FR2495550A1 - TRACTOR TRANSMISSION - Google Patents

Abstract

A. TRACTOR TRANSMISSION INCLUDING A MAIN GEAR SHIFT MECHANISM 6, AN AUXILIARY GEAR CHANGE MECANISM 8 AND A FORWARD - REVERSE GEAR TYPE 7 CHANGEOVER MECHANISM FOR TRANSMITTING POWER BETWEEN A POWER TRANSMISSION PROPULSION. B. TRANSMISSION CHARACTERIZED IN THAT THE MAIN SPEED CHANGE MECHANISM 6, THE FORWARD - REVERSE GEAR TYPE 7 SHIFT MECHANISM AND THE AUXILIARY SPEED MECHANISM 8 ARE MOUNTED IN THIS ORDER INSIDE A BOX TRANSMISSION, FROM FRONT TO REAR OF TRACTOR. C. THE INVENTION APPLIES TO TRACTOR TRANSMISSIONS.

Description

The invention relates to tractor transmissions and more

  particularly a transmission comprising a main gearshift mechanism, an auxiliary gearshift mechanism, and a gear-type forward-to-reverse switching mechanism,

  transmit the power of an engine to a propulsion system.

  In conventional tractor transmissions comprising a main gear shift mechanism, an auxiliary gear shift mechanism, and a gear-type forward-reverse gear mechanism, as described above, the forward gear mechanism - Reverse is fitted in one of three ways, namely either in combination with the main gearshift mechanism, or placed in front of the main gearshift mechanism, or

  placed behind the gearshift mechanism

  iary. The case in which the gear-type forward-reverse gear mechanism is combined with the main gearshift mechanism is simply the result of the need for the tractors to have multiple reverse speeds, as is still the case for ordinary motor vehicles. Such a type of construction does not correspond to the needs of modern tractors which must use several

  reverse speeds to perform their various functions.

  tions. To meet this need we now use several reverse speeds. In many cases, a forward / reverse switch mechanism provides multiple reverse speeds without

  require significant changes in the exchange rate mechanism

  main gear, is mounted in front of the main gearshift mechanism to reverse the direction of rotation of a drive shaft before applying power to

  the input of the main gearshift mechanism.

  However, this arrangement requires a gear change operation before reducing the speed of the engine by the main gearshift mechanism, which therefore has the disadvantage of having to engage gears in gear conditions. high rotation speeds, which corresponds to a missing operation

softness and flexibility.

  The solution of mounting the forward / reverse switching mechanism behind the main and auxiliary gearshift mechanisms has also been implemented. In such a mounting a hand lever for operating the switching mechanism, is provided in the vicinity of the hand lever for operating the main gearshift mechanism, near the driver's seat. This solution has the disadvantage of

  require a very long link mechanism linking

  the forward / reverse switch mechanism

at his hand lever.

The invention aims to remedy

  disadvantages of the constructions according to the prior art decribed

  above, by creating a rational arrangement of the mechanis-

  me switching forward - reverse gears type, which can be operated by a link mechanism

  simple and which allows to obtain a forward movement -

  reversing both soft and supple.

  To this end, the invention relates to a tractor transmission comprising a main gearshift mechanism, an auxiliary gearshift mechanism, and a gear-type forward-reverse gear mechanism for transmitting the gearbox.

  between an engine and a propulsion system, transmitted

  characterized in that the mechanism of change of

  Mainly, the gear-type forward-reverse gear mechanism and the auxiliary gear mechanism are mounted in this order inside a gearbox, moving from the front to the gearbox. back

of the tractor.

  More specifically, the construction according to the invention in which the main gearshift mechanism, the forward-reverse switching mechanism, and the auxiliary gearshift mechanism, are mounted inside a gearbox. transmission, in the order indicated above, when going from the front to the rear of the tractor, provides the advantages described

  hereinafter with respect to the constructions according to the prior art.

  Since the mechanism of com-

  forward / reverse change is mounted behind the main gearshift mechanism, the gear movement is under low speed conditions due to the presence of the main gearshift mechanism, which allows switching forward - reverser softer than if both mechanisms

  were mounted in reverse order.

  In addition, a hand lever for operating the forward / reverse switching mechanism is generally placed in the vicinity of a lever for driving the main shift mechanism, since switching operations between forward and reverse are often performed at the same time as

  main gearshift operations.

  The construction according to the invention, da: which the forward-reverse switching mechanism is mounted in front of the auxiliary speed change mechanism, makes it possible to place this forward-reverse switching mechanism closer to its hand lever. of

  maneuver only if it were mounted behind the mechanism of chan-

  auxiliary speed control, which simplifies the connection between the forward and reverse switch mechanism

  the back and its hand lever, as well as its

functioning.

  Other features and advantages of the invention will appear more clearly on reading the

  detailed description which follows and which refers to the drawings

  joints in which: - Figure 1 is a side view, in elevation, of a tractor, - Figure 2 is a vertical sectional view of the transmission, - Figure 3 is a vertical sectional view showing the mechanism of switching on

  forward-reverse according to the invention, and the system of -

  connection of this, - Figure 4 is a plan view of the hand levers,

  FIG. 3 is a cross-sectional view of

  1, and FIGS. 6 and 7 are views showing, for purposes of comparison, different forward / reverse switching mechanisms. FIG. 1 shows a four-wheel drive tractor comprising a tractor body mounted on a propulsion system A with front and rear drive wheels 1 and 2. The tractor comprises a motor E at its front end, t and a lifting arm 3 as well as a PTO shaft 4 at its rear end. These last two elements are intended to allow to couple to the tractor different types of tools

  -work such as a rotary cultivation tool or a mower.

  The power is transmitted from the engine E to the drive wheels 1 and 2 via a main clutch 5, a mechanism

  main gearshift 6, a switching mechanism

  forward-to-reverse gear type 7, an auxiliary gearshift mechanism 8 and a differential mechanism 9. Furthermore the power is transmitted to the PTO shaft 4 via clutch

  main 3 and another gearshift mechanism 10.

  Thus, the tractor is designed to be able to perform several

  functions by pulling and driving a work tool.

  This transmission structure allows

  both to transmit the power of the engine E to the front and rear wheels 1 and 2, and the PTO shaft 4, is described in more detail in Figure 2. The power of the engine E is

  transmitted to the input shaft 13 of the transmission, through

  mediate the main clutch 5 which is mounted in a crankcase

clutch 11.

  From the input shaft 13, the power is transmitted to a first propulsion system intermediate shaft 15 via the gear type main gear 6 for Bh to provide four speeds and- disposed in a first housing 14 removably mounted on the clutch housing 11. A

  from the input shaft 13 the power is also trans-

  set to PTO shaft 4 through the

  gear type shift mechanism 10 -

  also mounted in the first housing 14 and intended to provide

two speeds.

  From the first intermediate beam, the power is transmitted to the gear-type forward-reverse gear mechanism 7 housed in a spacer box 16 removably attached to the gearbox.

  first box or crankcase -14, then to a second intermediate shaft

  17 constituting the output shaft of the communication mechanism

  7. From the second intermediate shaft 17, the power is transmitted to the gear-type auxiliary gearshift mechanism 8 housed in a second housing 18 removably attached to the spacer 16, this mechanism being intended to provide two speeds, then the power is transmitted to a pinion shaft 19. From the pinion shaft 19 the power is transmitted to the rear wheels 2 via the differential mechanism 9, and to front wheels through a gear type transmission mechanism 20, and a

drive shaft 21.

  The first and second casings 14 and 18 form, with the spacer 16, a complete transmission box. The main gearshift mechanism comprises four gears 22a, 22b, 22c and 22d of different diameters, and fixed on the input shaft 13, as well as

  that four movable gears 23a, 23b, 23c and 23d mounted movably

  axial sliding on the first intermediate shaft 15 arranged parallel to the shaft 13. The movable gears 23a and 23b form a pair and the moving gears

  23c and 23d form another pair, these two pairs remaining

  respectively engaged with the gears 22a ... etc ...

  Two shift forks 24a and

  24b, respectively intended to move the two pairs of

  movable sheaves 23a ..., are fixed rigidly to a rod 26 slidably supported by a first housing element 25

  removably attached to the first housing 14.

  A transversely skewable hand lever 28 for operating the main shift mechanism is provided on a second housing member 27 removably attached to the first housing member 25, the hand lever 28 being selectively engageable with the housing members 28.

  two shift forks 24a and 24b.

  According to FIG. 3, the forward-to-backward switching mechanism 7 comprises an input shaft constituted by the first intermediate shaft 15, supported by a partition 16a and carrying a first gear 29 and a second gear 30 opposite to each other. one to the other side of the partition wall 16a. The first gear 29 rotates integrally with the first intermediate shaft while the second gear 30 can rotate freely relative to the first intermediate shaft 15. The partition wall 16a is constituted by an extension of the box

16.

  It is also planned another tree

  intermediate 31 arranged parallel to the first

  medial 15, between the partition wall 16a and a partition member 16b opposite the wall 16a. The intermediate shaft 31 carries a third gear 32 and a fourth gear 33 integrally rotating with the intermediate shaft 31. The third gear 32 is engaged with the first gear 29, and the fourth gear 33 is operably connected to the second gear 30 through an inverter gear 34, whereby the first and the second gears

  29 and 30 are constantly turning in opposite directions.

  The first intermediate shaft 15 carries at its rear end, a fifth gear 35, which rotates integrally with the shaft 15; the second intermediate shaft 17, abutting with the first intermediate shaft 15, carries at its front end, a two-stage gear 36 rotating integrally with the second shaft 17. An internally threaded movable gear 37 spans the first and second intermediate shafts 15 and 17 while being able to slide axially on these shafts, this gear 37 constituting with the fifth

  gearing 35 and the two-stage gear 36, a gear mechanism

  38. The moving gear 37 can slide between a position engaging the fifth gear 35 with the two-stage gear 36 (forcing the tractor forward, 9) and a position engaging the second gear. 30 with the two-stage gear 36 via a toothed portion 39 integral with the second gear 30 (which

  advance the tractor in reverse).

  A hand lever 40 for performing forward / reverse switching maneuvers is provided on the second housing member 27 adjacent and to the left of the biain lever 28 for operating the main gearshift mechanism. 6; this hand lever 40 can oscillate in the longitudinal direction of the tractor body and engages with an element 41 fixed to a first displacement rod 42 slidably mounted in the first housing element 25. A second displacement rod 43 is placed at below the rear end of the first displacement rod 42, and is supported in sliding first and a second partition walls 14a and 14b oppo to each other in the longitudinal direction of the tractor body The second displacement rod 43 is connected rigidly, by its front end, to the rear part of the first displacement rod 42, the connection being pi an arm 45. This second rod 43 carries at its rear end a fork element 44 engaging with the moving gear 37. The construction described above facilitates gear shifting and forward / reverse switching operations when the tractor is running smoothly. umis at frequent repetitions of front and back movements as pa]

  example when working with a mower.

  According to the figures, and more particularly according to FIG. 3, the reference numeral 50 designates a ball stop structure formed in the second partition wall 14b for holding the hand lever 40 in the desired operating position of the switching mechanism before reverse 7, this position corresponding to the step

  forward, in neutral or reverse.

  A third housing element 46 is attached to the first housing element 25 behind the second housing element 27, and a hand lever 47 is mounted on this third housing element 46 so as to be able to oscillate.

  laterally around a vertical axis to make a change

  The hand lever 47 is operatively connected to a displacement rod (not shown) supported by the first housing member 2c so as to slide in the longitudinal direction of the body. tractor. This displacement rod carries a range of

8 2495550

  displacement 48 mounted rigidly thereon and cooperating in operation with a moving gear 49 for transmitting power between the input shaft 13 of the transmission and

  the PTO shaft 4, with two possible speeds.

  According to FIG. 5, which represents a transmission embodiment variant, the main clutch is constituted by a clutch commonly called a "double-type clutch" capable of interrupting power transmission to the PTO shaft 4 in a first embodiment. step, and also interrupt the power transmission to the propulsion system A in a second operating step. In addition, in the forward / reverse gearing mechanism 7, the first to fourth gears 29, 30, 32 and 33 and the inverting gear have gear ratios such as the gears

  rear are greater than the forward speeds.

As described above, the box

  16 in which is housed the switching mechanism

  The forward / reverse direction 7 is removably attached to the first housing 14 in which is housed the main gearshift mechanism 6, and to the second housing 18 in which the auxiliary gearshift mechanism is housed.

  8. This provision has the advantages described below.

  There are cases where the tractor's reverse speeds should preferably be greater than its forward speeds, and there are also reverse cases. The forward / reverse switch mechanism must therefore be equipped with gears with gear ratios suited to the different functions of the tractor. Until now

  it was necessary to change the mechanism of chan-

  the main speed mechanism, the speed change mechanism

  auxiliary and -the forward-reverse switching mechanism to obtain different types of transmission, which

  led to very high manufacturing costs.

  According to the invention, on the contrary, it is not necessary to change the main gearshift mechanism 6, the first housing 14 in which is housed this main gearshift mechanism 6, the auxiliary gearshift mechanism 8 , and the second housing 18 in which is housed this gearshift mechanism

9 2495550

  auxiliary 8; only the switching mechanism works forward -

  Reverse 7 is interchangeable with its different gears transmission gears. We can thus obtain

  different transmissions by simply associating

  various forward-to-reverse mechanisms, to the main gearshift mechanism 6 and the auxiliary gearshift mechanism 8, and to assemble the gearbox 16 with the

first and second casings 14 and 18.

  The transmission according to the invention can also be adapted to tractors having different distances between the engine E and the rear wheels 2. This result is obtained by appropriately choosing the lengths of the spacing box 16 and the shafts of the mechanism of switching forward - reverse 7, so as to adjust

  wheelbase. The invention thus makes it possible to carry out a

  tractor mission in which one can vary the

  transmission ratios of the forward-switch mechanism

  reverse, and that is both simple to ride and good

market to manufacture.

  In the embodiments described here, the connecting structure for operating the forward-reverse switching mechanism is made from simple and compact components and still retains a very flexible and reliable switching operation. More particularly the levers to

  28 and 40, respectively, allowing to maneuver the

  The main gear change mechanism 6 and the forward / reverse switch mechanism 7 are provided on the gearbox above the change mechanism.

main speed 6.

  The first displacement rod 42 engaged with the hand lever 40 to perform the operation of

  switching forward - reverse, is mounted in

  in the transmission box. The second rod of

  43 is disposed below and substantially parallel to the first displacement rod 42, and is slidably supported by a pair of partition walls 14a and 14b opposite to each other in the transmission box. The second displacement rod 43 is connected rigidly, by its front end, to the first displacement rod 42, thanks to the connecting arm 45, and carries at its rear end the fork member 44 intended to engage with the mechanism of

  switching forward - reverse 7.

  Since the main gear change mechanism 6, the forward / reverse switch mechanism 7, and the auxiliary gear shift mechanism 8 are arranged in this order within

  of the gearbox, switching forward -

  reversing is done in low speed conditions performed by the main gearshift mechanism, and therefore softer and more flexible than if the forward-reverse switch mechanism 7 was placed behind the change mechanism 6. In addition, since the forward-reverse switch lever 40, and the main shift lever 28, are provided above the main gearshift mechanism 6, the operator can

  seize or release alternately very easily and very fast-

  one or the other of the hand levers 28 and 40 when performing a mowing operation or the like necessitating frequent and repeated maneuvers of the main gear change and the forward-to-march switching mechanism.

back.

  According to the invention, the forward-reverse switching mechanism 7 is placed in front of the auxiliary shift mechanism 8, as described above. The advantage of this arrangement, compared to the opposite arrangement lies in the fact that the hand lever 40 and the switching mechanism forward-reverse 7, are separated by a short distance, which

  helps simplify the linking mechanism between the two.

  In addition, the hand lever 40 and the forward-reversing switching mechanism 7 are connected by the first

  displacement rod 43 being placed below and carrying the ele-

  fork member 44, and the connecting arm 45 being mounted between the two displacement rods 42 and 43; that is to say in other words that the fork element 44 is connected, by a

  continuous single rod, at the forward switch lever -

  reverse 40 placed above the change mechanism

main speed 6.

  As a result, it is not necessary to modify the construction of the gearbox or to give it a curved shape. In addition, since the second displacement rod 43 passes through the opposite dividing partitions 14a and 14b inside the transmission box, in order to rest securely on these partitions, this second displacement rod 43 may be constituted by a piece thin and the connecting arm 45 does not need to be very strong, so that these connecting elements 42, 43 and 45 can be realized

in simple and compact form.

In the embodiments

  above, the switching mechanism forwards - backwards

  of gear type is realized in compact form thanks to.

  a rational arrangement of the gears. More specifically, the clutch mechanism 38 is placed between the input shaft 15 of the forward gearswitching mechanism 7, intended to receive the power of the main gearshift mechanism 6, and the output shaft 17 of the switching mechanism 7 for powering the auxiliary gearshift mechanism 8. This clutch mechanism 38 can be switched between a position directly coupling the input shaft 15 to the shaft 17, and a position connecting in operation the two shafts 15 and 17

  through the inverting gear 38.

  The input shaft 15 supports the first and second gears 29 and 30 on either side of the partition wall 16a supporting the input shaft 15; the first gear 29 rotates integrally with the input shaft 15 and the second gear 30 is rotatable relative to the drive shaft 15. The partition wall 16a further supports the intermediate shaft 31 parallel to the shaft input 15, this intermediate shaft 31 supporting the third and fourth gears 32 and 33 on either side of the partition 16a, and these two gears rotating integrally with the intermediate shaft 31 The third gear 32 is engaged with the first gear 29, and the fourth gear 33 is engaged with the second gear 29

  gear 30 through the inverter gear 34.

  In the construceicr, described above, the gears-type front-to-back switching mechanism 7, the pair of the first and second gears 29 and 307 and the pair of the third and fourth gears 32 and 33, respectively mounted on the input shaft 15 and on the intermediate shaft 31 (as necessary to reverse the drive transmission state), are separated on either side of the partition 16, as described above. Thanks to this arrangement, the reaction forces acting on these

  gears during power transmission, constant forces

  For example, the bending resistance forces acting respectively on the input shaft 13 and the intermediate shaft 31 are directed in directions allowing them to cancel each other. As a result, the input shaft 15 and the intermediate shaft 31 can each be constituted by a thin piece of relatively low strength, and the input shaft can protrude only slightly outside the bulkhead. separation 16a. These different features together contribute to a compact construction of the forward-step switching mechanism

rear gear type 7.

  For a better understanding of the advantages of the above construction, it may for example be compared to that shown in FIG. 6. The input shaft 15 here bears, on a portion projecting from the partition wall 16a, a first gear 29 rotating integrally with the input shaft 15 and a second gear rotatable relative to the input shaft 15, while the output shaft 17 carries a clutch member 51 axially slidable and rotatable integrally with the output shaft 17, while on the input shaft 15. This clutch member 51 can slide to switch between a position engaged with a toothed portion 52 of the input shaft 15 , (driving the tractor forward), and a position engaged with a toothed portion 53 integral with the second gear 30, (driving the tractor-in reverse). In this example the input shaft 13 must have a greater part of its projecting length

  out of the partition wall 16a that in the case of ltinven-

  because this protruding part must carry the first and the second gears 29 and 30 to the fdis.

  reaction forces acting on the first to fourth engi-

  Nines 29, 30, 32 and 32 during the power transmission all have the consequence of bending the input shaft 15 and the intermediate shaft 31 away from each other. To resist these bending forces, the type of construction of

  this example requires that the input shaft 15 and the input shaft

  31 are large and rigid.

  FIG. 7 shows another possible construction in which, in order to mount the first and second gears 29 and 30 on the input shaft, to reduce the length of the portion of the input shaft projecting out of the partition wall 16a, only the first gear 29 is mounted on the input shaft 15 so as to rotate integrally therewith, and the second gear 30 is mounted on the output shaft 17 so as to

turn relative to this one.

  However, the reaction forces acting on the first and second gears 29 and 30 give rise to forces tending to bend the corresponding ends of the input and output shafts 15 and 17 away from the intermediate shaft 31. This causes a movement between the clutch member 51 and the toothed portion 54 of the input shaft 15; this displacement adversely affects the flexibility of the forward and reverse switching, so

  is still necessary that the input shaft 15 and the

  31 are large and solid.

  The embodiments of the invention

  tion described above make it possible to solve this problem of

rational way.

  Moreover, since the mechanism

  main gearshift 6, the switching mechanism

  forward-reverse gear type 7, and the auxiliary gearshift mechanism 8 are mounted in this order inside the gearbox, the forward-reverse gear is smoothly operated under the conditions of low speed obtained thanks to the mechanic

main gearshift.

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  By arranging the switching mechanism

  forward-reverse 7 closer to the main gearshift mechanism 6 than the auxiliary gearshift mechanism 8, the forward-reverse gear mechanism can now be placed closer to the shift lever reverse forward movement 40 which is generally located in the vicinity of the operating device of the main gearshift mechanism 6, because the forward-to-reverse commutation is often done

  at the same time as the main gearshift operation

  blade. The shortening of the distance between the forward-reverse switching mechanism 7 and the corresponding lever 40 has the advantage of simplifying the mechanism.

link between the two.

Claims (4)

  1.- Tractor transmission comprena: a main gearshift mechanism (6), an auxiliary gearshift mechanism (8j, and a gear-type forward-reverse gear mechanism (7) for transmitting the power between a motor (E) and a propulsion system (A), transmission characterized in that the main gearshift mechanism (6), the gear-type forward-reverse gear mechanism (7), and the auxiliary gearshift mechanism (8) are mounted in this order inside a gearbox, moving from the front to the rear of the tractor.   2.- Transmission according to the claim   1, characterized in that it comprises a first casing (14) in which is housed the main quick change mechanism (6), a second casing (18) in which is housed the auxiliary gear change mechanism (8). ), and a drink '   spacer (16) removably attached to the first and   second housings (14, 18) and in which is housed the gear - type forward - reverse gearing mechanism 7. 3.Transmission according to any one   Claims 1 and 2, characterized in that it comprises   a hand lever (28) for operating the main gearshift mechanism (6), a hand lever (40)   for operating the forward motion mechanism -   a gear-type reverse gear (7), these two hand levers (28, 40) being mounted on the gearbox, a first displacement rod (42) slidable under the actio3 of the hand lever (40) for operate the switching mechanism: gear-type forward-reverse gear (7), a   second displacement rod (43) disposed substantially parallel   parallel to the first displacement rod (42.) and passing through a pair of opposed parallel partition walls (14a, 14b) mounted in the transmission box, these partitions slidably supporting the second rod (43), a pitch linkage (45) rigidly connecting one end of the second displacement rod (42), and a fork member (44) attached to the other end of the. second displacement rod (43 2495550   in order to maneuver the forward-switch mechanism   reverse gear type (7).   4.- Transmission according to any one   Claims 1 to 3, characterized in that the mechanism   forward-reverse gearswitch (7) includes an input shaft (15) for transmitting power between the main gearshift mechanism (6) and the forward-reverse gear mechanism of gear type (7), an output shaft (17) for transmitting power between the mechanism (7) and the mechanism   an auxiliary gear change mechanism (8), a gearing mechanism   yage (38) for switching between a direct connection position between the input shaft (15) and the output shaft (17) and a position operatively connecting the input shaft (15). ) to the output shaft (17) via an inverting gear (34), the input shaft (15) carrying, for the operating connection with the inverting gear (34), a first gear (29) and a second gear (30) arranged on either side of a partition wall (16a) supporting the input shaft (15), the first gear (29) being attached to the input shaft (15), the second gear (30) freely rotatable on the input shaft (15), and a transmission shaft (31) supported by the partition (16a) parallel to the shaft input shaft (15), this transmission shaft (31) carrying a third gear (32) and a fourth gear (33) arranged on either side of the partition (16a) and rotating in unison, the third gear (32) being engaged with the first gear (29), and the fourth gear (33) being engaged with the second gear (30) through the gear inverter (34).