JP4475926B2 - PTO shaft drive structure of tractor - Google Patents

Description

  The present invention relates to a PTO shaft drive structure for a tractor having a rear PTO shaft at the rear end of a mission case at the rear of the fuselage.

  The rear PTO shaft is generally configured to receive power transmission from a PTO transmission system that is independent of the traveling transmission system, but is switched to a so-called ground PTO mode in which the rear PTO shaft is driven at a speed synchronized with the traveling speed. Some are made possible. With a tractor that can switch and select the drive mode of the rear PTO shaft, for example, the transplanter connected to the rear of the fuselage can be driven at a speed synchronized with the traveling speed, so that the planting in the traveling direction is possible even if the traveling speed changes The pitch (between stocks) can be maintained at the set value, and the driving trailer wheels connected to the rear of the fuselage can be driven at a speed synchronized with the traveling speed of the tractor. It becomes possible to carry out transportation work by demonstrating.

As means for enabling switching between a “ground PTO cutting” mode in which the rear PTO shaft is driven irrespective of the traveling system and a “ground PTO entering” mode in which the rear PTO shaft is driven at a speed synchronized with the traveling speed, parallel to the traveling transmission system is possible. A constant mesh type transmission switching mechanism is provided in the middle of the PTO transmission system deployed in the, and the shift sleeve that is always linked to the PTO shaft is shifted in the forward direction to engage the transmission member of the PTO transmission system. "Ground PTO cutting" mode is provided, and the shift sleeve is operated in the reverse direction to engage with the transmission member linked to the traveling transmission system and disengage from the transmission member of the PTO transmission system. Are known to be configured to provide a "mode" (see, for example, Patent Document 1).
JP-A-5-162550 (paragraph 0009, FIGS. 1 to 4)

  When the rear PTO shaft is driven by the original PTO transmission system in the “Ground PTO cutting” mode, the work device linked to the rear PTO shaft is often driven at high speed, and the transmission to the rear PTO shaft is cut off. Even so, the work device continues to rotate due to inertia, and when the work device is a rotary tiller, even if it is lifted on the ground and its drive is cut off, the inertia rotates and the soil adhering to the tilling nail is scattered around. Further, when the working device is a mowing device, there is a risk that even the grass that is not cut will be cut by inertial rotation.

  Generally, as a means for preventing the inertial rotation of the PTO shaft, a configuration is adopted in which a PTO clutch and a PTO brake are introduced into the PTO transmission system, and the PTO brake is braked in conjunction with the turning operation of the PTO clutch. However, in the PTO transmission structure capable of turning on and off the ground PTO, the inertial rotation of the work device has not yet been taken into consideration, and it is desirable to have a function of preventing the inertial rotation of the work device in order to improve practicality.

  The present invention has been made in view of such circumstances, and in a PTO shaft drive structure capable of turning on and off the ground PTO, the inertial rotation prevention function of the work device linked to the rear PTO shaft is rationally exhibited. The main purpose is to make it possible.

1st invention is the PTO shaft drive structure of the tractor provided with the rear PTO shaft at the rear end of the mission case at the rear of the aircraft,
“Ground PTO entering” mode for transmitting the transmission power through the traveling transmission mechanism to the rear PTO shaft, and “Grand PTO” for transmitting the power of the PTO transmission system arranged in parallel with the traveling transmission mechanism to the rear PTO shaft. PTO mode switching means for selecting the “disengaged” mode, and a PTO clutch for intermittently connecting the PTO transmission system in the transmission better than the PTO mode switching means, and a transmission lower side in conjunction with the clutch disconnection operation of the PTO clutch. A PTO brake that applies braking, and a PTO transmission mechanism interposed in the PTO transmission system between the PTO brake and the PTO mode switching means, and the PTO clutch, PTO brake, PTO transmission mechanism, and PTO mode switching means Placed in front of the differential mechanism of the rear wheel, switching operation of the PTO transmission mechanism That the PTO shift lever, the base portion swingably supported laterally outwardly of the upper transmission case at fulcrum around laterally extending, the operation of the driver's seat extends a PTO shift lever forward from the base portion The ground PTO lever for switching the PTO mode switching means is positioned on the lateral side, and the base portion of the ground PTO lever is located around the swing fulcrum of the left-right direction located below the swing fulcrum of the PTO shift lever. The ground PTO lever is supported so as to be swingable laterally outwardly, and the ground PTO lever extends upward in a state of crossing the PTO speed change lever in a side view, and the operation portion is positioned on the side of the driver seat, so that the PTO speed change a restraint pin which rotates integrally with the PTO shift lever about the fulcrum of the lever, the grayed around the swing fulcrum of the ground PTO lever In the state where the ground PTO lever is operated to the “entering ground PTO” position by the mutual check production by engagement with the check groove that rotates integrally with the end PTO lever, the PTO speed change lever is moved from the neutral position to the speed change position. Inhibition of operation, and in a state where the PTO shift lever is operated to the shift position, it is prevented that the ground PTO lever is switched from the “Ground PTO cut” position to the “Ground PTO entered” position. The mutual checking means is arranged across the base portion of the PTO shift lever and the base portion of the ground PTO lever on the lateral outer side of the transmission case.

  According to the above configuration, when a normal working device such as a rotary tiller or a mowing device is driven by the rear PTO shaft, the ground PTO lever is operated to the “ground PTO cutting” position. In the mode, the PTO speed change mechanism can be arbitrarily changed using the PTO speed change lever. Further, in the “Ground PTO cutting” mode, the power transmission to the rear PTO shaft can be interrupted at any time by operating the PTO clutch to be cut off, and the brake is immediately braked by the rear PTO shaft from which the power transmission is cut off. Rotational inertia prevents the rear PTO shaft from rotating.

  Here, since the PTO transmission mechanism is located on the lower transmission side of the PTO clutch and the PTO brake, even when the PTO brake is disengaged and the PTO brake is braked, the rear PTO The shaft can be freely rotated by an external force, and rotational phase alignment such as spline alignment when the input shaft of the working device and the rear PTO shaft are linked and connected can be easily performed.

  Further, when the transplanter or the drive type trailer is driven by the rear PTO shaft, the ground PTO lever is operated to the “entering ground PTO” position with the PTO shift lever being in a neutral position. Accordingly, power transmission from the PTO transmission system to the rear PTO shaft is interrupted by the PTO transmission mechanism regardless of whether the PTO clutch is turned on or off, and the power of the traveling system is transmitted to the rear PTO shaft.

  In this case, when the traveling is stopped, the rear PTO shaft is also in a drive stop state, so that a brake for braking the rear PTO shaft is unnecessary. Further, when it is desired to stop the traveling and rotate the rear PTO shaft by hand as described above, the PTO mode switching means is kept neutral, and the rear PTO transmission system and the traveling system are both in the rear PTO. It is only necessary to reveal a state where the shaft is insulated.

  Therefore, according to the first aspect of the present invention, the PTO clutch and the PTO brake are provided only in the “Ground PTO cutting” mode while having the function of selectively using the “Grand PTO cutting” mode and the “Grand PTO cutting” mode. The function to prevent the inertial rotation of the working device interlocked with the rear PTO shaft can be exhibited rationally, and the rotational phase of the rear PTO shaft can be easily adjusted as necessary. It was also possible to achieve practical convenience.

  Further, since the mutual check means is provided outside the mission case, the check operation state can be visually confirmed from the outside, and maintenance such as inspection after assembly and parts replacement can be easily performed.

  Embodiments of the present invention will be described below with reference to the drawings.

  The whole side surface of the tractor with a cabin provided with the PTO shaft drive structure concerning this invention is shown by FIG. This tractor includes a front wheel 4 that can be steered in front and rear of a monobody type vehicle body that is directly connected to an engine 1, a clutch housing 2, and a transmission case 3, and a rear wheel 5 that is a main propulsion wheel having a fixed orientation. It is configured as a four-wheel drive type that is attached to the rear of the transmission case, and various working devices can be connected to the three-point link mechanism 6 provided at the rear part of the transmission case so as to be able to drive up and down. A cabin 7 that is configured so as to be connectable and covers the operation unit is provided upright.

  As shown in FIGS. 10 and 11, a foot window 7 b for seeing through the front wheel 4 and the like is provided at the left and right lower portions of the windshield 7 a in the cabin 7. The foot window 7b is configured to be able to swing and open forward by a small angle via a hinge 38 at the lower end thereof, and is closed and locked by a refraction link type lock lever 39 provided at the upper part thereof. The outside air can be introduced into the cabin by opening the foot window 7b during traveling. Therefore, when the foot window 7b is opened and the hatchback type rear window 7c provided on the back of the cabin is opened, the cabin can be efficiently ventilated, and even in a tractor equipped with a cabin not equipped with an air conditioner. Comfortable summer driving with ventilation.

  FIG. 3 shows an outline of the transmission system. The output of the engine 1 is transmitted to the main shaft 9 through the main clutch 8, and the power transmitted to the main shaft 9 is branched into a traveling system and a PTO system in the transmission case 3.

  The power branched into the traveling system is a bevel pinion gear which is a final transmission shaft through a traveling transmission mechanism including a main gear transmission mechanism 10 that performs four-stage shifting, a forward / reverse switching mechanism 11, and an auxiliary gear transmission mechanism 12. It is transmitted to the shaft 13 and transmitted to the left and right rear wheels 5 via the differential mechanism 14.

  As the main gear speed change mechanism 10, a synchromesh type speed change mechanism that selectively shifts the two shift sleeves 15 and 16 back and forth to perform four-speed shift is adopted, and the forward / reverse switching mechanism 11 is also a shift sleeve 17. The sub-gear transmission mechanism 12 is a constant mesh transmission mechanism that shifts the shift sleeve 18 back and forth to perform a two-step shift. A main transmission lever 19 for operating the main gear transmission mechanism 10 and an auxiliary transmission lever 20 for operating the auxiliary gear transmission mechanism 12 are arranged on the left side of the driver seat 21 and a forward / reverse switching mechanism. 11, a forward / reverse switching lever 22 is provided on the left side of the steering handle 23.

The power branched into the PTO system is transmitted to the rear PTO shaft 27 protruding from the rear end of the transmission case via the PTO clutch 25 with brake and the PTO transmission mechanism 26.

  As shown in FIG. 5, the PTO clutch 25 is engaged with the driving side clutch boss 28, the driven side clutch drum 29, the clutch boss 28, and the clutch drum 29. A hydraulically operated multi-plate clutch composed of a piston member 31 fitted inside and a return spring 32, etc. is employed, and the piston member 31 is advanced against the return spring 32 by supplying pressure oil. By displacing, the friction plate 30 group is pressed and brought into a “clutch engaged” state. When the pressure oil is discharged, the piston member 31 is pushed back by the internal spring 32, thereby releasing the pressure contact of the friction plate 30 group. This results in a “clutch disengagement” condition. A rotary type switching valve 33 that controls supply and discharge of pressure oil to and from the PTO clutch 25 is attached to the right outer surface of the transmission case 3, and a PTO clutch lever 34 that operates the switching valve 33 is connected to the right side of the driver seat 21. It is arranged at the rear part so that it can swing back and forth. As shown in FIG. 6, the operation arm 35 connected to the rotary spool 33 a of the switching valve 33 and the PTO clutch lever 34 are interlocked and connected by a release wire 36.

  The PTO clutch 25 is equipped with a PTO brake 40 that acts on a clutch drum 29 that is a driven member. The PTO brake 40 includes a friction plate 42 connected to the piston member 31 through a through pin 41 so as to be integrally displaceable, and a brake plate loosely fitted to the clutch drum 29 and supported non-rotatably on the transmission case side. 43. In the “clutch-in” state in which the pressure oil is supplied to the PTO clutch 25 and the piston member 31 moves forward to the right in the drawing, the friction plate 42 is connected to the piston member as shown in FIG. 31 is moved backward together with the brake plate 43 and separated from the brake plate 43 to bring about a “brake release” state. The pressure oil is removed from the PTO clutch 25 and the piston member 31 moves backward to the left in the figure. ”State, the friction plate 42 is moved together with the piston member 31 that is moved backward by the spring and is elastically pressed against the brake plate 43, so that the“ brake operation ”state is established. As soon as the PTO clutch 25 is disengaged, the clutch drum 29 is braked, and the rear PTO shaft 27 linked to the clutch drum 29 is prevented from continuing to rotate. ing. Accordingly, when a working device that rotates at high speed is coupled to the PTO shaft 27, it is possible to prevent the PTO shaft 27 from continuing to rotate due to the rotational inertia of the working device when the PTO clutch 25 is turned off.

  An auxiliary spring 44 is interposed between the friction plate 42 and the clutch drum 29, and the friction plate 42 is braked by the elastic biasing force of the return spring 32 and the auxiliary spring 44 built in the PTO clutch 25. A desired braking force is brought about by being pressed strongly by 43.

As shown in FIG. 9, the PTO transmission mechanism 26 employs a constant mesh transmission mechanism that shifts the shift sleeve 45 back and forth by a shift fork 46 to perform two-step shift, and the shift fork 46 is An operation rod 49 includes a rotation operation shaft 47 penetratingly mounted on the right side wall of the mission case 3 so as to perform a shift operation, and a PTO speed change lever 48 arranged to swing around a fulcrum a on the right side of the driver seat 21. Linked together. The operating portion 48A of the PTO speed change lever 48 is disposed on the side of the driver seat 21.

  The output side transmission shaft 51 of the PTO transmission mechanism 26 is arranged in parallel near the bevel pinion shaft 13 which is a traveling system transmission shaft and is butt-coupled concentrically with the rear PTO shaft 27, and this output side transmission shaft A gear G1 loosely fitted to the bevel pinion shaft 13 is engaged with a power take-off gear G2 and a shift sleeve 52 detachably engageable with a boss of the gear G1 is fitted to the output transmission shaft 51 with a spline. Has been.

  In the shift sleeve 52, when the shift three 52 is shifted rearward and engaged with the boss of the gear G1, the power of the traveling system taken out from the bevel pinion shaft 13 is transmitted through the gears G2 and G1 and the shift sleeve 52. As a result, the rear PTO shaft 27 is driven at a speed synchronized with the traveling speed, that is, a state of “entering the ground PTO”, and the shift is performed as shown in FIG. When the sleeve 52 is shifted forward and detached from the boss of the gear G1, the power of the traveling system is cut off from the rear PTO shaft 27, and the rear PTO from the output side transmission shaft 51 of the PTO transmission mechanism 26 is cut off. A state in which the power of the PTO system that has passed through the PTO transmission mechanism 26 is transmitted to the shaft 27, that is, a "ground PTO cutting" state is brought about.

As shown in FIG. 8, the shift fork 53 for shifting the shift sleeve 52 is engaged with an operation shaft 54 penetratingly mounted on the right side wall of the mission case 3. A connected ground PTO lever 55 is provided on the right side of the driver seat 21 so as to be swingable back and forth around the fulcrum b. The operation portion 55 </ b> A of the ground PTO lever 55 is disposed on the side of the driver seat 21.

  Here, when the “rear PTO shaft 27” is driven at a speed synchronized with the traveling speed as described above, the rear PTO shaft 27 is disconnected from the PTO transmission system in order to avoid double transmission. Therefore, the ground PTO lever 55 and the PTO speed change lever 48 are linked to each other by the following mutual check means outside the mission case.

  That is, as shown in FIG. 6, check arms 56 and 57 project from the bases of the PTO speed change lever 48 and the ground PTO lever 55, respectively, and a check groove 58 is formed in the check arm 57 of the ground PTO lever 55. The check arm 56 of the PTO speed change lever 48 is provided with a check pin 59 that engages with the check groove 58. Here, the check groove 58 includes a first circular hole 58a having a partial arc shape centering on the fulcrum b of the ground PTO lever 55, and a second long hole 58b substantially orthogonal to the first long hole 58b, and The second long hole 58b is formed in a partial arc shape with the fulcrum a of the PTO speed change lever 48 as the center when the ground PTO lever 55 is in the “ground PTO cutting” position.

  FIG. 6 shows a state where the PTO speed change lever 48 is in the “neutral” position and the ground PTO lever 55 is in the “ground PTO cutting” position. At this time, the check pin 59 intersects the check groove 58. Is located.

  In this state, the check pin 59 can move to either the first long hole 58a or the second long hole 58b of the check groove 58, so that the PTO speed change lever 48 is "neutral" as shown in FIG. The ground PTO lever 55 is switched to the “Ground PTO entered” position while being held in the position, or the ground PTO lever 55 is held at the “Ground PTO cut” position as shown in FIG. Thus, the PTO speed change lever 48 can be switched to the “low speed” position or the “high speed” position.

  In the state of “entering the ground PTO” shown in FIG. 7A, since the check pin 59 has moved to the back end of the first long hole 58a, the PTO speed change lever 48 is moved to the “low speed” or “high speed” position. When the PTO speed change shown in FIG. 7B is “low speed” or “high speed”, the check pin 59 has moved to the far end of the second long hole 58b. The operation of the ground PTO lever 55 to “enter the ground PTO” is prevented. In this way, the operation mechanism prevents the power transmission from the PTO system and the traveling system from appearing simultaneously.

  Therefore, when the rear PTO shaft 27 is driven in the “ground PTO cut” state, the rear PTO shaft 27 is linked to the PTO clutch 25 via the PTO transmission mechanism 26 selected as “low speed” or “high speed”. Therefore, braking is applied to the rear PTO shaft 27 in accordance with the PTO clutch disengagement operation as described above. However, when the rear PTO shaft 27 is driven in the “entering ground PTO” state, the rear PTO shaft 27 is driven. 27 is isolated from the PTO clutch 25 via the PTO speed change mechanism 26 that is held in a “neutral” state. Therefore, to stop the rear PTO shaft 27 during traveling, the ground PTO lever 55 is moved to the “ground PTO cut” position. A switching operation may be performed.

  In the above embodiment, a tractor having a specification equipped with only the rear PTO shaft 27 has been described. However, a specification in which a mid PTO shaft linked to the rear PTO shaft 27 is projected from the lower abdomen of the transmission case 3 to the front. Can also be implemented.

Overall side view of tractor Plan view around the driving unit without cabin Schematic side view of transmission system Longitudinal side view showing the main parts of the transmission system Longitudinal side view of PTO clutch Side view showing mutual check means between ground PTO lever and PTO speed change lever Side view showing the operating state of the mutual check means Front view of mutual check means Longitudinal front view of PTO speed change operation unit Front view of cabin Vertical side view showing the opening and closing structure of the foot window

3 Transmission case 10 Transmission mechanism (main gear transmission mechanism)
11 Traveling transmission mechanism (forward / reverse switching mechanism)
12 Traveling transmission mechanism (sub-gear transmission mechanism)
21 Driver's seat 25 PTO clutch 26 PTO speed change mechanism 27 Rear PTO shaft 40 PTO brake 48 PTO speed change lever
48A Operation section 55 Ground PTO lever
55A Operation part 58 Checking groove 59 Checking pin
a PTO shift lever swing fulcrum
b Swing fulcrum of ground PTO lever

Claims (1)

In the PTO shaft drive structure of a tractor equipped with a rear PTO shaft at the rear end of the mission case at the rear of the aircraft,
“Ground PTO entering” mode for transmitting the transmission power through the traveling transmission mechanism to the rear PTO shaft, and “Grand PTO” for transmitting the power of the PTO transmission system arranged in parallel with the traveling transmission mechanism to the rear PTO shaft. PTO mode switching means for selecting the “off” mode,
A PTO clutch that intermittently connects the PTO transmission system in the transmission better than the PTO mode switching means, and a PTO brake that brakes the lower transmission side in conjunction with the clutch disengagement operation of the PTO clutch,
A PTO transmission mechanism is interposed in the PTO transmission system between the PTO brake and the PTO mode switching means,
The PTO clutch, PTO brake, PTO speed change mechanism, and PTO mode switching means are arranged in front of the rear wheel differential mechanism,
The base of the PTO speed change lever for switching the PTO speed change mechanism is supported on the laterally outer side of the upper part of the transmission case around the left and right swing fulcrum, and the PTO speed change lever is extended forward from the base. The operation part is positioned on the side of the driver's seat, and the ground PTO lever for switching the PTO mode switching means is oscillated in the left-right direction with its base located below the fulcrum of the PTO speed change lever. Around the fulcrum is supported swingably on the lateral outer side of the upper part of the transmission case. From this base, the ground PTO lever is extended upward in a state of crossing the PTO shift lever in a side view, and the operation part is located on the side of the driver seat. Located in
Engagement between the and restrain pin to pivot said PTO shift lever integrally around the swing fulcrum of the PTO shift lever, restrain groove the pivots ground PTO lever integrally around the swing fulcrum of the ground PTO lever When the ground PTO lever is operated to the “entering ground PTO” position, the PTO speed change lever is prevented from being operated from the neutral position to the speed change position. dual control means for restraining prevented from being switched operated to the "ground PTO on" position from the ground PTO lever is "ground PTO cutting" position in a state of being operated to the shift position, the at lateral outer transmission case PTO there was placed across the base of the shift lever and the base of the ground PTO lever PTO shaft drive structure of the tractor characterized by and.

Images