JPS62268735A - Automobile power transmission device - Google Patents

Abstract

PURPOSE:To install oil passages easily, by providing an oil pump which is driven in association with a shaft to which engine power is transmitted and supplying oil discharged from the pump to a clutch oil passage and lubricating oil passages defined through the shaft center of a speed change shaft. CONSTITUTION:A transmission case has an input shaft 7, first and second main speed change shafts S1, S2, an auxiliary speed change shaft S3, a PTO shaft S4 and a front wheel drive shaft S5 disposed in parallel in it. A wet type multi- disk main clutch 17 is coaxially mounted on the first speed change shaft S1. The wet type multi-disk main clutch 17 is supplied with engine power from an input shaft 7 through a chain trained around sprockets 16, 18. The respective speed change shafts S1-S3 are provided with hydraulic speed change clutches 51, 52, 54, 39 and the first speed change shaft S1 is associated with a clutch shaft 20. A pump shaft SP associated with the input shaft 7 has an end provided with a gear pump 65 and oil discharged therefrom is supplied to lubricating oil passages 74, 76 and a clutch oil passage 77.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a power transmission device for a vehicle, and the power transmission device of the present invention is particularly suitable as a power transmission device for a tractor for use in agriculture or the like.

In conventional agricultural tractors, the engine is usually mounted on the front part of the vehicle body, and the transmission case is mounted on the rear part. The output shaft of the engine is connected to a propeller shaft via a main clutch, and the propeller shaft extends rearward along the vehicle body and is connected to an input shaft pivotally supported by a transmission case.

A transmission mechanism is built into the transmission case, and engine power input to the input shaft is transmitted to an output shaft via the transmission mechanism, and the output shaft drives the rear wheels. In the case of four-wheel drive, the output shaft is further connected to a front wheel drive propeller shaft, which extends forward through the transmission case to drive the front wheels.

Most of the above-mentioned speed change g1 structures have two shafts arranged parallel to each other and selectively connected through gears with various tooth ratios, but the I! 1 ton is allowed to idle relative to the shaft, and a hydraulic clutch attached to the shaft adjacent to the gear is engaged, thereby connecting the gear to the shaft via the hydraulic clutch, and thus, There are some devices in which rotation is transmitted to the other shaft through a gear connected to the shaft.

1 and then.

The present invention improves a power transmission device having a transmission mechanism using such a hydraulic clutch, and in particular shortens (simplifies) oil passages for the clutch oil that operates the hydraulic clutch and lubricating oil for various bearings, gears, etc. The aim is to make the device more compact and to allow operations such as gear shifting and starting to be carried out smoothly.

. For this reason, the power transmission device of the present invention includes a transmission shaft supported on a transmission case, and a transmission shaft mounted on the transmission case coaxially with the transmission shaft to transmit engine power to the transmission shaft. A hydraulic pump for gear shifting is provided on the transmission shaft, and a hydraulic pump is operatively connected to a shaft for transmitting engine power to the clutch and mounted on the transmission case. A multi-disc clutch is provided, and a clutch oil passage and a lubricating oil passage extending in the axial direction are provided in the axial center of the speed change shaft, and these oil passages are connected to the hydraulic pump.

In the present invention, as described above, @
Since a clutch oil passage and a lubricating oil passage are provided that extend in the linear direction, each hydraulic clutch, bearing, @car, etc. can be lubricated from the end of the transmission shaft all at once, and the length of the oil passage components can be shortened. , can be made simple. In addition, since the multi-disc main clutch and the hydraulic multi-disc clutch for gear shifting are arranged on the same axis, the oil passage in the axial direction provided on the shifting shaft is extended to the main clutch. By doing so, the oil supply ports for the main clutch and the speed change clutch can be gathered at one location on the shaft end. Since the hydraulic pump that supplies clutch oil and lubricating oil is installed in the transmission case, the oil supply path from the pump to the oil supply port at the end of the shaft can be easily routed and is highly reliable. This hydraulic pump is operatively connected to a shaft that transmits engine power to the main clutch.
Since it constantly rotates and supplies pressurized oil regardless of whether the main clutch is engaged or released, it always provides a constant starting feeling. Further, by placing the main clutch in front of the hydraulic clutch, rotation of the hydraulic clutch can be immediately stopped when the main clutch is disengaged, thereby reducing shift shock.

Branch”L 邂 Hereinafter, the present invention will be described with reference to illustrated embodiments.

FIG. 1 is a side view of an agricultural tractor to which the present invention is applied.
1 is the rear wheel, and 2 is the front wheel. An engine 3 is mounted on the front part of the vehicle body, and a transmission case 4 is mounted on the rear part. The output shaft of the engine 3 is connected to the propeller shaft 1-6 via the 'fAmi vehicle 5, and the propeller shaft 6 is connected to the propeller shaft 6.
extends rearward from the lower part of the vehicle body and is connected to the input shaft 7 of the transmission case 4. The transmission case 4 is fixed to a vehicle body frame 8, a part of which is partially shown, and has a power transmission device built therein. The input shaft 7
The engine power input to the vehicle is outputted to the rear shaft 9, the PTO shaft S4, and the front wheel drive shaft S5 after being appropriately changed in speed through the power transmission device. The PTO shaft S4 transmits power to a working machine such as a rotary working machine connected to the rear of the tractor. The front wheel drive shaft S5 transmits power to the front wheels 2 via the front wheel drive propeller shaft 10. Reference numeral 11 denotes a hydraulic cylinder that raises and lowers the working machine via a lift arm 12.

13 is a seat, and 14 is a handle.

FIG. 2 is a cross-sectional view showing the power transmission device inside the mission case 4, and as shown in the figure, input @h7, first main shift shaft S1, second main shift shaft S2, auxiliary shift shaft S3, P TO @
The axes S4 and S5 are arranged parallel to each other. However, these axes are not arranged one above the other in one plane as shown in FIG. Fig. 3 shows the actual arrangement of the respective axes. For example, the first main transmission IrllllS1 and the second main transmission @S2 are arranged side by side at almost the same height, and the 01 transmission axis S3 and the front wheel drive 4i1+ 85 are also at almost the same height as the first main transmission shaft S.
1. They are arranged side by side slightly to the lower left of the second main transmission shaft S2. And P T O@S 4 is arranged at the uppermost position.

The input shaft 7 is connected to the propeller shaft 6 as described above.
is rotatably supported by a transmission case 4 and a clutch housing 15 fixed thereto via a bearing, and a sprocket 16 is fixed to this input shaft 7. The input shaft 7 transmits engine power to a sprocket 18 provided on a main clutch 17 of a multi-plate type via a chain.

As shown in an enlarged view in FIG. 4, the main clutch 17 has a clutch shaft 20 that is pivotally supported to the mission case 4 via a ball bearing 19, and the sprocket 18 is attached to the clutch shaft 20 by a needle. It is relatively rotatably supported via a bearing 21 . A bottomed cylindrical drive member 23 is fixed to the sprocket 18 via a spring member 22 in order to absorb the impact when the clutch is connected.
A plurality of drive clutch plates 2 are connected via splines to the inner peripheral surface of the
4 is axially displaceably received. clutch f
A driven member 25 in the shape of a cylinder with a bottom is also integrally fixed to the i20. A plurality of driven clutch plates 26 are received on the outer circumferential surface of the driven member 25 via splines so as to be displaceable in the axial direction, and these driven clutch plates 2G and the driving clutch plates 24 are arranged alternately. Arranged. A disc-shaped pressure contact plate 27 having approximately the same diameter as the flange 25a provided at the end of the driven member 25 is provided so as to rotate integrally with the driven member 25 and to be relatively displaceable in the axial direction. ing.

The press plate 27 has a boss 28 that protrudes through a hole provided in the bottom wall of the driven member 25, and a lifter plate 29 is fixed to the end surface of the boss 28. A coil spring 30 is sandwiched between the lifter plate 29 and the bottom wall surface of the driven member 25, and is normally used in a direction in which the flange 25a of the driven member 25 and the pressure contact plate 27 are brought closer together, that is, the drive clutch plate. A biasing force is applied in the direction of pressing the driven clutch plate 24 and the driven clutch plate 2G together. The lifter plate 29 is received from behind by an actuation piece 32 via a ball bearing 31, and the actuation piece 32 is moved by a lever 33 against the coil spring 30 toward the pressure contact plate 27 along the clutch shaft 20. By pushing in, the pressure contact plate 27 moves away from the flange 25a of the driven member 25, and the state of pressure contact between the driving clutch plate 24 and the driven clutch plate 26 is released. That is, the main clutch 17 is in a disengaged state.

A gear ``13'' is integrally formed at the end of the clutch shaft 20 that protrudes into the mission case 4.The end of the first main transmission shaft S1 is also coaxially connected to the end of the clutch shaft 20, and a needle bearing 34 is attached thereto. The first main transmission @S1 is supported at its other end and intermediate portion by ball bearings 35, 35, respectively, and extends back and forth within the mission case 4. There is.

A second main transmission shaft S2 is disposed adjacent to and parallel to the first main transmission @S1. The second main transmission shaft S2 is rotatably supported by the front wall of the transmission case 4 and a bearing wall 36 provided on the transmission case 4 via ball bearings 37 and 38, respectively. A gear G23 that constantly meshes with the gear G13 of the clutch shaft 20 is fixed to the front end of the second main transmission shaft S2. Gear G and gear G23 have the same diameter, and therefore, when the main clutch 17 is engaged, the second main transmission shaft S2 is rotationally driven from the clutch shaft 20 via the gear "13." 23 at the same rotational speed as the clutch shaft 20. Ru. The other end of the second main transmission shaft S2, that is, the end that penetrates the bearing wall 36 and protrudes rearward, is located close to the bearing wall 36 and has a low speed (1
A speed change clutch 39 is provided. As shown in more detail in FIG.
A cylindrical driving member 40 with a bottom is fixed to the main transmission shaft S2, and an annular bearing plate 41 is provided on the open end surface of the driving member 40.
is fixed. Then, on the inner circumferential surface, the bearing faces the drive clutch plate 24 of the main clutch 17, facing the plate 41.
A plurality of drive clutch plates 42 similar to the above are axially displaceably received via splines. Drive member 40
An annular cylinder portion 43 is formed by a peripheral wall portion 40a, a bottom wall portion 40b, and a boss portion 40c fitted to the second main transmission shaft S2. It is fitted and urged toward the bottom wall portion 40b by a spring 45. An oil passage 46 is provided in the boss portion 40c so that hydraulic pressure can be supplied between the operating member 44 and the bottom wall portion 40b of the drive member 40, and the second oil passage 46 is formed in the transmission shaft S2. It communicates with a clutch oil passage 47 that is supplied with oil via a control valve from an oil pump, which will be described later. A low speed change drive gear G21 is mounted on the second main speed change shaft S2 adjacent to the drive member 40 and is connected to the needle bearing 4.
It is rotatably mounted via 8. A driven member 49 of the low-speed hydraulic transmission clutch 39 is integrally formed with the gear G21, and enters into the cylinder portion 43 of the drive member 40. A plurality of driven clutch plates 50 are received on the outer peripheral surface of the driven member 49 via splines so as to be displaceable in the axial direction.
0 and the drive clutch plates 42 are arranged alternately.

Since the low-speed hydraulic gear shift clutch 39 is configured as described above, oil flows into the clutch and oil passage 4 when the gear shift operation is performed.
7. When the oil is supplied behind the actuating member 44 through the oil passage 46, the actuating member 44 is pushed forward by the hydraulic pressure, and the driving clutch plate 42 and the driven clutch plate 50 are brought into pressure contact with each other. Therefore, the rotation of the second main transmission S2 is caused by the rotation of the driving member 40, the driving clutch plate 42, the driven clutch plate 50. The signal is transmitted to the gear G21 via the driven member 49, and the gear G21 is transmitted to the second gear G21.
It rotates integrally with the main transmission @S2. Since the gear G21 meshes with the low speed change driven gear G11 fixed to the first main speed change shaft S1, the engagement of the low speed hydraulic speed change clutch 39 causes the first main speed change shaft S1 to shift between the gear G and the gear G11. Rotationally driven with a reduction ratio according to the tooth number ratio. When the low-speed hydraulic transmission clutch 39 is disengaged, the gear G21 is the gear G.
11 from the first main transmission shaft S1 side and rotates freely around the second main transmission shaft $2.

A 2-speed hydraulic transmission clutch 51 is located at the front end of the first main transmission shaft S1.
and a three-speed hydraulic transmission clutch 52. These hydraulic speed change clutches 51, 52 are all constructed in exactly the same way as the low speed hydraulic speed change clutch 39. However, the drive members 51a, 52b of these clutches (
(see FIG. 4) are integrated, and each cylinder portion is formed back-to-back U in this integrated driving member. When the second-speed hydraulic transmission clutch 51 is operated, the second main transmission shaft S2
The rotation of the clutch shaft 20 is transmitted to the first main transmission @S1 via the 2nd speed hydraulic transmission clutch 51, and when the 3rd speed hydraulic transmission clutch 52 is actuated, the rotation of the clutch shaft 20 is transmitted to the gear G13.3rd speed hydraulic transmission clutch 51. via the transmission clutch 52
It is transmitted to the main transmission shaft $2.

A 4-speed and reverse hydraulic transmission clutch 54 having the same configuration as each of the hydraulic transmission clutches 39, 51, and 52 is also provided at the intermediate portion of the second main transmission shaft S2, and this 4-speed and reverse hydraulic transmission clutch 54 is operated. When this happens, the rotation of the second main transmission shaft S2 is transmitted to the first main transmission shaft S through the clutch 54 and teeth l1G24.
The signal is transmitted to the gear G14 fitted with 'TI'. Gear G2
4 is also integrated with the reverse drive gear G2R, and by operating the 4th speed/reverse hydraulic transmission clutch 54, the rotation of the second main transmission shaft S2 is also controlled via the gear G2R and the idle gear 57 (FIG. 2). This is transmitted to the reverse driven gear G1R loosely fitted to the first main transmission shaft S1. First main shift shaft 8
1 is selectively connected to either the gear G14 or the gear G11i by a selector 60 which can be moved by 1 in the axial direction.

In this manner, the first main transmission shaft S1 is given a rotation speed of four forward speeds and one reverse speed, but the rotation of the first main transmission shaft S1 is further transmitted to the sub-transmission shaft S3 with a gear ratio of three speeds. Reportedly. The sub-transmission shaft S3 is connected to the rear axle 9 (FIG. 1) via a differential m-wheel device and a final reduction gear (not shown), and thus 12 forward gears and 3 reverse gears can be shifted.

As can be seen from FIG. 3, the front wheel drive shaft S5 is arranged adjacent to the auxiliary transmission shaft S3, and the gear G5 that meshes with the gear G fixed to the auxiliary transmission shaft S3 is set to front wheel drive @S5 by the selector 61. When connected, the rotation of the auxiliary gearbox S3 is transmitted to the front wheel drive @S5, and the front wheels 2 are driven via the front wheel drive propellers 1 to 10 as described above.

As explained with reference to FIG. 3, the PTO shaft S4 is arranged at the uppermost position inside the mission case 4, and its rear end protrudes outward from the mission case 4 so that it can be connected to the working drive system. ing. This PTO axis S
4 is a gear G4 selectively connected by a selector 62;
1 or gear G42.1 selectively connected by selector 64. It is driven from the second main transmission @S2 via G43 at three rotational speeds: low, medium, and high.

Mission case 4 has each of the above axes 7, 20°Sl...
- In addition to S5, a pump shaft SP is roughly arranged parallel to each of the above-mentioned axes. A gear G is fixed to the pump shaft SP, and the gear G is always meshed with the gear G7 fixed to the input shaft 7.

The front end of the pump shaft SP is connected to a hydraulic pump 65, which is a gear pump, for example, which is fixed to the transmission case 4, and the hydraulic pump 65 is driven by the pump shaft SP. A portion of the oil discharged from the hydraulic pump 65 is sent to an oil inlet 66 provided at the front end of the clutch shaft 20 of the main clutch 17 via an oil passage (not shown) provided along the clutch housing 15. It will be done. As shown in FIG. 4, an axial hole 67 passes through the shaft center of the clutch shaft 20 in the front and back, and the #J end is supported at the rear end of the clutch shaft 20 via a needle bearing 34. The first main transmission shaft S1
A hole 68 coaxial with the hole 67 is also provided at the front end of the holder.

Two inner and outer tube pieces 69 and 70 with different diameters are inserted into these holes 67 and 68, and the inside of the tube piece 69, between the tube piece 69 and the tube piece 70, and the tube piece 70 are inserted. Oil passages 71, 72, and 73 are formed between the holes 67 and 67, respectively. These oil passages 71, 72, and 73 all communicate with the oil inlet 66 at the front end of the clutch shaft 20, and as can be seen from the figure, the oil passage 71 is connected to the two-speed hydraulic transmission clutch 5.
The oil passage 72 forms a clutch oil passage for supplying clutch oil to the third-speed hydraulic transmission clutch 52, and the oil passage 73 serves as a medium lubricating oil passage for lubricating the needle bearing 34. It becomes. Further, the clutch shaft 20 is provided with a radial opening that communicates the lubricating oil passage 73 with the main clutch 17, and the oil supplied into the main clutch 17 through this opening connects the driving clutch plate 24 with the lubricating oil passage 73. The space between the drive clutch plate 26 and the drive clutch plate 26 is lubricated. That is, the main clutch 17 is a wet multi-disc type clutch.

In this way, the oil discharged from the hydraulic pump 65 is transferred to the clutch shaft 2.
The main clutch 17 is guided to one oil inlet 66 provided at the front end of the main clutch 17 through oil passages 71, 72, 73 provided in the axial direction at the axial center of the clutch shaft 20 and the first main transmission shaft S1. Also, lubricating oil can be supplied to the needle bearing 34 and clutch oil can be supplied to the second-speed hydraulic transmission clutch 51 and the third-speed hydraulic transmission clutch 52. The oil passage 71 is also located in the rear half of the first main transmission shaft S1.
Separately from the above, a lubricating oil passage 74 is bored in the shaft center portion. The oil discharged from the hydraulic pump 65 is supplied to this lubricating oil passage 74 through the oil-filled lower 5 provided at the rear end, and is sent to the needle bearings 58, 56, 53 through the lubricating oil passage 74. and 2-speed hydraulic transmission clutch 5.
It is sent to the first and third speed hydraulic transmission clutches 52 to lubricate their hybrid clutch plate portions.

A similar lubricating oil passage 7G and clutch oil passage 77 are also provided on the second main shift shaft S2, and are supplied with oil from both ends of the second main shift 'MS2. In addition, as mentioned above, the second main transmission shaft S2 operates at a speed ratio of 1:1 through the gear G13 and the gear G23. , so the main clutch 17 can be directly connected to the second main transmission @S2, and therefore the main clutch 17 can be installed on the first main transmission shaft S1 side, or the main clutch 17 can be directly connected to the second main transmission @S2. Depending on whether it is attached to the shaft S2 side, the rotation direction of the PTCIS 4 may be set to "clockwise as seen from the rear" as per the standard. When installing the main clutch 17 on the second main transmission @S2 side, as shown in Fig. 3, the second main transmission shaft S2 and the input shaft 7 are relatively close to each other. The input shaft 7 may be connected to the input shaft 7 by a gear instead of a sprocket and a chain.

As shown by the oil level in FIG. 3, the lubricated oil stored in the transmission case 4 passes through the oil filter 78, returns to the suction vibe 79, is sucked into the hydraulic pump 65, and is recirculated.

The configuration of the illustrated embodiment has been described in detail above, but to summarize, this dynamic saw transmission device is pivotally supported in the transmission case 4! First main shift II! 11S1 (or second main transmission shaft S2) is mounted on the Mitsushicon case 4 on the same axis as the first main transmission shaft 31 (second main transmission shaft S2>) and transmits engine power to the first main transmission shaft S1. A wet multi-disc main clutch 17 that transmits engine power directly or indirectly via the second main transmission shaft s2 (directly to the second main transmission shaft s2), and a shaft 7 that transmits engine power to the clutch 17 are actuated. a hydraulic pump 6 connected to the transmission case 4 and mounted on the transmission case 4;
5, and the first main transmission shaft Sl (second main transmission shaft S2
) is equipped with a hydraulic hydraulic multi-disc clutch 51.52 (39
, 54), and a clutch oil passage 71.72 (77) and a lubricating oil passage 73.7 extending in the axial direction at the axial center of the first main transmission shaft 81 (second main transmission @S2).
4 (713), and these oil passages are connected to the hydraulic pump 65.

1. In the present invention, as described above, since the clutch oil passage and the lubricating oil passage extending in the axial direction are provided in the axial center of the transmission shaft, oil supply to each hydraulic clutch, bearing, gear, etc. is carried out from the transmission shaft. This can be done all at once from the end of the oil passage, and the length of the components of the oil passage can be shortened to ni. In addition, since the water-type multi-disc main clutch and the hydraulic multi-disc clutch for gear shifting are arranged on the same axis, the oil passage in the axial direction provided on the gear shifting shaft is extended to the main clutch. By doing so, the oil supply ports for the main clutch and the speed change clutch can be gathered at one location on the shaft end. Since the hydraulic pump that supplies clutch oil and lubricating oil is installed in the transmission case, the oil supply path from the pump to the oil filler port at the end of the shaft can be easily routed! This hydraulic pump is simple and highly reliable, but in addition, this hydraulic pump is operatively connected to the shaft that transmits engine power to the main clutch, and constantly rotates regardless of whether the main clutch is engaged or disengaged, pumping out pressurized oil. , so you can always achieve a constant starting feeling. Further, by placing the main clutch in front of the hydraulic clutch, rotation of the hydraulic clutch can be immediately stopped when the main clutch is disengaged, thereby reducing shift shock.

[Brief explanation of the drawing]

Fig. 1 is a side view of an agricultural tractor to which the present invention is applied, Fig. 2 is a sectional view showing the power transmission device of the same tractor, and Fig. 3 is a drawing showing the actual arrangement relationship of each shaft of the power transmission device. FIGS. 4 and 5, which are end views of the device viewed from the front to the rear, are partially enlarged views of FIG. 2, respectively. 1... Rear wheel, 2... Front wheel, 3... Engine, 4...
...Mission case, 5.Reduction gear, 6.Propeller shaft, 7.Input shaft, 8.Vehicle frame, 9.Rear axle, 10.Front wheel drive blower shaft, 11 ...Hydraulic cylinder, 12...Lift arm, 13...Seat, 14...Handle, 15...
・Clutch housing, 1G... Sprocket, 17
...Main clutch, 18...Sprocket, 19...
・Ball bearing, 20... Clutch shaft, 21... Needle bearing, 22... Spring member, 23... Drive member, 24
... Drive clutch plate, 25 ... Driven member, 26.
... Driven clutch plate, 27... Pressure contact plate, 28...
Boss, 29... Lifter plate, 30... Coil spring, 31... Ball bearing, 32... Operating part, 33...
・Lever, 34... Needle bearing, 35... Ball bearing, 36... Bearing wall, 37. 38... Ball bearing, 39.
・・Low speed hydraulic transmission clutch, 40 ・・Drive member, 41
...The receiver is a plate, 42...Drive clutch plate, 43...
Cylinder part, 44... Operating member, 45... Spring, 46... Oil passage, 47... Clutch oil passage, 4
8... Needle bearing, 49... Driven member, 50...
... Driven clutch plate, 51... 2nd speed hydraulic gearshift clutch, 52... 3rd gear hydraulic gearshift clutch, 53... Needle bearing, 54... 4th speed and reverse hydraulic gearshift clutch, 5
6... Needle bearing, 57... Idle gear, 58
...Needle bearing, 60.61.62...Selector, 64...Selector, 65...Hydraulic pump, 6
6... Oil inlet, 67° 68... Hole, 69.70...
・Pipe piece, 71.72.73...Oil passage, 74...
Lubricating oil passage, 75... Oil inlet, 76... Lubricating oil passage, 17... Clutch oil passage, 78... Oil filter, 79... Suction pipe, Sl... First main gear shift shaft , SP...Second main transmission shaft, S
3... Sub-transmission shaft, S4... PTO axis, S5... Front wheel drive shaft, G... Gear, SP... Pump shaft.

Claims (1)

[Claims] In a power transmission device for a vehicle that changes and transmits engine power, there is a transmission shaft that is rotatably supported in a transmission case, and a transmission shaft that is mounted on the transmission case coaxially with the transmission shaft and that transmits the engine power to the transmission shaft. A hydraulic hydraulic multi-disc clutch for speed change is provided on the speed change shaft, and includes a plate-shaped main clutch and a hydraulic pump operatively connected to a shaft that transmits engine power to the clutch and mounted on the transmission case. What is claimed is: 1. A power transmission device for a vehicle, comprising: a clutch oil passage and a lubricating oil passage extending in the axial direction at the axial center of the speed change shaft; and these oil passages are connected to the hydraulic pump.