speed position of the lowest speed, and then the auxiliary transmission section C is switched by driving the actuator. Such a control process can prevent an abrupt shift shock.

  In the case where the main clutch that is turned on and off by stepping on the clutch pedal is provided at the output position of the engine 62, the intention of the operator can be reflected by stopping the automatic shift control during the clutch pedal operation. . In addition, an inadvertent shift can be prevented by stopping the increase / decrease shift control of the main transmission A during the shift of the sub-transmission C.

(Another shift operation part)
As another configuration, as shown in FIGS. 7A to 7C, the auxiliary transmission changeover lever L includes the increase / decrease button switches B <b> 1 and B <b> 2 of the main transmission unit A, and the additional transmission unit B. The operability can be improved by providing the high / low changeover switch B3. FIG. 7 (a) arranges the high / low changeover switch B3, which is shifted to “high” when pressed, in the lever L, and FIG. 7 (b) shows the high / low changeover by the operation in the front-rear direction. The changeover switch B3 is arranged at the top of the lever L, and FIG. 7C is an example in which the high / low changeover switch B3 that is shifted to “high” when arranged is arranged at the top of the lever L.

  As shown in an exploded perspective view (a) and a partially enlarged view (b) of FIG. 8, the switching lever L of the sub-transmission unit C is configured to be attached to the operator seat Ha of the control unit H, thereby moving the seat back and forth. Even if it is moved up and down, the positional relationship between the seat and the switching lever L is maintained, and the operability of the lever can be improved. The switch is an example in which increase / decrease button switches B1 and B2 and a high / low changeover switch B3 which is “high” when pressed are collectively arranged.

  Further, as shown in an exploded perspective view (a), a partially enlarged view (b), and a principal enlarged view of another configuration example of the switching lever in FIG. 9, the switching lever L is operated in a straight line, and is in a neutral (N) position. In order to prevent erroneous operation, a check groove is formed in the lever guide portion G, and a limit switch S is provided to prevent erroneous operation due to contact such as when getting on and off as a two-stage motion configuration at the N position. As described above, by performing the linear operation, it is possible to improve the operability and prevent an erroneous operation.

As for the transmission gear ratio of the additional transmission section B, as shown in the gear ratio combination list in FIG. 6, four-stage switching of “LL”, “L”, “M”, and “H” is performed by an integral combination with the auxiliary transmission section C. The H-pattern lever guide can be configured as an integral auxiliary transmission unit.
In this case, as shown in the perspective view of the main part of FIG. 10, the switching lever L can be operated without causing a sense of incongruity by performing a linear operation corresponding to the switching of the additional transmission unit B. Become.

(Transmission transmission)
Hereinafter, the transmission configuration of the transmission and the hydraulic control configuration thereof will be described in detail.
In FIG. 2 described above showing the power transmission system diagram of the tractor of this embodiment, the engine 62 has a projecting engine shaft 1 on the rear side, and this engine shaft 1 is connected to the input shaft 2 of the clutch housing portion. The output shaft 3 and the PTO shaft 14 at the rear end are interlocked via a transmission mechanism in the transmission case, and the front wheel output shaft 5 provided at the lower part of the transmission case is interlocked. This output shaft 3 is supported along the front-rear direction at a substantially central portion of the rear portion in the transmission case, has a drive pinion gear 53 at the rear end, meshes with the diff ring gear 46 of the rear differential 45, and rotates along the rear axle housing. The mounted rear differential shaft 10 and rear wheel shaft 11 are interlocked via a planetary reduction mechanism. The front wheel output shaft 5 is connected to the input shaft 26 of the front differential 47 provided at the center of the front axle housing from the lower part of the transmission case through the lower part of the engine 62, and is mounted along the front axle housing. It is configured to be linked to the front wheel shaft 13 via the front differential shaft 12 and the planetary speed reduction mechanism. Note that gear drive shafts 15 and 17 for taking out power from the input shaft 2 to the hydraulic pump 80 (FIG. 11) are arranged in parallel with the input shaft 2.

  The transmission of this embodiment is provided with a PTO clutch pack 66 on a PTO countershaft 9 having a PTO shift counter gear 44 that is linked to an input gear 31 from an input shaft 2 driven by the engine shaft 1. The input shaft 2 is provided with forward / reverse switching gears 42, 42 for forward / reverse switching in the idle state, and the reverse counter forward / reverse switching gear 42 has a back counter shaft 8 arranged in parallel with the input shaft 2. A back counter gear 43 provided on the main transmission shaft 19 is engaged, and the other forward-side forward / reverse switching gear 42 is provided with an input gear 48 fixed on the main transmission shaft 19 and an effective free rotation on the main transmission shaft 19. Four main transmission gears 33 having different diameters are provided. These four main transmission gears 33 are configured as a four-speed transmission, and are switched and shifted by the clutch pack 76. The transmission including the four main transmission gears 33 is referred to as a main transmission A.

  On the main transmission shaft 19, of the four main transmission gears 33 of the main transmission A, the main transmission gear 33 (for first speed) having the smallest effective diameter and the main transmission gear having the third smallest effective diameter are provided. The clutch pack 76 is fixed between the main transmission gear 33 (for the third speed) and the main transmission gear 33 (for the second speed) having the second smallest effective diameter and the main transmission gear 33 (for the fourth speed) having the largest effective diameter. The clutch pack 76 is fixedly provided. Each of the two clutch packs 76 is provided with a friction clutch that connects each main transmission gear 33 so as to rotate integrally with the main transmission shaft 19.

  Further, the input gear 48 that can mesh with the forward gear of the forward / reverse switching gear 42 meshes with the back counter gear 43 on the back counter shaft 8 together with the reverse gear of the forward / reverse switching gear 42. Of the switching gears 42, the forward gear 42 and the reverse gear 42 are alternatively integrated with the input shaft 2 by switching between the two forward / reverse switching clutch packs 60 composed of independent front and rear friction clutches, It is the structure switched to forward travel and reverse travel. A configuration including these gear 42, clutch pack 60 and the like including a hydraulic cylinder 85 (FIG. 11) to be described later is referred to as a forward / reverse clutch D.

  Further, a forward / reverse switching lever 115 for manually switching the forward / backward clutch D is provided at the post portion of the steering handle 73, the clutch pedal 119 is provided below the handle post 73, and the clutch pedal 121 is provided near the handle.

  The sub-transmission shaft 20 provided coaxially with the main transmission shaft 19 is provided with two high and low-speed switching gears 34 having different effective diameters that are switched and shifted by the clutch pack 76. Furthermore, it can decelerate and can switch to high speed and low speed. The gear configuration that can be switched between high speed and low speed is referred to as a high / low transmission B.

  Further, an output shaft 3 having three auxiliary transmission gears 35 having different effective diameters is arranged coaxially with the auxiliary transmission shaft 20. The output shaft 3 is configured to be shifted in three stages by the auxiliary transmission gear 35. The configuration of the gear 35 capable of three-speed shifting is referred to as an auxiliary transmission device C.

Further, a creep counter shaft 21 having a creep counter gear 49 that meshes with the auxiliary transmission gear 35 is provided in parallel with the output shaft 3. A travel counter shaft 6 having a main transmission counter gear 39 and a high / low speed switching gear 40 meshing with the main transmission gear 33 and the high / low speed switching gear 34 is disposed in parallel with the main transmission shaft 19 and the auxiliary transmission shaft 20. Rotation transmitted from the main transmission shaft 19 is changed by the main transmission gear 33, and the rotation is switched between the high and low speeds provided on the auxiliary transmission shaft 20 via the main transmission counter gear 39 and the high and low speed switching gear 40 in sequence. It is transmitted to the gear 34. The power transmitted to the high / low speed switching gear 34 is transmitted to the output shaft 3 through the clutch pack 76 and through the transmission mechanism by the auxiliary transmission gear 35 provided on the auxiliary transmission shaft 20.
In the traveling power transmission system of the present embodiment, a forward / reverse rotation PTO that is a transmission mode for rotating the PTO interlocking shaft 4 provided with a PTO forward / reverse switching gear 37 mechanism is provided.

  A front wheel interlocking gear 51 that has a front wheel interlocking gear 51 that rotatably supports the subtransmission countershaft 27 of the subtransmission countergear 38 that meshes with the subtransmission gear 35 and that is interlocked from the output shaft 3 via the front wheel take-out gear 36. A shaft 28 is provided, and a PTO reduction shaft 23 having a PTO reduction gear 50 is provided on the front extension axis of the front wheel interlocking shaft 28. Further, a PTO interlocking shaft 4 is provided at a position parallel to the front wheel interlocking shaft 28, and the PTO forward / reverse switching gear 37 for switching the PTO interlocking shaft 4 between forward rotation and reverse rotation at the front end on the same axis as the PTO interlocking shaft 4. The switching shaft 22 and the PTO transmission shaft 18 of the PTO transmission gear 32 are arranged.

  A PTO reverse rotation counter shaft 24 having a PTO reverse rotation counter gear 52 that meshes with the PTO normal / reverse switching gear 37 is provided on the side of the PTO forward / reverse switching shaft 22, and the input shaft is inserted by the insertion of the PTO clutch pack 66. Power is transmitted from 2 to the PTO forward / reverse switching shaft 22 via the PTO transmission gear 32, the PTO transmission counter gear 44, the PTO forward / reverse switching gear 37, and the like. The forward / reverse switching gear 37 uses a clutch ring having the same form as the PTO transmission gear 32. A reverse rotation counter shaft 24 having a PTO reverse rotation counter gear 52 is provided on the side of the PTO normal / reverse switching shaft 22, and the PTO reverse rotation counter gear 52 receives the interlocking from the PTO reduction gear 50 and performs PTO forward / reverse switching. The gear 37 can be reversely rotated. A deceleration shaft 23 is disposed behind the PTO counter shaft 9.

  Further, the front wheel output shaft 5 arranged at the lower stage in the transmission case is mounted on the rear bottom portion of the transmission case, and is connected to the input shaft 26 of the front differential 47 through the front wheel interlocking shaft 25 and the coupling. To do. A front wheel drive shaft 7 is disposed on the side of the front wheel output shaft 5. A front wheel gear 55 is provided at the rear end of the front wheel drive shaft 7. Further, the first front wheel interlocking gear 51 on the front wheel interlocking shaft 28 meshes with the front wheel take-out gear 36 at the rear end portion of the output shaft 3 and is transmitted to the front wheel interlocking shaft 28 via the first front wheel interlocking gear 51. The driving force of the output shaft 3 is transmitted to the second front wheel interlocking gear 54 that rotates integrally with the front wheel interlocking shaft 28, and is transmitted from the front wheel interlocking gear 54 to the front wheel driving shaft 7.

  A front wheel drive clutch pack 67 is provided on the front wheel drive shaft 7, and geared from the front end of the drive shaft 7 to the front wheel output shaft 5. Further, two front wheel drive switching gears 41 having different effective diameters are arranged on the left and right sides of the front wheel drive clutch pack 67, and the two front wheel drive switching gears 41 are provided with two effective wheel diameters provided on the counter shaft 59. The front wheel drive shaft 7 can be driven at either one of the two reduction ratios by meshing with the drive counter gear 56 and selectively connecting the front wheel drive clutch pack 67.

  When the front wheel drive clutch pack 67 is shifted to the neutral position, the front wheel 61 is not driven, and a rear wheel drive two-wheel drive mode is adopted. When the front wheel drive clutch pack 67 is switched by a hydraulic operation to shift to the low speed position, the front wheel 61 is moved to the rear. A four-wheel drive configuration in which the wheel 63 is driven at a constant speed of about one time with respect to the wheel 63 is used. When the front wheel drive clutch pack 67 is switched by a hydraulic operation and shifted to a high speed position, the front wheel 61 is moved to the rear wheel 63 by about It is possible to travel by adopting a four-wheel drive mode in which the driving speed is doubled.

  With the meshing transmission having the above-described configuration, the rotational power of the engine 62 is transmitted through the forward / reverse clutch D that constitutes the main clutch, to the main transmission A that has four speeds, and to the high speed that has two speeds. The low transmission B and the sub-transmission C comprising three speeds are shifted to any one of a total of 24 speeds, and the rotational power obtained is driven through the rear differential 45 to drive the rear wheels 63. The rotational power changed by the auxiliary transmission C is also transmitted to a front wheel drive clutch pack (two-wheel drive / four-wheel drive switching clutch) 67, which causes the front wheels 61 to be “constant speed” or “acceleration”. After switching, the front wheel 61 is driven through the front differential 47.

  Further, the PTO transmission gear 32, the traveling main transmission gear 33, the high / low speed switching gear 34, the auxiliary transmission gear 35, and the like are arranged along the axis of the output shaft 3 having the drive pinion gear 53. The transmission of the traveling system is interlocked with the drive pinion gear 53 via the main transmission gear 33, the high / low speed switching gear 34, the multiple transmission gear 35, etc. arranged on the axis of the output shaft 3 from the input shaft 2. Further, the PTO shift is linked via a PTO transmission gear 32 provided at the front end portion on the axis of the output shaft 3.

Next, FIG. 11 shows a hydraulic circuit diagram of the tractor of this embodiment.
In the hydraulic circuit diagram of FIG. 11, left and right brake cylinders 83 that brake left and right rear wheels 63 independently, a four-wheel drive clutch cylinder 99 that switches the power transmitted to the front wheels 61 to “constant speed” or “acceleration”, steering A power steering device 103, a PTO clutch cylinder 104, PTO clutch pressure control valves 105, 106, and the like that are operated by rotating the handle 73 are provided. In addition, the circuit 101 of the dashed-dotted line portion is a main hydraulic circuit (working machine lifting / lowering, horizontal working machine extraction, external hydraulic pressure taking out, etc.) and has little relation to sub-circuits (running / brake / diff lock / PTO side circuit). Is omitted.

  The hydraulic oil discharged from the hydraulic pump 80 is hydraulically actuated by the hydraulic clutch cylinder 87 and the hydraulic pressure which actuate the gears 33 for the fourth speed and the second speed of the main transmission A via the clutch pack 76 via the pressure reducing valve 81a. A hydraulic clutch cylinder 91 and a hydraulic clutch which are supplied to a shift control valve 89 for switching the 4-2 speed for switching the clutch cylinder 88 and further operate the first speed gear 3 and the third speed gear 33 of the main transmission A, respectively. This is supplied to a shift control valve 93 for switching the first to third speeds for switching the cylinder 92.

The hydraulic fluid that passes through the pressure reducing valve 81 a is supplied to the switching valve 86 that switches between the forward clutch and the reverse clutch D of the forward / reverse clutch cylinder 85 via the on / off control valve 129 of the forward / reverse clutch cylinder 85. The forward clutch pressure sensor 110 and the reverse clutch pressure sensor 111 can detect which hydraulic fluid is supplied to the forward clutch D of the forward / reverse clutch cylinder 85.

  Similarly, the hydraulic oil supplied to the hydraulic clutch cylinders described above and below is configured to be detected by a pressure sensor provided in an oil path on the inlet side to each hydraulic clutch cylinder.

  The hydraulic oil discharged from the hydraulic pump 80 is branched and supplied to the left and right brake cylinders 83 via the pressure reducing valve 81b and the brake valve 82a. The brake valve 82a is a switching control valve for selecting the rear wheel 63, and the brake valve 82a is integrated with a pressure control valve 82b for adjusting the brake force.

Further, the hydraulic oil passing through the pressure reducing valve 81b is transmitted to the clutch pack 76 at one of the two gears 40 of "high speed" and "low speed". Is supplied to the control valves 96a and 96b for switching the high / low hydraulic clutch cylinder 95 to be operated.
Further, the hydraulic oil passing through the pressure reducing valve 81 b is branched into the front-wheel differential lock cylinder 98 a for the front differential 47 and the rear-difference lock cylinder 98 b for the rear differential 45 through the differential lock control valve 97.

Further, hydraulic oil 99 for switching the gear 41 of the front wheel drive clutch pack 67 is supplied with hydraulic oil via the switching control valve 94 and the pressure reducing valve 81b.
Similarly, the hydraulic fluid passing through the pressure reducing valve 81b is supplied to the PTO clutch cylinder 104 via the PTO valves 105 and 106, and adjusts the pressure of the PTO clutch.
Further, the hydraulic pressure from the hydraulic pump 80 shown in FIG. 11 is configured to supply hydraulic oil to the orbit roll 107 that is operated by operating the power steering handle.

It is a body side view of a work vehicle. It is a transmission system expansion | deployment figure of the transmission transmission apparatus of a working vehicle. It is a top view of a gear shift drive part. FIG. 4 is a front view of the gear shift drive unit of FIG. 3. It is a lever guide pattern (a), an operation system configuration diagram (b). It is a combination list of gear ratios. It is another structural example (a)-(c) of a speed change operation part. It is the disassembled perspective view (a) of the switching lever, and its partial enlarged view (b). It is a disassembled perspective view (a) of another structural example of a switching lever, a partial enlarged view (b), and a principal part expanded block diagram. It is a principal part perspective view of another structural example of a switching lever. FIG. 4 is a hydraulic control diagram of the transmission gearing device.

Explanation of symbols

35 gear 62 engine (motor)
76 Switching clutch A Main transmission part B Additional transmission part B1, B2 Increase / decrease button switch B3 High / low switching button C Sub-transmission part Ca Actuator D Forward / reverse switching part L Switching lever S Sensor (neutral detection means)
T gear transmission

Claims (2)

Forward / reverse switching for switching the rotational direction between the main clutch for driving that receives the output of the prime mover and the auxiliary transmission portion (C) that outputs power to the traveling axle side so that the gear can be shifted. A plurality of transmission systems having different gear ratios in series with a part (D), a main transmission unit (A) that performs transmission in multiple stages, and an additional transmission unit (B) that performs transmission in at least two stages In a traveling speed change transmission device for a work vehicle provided with a switching clutch for switching between
The additional transmission unit (B) is disposed at the power input position of the sub-transmission unit (C), and when the sub-transmission unit (C) is shifted, any one of the switching clutches (76) of the additional transmission unit (B). ) Is configured to be capable of moving and operating, a traveling speed change transmission device for a work vehicle.   The auxiliary transmission unit (C) is provided with neutral detection means (S) for detecting a neutral state of non-transmission, and a switching clutch closer to the auxiliary transmission unit (C) in the additional transmission unit (B). 2. The traveling speed change transmission device for a work vehicle according to claim 1, wherein transmission cutoff control is performed for (76) in accordance with the detection operation of the neutrality detection means (S).

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