GB2207101A - PTO shaft driving apparatus in a tractor - Google Patents

Description

1 22' 0 710 1 PTO SRAFT DRIVING APPARATUS IN A TRACTOR The present

invention relates to a power transmission system in a tractor such as for agricultural use,and more particularly to a PTO shaft driving apparatus in a tractor provided with a plurality of power take-out shafts (through this specification and the. claims, abbreviated as "PTO shaft") such as a rear PTO shaft, a front PTO shaft and the like in a transmission case.

In a tractor for agricultural use, on a front portion of a vehicle body is loaded an engine, and on a rear portion isloaded a transmission case. An output shaft of the engine is connected to an input shaft of a transmission case via a propeller shaft. Within the transmission case is contained a speed- changer mechanism, so that engine power input to the above-mentioned input power is transmitted at a changed speed to a final shaft via the speed-changer mechanism.

In the transmission case is provided a PTO shaft or shafts, the input engine power is also transmitted to these PTO shafts. and the power is transmitted to working machines connected to the tractor via the PTO shafts. In the prior art, for instance, a tractor having three PTO shafts consisting of a rear PTO shaft, a middle PTO shaft and a front PTO shaft and adapted to drive the respective working machines connected to the rear portion, middle portion and front portion of the vehicle body, respectively, through these PTO shaftsr has been known.

.. --------------- A A working machine connected to the f ront portion of the vehicle body is, for instance, a mower, and in this case, sometimes the work is done by means of that mower only, and other times the mown grasses are gathered by means of a sweeper connected to the rear portion of the vehicle body.

In additiont sometimes an additional mower is further connected to the middle portion of the vehicle body, and after grasses have been roughly mown by the mower at the front portion, finishing is effected by the mower at the middle portion.

As will be seen from the above, since the respective PTO shaf ts at the f ront, middle and rear portions are used as combined in an appropriate combination depending upon the kind of work, it is desirable for enhancing a utilization is efficiency of power to make any provision such that power may be transmitted from the engine to only the PTO shafts which are used during the work. ' However, on the other hand it is inevitable that a drive structure for the PTO shafts becomes complicated if one tries to realize such provision.

Accordingly, the present invention has it as an object to provide a simple and small-sized PTO shaft driving apparatus in which the mode of power transmission to a -25 plurality of PTO shafts can be switched in a simple manner.

To that end, according to the present invention, in a PTO shaft driving apparatus in a tractor provided with a plurality of PTO shafts for driving a plurality of working machines mounted to a vehicle body, within a transmission 1 i 1 i j i 1 1 k_ case is provided a PTO transmission shaft connected via a PTO clutch to an input shaft of the transmission case so that power may be transmitted to the above-mentioned plurality of PTO shafts via the aforementioned PTO transmission shaft.

According to the present invention, since a plurality of PTO shafts are driven by a single PTO transmission shaft connected via a PTO clutch to an input shaft driven by an engine, surplus shafts or belts are not necessitated, and the drive system becomes simple.

In addition, inasmuch as a PTO drive sub-system can be, as a whole, disconnected from an engine or connected to an engine by disconnecting or connecting the above-mentioned PTO clutch and thus a PTO drive sub-system and a travelling drive sub-system are independent of each other, the driving is condition of the respective PTO shafts would not be influenced by the travelling condition of the tractor. When the working machines are not used, loss of engine power caused by idling of the shafts in the PTO drive sub-system, can be avoided by cutting off the corresponding subsystem from the engine.

Furthermore, by providing a power transmission switching apparatus capable of selectively transmitting power to the respective PTO shafts, on the above-described PTO transmission shaft, power transmission to a plurality of PTO shafts can be switched over various combinations by means of a simple and compact apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS:

1 Fig. 1 is a system diagram showing a power transmission system according to one preferred embodiment of the present invention; Fig. 2 is a cross-section view showing in more detail a structure of a part of the power transmission system in Fig. 1; Fig. 3 is a general side view of a tractor embodying the present invention; Fig. 4 is a developed longitudinal cross-section view showing a power transmission system according to another preferred embodiment of the present invention taken along the planes successively connecting the axes of the respective shafts and then developed; and Fig. 5 is a transverse cross-section front view of the same power transmission system.

A tractor 80 embodying the present invention is generally shown in a side view in Fig. 3, in which f ront wheels 82 are mounted to a f ront portion of a vehicle body f rame 81 and rear wheels 83 are mounted to a rear portion of the same. On a front upper portion of the vehicle body frame is loaded an engine 84, and an output shaf t of the engine 84 is connected to an input shaft of a transmission case 1 via a flywheel 85 and a propeller shaft 86. Within the transmission case 1 is contained a power transmission mechanism as will be described later, and the engine power input to the above-described input shaft is output to a rear axle 28 and a front wheel drive shaft 87 after it has been i 1 t appropriately speed-changed through the power transmission mechanism.

Prom the transmission case 1 also project three PTO shafts consisting of a front PTO shaft 70, a middle PTO shaft 41 and a rear PTO shaft 44, and the engine power input to the above-described input shaf t is transmitted also to these PTO shafts. To the respective PTO shafts are connected a front working machine F, a middle working machine M and a rear working machine R, respectively, through working machine io drive shafts 70a, 41a and 44a. In the illustrated embodiment, the front working machine F and the middle working machine M are mowers, while the rear working machine R is a sweeper. High grasses are roughly mown by the front working machine F, then the grasses are mown for finishing by the middle working machine M, and the mown grasses are gathered by the rear working machine R. As a matter of course, the mode of use of the tractor 80 should not be limited to the above-described mode, but it is possible to connect various kinds of working machines to all or a part the respective PTO shafts 70, 41 and 44 as combined various combinations to perform works adapted to respective objects.

of in the Fig. 1 is a system diagram of the power transmission mechanism within the transmission case 1 in the tractor 80.

At the front end of the transmission case 1 is integrally mounted a main clutch case 2, and an input shaft 5 is pivotably supported from a front wall la of the transmission case 1 and the main clutch case 2 via bearings 3 and 4, respectively. The input shaf t 5 is connected to the engine 84 via the flywheel 85 and the propeller shaft 86 as described above, and it is always rotating upon operation of the engine. A gear 6 is fixed secured to the input shaft 5, and this gear 6 is always meshed with a gear 8 loosely fitted around a main shaft 7. Rotation of the gear 8 is transmitted to the main shaf t 7 via a main clutch 9 of wet multi-disc type disposed within the main clutch case 2. The main shaft 7 is rotatably supported from the front wall la and a middle wall lb of the transmission case 1 via bearings 10 and 11.

Within the transmission case 1 is also disposed a counter shaft 12 that is rotatably supported similarly from the front wall la and middle wall lb adjacent to the main shaf t 7, and a main speed changer 13 is provided between -these shafts 7 and 12.

The main speed changer 13 is composed of a 3rd-speed drive gear 14, a 2nd-speed drive gear 15, lst-speed drive gear 16 and a back drive gear 17, which are f ixedly mounted on the main shaft 7, and a 3rd-speed driven gear 18, a 2nd speed driven gear 19 and a lst-speed driven gear 20 meshed with the aforementioned gears 14, 15 and 16, respectively, and a back driven gear 21 meshed with the above-described back drive gear 17 via an idle gear, which are all loosely fitted around the counter shaft 12, and rotation of the main shaft 7 is transmitted to the counter shaft 12 at a desired speed-change ratio by connecting any one of the above described driven pears 18 to 21 to the counter shaft 12 by the intermediary of- a selector. 22 that is rotatable integrally with and slidable in the axial direction of the counter shaft 12.

1 1 i i 3 1 The transmission case 1 is partitioned into a main speed-changer case a and a subsidiary speed-changer case b by the above-mentioned middle wall lb. The counter shaft 12 extends beyond the middle wall lb into the subsidiary speed- s changer case b, and in the subsidiary speed-changer case b it is connected to a final shaft 24 via a subsidiary speedchanger 23 which consists of a gear mechanism almost similar to the above-described main speed-changer 13, so that the rotation of the counter shaft 12 is further speed-changed and transmitted to the final shaft 24. The final shaft 24 extends into a rear case 25 additionally provided at the rear end of the transmission case 1, an output bevel gear 26 provided at the rear end of that shaft 24 is meshed with an input larger bevel gear of a differential device 27, and so, rear wheels 28 are driven via the differential device 27. The final shaft 24 also drives the front wheel drive shaft 87 (Fig. 3) via a gear 29.

The above-described power transmission route branched f rom the input shaf t 5 by the gear 6 and reaching the f inal shaft 24, forms a travelling drive sub-system for driving the wheels of the tractor.

Furthermore, another drive sub-system, that is, a PTO drive system is branched from the input shaft 5 in parallel relationship to the abovedescribed travelling drive subsystem. More particularly, to the input shaft 5 is mounted a PTO drive gear 31 via a one-way clutch 30, and power for driving a PTO shaft is taken out through this gear 31. The one-way clutch 30 allows torque transmission from the input shaft 5 to the gear 31, but it prevents torque transmission i k from the gear 31 to the input shaft 5. The gear 31 is meshed with an intermediate gear 32a loosely f itted around the main shaft 7 so as to be freely rotatable, and another intermediate gear 32b that is integral with the aforementioned intermediate gear 32a is meshed with a PTO driven gear 33. This gear 33 is loosely fitted around a PTO transmission shaft 36 that Is supported from the abovementioned front wall la and middle wall lb via bearings 34 and 35, respectively, and also it is connected via a PTO 10 clutch 37 to the PTO transmission-shaft 36.

The front PTO shaft 70 is disposed in parallel PTO transmission shaft 36, and a drive gear 71 provided on the shaft 36 and a driven gear 72 provided on the shaft 70 are meshed with each to the f ixedly f ixedly other.

Separately from the above-mentioned front PTO shaft 70, a middle PTO shaft 41 is disposed likewise in parallel to the PTO transmission shaft 36. Furthermore, at the rear of the PTO transmission shaft 36 and on the same axis as the shaft 36 is disposed a rear PTO transmission shaft 39 which has its front end rotatably supported by the rear end of the shaft 36 and its rear end pivotably supported from the rear wall of the rear case 25 via a bearing 38.

And at the rear end portion of the PTO transmission shaft 36 is provided a power transmission switching device S.

This switching device S consists of a selector gear 40 that is slidable in the axial direction, and the respective shafts 36 and 39 are adapted to be connected together by the aforementioned selector gear 40 being positioned across the PTO transmission shaft 36 and the rear PTO transmission shaft k.

39. The selector gear 40 is adapted to be engaged with and disengaged from a gear 42 mounted on a middle PTO shaft 41. And this selector gear 40 can occupy four positions consisting of the leftmost position where it is not meshed with the gear 42 nor it is not engaged also with the rear PTO transmission shaft 39, the middle left position where it is meshed with the gear 42 but is not engaged with the rear PTO transmission shaft 39, the middle right position where it is meshed with the gear 42 and is also engaged with the rear PTO transmission shaft 39, and the rightmost position where it is not meshed with the gear 42 but is engaged with the rear PTO transmission shaft 39, and depending upon these positions, the rotation of the PTO transmission shaft 36 can be transmitted to the front PTO shaft 70 only, to both the front PTO shaft 70 and the middle PTO shaft 41, to all the front PTO shaft 70, the middle PTO shaft 41 and the rear PTO transmission shaft 39, or to both the front PTO shaft 70 and the rear PTO transmission shaft 39.

The front PTO shaft 70 projects forwards from the 20 transmission case 1, and it transmits power to a working machine F mounted to the front portion of the vehicle body of the tractor through a working machine drive shaft 70a (Fig. 3) connected to the shaft 70 via a universal joint. Likewise, the middle PTO shaft 41 transmits power to a working machine M mounted to the middle portion of the vehicle body of the tractor. The rear PTO transmission shaft 39 is connected via a gear device 43 to a rear PTO shaf t 44, and this rear PTO shaft 44 transmits power to the working machine R mounted to the rear portion of the vehicle body of the tractor.

Reference numeral 45 designates a hydraulic pump for feeding lubricant oil to the respective lubricating portions within the transmission case 1, and this pump is driven by the input shaft 5 via a pump drive shaft 46. Reference numeral 47 designates a hydraulic pump for applying a hydraulic pressure to a hydraulic cylinder not shown for vertically moving a working machine, and this pump is driven by another pump drive shaft 48 gear-coupled to the abovementioned pump drive shaft 46.

Fig. 2 is a cross-section view showing in more detail the structure of a part of the above-described travelling drive sub-system and PTO drive subsystem, and in Figs. 1 and 2 similar component parts are given like reference numerals. Now supplementing the previous explanation with reference to 9 Fig. 2, the gear 8 that is 'always meshed with the gear 6 mounted on the input shaft 5 is loosely fitted around the main shaft 7 via a needle bearing 49 so as to be freely rotatable, and a clutch outer 50 of the main clutch 9 is connected to the same gear 8. The main clutch 9 is a multiplate wet type clutch, whose clutch inner 51 is mounted to the f ront end of the main shaft 7 so as to be rotatable integrally therewith. In the clutch outer 50 and the clutch inner 51, respectively, are provided a large number of clutch plates 52 which are arrayed alternately so as to be displaceable in the axial direction. Around a boss of the clutch inner 51 is fitted a pressure plate 53 so as to be displaceable in the axial direction, and the pressure plate i i i 1 A 53 is connected to a lif ter plate 54 via a projecting piece 53a, which projects forward penetrating through an opening portion provided in the clutch inner 51. Between the clutch lifter plate 54 and the clutch inner 51 is interposed a spring 55, hence the pressure plate 53 is made to press the clutch plates 52 by the resilient force of the spring 55, thereby the clutch plates 52 are made to press each otherr resulting in connection of the main clutch 9, and the engine power is transmitted from the input shaft 5 through the main clutch 9 to the main shaft 7. If an operation member such as a pedal provided on the vehicle body is operated, a shaft 57 is made to move backwards (rightwards as viewed in Fig. 2) via an actuation mechanism 56 linked to the operation member, and as the lifter plate 54 also moves jointly with the shaft 57, the pressure plate 53 retires backwars and the main clutch 9 is disconnected.

The gear 31 referred to previously, is loosely fitted around the input shaft 5 via a needle bearing 58, and also it is coupled to the input shaf t 5 via the one-way clutch 30.

The intermediate gear 32a meshed with this gear 31 is rotatably supported on the main shaft 7 via a needle bearing 59 jointly with the other intermediate gear 32b formed integrally therewith, and the gear 33 meshed with the intermediate gear 32b is loosely fitted around the PTO transmission shaft 36 via a needle bearing 60. A clutch inner 61 of the PTO clutch 37 is formed integrally with the gear 33, and an clutch outer 62 of. the same clutch 37 is fixedly secured to the PTO transmission shaft 36. On the inner circumferential surface of the clutch outer 62 and the p k outer circumferential surface of the clutch inner 61, respectively, are provided clutch plates 63 alternately and in a displaceable manner in the axial direction, and as a res ult of an operation member 64 being made to press the clutch plates 63 by a hydraulic pressure applied to its backside through an oil passageway 65,, the clutch plates 63 press each other, resulting in connection of the PTO clutch 37, and rotation of the gear 33 is transmitted via the PTO clutch 37 to the PTO transmission shaft 36.

To the PTO transmission shaft 36 is coupled.a front PTO shaft 70 through gears 71 and 72. In the rear end portion of the PTO transmission shaft 36 is rotatably fitted a front end of the rear PTO transmission shaft 39 via a- needle bearing 66. and splines 67a and 67.b are notched on the circumferential surfaces having the same diameter of the PTO transmission shaft 36 and the rear PTO transmission shaft 39. And the selector gear 40 is slidably engaged with these splines 67a and 67b. Between the gear 42 provided on the middle PTO shaft 41 and the selector gear 40 is interposed an intermediate gear 68, and the face width of the -intermediate gear 68 is chosen about twice as large as the face width of the sel'ector gear 40. When the selector gear 40 is engaged with the spline 67a only and is meshed with the intermediate gear 68 as shown by solid lines in Fig. 2, rotation of the PTO transmission shaft 36 is transmitted to only the front PTO shaft 70 coupled to that shaft 36 via the gears 71 and 72, and the middle PTO shaft 41, but when the selector gear 40 is engaged with both the spline 67a and the spline 67b and is meshed with the intermediate gear 68 as shown by dash 3 0' 1 lines 40a, the rotation of the PTO transmission shaft 36 is transmitted all the front PTO shaft 70, the middle PTO shaft 41 and the rear PTO transmission shaft 39. If the selector gear 40 is further displaced backwards, thus the meshing with the intermediate gear 68 is released, and it occupies the position to be engaged with both the -spline 67a and the spline 67b as shown by dash lines 40b, then the rotation of the PTO transmission shaft 36 is transmitted to only the front PTO shaft 70 and the rear PTO transmission shaft 39.

When the selector gear 40 slides up to the foremost position and the meshing with the intermediate gear 68 is released as shown by dash lines 40c, the rotation of the PTO transmission shaft 36 is transmitted to only the front PTO shaft 70.

As described above, in the illustrated embodiment, within the transmission case 1 the travelling drive subsystem and the PTO drive sub- system are branched respectively via the pears 6 and 31 in parallel to each other f rom the single input shaft 5 that is driven by the engine, and these respective sub-systems are adapted to be connected to the above- mentioned input shaft 5 by the intermediary of the main clutch 9 and the PTO clutch 37,r respectively. Accordingly, the power transmission through the travelling drive subsystem and the power transmission through the PTO drive subsystem are effected independently of each other, hence the driving condition of the working machine by the PTO shaft would not be influenced by the travelling condition of the tractor, and when the working machines are not used, the PTO 1 drive sub-system can be perfectly disconnected from the engine.

Furthermore, by means of the power transmission switching apparatus S having an extremely simple structure in which the selector gear 40 is slidably spline-engaged with both the PTO transmission shaft 36 and the rear PTO transmission shaft 39r transmission of engine power can be switched to be preset in 4 ways, that is, among (I) transmission to the front PTO shaft 70 only. (1) transmission to the front PTO shaft 70 and the middle PTO shaft 41, (2) transmission to the front PTO shaft 70, the middle PTO shaft 41 and the rear PTO transmission shaft 39. and (9) transmission to the front PTO shaft and the rear PTO transmission shaft 39, and so, the power transmission system can be efficiently adapted various modes of use of a tractor.

While description has been made above in connection to a tractor provided with three front, middle and rear PTO shafts, the three PTO shafts are not always necessitated, but it is also possible to apply the present invention to a tractor provided with, for instance, two middle and rear PTO shafts.

Now- another preferred embodiment of the present invention will be described with reference to Figs. 4 and 5. in this preferred embodiment also, the transmission case 1 is partitioned into a main speed-changer case a and a subsidiary speed-changer case b, and a main clutch case 2 is integrally mounted at the front end of the transmission case 1. Engine power is transmitted from an input shaft 5 to a main shaft 7 for travelling use through gears 6 and 8 and a multi-plate i -Is- wet type main clutch 9, and on the other hand it is transmitted to a PTO transmission shaft 36 via a one-way clutch 30, a PTO drive gear 31, an intermediate gear 32 loosely fitted around the main shaft 7, a PTO driven gear 33 and a PTO clutch 37. The above-described construction is quite the same as that shown in Fig. 2.

On the travelling main shaft 7 are rotatably fitted and mounted a back drive gear 119 and a lstspeed drive gear 120 at its rear portion, and a 2nd-speed drive gear 121 and a lo 3rd-speed drive gear 122 are fixedly secured to its front portion. A travelling main counter shaft 123 is rotatably supported obliquely above the travelling main shaft 7 (See Fig. 5) in parallel to the main shaf t 7. On this travelling main counter shaft 123 are integrally formed a back driven gear 124 and a lst-speedc driven gear 125, and also a 2ndspeed driven gear 126 and a 3rd-speed driven gear 127 are rotatably mounted thereon. The back driven gear 124 is coupled to the back drive gear 119 via a back idle gear 128. The lst-speed driven gear 125. the 2nd-speed driven gear 126 and the 3rd-speed driven gear 127 are respectively meshed with the lst- speed drive gear 120, the 2nd-speed drive gear 121 and the 3rd-speed drive gear 122.

On the travelling main shaft 7 are disposed a ba.ck travelling hydraulic clutch 129 and a lst-speed hydraulic clutch 130, respectively adjacent to the back drive gear 119 and the lst-speed drive gear 120. Likewise, on the travelling main counter shaft 123 are disposed a 2nd-speed hydraulic clutch 131 and a 3rd-speed hydraulic clutch 132, respectively, adjacent to the 2nd-speed driven gear 126 and i the 3rd-speed driven gear 127. And respective clutch inners 129a, 130a, 131a and 132a of the back travelling hydraulic clutch 129, the lst-speed hydraulic clutch 130, 2nd-speed hydraulic clutch 131 and the 3rdspeed hydraulic clutch 132, respectively, are integrally coupled with the back drive gear 119r the lst-speed drive gear 120, the 2nd-speed driven gear 126 and the 3rd-speed driven gear 127. Accordingly, by connecting any one of the back travelling hydraulic clutch 129, the Ist-speed hydraulic clutch 130r the 2nd-speed hydraulic clutch 131 and the 3rd-speed hydraulic clutch 132, the travelling main counter shaft 123 is rotationally driven into a back travelling state, a lst-speed travelling state, a second-speed travelling state or a 3rd-speed travelling state.

A front end of a travelling subsidiary counter shaft 134 in a multi-stage gear type travelling subsidiary speedchanger 133 is integrally splinefitted in the rear end portion of the travelling main counter shaft 123, and the rear end of that travelling subsidiary counter shaft 134 is rotatably supported from a rear wall lc of the transmission case 1 via a bearing. On the travelling subsidiary counter shaft 134 are integrally formed a subsidiary lst-speed drive gear 135, a subsidiary 2nd-speed drive gear 136 and a subsidiary 3rd-speed drive' gear 137 at its rear, middle and front portions, respectively, and behind the subsidiary lstspeed drive gear 135 is rotatably fitted an idle drive gear 138.

Under the travelling subsidiary counter shaft 134 are provided an idle shaft 139 and a rear wheel dive shaft 140, 1 1 1 0 which are rotatably supported from the middle wall lb and the rear wall lc of the transmission case 1. Around the idle shaft 134 are rotatably fitted idle gears 141 and 142, respectively. On the rear wheel drive shaft 140 are rotatably mounted a subsidiary lst-speed driven gear 143 and a subsidiary 3rd-speed driven gear 145, respectively, at its central and front portions, and between these subsidiary driven gears is mounted by spline-fitting a subsidiary lst speed shift gear 144. Reference mumeral 146 designates a front wheel drive gear that is integrally mounted by fitting on the rear wheel drive shaft 140 at the rear of the subsidiary lst-speed driven gear 143. A large diameter portion 141a of the idle gear 141 i subsidiary lst-speed drive gear 135 on the travelling subsidiary counter shaft 134. while a smaller diameter portion 141b of the same idle gear 141 is meshed with a larger diameter portion 138a of the idle drive gear 138. A larger diameter portion 142a of the idle gear 142 is meshed with the front wheel drive gear 146, while a smaller diameter portion 142b of the same is meshed with an idle driven gear 148 on a front wheel drive shaft 147. The subsidiary lstspeed shift gear 144 is disengageably meshed with the subsidiary 2nd-speed drive gear 136 on the travelling subsidiary counter shaft 134, and also it is adapted to be disengageably fitted by spline to the subsidiary lst-speed driven gear 143 or the subsidiary 3rd-speed driven gear 145.

The above-described front wheel drive shaft 147 is p'tioned under the idle shaft 139 as will be seen in Fig.

osi 5, and it is rotatably supported from the walls la, lb and lc s meshed with the A A of the transmission case 1 and the end wall 2a of the main clutch case 2. And the above-mentioned idle driven gear 148 is adapted to be engaged with or disengaged from the front wheel drive shaft 147 by movement in the axial direction of the selector 149.

Next, description will be made on the PTO drive sub system.

On the rear portion of the PTO transmission shaft 36 coupled to the input shaf t 5 through the gears 31, 32 and 33 and the PTO clutch 37, is integrally formed a -rear output gear 154, and also a rear PTO transmission shaft 155 is fitted to the rear portion in a relatively rotatable manner.

The rear portion of the rear PTO transmission shaft 155 is rotatably supported via a bearing from the rear wall lc of the transmission case 1.

A PTO counter shaft 156,is rotatably supported from the middle wall lb and the rear wall lc of the transmission case 1 under and adjacent to the rear PTO transmission shaft 155.

Extending over these shafts 155 and 156, a PTO multi-s.tage gear speed-changer is formed. That is, on the PTO counter shaft 156 are integrally and successively formed a counter gear 157, a gear 158 and a gear 159, the latter two gears having a smaller diameter than the countergear 157. On the other hand, around the rear PTO transmission shaft 155 is rotatably fitted a gear 160 which is meshed with the gear 159, and also is f itted by spline a shif ter gear 161 that is engageable with and disengageable from the gear 158.

Furthermore, at the front end of the PTO counter shaft 156 is provided a hydraulic brake 162. This hydraulic brake - 1 i I 1 162 is composed of a brake housing 163 integrally connected to the middle wall lb, a brake piston 164 fitted in the brake housing so as to be slidable in the axial direction, brake discs 165 spline-fitted around the PTO counter shaft 156, a friction plates 166 locked to the brake housing 163 so as to come into contact with the brake discs 165 in a releasable manner, and a compression coil spring 167 for biasing the brake discs 165 and the friction plate 166 so as to be brought into press contact with each other. A brake chamber 168 formed by the brake housing 163 and the brake piston 164 is communicated with an oil passageway 169 in the PTO transmission shaft 36 and the rear PTO transmissionshaft 155. Accordingly, in the case where pressurized oil is not fed through the oil passageway 169, the PTO clutch 37 is disconnected and the hydraulic brake 162 is set in a braking condition, and in the case where pressurized oil is fed through the oil passageway 169, the PTO clutch 37 is connected and the hydraulic brake 162 is set in an unbraking condition.

At the front end of the PTO transmission shaft 36 is integrally secured, by fitting, a front output gear 170. In addition, sideways of and adjacent to the PTO transmission shaft 36 is rotatably supported a front PTO shaft 171 from the front wall la of the tiansmission case 1 and the end wall 2a of the main clutch case 2 via bearings. Around the front PTO shaft 171 is rotatably fitted a gear 172 that is meshed with the front output gear 170. On both the front PTO shaft 171 and the gear 172 is spline-fitted a dog clutch 173, and provision is made such that when the dog clutch 173 is w! k shifted backwards, the front PTO shaft 171 and the gear 172 may be connected with each other, but when the dog clutch.173 is shifted forwards, the front PTO shaft 171 and the gear 172 may be disconnected.

As the preferred embodiment illustrated in Figs. 4 and 5 are constructed in the above-described manner,, in the case where the input shaft 5 is rotationally driven by the engine and the clutch lever 117 in the operating mechanism 56 is not applied with an operating torque in the anticlockwise direction, the main clutch 9 takes a connected state, hence the torque on the input shaft 5 is transmitted through the travelling drive gear 6, the travelling clutch gear 8 and the travelling main clutch 9 to the travelling main shaft 7, and the travelling main shaft 7 is rotationally driven.

Under the rotationally driven condition of the travelling main shaft 7, if pressurized oil is fed to any one of the back travelling hydraulic clutch 129, the lst-speed hydraulic clutch 130. the 2nd-speed hydraulic clutch 131 and the 3rd-speed hydraulic clutch 132 to connect it, then. the travelling main counter shaft -123 and the travelling subsidiary counter shaft 134 would rotate in the back travelling, lst-speed, 2nd-speed or 3rd-speed condition.

If the clutch lever 117 is rocked in the anticlockwise direction, the travelling main clutch 9 becomes a disconnected condition, and the travelling main shaft 7 stops to rotate.

Under the condition where the travelling main counter shaft 123 and the travelling subsidiary counter shaft 134 have been rotationally driven, if the subsidiary lst-speed i i i 1 1 i 1 i i i 1 1 1 1 It k 1 shif t gear 144 is shif ted to the rearmost position A, then the subsidiary lst-speed shift gear 144 is spline-f itted to the subsidiary lst-speed driven gear 143, and so, the torque on the travelling subsidiary counter shaft 134 is transmitted to the rear wheel drive shaft 140 through the subsidiary lst speed drive gear 135, the idle gear 141, the subsidiary lst speed driven gear 143 and the subsidiary lst-speed shift gear 144.

If the subsidiary 1st-speed shift gear 144 is shifted to the position B in front of the position A, then that gear 144 is not coupled to any gear, and hence the torque on the travelling subsidiary counter shaft 134 is not transmitted to the rear wheel drive shaft 140.

If the subsidiary lst-speed shift gear 144 is shifted to the position C or the position D which is in f ront of the position B, then the subsidiary lst-speed shift gear 144 is meshed with the subsidiary 2nd-speed drive gear 136, hence the torque on the travelling subsidiary counter shaft 134 is transmitted to the rear wheel drive shaft 140 through the subsidiary 2nd-speed drive gear 136 and the subsidiary lst speed shift gear 144, and the power transmission is set at the subsidiary 2nd-speedj, or the subsidiary lst-speed shift gear 144 is spline-fitted to the subsidiary 3rd-speed driven gear 145, and the power transmission is set at the subsidiary 3rd-speed.

Under the condition where the rear wheel drive shaft 140 is rotated and the rear wheels are driven, if the selector 149 is spline-fitted to the idle driven gear 148, then the front wheel drive shaft 147 also rotates and the front wheels 1 are also rotationally driven. If the selector 149 is disengaged from the idle driven gear 148, then the front wheel drive shaft 147 is disconnected from the rear wheel drive shaft 140, and so, power transmission to the front wheels are cut off.

Under the condition where the input shaf t 5 has been rotationally driven, if pressurized oil is fed to the oil passageway 169r then the PTO clutch 37 is connected, simultaneously therewith the hydraulic brake 162 becomes an unbraking state, and so, the PTO transmission shaft 36 is rotationally driven.

Under this condition. if the shifter gear 161 is shifted to the rearmost position (I), or to the position (II), the position (III) or the position (IV) in front of the position (1), then the gear 160 meshed with the gear 159 is directly coupled to the rear PTO transmission shaft 155 by the shifter gear 161 and the power transmission is set at the PTO lst speed (in the case of the position (I)), or the shifter gear 161 is not coupled to any gear and the power transmission is set at the neutral (in the case of the position (II)), or the shif ter gear 161 is meshed with the gear 158 and the power transmission is set at the PTO 2nd speed (in the case of the position (III)), or the rear PTO transmission shaft is directly coupled to the PTO transmission shaft 36 by the shifter gear 161 and the power transmission is set at the PTO 3rd speed (in the case of the position (IV)).

Under the condition where the PTO transmission shaft 36 has been rotationally driven, if the dog clutch 173 is 30- i 1 1 1 1 1 1 1 i i i i 1 J 11 shif ted backwards, then the gear 172 is coupled to the front PTO shaft 171, and this shaft 171 is rotationally driven.

Under the condition where the PTO transmission shaft 36 has been rotationally driven in the above-described manner, if the pressurized oil in the oil passageway 169 is discharged, then the PTO clutch 37 becomes cut off, and at the same time, the hydraulic brake 162 takes a braking state. Accordingly, even if a drag should remain at the PTO clutch 37 or a rotational inertia should act upon the PTO drive sub- system, owing to the braking force acting upon the PTO counter shaft 156, the PTO transmission shaft 36, the rear PTO transmission shaft 155 and the front PTO shaft would stop immediately.

In the illustrated embodiment, since the PTO transmission shaft 36 is disposed under the main shaft of the travelling drive sub-system adjacent and in parallel thereto, and also since the rear PTO transmission shaft 155 and the PTO counter shaft 156 are disposed under the travelling subsidiary counter shaft 134 in parallel thereto, the total length of the power transmission system is not increased, but becomes compact.

in addition, since the PTO clutch 37 is positioned between the 2nd-speed drive gear 121 and the 3rd-speed drive gear 122 on the travelling main shaft 7, and since the PTO clutch 37 is disposed on the opposite side to the 2nd-speed hydraulic clutch 131 and the 3rd-speed hydraulic clutch 132 on the travelling main counter shaft 123 with respect to the travelling main shaft 7, the PTO clutch 37 can be disposed close to the travelling main shaft 7 without being interfered by the 2nd-speed hydraulic clutch 131 and the 3rd-speed hydraulic clutch 132, hence the power transmission system.can be constructed in a compact form with respect to the vertical and horizontal directions, and the transverse cross-section area of the transmission case can be reduced.

Furthermore#, as the PTO counter shaft 156 was disposed in parallel to the rear PTO transmission shaft 155 and the hydraulic brake 162 was disposed at the front end of the same PTO counter shaf t, the power f or the f ront PTO shaf t can be taken out from the front end portion of the PTO transmission shafts 36 and 155, and the power for the rear PTO shaft can be taken out from the rear end portion of the same.

The constitution that the PTO clutch 37 and the PTO multi-stage gear speed-changer are respectively disposed on the PTO tranamission shaft 36 at front and rear positions thereof and the hydraulic brake 162 position between the PTO cluth and speed-changer, enables to utilize is disposed at the middle the PTO multi-stage gear the space within the transmission case effectively. In place of the PTO multi- stage gear speed-changer including the rear PTO transmission shaft 155 and PTO counter shaf t 156 in Fig. 5, there may be provided a power transmission switching apparatus S as shown in Figs. 2 and 3.

30- 1 1 j 1 1 i i i i i i 1 1 lp k - -2s-

Claims (18)

1. A PTO shaft driving apparatus in a tractor provided with a plurality of PTO shafts for respectively driving a plurality of working machines mounted to a vehicle body, characterized in that within a transmission case is provided a PTO transmission shaft connected via a PTO clutch to an input shaft of said transmission case, and power is transmitted to said plurality of PTO shafts through said PTO transmission shaft.

2. An apparatus as claimed in Claim 1, wherein on said PTO transmission shaft is provided a power transmission switching apparatus capable of selectively transmitting power to at least one of said PTO shafts.

3. An apparatus as claimed in Claim 2, wherein said transmission case is partitioned into a main speed-changer case in the front and a subsidiary speed-changer case at the rear, said PTO clutch is disposed in said main speed-changer case, and said power transmission switching apparatus is disposed.in said subsidiary speed-changer case.

4. An apparatus as claimed in Claim 2, wherein a rear PTO shaft extending from the rear portion of said transmission case and a middle PTO shaft extending from the middle portion of said transmission case are provided, at the rear of said PTO transmission shaft is disposed a rear PTO transmission shaft along the same axis with its end portion held adjacent to said PTO transmission shaft, said rear PTO shaft is connected to said rear PTO transmission shaft, and there is provided a selector gear that is slidable in the back and forth directions along splines provided on said PTO 1 11 transmission shaft and rear PTO transmission shaft for connecting and disconnecting said both transmission shafts and for being engaged with and disengaged from a gear provided on said middle PTO shaft.

5. An apparatus as claimed in Claim 3r wherein between said PTO clutch and said input shaft is interposed a one-way clutch for cutting off torque transmission from the side of said PTO clutch to the side of said input shaft.

6. An apparatus as claimed in Claim 1, wherein said 10 transmission case is partitioned Anto a main speed-changer case in the front and a subsidiary speed-changer case at the rear, a travelling multi-stage gear hydraulic main speedchanger and said PTO transmission shaft are disposed within said main speed-changer case, and a travelling multi-stage gear speed-changer and a PTO multi-stage gear speed-changer connected to said PTO transmission shaft are disposed within said subsidiary speed- changer case.

7. An apparatus as claimed in Claim 6, wherein said PTO multi-stage gear speed-changer is composed of a rear. PTO transmission shaft having its front end portion rotatably fitted to the rear end portion of said PTO transmission shaft, a PTO counter shaft disposed in parallel to said rear PTO transmission shaft and connected via gears to said PTO transmission shaft, and a plurality of gear trains for selectively connecting said rear PTO transmission shaft and said PTO counter shaft.

8_. An apparatus as claimed in Claim 1, wherein a travelling main shaft is disposed adjacent to said PTO transmission shaft and in parallel to said PTO transmission shaft, a 1 1 f i i i f i i i i i 1 1 1 j i 1 i i i 1 1 -1 1 11 travelling hydraulic speed-changer clutch is provided at one end of said travelling main shaft, an intermediate gear for connecting said input shaft to said PTO clutch is loosely fitted around said travelling main shaft, and said PTO clutch is disposed at a middle position in the back and forth directions between said travelling hydraulic speed-changer clutch and said intermediate gear.

9. An apparatus as claimed in Claim 6, wherein said PTO clutch is provided at the front end portion of said PTO transmission shaft.

10. An apparatus as claimed in Claim 7, wherein a braking apparatus is provided on said PTO counter shaft.

11. An apparatus as claimed in Claim 10, wherein said braking apparatus and said PTO clutch are a hydraulic brake and a hydraulic clutch, respectively, these hydraulic brake and hydraulic clutch are simultaneously fed with pressurized oil or made to discharge pressurized oil through a same hydraulic route, and thereby said hydraulic brake becomes an unbraking state or a braking state, respectively, as interlocked with engagement and disengagement of said hydraulic clutch.

12. A PTO shaft driving apparatus in a tractor provided with a plurality of PTO shafts for respectively driving a plurality of working machines mounted to a vehicle body; characterized in that within a transmission case is provided a PTO transmission shaft operatively connected to an input shaft of said transmission case which is connected to an engine, power is transmitted to said plurality of PTO shafts through said PTO transmission shaft, and on said PTO transmission shaf t is provided a power transmission switching apparatus which can selectively transmit power to said respective PTO shafts.

13. An apparatus as claimed in Claim 12, wherein said transmission case is partitioned into a main speed-changer case in the f ront and a subsidiary speed-changer case at the rear, and said power transmission switching apparatus is disposed within said subsidiary speed-changer case.

14. A PTO shaf t driving apparatus in a tractor provided 10 with a plurality of PTO shafts for respectively driving a plurality of working machines mounted to a vehicle body; characterized in that within a transmission case is provided a PTO transmission shaft connected to an input shaft of said transmission case which is connected to an engine, and power is transmitted to said plurality of PTO shafts through said PTO transmission shaft, said transmission case is partitioned 30- into a main speed-changer cas in the f ront and a subsidiary speed- changer case at the rear, a travelling multi-stage gear hydraulic main speed-changer and said PTO transmission shaft are disposed within said main speed-changer case, and a travelling multi-stage gear subsidiary speed-changer and a PTO multi-stage gear speed-changer connected to said PTO transmission shaft are disposed within said subsidiary speedchanger case.

15. An apparatus as claimed in Claim 14, wherein said PTO multi-stage gear speed-changer is composed of a rear PTO transmission shaft having its front end portion rotatably fitted to the rear end of said PTO transmission shaft, a PTO counter shaft disposed in parallel to said rear PTO i 1 i i 1 1 i i i 1 i i 4 transmission shaft and coupled to said PTO transmission shaft via gears, and a plurality of gear trains for selectively connecting said rear PTO transmission shaft and said PTO counter shaft.

16. A PTO shaft driving apparatus in a tractor provided with a plurality of PTO shafts for respectively driving a plurality of working machines mounted to a vehicle body, comprising:

an input shaft provided in a transmission case and connected to an engine; a PTO transmission shaft operatively connected to said input shaft; a PTO clutch provided on said PTO transmission shaft at a front position thereof for connecting and disconnecting a power transmission route from said input shaft to said PTO transmission shaft; a power transmission switching apparatus provided on said PTO transmission shaft at a rear position thereof which can selectively transmit power to said respective PTO shafts; and a braking apparatus provided on said PTO transmission shaft at a middle position in the back and forth directions which can brake said PTO transmission shaft.

17. A PTO shaft driving apparatus in a tractor provided with a PTO shaft for driving a working machine mounted to a vehicle body, comprising:

an input shaft provided in a transmission case and connected to an engine; 1 4 1 1 1 p.

a PTO transmission shaft operatively connected to said input shaft; a PTO clutch provided on said PTO transmission shaf t at a front position thereof for connecting and disconnecting a power transmission route f rom said input shaft to said PTO transmission shaft; i i i a PTO multi-stage gear speed-changer provided on said PTO transmission shaft at a rear position thereof; and a braking apparatus provided on said PTO transmission shaft at a" middle position in the back and forth directions which can brake said PTO transmission shaft.

18. A PTO shaft driving apparatus substantially as herein described with reference to, and as shown in, Figures 1 and 2 or Figures 4 and 5 of the accompanying drawings.

1 1 i t P:

i 1 i i i 1 i Published 1988 at The Patent Office. State House. 66 71 High 1-1&-borr-. London WCIR 4TP- Purther copies maybe obzained from The Patent Office, Sales Branch, St Mary Cray. Orpington. Kent BR5 3RD Printed by Multiplex techniques ltd, St Mary Cray. Kent. Con. l!8-,