GB2126543A - Front power take-off for tractors - Google Patents

Abstract

A tractor has a front wheel drive and a front power take-off shaft 44. The wheels are driven through a differential unit 12 via a train consisting of pinion shaft 18, gear 19, and gear 20 mounted on the forward end of a drive shaft driven by the main gearbox 1. The power take-off shaft 44 is driven by gears 48 and 47 the latter being mounted on a drive shaft 38, 39 connected to the main gearbox 1. The two drive shafts are disposed beneath and to the left and right of the drive pinion shaft 18. The drive gears 20 and 48 overlap in the longitudinal direction and are widely spaced laterally to allow the drive gear case 8 to be high enough from the ground to reduce the risk of collision with ridges when travelling over uneven ground. <IMAGE>

Description

SPECiFICATION Front power take-off for tractors This invention relates to a front powertake-off in which the front wheels of a tractor are driven by rotary powertaken out from two portions of a section in the vicinity of a lower section ofthe tractor transmission case, and transmitting power to a front power take-off shaftfor driving on auxiliary machine.

The conventional take-off means for such front wheel driving power and front auxiliary machine driving power is so formed that the rotary power for a front wheel driving powertake-offshaftand a front working power take off driving shaft, which project from and are pivotablysupported on a lower portion of the transmission case, is transmitted via universal joint shafts to frontwheel-driving differential mechanism and a front auxiliary machine. In this take-off means, the transmission mechanism can be constructed simply butthe universal jointshafts are not supported firmly. This admits the problem that the universal joint shafts vibrate greatly when they are rotated, and so they cannot be rotated at a high speed, nor can a high torque be transmitted.These universal joint shafts are provided projecting from a lower portion ofthetransmission case, and a driving gear case containing therein two pairs of gear mechanisms for transmitting the rotary power ofthe universal joint shafts to the differential mechanism driving the front wheels and the front working powertake-off drive shaftare generally positioned below the lower portion ofthe transmission case, reducing, the clearance of thetractorbodyovertheground. Consequently, when the tractor is driven over a ridge between rice fields, these projecting parts sometimes collide with the ridge. Thus,the conventional front powertake-off has problems with respect to the movement of the tractor as well.

An object of the present invention is to provide a front powertake-offfortractors free from the above defects. According to the present invention there is provided a front power take-off assembly for a tractor comprising a drive pinion shaft in a differential unit for driving the frontwhee!s, which drive pinion shaft is positioned in that portion of a front axle housing corresponding to the center of vertical pivotal move mentsofsaid housing, a frontworking power output shaft and a front wheel drive power input shaftfor driving a drive pinion, which are disposed in such a mannerthatthe axes ofthese power shafts are positioned underand on the right and left sides of said drive pinion shaft, and two transmission shafts disposed in right and left portions of a lower section of a transmission case and connecting driving mechanisms provided in said right and left portions ofthe lowersection of said transmission case to said power shafts. The rotary power taken out from thetransmis- sion case may be transmitted by ordinarytransmission shafts to their respective front powertake-off portions at a high speed, with a laterally balanced rotational force, and no deflection ofthe axes thereof.

The front powertake-off may be provided in a drive gear case with drive gear mechanismsforthe front wheels and a front auxiliary machine. These drive gear mechanisms may extend overlapping one another in the longitudinal direction in positions sufficiently away from the ground surface in such a manner that the axes ofthese drive gear mechanisms are space far from each other in the lateral direction to thereby allow the drive gear case to be positioned sufficiently high as compared with the drive gear case in the conventional front powertake-off of thins kind, so the tractor can be moved over a ridge between rice fields withoutthe case colliding with the ridge.

In order that the invention may be readily understood, certain embodiments thereof will now be described by way of example with reference to the accompanying drawings in which Fig. is a side elevation view of a tractor; Fig. 2 is a sectional view taken along the folding section line A-B-C in Fig. 5; Fig. 3 is a sectional view taken along the folding section lineA-B-G-D-E in Fig. 5; Fig.4 is a sectional view taken along the folding section line A-B-C-D-E in Fig. 5; Fig. 5 is a sectional view taken along the arrow line H-H in Fig. 3; and Fig. 6 is a side elevational view in longitudinal section of another example ofthe bearing unit shown in Fig. 4.

A powertake-off case 2 is mounted to, for example, the rear, right portion of a lowersurface of a transmission case 1 as shown in Fig. 2. Afrontwheel drive powertake-off shaft 6 is supported in a bearing5 provided in the powertake-offcase 2 and a bearing 4 provided in a bearing cylinder 3 secured to the power take-off case 2so as to project forward therefrom.

A drive gear case 8 is provided at a lower portion of the front frame 7 of the tractor. The rear portion of the front wheel drive power input shaft 10, which is supported in the drive gearcase8by bearings9, and the front portion ofthefrontwheel drive power take-off shaft 6 are connected together via a transmission shaft 11.

A rear pivot 14 of a front gear case 13, in which a differential mechanism 12 for driving the front wheels is provided, is rotatably supported on the front frame 7, and a front pivot 15thereof on a front pivot bearing 16 secured to the front frame 7. Afront axle housing 17 is fixed to the front gear case 13 and extends to the right and lefttherefrom, and is provided therein with right and left front shafts rotatably supported therein.

This front axle housing 17 is so formed that right and left portions of the housing 17 can be moved pivotally in the vertical direction aboutthe axes of the front and rear pivots 15, 14. A drive pinion shaft 18 in the differential mechanism 12 for driving the front wheels is supported concentrically with the rear pivot 14. The axis of the front wheel drive powertake-offshaft 6, i.e.

front wheel drive power input shaft 10, is positioned on the lower right side ofthe drive pinion shaft 18 (referto Fig. 5). Agear 19 is mounted onthedrive pinion shaft 18 extending intothe drive gear case 8.

The gear 19 is meshed with a gear 20 mounted on the front wheel drive power input shaft 10. The front wheel drive powertake-off shaft 6 is driven by gear change mechanism 21 provided in the transmission case 1. The engine output is transmitted to an input shaft 23 via a clutch 22, and the rotation ofthe input shaft23 to a rearwheel-driving rear drive pinion shaft 24 by the gear change mechanism 21. The rotation of a gear25 mounted on the reardrive pinion shaft 24 is transmitted to a clutch gear 28, which is mounted loosely on the front wheel drive powertake-offshaft6 via counter gears 26,27 to allow clutch teeth 28a on the clutch gear 28 to engage with and disengage from clutch teeth 6a provided on the front wheel drive power take-off shaft 6.

Reference numerals 29,30 denote shaft couplings, and 31 represents an extensible shaft cover.

A powertake-offcase 32 is secured to, for example, the left lower surface of the transmission case 1 in front of the power take-off case 2, as shown in Fig. 3.

The front portion of a front working power take-off drive shaft 35 is supported on bearings 33,34 and extends forward from the power take-off case 32. The rear portion of a front working power input shaft 38 supported in the drive gearcase8 by bearings 36,37 is connected to the front portion of the front working power take-off drive shaft 35 via a transmission shaft 39. As shown in Fig. 5, the axes of the front working power input shaft 38 and front wheel drive power input shaft 10 are spaced far from each other in the lateral direction. Moreover, the position of the axis of thefrontworking power input shaft 38 is under and on the left side of the drive pinion shaft 18, and spaced as close as possible to the same shaft 18.

The front portion of a front working power output shaft 42 is supported in the drive gear case 8 by bearings40,41 and positioned under the front gear case 14. A bearing unit 43 is secured to the front pivot receiver 17. Afrontworking powertake-off shaft 44 is positioned under the front gear case 13 and supported on the bearing unit 43 via a bearing 45. The front working powertake-off shaft 44 and front working power output shaft 42 are connected together by a shaft coupler 46. A gear 47 mounted on the front working power input shaft 38 and a gear48 mounted on thefront working power output shaft 42 are meshed with each other.The gear 48 is positioned so as to overlap, in a front or rear elevationa I viewthereof as shown in Fig. 5, the gear 20 mounted on the front wheel drive power input shaft 10, and so as to be staggered from each other in the longitudinal direction in a side elevational viewthereofas shown in Fig.

4. The front working power output shaft 42 is disposed so thatthe axis of shaft 42 is in the highest possible position, which is moreover underthe center of pivotal movements ofthe front axle housing 17 and spaced as close as possible to the axis of drive pinion shaft 18. The rotation of a power take-off input shaft 49, which is driven by the engine, is so controlled that its rotation is trnasmitted to a counter shaft 51 via a PTO clutch 50, or nottransmitted thereto. Change gears 53,54 are mounted loosely on a rear working powertake-off shaft 52, and teeth 51a, 51b provided on the counter shaft 51 are constantly meshed with change gears 53,54, respectively.A slide coupling 56 is engaged with clutch teeth of a hub 55 mounted on the rear working powertake-offshaft 52, can be moved in the axial direction only, and can be engaged with and disengaged from the clutch teeth of change gear53 or54.

A clutch gear 57 mounted loosely on the front working powertake-offdriveshaft35 is constantly meshed with change gear 54via a counter gear 58 supported via a shaft in the power take-off case so as to allow clutch teeth 57a ofthe clutch gear 57 to engage with and disengage from the clutch teeth 35a provided on the front working powertake-off drive shaft 35.

Reference numerals 59,60 denote shaft couplings, 61 denotes an extensible shaft cover, 62 a shaft cover, and 63 a coverforthe drive gear case 8.

In a second embodiment shown in Fig. 6, a bearing unit 65 provided with a gear chamber 64 is used instead of the bearing unit 43 referred to previously. A front working power take-off shaft 66 is divided into a front working powertake-off lower shaft 67, which is supported at the front portion thereof on the bearing unit 65 and connected at the rear end portion thereof to the output shaft 42, and a front working power take-off upper shaft 69, which is supported on the bearing unit 65so as to be operatively connected to the front working powertake-off lower shaft 67 via a gear mechanism 68. Accordingly, when gears in the gear mechanism 68 are replaced with other ones, the rotational speed of the front working power take-off upper shaft 69 can be changed.

Either the front wheel drive power take-off shaft 6 or the front working powertake-off drive shaft 35 may be disposed on the right or left side of the drive pinion shaft 18.

Therefore, when the slide coupling 56 is moved forward so as to engage with the change gear 53, the rear working powertake-off shaft 52 is rotated at high speed bythe rotary power transmitted to the counter shaft 51 via the PTO clutch 50. Conversely, when the slide coupling 56 is moved backward to engage with the change gear 54, the rear working power take-off shaft 52 is rotated at low speed.

On the other hand, when the PTO clutch 50 is in the connecting state, the clutch gear 57 is driven constantly by the change gear 54 and counter gear 58.

Accordingly, when the clutch teeth 57a oftheclutch gear 57 are brought into engagement with the clutch teeth 35a of the front working power take-off drive shaft 35 as shown in Fig. 3, the rotary power is output from the front working power take-off shaft 44 or 67.

When the clutch gear 57 is moved to a position in which the clutch teeth 57a are disengaged from the clutch teeth 35a, the front working power take-off shaft 44 or 67 remains stopped.

As described above, the front power take-off according to the present invention comprises: a drive pinion shaft 18 in a differential mechanism 12 for driving the front wheels, and this drive pinion shaft 18 is positioned in the part of a front axle housing 17 corresponding to the center of its vertical pivotal movements; a frontworking power output shaft 42 and a front wheel drive power input shaft 10for driving the drive pinion disposed in such a manner thatthe axes of these power shafts 42, 10 are positioned under and on the right and left sides of the drive pinion shaft 18; and two transmission shafts disposed in right and left portions of the lower section of a transmission case 1 and which connect driving mechanisms provided in the right and left portions of the lower section of the transmission case 1 to the power shafts 42, 10. Thus the rotary power taken-out from the transmission case 1 can be transmitted by ordinary transmission shafts (not universal joint shafts) to their respective front power take-off po rtions at a high speed with laterally balanced rotational forces and no deflection of the axes thereof.In the embodiments described above, a drive gear mechanism consisting of, for example, gears 47 and 48, for rotating the front working power output shaft 42 by a frontworking power input shaft 38 disposed in the preceding position in the powertrain, and a drive gear mechanism consisting of, for example, gears 19 and 20, for rotating the drive pinion shaft 18 by the front wheel drive power input shaft 10 disposed in the preceding position in the power train, are provided in one drive gear case 8. This allows the dimensions of the drive gearcase 8, which contains these two driving gear mechanisms together and which constitutes the lowest part of the tractor body, to be minimized.

Accordingly, there is little possibilitythatthe drive gear case 8 will collide with plants growing on the ground. In the embodiment, in which the axes ofthe frontworking power input shaft 38 and front wheel drive power input shaft 10, which are supported in the gear case 8, are spaced far from each other in the lateral direction, and in which the axis ofthefront working power output shaft 42 is spaced as close as possible to the drive pinion shaft 18, the front working power output shaft 42, i.e. the lowest shaft among the mentioned shafts, can be disposed in a sufficiently high position. Therefore, there is no possibility that the front working power output shaft 42 will collide with a ridge between rice fields.

In the embodiment, in which thefrontwheel drive power input shaft 10 and front working power output shaft 42 are positioned in such a mannerthatthe gears mounted fixedly thereon overlap each other in a front elevational viewthereof and are staggered from each other in the longitudinal direction in a side elevational view thereof with the axis ofthe front working power outputshaft42 set close to that of the drive pinion shaft 18, the front working power output shaft 42 can be put sufficiently close to the frontwheel drive power input shaft 10. Moreover, the front working power output shaft 42 can be provided in a position close to and lust under the drive pinion shaft 18, which is in the center of rotation ofthe front wheels.Consequently, the front working power output shaft 42 is raised to a sufficiently high position, so thatthe minimum height of the tractor body above the ground surface is increased to preclude the possibilitythattheseshafts will collide with a ridge between rice fields when the tractor is driven over it.

Thefrontworking power output shaft42 can be supported in a position in which the axis ofthis shaft 42 is close to that ofthe drive pinion shaft 18 disposed in the center of pivotal movements of the front axle housing 17 without being obstructed by the gear 20 mounted on the frontwheel-drive power input shaft 10. Therefore, variations in the bending angle of a universal joint portion of a universal joint shaft, which connects the front working power output shaft 42 (front working powertake-off shaft 44 connected thereto in the embodiments) disposed close to the drive pinion shaft 18 which stays in the same position during pivotal movements of the front axle housing 17 to a driving shaft of an auxiliary machine (not shown), when the tractor moves can be minimized.Owing to the successful reduction of variations in the bending angle of the universal joint portion, the rotary power can be transmitted from the universal joint shaft to the auxiliary machine efficiently and smoothlywith little noise.

In the embodiment in which the front working power take-off shaft 44 connected to a front portion of thefrontworking power output shaft42 is supported in a position close to and under the front axle housing 17, it is very convenient to use the front working power take-off shaft 44, supported sufficiently low above the ground surface, to drive an input shaft, which is disposed close to the ground surface, of a ground treating machine connected to a front portion of the tractor.

In the embodiment in which the working power is taken-off by the front working powertake-off upper shaft 69 provided in a position which is higher than the front working powertake-off shaft 44via the front drive gear mechanism, an auxiliary machine can be conveniently driven with the front working power take-off upper shaft 69 supported in a suitably high position.

The present invention is of course not limited to the above embodiment and may be modified in various ways within the scope ofthe appended claims.

Claims (8)

1. Afront powertake-off assembiyfor a tractor, comprising a drive pinion shaft in a differential unit for driving the front wheels, which drive pinion shaft is positioned in that portion of a front axle housing corresponding to the center of vertical pivotal move mentsofsaid housing, a front working power output shaft and a front wheel drive power input shaft for driving a drive pinion, which are disposed in such a mannerthatthe axes ofthese power shafts are positioned under and on the right and left sides of said drive pinion shaft, and two transmission shafts disposed in right and left portions of a lower section of a transmission case and connecting driving mechanisms provided in said right and left portions ofthe lower section of said transmission caseto said power shafts.

2. An assembly according to claim 1, wherein a drive mechanism for rotating said frontworking poweroutputshaftvia one of said transmission shafts, and a drive gear mechanism for rotating said drive pinion shaft via said front wheel drive power input shaft are housed in one drive gear case provided at a front location ofthetractor.

3. An assembly according to claim 1 or 2, wherein said front working power input shaft and said front wheel drive power input shaft, which are connected to said transmission shafts and supported in said driving gear case, are so disposed that the axes of said power input shafts are spaced far from each other in the lateral direction, the axis of said front working power output shaft being spaced as close as possible to said drive pinion shaft.

4. An assembly according to claim 1,2 or 3, wherein, in orderto form said drive gear mechanism, said front wheel drive power input shaft and said front working power shaft are so positioned that gears mounted on said power shafts overlap each other when viewed from the front and are staggered from each other in the longitudinal direction, the axis of said front working power output shaft being set in a position close to that of said drive pinion shaft.

5. An assembly according to any of the preceding claims wherein a front working powertake-off shaft, which is connected to a front portion of said front working power output shaft so as to take out the working power, is supported in a position close to and under said front axle housing.

6. An assembly according to anyofthepreceding claims wherein the working power is taken out by a frontworking powertake-offuppershaft,which is provided in a position higher than said front working powertake-off shaft, via said front drive gear mechanism driven by said front working powertake-off shaft.

7. A front power take-off assembly substantially as hereinbefore described with reference to the accompanying drawings.

8. A tractor incorporating a front powertake-off assembly according to any of the preceding claims.