FR2487741A1 - IMPROVED TRANSFER BOX FOR VEHICLE WITH MULTIPLE DRIVE MODES - Google Patents

Abstract

THIS TRANSFER BOX 10 IS OF THE TYPE WHICH INCLUDES AN INPUT SHAFT 14 AND SPEED CHANGE MEANS 44 ALLOWING TO CHOOSE BETWEEN A LOW SPEED OPERATION MODE AND A HIGH SPEED OPERATION MODE. THE INPUT SHAFT DRIVES AN INTERMEDIATE SHAFT 16 WHICH IN TURN DRIVES A REAR OUTPUT SHAFT 18. A FRONT OUTPUT SHAFT 20 IS COAXIALLY ALIGNED WITH THE REAR OUTPUT SHAFT AND AT ITS REAR END 80 SHAPED IN ONE SLEEVE ROTATED ON THE FRONT END 82 OF THE REAR OUTPUT SHAFT, WHICH SUPPORTS IT. A CLUTCH 86 A CRABOT IS MOUNTED AXIALLY SLIDING ON THE REAR OUTPUT SHAFT, WHICH IT IS SOLIDARITY IN ROTATION, TO BE ABLE TO SELECTIVELY COUPLING TO PART OF THE REAR END OF THE FRONT OUTPUT SHAFT OR DISCONNECT FROM THIS PART.

Description

The present invention relates to a trans-

  fert perfected and more particularly to such a bot-

  transfer te which comprises a rear output shaft and a coaxially aligned front output shaft, and means for selectively coupling the output shafts, means which are arranged inside the casing of the boot

  transfer to ensure operation and lubrication

tion improved.

  There are a number of multi-drive vehicles that use a gear boot

  main and a transfer boot which is capable of providing

  drive power to the rear axle alone or simultaneously-

  ment to the rear and front axles. Transfer boots

  characteristics of this type have been described in the short-

  vets from USA no 3,095,758, no 3,557,634 and no 3,679,016.

  It is not uncommon to provide in the boots of trans-

  fert means capable of fulfilling a function of transmission-

  energy with multiple speed ratios, in the form of high and low speed operation. Transfer boots such as those described in the patents of

  EUA No. 3,941,199 and No. 4,188,838 contain such charac-

  and significantly increase relationships

  of selective operating speeds that are available to

  tion of the driver of a vehicle using a life boot

  main braids in combination with the transfer boot.

  However, when studying and performing bot-

  you are always concerned with this type of transfer

  that the model can be easily assembled, that

  no unnecessary element which would increase the total weight be

  included and the elements can be properly read

  burnished to ensure efficient and reliable operation

of the transfer boot.

  Therefore, one of the objects of the present invention

  is to create an improved transfer case which

  carries features that remove the inu-

  tiles to facilitate assembly and reduce

  of the total weight of the transfer case.

  Another object of the present invention is to achieve

  a transfer boot in which the important elements

  critical tance are arranged inside the housing of a

  that facilitates lubrication during operation

transfer box.

  These goals, as well as other goals of the present in-

  vention are achieved in a preferred embodiment of the invention by means of a transfer box of the type which is capable of receiving input energy from a torque transmitting energy source and of supplying energy

  output to a rear axle configuration and to a con-

  front axle figuration. This type of transfer boot includes

  carries a housing and an input shaft rotatably mounted internally

  crankcase and coupled to the power source. A pi-

  gnon of low speed and a pinion of high speed are mounted so as to be able to rotate independently around the input shaft, and means for selectively coupling one of the pinions of low speed and high speed to the shaft d input so that it rotates with it and to decouple it from the input shaft are also included. A

  intermediate shaft is mounted parallel to the drive shaft

  trée, with rotation inside the casing, and a pinion inter-

  medium speed and an intermediate gear of

  high speed are attached to this intermediate shaft. The PI-

  low speed intermediate gear and the intermediate gear

  diary of high speed are constantly in alignment and meshed respectively with the pinion of low speed and with the pinion of high speed to cause the rotation of the intermediate shaft in response to the rotation of one

  either of the gears of low speed and high speed-

  se. The improvement brought to the transfer boot

  sist in a rear output shaft which is mounted, parallel-

  to the input shaft and to the intermediate shaft, rotating

  tion inside the housing and on which a pin is fixed

  output pin constantly in alignment and meshed with the high speed intermediate gear. The output tree

  rear has a rear end which extends out-

  of the casing to be coupled to the rear axle configuration, and a first support bearing is fixed to a rear wall of the casing between this rear end and the output pinion. The rear output shaft has a front end located inside the housing, and a second support bearing is fixed to an interior partition

  of the casing between this front end and the output pinion.

  A front output shaft is aligned coaxially with the rear

  rear outlet bre and is rotatably mounted in a re-

  intermediate region of its length by means of a bearing

  carried at a front wall of the housing. The sort tree

  front tie has a front end that extends out of the

  casing to be coupled to the front axle configuration.

  The front output shaft has a rear end which is shaped

  mée in a sleeve mounted around the front end of the ar-

  rear exit bre, so as to be carried by the latter

  while being able to rotate relative to the rear output shaft. The box also includes coupling means mounted axially sliding on the rear output shaft so as to rotate with it and to be able to be

  selectively mated with part of the ar-

  of the front output shaft or uncoupled from this part. Other characteristics and advantages of the invention

  will emerge from the description which follows given as

  non-limiting example and with reference to the appended drawings, in which: FIG. 1 is a front view in elevation of the preferred transfer boot which includes various features of the invention; - Fig. 2 is a rear elevation view of the

  preferred transfer boot with various features

the invention;

  - Fig. 3 is a view taken in section along the line

  gene 3-3 of FIG. 1; - Fig. 4 is a sectional view taken along line 4-4 of FIG. 1;

  - Fig. 5 is a view taken in section along the line

gene 5-5 of FIG. 1.

  As can be seen in Figs. 1, 2 and 3, the preferred transfer case 10 has various characteristics of the invention and is of the type which is intended to be used

  in a 6x6 type road vehicle. Essentially, the e-

  energy output from a conventional vehicle transmission

  road cule is supplied to the transfer boot 10, which

  the in turn includes a gear train to allow

  selectively operate at high speed or at

  low speed in order to usefully double the number of reports

  speed ports that can be obtained with the boot of

  classic vehicle speeds. In addition, the trans-

  preferred fert 10 includes means for providing selective-

  output energy only at a rear axle configuration or to split the output energy between

  a rear axle configuration and an axle configuration

front god.

  The basic active elements of the trans-

  fert 10 are enclosed as a whole inside a

  casing 12, and they comprise an input shaft 14, a rear

  intermediate bre 16, a rear output shaft 18 and a front output shaft 20. An input coupling member

  22 is rigidly fixed to the input shaft 14 and receives di-

  the power output from the gearbox (not

  shown) of the vehicle. The input shaft 14 is mounted at ro-

  tation in a front bearing 24 and in an rear bearing

  rière 26. A low speed pinion 28 has a plain bearing 30 and is mounted for rotation around the input shaft 14. The spacing washers 32 and 34 arranged on either side of the low speed pinion 28 maintain the pinion 20 in an axial position adjacent to the bearing 24. In a similar manner, a high speed pinion 36 has a plain bearing 38 so as to be able to rotate around the other end of the input shaft 14. Des spacers 40, 42 are also used to hold the high speed pinion 36 adjacent to the bearing 26 of

the input tree.

  A speed change mechanism 44 is used to couple the input shaft 14 either to the low speed pinion 28 or to the high speed pinion 36, of the

  desired way. The mechanism will be described in detail below.

  me 44 shift but at this point we can in-

  indicate that it essentially comprises an annular clutch collar 46 provided with an internal toothing which is slidably mounted on corresponding elongated teeth 48 of a

  part 50 of larger diameter of the input shaft 14 if-

  killed between the pinion 28 of low speed and the pinion 36 of high speed. To couple the clutch collar 46 and, therefore, the input shaft 14 to the pinion 28 of small

  speed, the clutch collar 46 must be moved axially-

  forward towards the pinion 28 of small speed-

  se. A series of teeth 52 extending outwards, form-

  mées on the front end of the clutch collar 46, must

  wind be aligned with a series of teeth 54 extending inwardly formed on a cylindrical projection 56 extending rearward of the pinion 28 of low speed

  and mesh with those teeth. Similarly, for delivery

  bend the clutch collar 46 and, as a result, the drive shaft

  trée 14 to pinion 36 of high speed, the clutch collar

  yage 46 must be moved axially in the direction of the pinion 36 of high speed. In this case also, a series of teeth 58 extending outwards, formed on the rear side of the clutch collar 46, must be aligned.

  with a series of teeth 60 extending inwards for-

  més on a cylindrical projection 62 extending towards the a-

  from the high speed pinion 36 and mesh with these

  teeth. Although the shift mechanism 44 can-

  occupy a neutral position in which neither the pinion 28

  of low speed nor the pinion of high speed is ef-

  effectively coupled to the input shaft 14, it can be seen that the clutch collar 46 of the gear change mechanism 44 is designed to ensure that only one of the pinions 28, 36 can be coupled to the input shaft. entry 14 at any given time. The intermediate shaft 16 is used to transmit the driving energy either of the pinion 28 of low speed, or

  from the high speed pinion 36 to the rear output shaft 18.

  The intermediate shaft 16 is rotatably mounted inside

  of the casing 12 by means of a front bearing 64 and a roller

  rear 66. An intermediate pinion 68 of small speed-

  is rigidly attached to the intermediate shaft 16, at the end

  mite before the latter, so as to be arranged in line-

  ment with the pinion 28 of low speed and constantly in meshing contact with it. In the same way, a pinion

  high speed intermediate 70 is rigidly attached to the rear

  intermediate bre 16, at the rear end of the latter,

  in alignment with the pinion 36 of high speed and constam-

  lie in meshing contact with him. Although the pinions 28, 68 and the pinions 36, 70 remain respectively engaged

  throughout the operating life of the trans boot

  fert 10, we can see that there is only one of the two pinions 28, 36 which is directly coupled to the input shaft 14 to transmit the force applied to the intermediate shaft

16 in order to cause its rotation.

  The rear output shaft 18 is rotatably mounted inside the casing 12 by means of a front bearing 72 which is carried by an internal partition 73 of the casing 12, and

  by means of a rear bearing 74 mounted at the level of the

2487? 4 I

  rear king 104 of the housing 12. An output pinion 76 is ri-

  rigidly fixed to the output shaft 18 between the bearings 72, 74 so as to be aligned with the intermediate pinion

  high speed of the intermediate shaft 16 and constam-

  lie in meshing contact with him. Therefore, a

  rotation is communicated to the output shaft 18 via the

  median of the intermediate shaft 16 whatever that of the pinions 28, 36 of the input shaft 14 which is actually used. Whenever one of the input gears 28, 36

  is coupled to the input shaft 14 via the mete

  gear change gear 44, the other input pinion 36, 28 can rotate independently with respect to the input shaft 14 while being driven in a condition of absence of

  load by its respective intermediate pinion 70, 68 of the rear

intermediate bre 16.

  As can be seen in Fig. 3, the output shaft

  front 20 is aligned coaxially with the rear output shaft

  18 but is not truly integral in rotation with the rear output shaft 18. The shaft 20 is mounted, in a region located in the middle of its length, in a bearing

  78 mounted in the front wall 94 of the casing 12, and it is

  formed into a sleeve at its rear end 80 so as to surround

  rer without play an end portion 82 extending towards the front of the rear output shaft and to rotate around it. The sleeve 80 has teeth or claws 84 extending rearward which are adapted to engage with teeth or conjugated claws 85 of a clutch 86 with dog clutch

  when the motive energy must be transmitted to the two ar-

  outlet belts 18, 20. The clutch 86 with a dog clutch has an internally grooved hole 88 which is slidably mounted on

  a region 89 provided with axially aligned grooves of the ar-

  rear output bre 18. As a result, a coupling between the output shaft 18 and the output shaft 20 can be

  effected by a selective displacement of the clutch 86 to cra-

  bot axially forward to cause the arrival of the grif-

248774 1-

  fes 85 in engagement with the claws 84 of the output shaft

before 20.

  As explained above, the output shafts 18 and 20 and the means which serve to couple them are well arranged inside the casing 12. In a con-

  figuration of the prior art, the output shaft ar-

  rière is much longer and extends far in front of the low speed intermediate gear. Therefore, a

  protruding housing part must be added to the main housing

  cipal to contain the front output shaft and the means

  coupling. Furthermore, in this configuration of tech-

  anterior picnic, the front output shaft is fitted with a

  rear extending end tie which is received in a front end formed as a sleeve of the output shaft

  back. As a result, a clutch with teeth extends

  backward is axially sliding on the former

  rear end of the front output shaft. Part of ex-

  radially extending end must be rigidly mounted

  on the front end of the rear output shaft for

  ter the dog teeth, which complicates assembly and

mounting.

  As explained above, the transfer boot pre-

  fairy 10, when mounted on a vehicle, allows selective high speed and low speed operation of the rear output shaft 18, which is coupled by means of a coupling member 90 to a drive shaft of the rear axle configuration (not shown), or of the rear output shaft 18 and of the front output shaft, which is coupled by means of a coupling member 91 to a drive axle of the front axle configuration (not shown). However, other characteristics of the transfer boot should also be described.

  preferred 10 which are necessary to ensure its functioning

  correct before describing in detail the means used to choose high speed operation or

248774 1

  low speed operation and the means used

  for coupling and uncoupling the output shaft before 20.

  The basic lubrication of the transfer boot is provided by a reserve of lubricating oil contained in a tarpaulin 92 of oil formed in the lower part

  from the crankcase 12. The oil is generally transmitted to the ele-

  active elements and to the bearings and support bearings mentioned above by means of spray lubrication. An oil filling orifice 93 formed in the front wall 94 is used to introduce lubricating oil to a predetermined level before the transfer boot 10 is put into service. A drainage orifice 96 is provided for allow oil to be drained from the oil tank 92 when desired. Oil retention seals 97 are used in combination with each of bearings 24, 78 and

  74 mounted at the walls of the casing 12, these seals

  turning the shafts to retain all of the oil in the bearing region. Bearings 26, 64, 66 and 72

  are actually located inside the housing and therefore

  quent, they do not require the use of retaining seals

  of this type of oil to function properly.

  We can now see that the position of the ar-

  rear output bre 18, front output shaft 20 and clutch 16 are preferable to the prior art configuration mentioned above. Claws 84

  extending backwards, the clutch 86 and the clutch

  splined gion 89 of the rear output shaft 18 are available

  located in a median location inside the casing 12,

  in the vicinity of the oil tank 92. In addition, they are dis-

  placed between the intermediate pinion 68 of low speed and the intermediate pinion 70 of high speed to easily receive the oil projected by the pinions 68, 70 when the latter rotate during the operation of the boot

  transfer. The claws 84 collect oil for

  supply reserve vir for the end part 82 extending towards the front of the rear output shaft 18 and for the rear end part 80 of the front output shaft 20 which is sleeved thereon . The configuration of the prior art does not provide such lubrication since these elements are located in the part of

  protruding sump away from the oil cover and the

  oil splits made by intermediate gears

  low speed and high speed. Efforts made

  killed for lubrication by means of passageways

  in the rear output shaft to its end a-

  were not as effective as the pre-

fairy of the present invention.

  Due to the positioning of the input shaft 14 in the upper region of the casing 12 and due to the movements

  which may exist during normal operation

  poorly between the low speed pinion 28, the gear change mechanism 44, the high speed pinion 36 and the input shaft 14, additional means for lubricating

  these items are supplied in the preferred transfer boot

  ree 10 by an oil pump 98 mounted at the rear end

  of the input shaft 14. The lubrication pump 98 as-

  worse oil in a supply line 102 which

  stretches along a rear wall 104 of the trans-

  fert 10 to receive oil from oil tarpaulin 92

  through a filter mounted in a fitting 106 fixed in the part

  bottom of the housing. A description will be given below

  detailed description of the structure and operation of the oil pump 98. A speedometer 108 is also mounted

  in the rear wall 104, this counter being of the type with

  blasting with worm gear and directly measuring the speed of the intermediate shaft 16. A parking brake 110 (shown in broken lines in FIGS. 2 and 3) is associated with the coupling member 90 of the shaft rear outlet 18 and is operated in a manner well known in the art

prior art.

248774 1

  As can be seen in Fig. 4, the mechanism 44

  gear change is basically operated

  how to cause high speed or low speed operation

  speed according to the axial positioning of a connecting rod

  gear change rod or rod 112. A linkage (not shown) is connected to the front end 114 of the

  gear shift rod 112, which is essential-

  designed to be able to be positioned in any one

  only three positions with respect to the housing 12. As we

  will explain in detail below, three circumferential grooves

  116 are formed in the rear end of the rod

  speed change wheel 112 so that it can cooperate

  rer with a ball and spring device of the prior art. However, at this point, it is enough to understand

  that the gear shift rod 12 can be selected

  tively moved between these three positions in the boot

  preferred transfer 10 when switching to high speed-

  get on or off at high speed or at low speed or

  out of the low speed is suitable and is desired. In the po-

  sition shown in Fig.4, the mechanism 44 of change-

  speed is in the neutral position, in which neither

* the low speed pinion 28 nor the high speed pinion 36-

  tesse is coupled to the input shaft 14. The collar of em-

  clutch 46 is disposed in the center of the elongated teeth 50 of the input shaft 14. The position of the clutch collar 46

  is determined by the position of a fork 118, which

  the is determined, in turn, by the position of the biellet-

  shift 112 te, at which the fork

  is rigidly fixed by a locking member 120. The four-

  chette 118 has an internal groove 122 which surrounds par-

  the cylindrical outer periphery 124 of the neck

clutch link 46.

  However, for the mechanism 44 to change

  speed works properly to choose the work

  high speed or low speed operation,

248774 1

  12- it is not enough to simply provide linkages and gears making it possible to correctly couple the elements in a way which ensures the transmission of the torque. It is also essential to ensure that the elements to be coupled rotate at the same relative speed so that the corresponding gears mesh. This is achieved in the preferred transfer boot 10 by providing

  the clutch collar 46 of a synchronizer 126. The syn-

  chronograph 126 has a pair of synchronization rings

  tion 128, 130 which are respectively associated with the protuberance

  cylindrical rancid 56 extending towards the rear of the pinion 28

  at low speed and at the cylindrical projection 62 extends

  dant forward of the pinion 36 of high speed. The Rings

  are made of brass and are axial-

  separate, but they are joined together in

  the preferred synchronizer by six rods or pins 132

  regularly spaced between them. Six holes

  134 regularly spaced formed around the clutch collar-

  ge 46 are adapted to receive pins 132, which

  cross, so that during the operation of the syn-

  chroniser 126 and clutch collar 46, the whole turn-

  not in its entirety with the input shaft 14. Therefore, as explained above, when the clutch collar 46

  is moved axially to ensure selected operation

  tif desired at low or high speed, the clutch collar

  yage 46 must slide axially along each pin

132.

  However, the clutch collar 46 is not free to slide without hindrance relative to the pins 136 of the

  made of two characteristics which are incorporated in the syn-

  chroniser 126. The first characteristic consists in the use of plunger and spring assemblies 137, one of which is disposed inside the clutch collar 46 at the level of

  each of the holes 134 which pass through it. The diver is con-

  received to be received in a judgment 138 which is formed in the

  inner surface of each pin 132 in a place

  axially central to the latter. Therefore,

  each plunger and spring assembly 137 is received internally

  laughing at the corresponding stop 138 when the em-

  clutch 46 is in the neutral position, as shown

  shown in Fig. 4, so that this relative axial position

  ve is maintained until a positive force is exerted

  created by fork 128 to modify the position of the neck

  clutch link 46. Second, each pin 132 is

  provided with a circumferential groove 140 formed in its part

  central tie, so that each hole 134 of the collar of em-

  clutch 46 is positioned inside the circumferential groove

  ferential 140 when the clutch collar 46 is in

  the neutral position. The circumferential groove 140 is mutually

  denies, at each of its ends, an inclined surface 142

  which ends at its junction with a cylindrical surface ex-

  144 formed at each end of the pin 132.

  Therefore, while the interior dimensions of each

  that hole 134 of the clutch collar 46 allow the hole to

  receive the cylindrical surface 144, when the em collar

  clutch 46 is in the neutral position, the hole 134 must be correctly aligned with the groove 140 before the cylindrical surface 144 can be received there. In other words, if the hole 134 is not properly aligned with the cylindrical surface 144, the appropriate inclined surface 142 acts on the edge of the hole 134 (when sufficient axial force is applied to the clutch collar 46) to rotate the clutch collar 46 relative to the pins 132 until

  that correct alignment is performed.

  During operation in the neutral position,

  as shown in Fig. 4, each synchro ring

  nization 128, 130, can rotate freely in relation to the

  respective cylindrical protuberance 56, 62. However, each

  synchronization ring 128, 130 is provided with a sur-

  tapered inner face 146 which is adapted to enter 2487741t

  in sliding contact with a corresponding frustoconical surface

  dante 148 formed on its respective cylindrical protuberance 56, 62. Consequently, the surfaces 146, 148 are capable

  to establish a sliding contact, but the application of a

  this axial to the synchronization ring 128, 130 increases the friction contact between the surfaces 146, 148 until

  that the synchronization ring 128, 130 rotates at the same speed

  relative size than its respective cylindrical protuberance

56, 62.

  To allow a full understanding of how

  44 gear change mechanism and collar

  clutch 46, as explained above, it may be pre-

  fable to give an example of a characteristic shift operation. It is assumed that the gear change mechanism 44 is in the position corresponding to low speed operation, the clutch collar 46 being positioned axially forward so that the teeth 52, 54 are engaged, the shaft d entry 14, the collar

  clutch 46, synchronizer 126 and pinion 28 of pe-

  tite speed turning all at the same speed. It is further assumed that the suitable operating conditions for the motor and the speed boot are fulfilled so that the transfer boot 10 can be placed in the mode

  high speed operation. We then activate the trin-

  associated glazing for axially displacing the speed change rod 112 towards the rear. Although we planned

  to describe them below, it is preferable at this stage to

  glige all the restraining forces which can act on the

  grooves 116 of the speed loading link 112.

  Consequently, the link 112 moves axially towards the rear to cause the action of the fork 118 on the clutch collar 46 so as to disengage the teeth 52, 54, when the clutch collar 46 slides along

  rods or pins 132. When the neutral position is reached

  color, each of the plunger and spring assemblies 137 is

  engaged in the stop 138 of the rod or pin 132 corresponding

  dante to center the clutch collar on these rods in

  a position such as it is inside the ra-

  circumference 140 of each rod 132.

  When an effort is made to switch to

  high speed operation, uninterrupted force exerted

  created in a direction oriented axially rearwards a

  so that the fork 118 acts on the clamp

  clutch 46. However, the clutch collar 46 cannot move freely backwards, since it is

  now positioned inside the circumferential groove

  140 of each pin or rod 132, without entering

  interaction contact with the inclined surface 142. The con

  tact of interaction with the inclined surface 142 has the effect

  that the clutch collar 46 applies an axially directed force

  Lement backward to the synchronizer 126 to bring the surfaces 146, 148 of the synchronization ring 130 and the cylindrical protrusion 62 into increased sliding contact. If, as can be expected, the high speed pinion 36

  rotates at a relatively lower speed than those.

  previously mentioned, the contact between the surfaces

  these 146, 148 apply a braking force to the synchronizer 126. However, since the clutch collar 46 is directly coupled to the input shaft 14, there is an uninterrupted contact between the clutch collar 46 and the sloping surfaces 142 which prevent proper alignment

  holes 134 of the clutch collar 46 with the cy-

  lindric 144 of each of the pins 132. This contact

  teraction between the clutch collar 46 and the surface

  cline 142 continues until the relative speed of

  the synchronization ring 130 and the cylinder protrusion

  drique 62 (and thus pinion 36 of high speed) are almost identical. As a result, the input shaft 14 is made to rotate at the same speed as the pinion 36 of

  great speed. Once the input shaft 14 and the pi-

  gnon 36 of high speed rotate at the same speed, the

  following the application of a force by fork 118 to

  clutch collar 46 has the effect that the clutch collar

  ge comes into sliding contact with the inclined surface 142, which has the effect of aligning it with the cylindrical surface 144 situated at the rear end of the pin 132. Once this alignment is obtained, the clutch collar 46 can move axially backwards and the teeth 58, 60,

  are properly aligned to mesh.

  It will be clear that a similar operation is carried out if it appears desirable to switch from the high speed operating mode to the low speed operating mode, since the synchronizer 126 again ensures that the speeds are correctly matched and

  that the sprockets can be properly aligned to

  grener. It will also be clear that the mechanism

  44 shifting works in a similar way

  ble even if the clutch collar 46 is initially available

  in the neutral position and you want to switch to either high speed or

low speed.

  As mentioned above, the grooves 116 have also

  Lely been used in the prior art to also create forces which act on the shift rod 112 to help fix its position at

  during the gear change. A position configuration-

  using a spring ball was used for this

  fine in technique and generally served to

  blir a "preferred" axial positioning of the link rod

  during a gear change operation. In the preferred transfer boot 10, a locking device 146 fulfills this function and has other characteristics which are advantageous for correct operation of the

transfer box.

  The preferred locking device 146 includes means for preventing a selective axial position change of the speed change link 112 from one position to another if there is any possibility that a torque could impede the operation of gear change is transmitted to the transfer box. The locking device 146 comprises a jack, the cylinder 148 of which is mounted on the casing 12 in general alignment with the

  part of the gear change rod 112 which comprises

  carries the circumferential grooves 116. Inside the cylinder 148 of the jack is disposed a piston 150 and a rod

  piston 152 which ends with a device 154 for posi-

  operation of the link which replaces the ball of the confi-

  guration of classic positioning with spring ball. At

  during normal operation, a spring 156 mounted inside the

  inside the cylinder 148 of the cylinder is compressed between the

  ton 150 and the inner end wall 158 of the cylinder to apply a biasing force to the device 154

  positioning. Therefore, the device 154 is sol-

  licit in the direction of the outer surface of the speed change rod 112 to oppose the selective axial displacement of the speed change rod 112 from one circumferential groove 116 to another during normal operation. In the preferred locking device 146, a normal selection operation can only occur if the vehicle's main gearbox is placed in the neutral position, so that it cannot

  be transmitted from the vehicle engine torque via the

  gearbox to transfer boot 10

  during the gear change operation.

  Thus, the preferred locking device 146 uses

  reads a compressed air supply connected to an inlet 160 to apply a force to the piston 150 each

  once the vehicle's gearbox is in a position

  tion other than the neutral position. When the vehicle is

  in an engine mode, the compressed air has the expected effect of

  apply sufficient force to the piston 150, to the rod 152

  and to the positioning device 154 so that this arrangement

  tif 154 is firmly retained in the circumferential groove

  116. Any effort made to change the ratio of the transfer boot 10 during this engine mode thus meets the resistance produced by the insertion of the

  device 154 in the groove 116, so that a rest

  axial actuation of the speed change rod 112

  prevented himself. Consequently, during normal operation, the speed change rod 112 can be positioned in any axial location chosen against the resistance produced by the biasing force of the spring 156, and it is generally , detention

  in the selected position when the device 154 posi-

  fully engaged in the circumferential groove

  ferential 116 appropriate. However, once the motive energy is again applied to the input shaft 14 of the

  transfer boot 10 when the gear boot is action-

  Born out of neutral mode, this condition is detected in the vehicle control system in a manner well known in the prior art, and a control signal is transmitted so that compressed air is supplied to the port. entry 160 so as to prevent any further change from

  axial position of the speed change rod.

  Once the gearbox has been returned to neutral mode, the control system detects this condition and

  suppresses the sending of pressurized air to cylinder 1.46 to

  put the transfer boot 10 to be put back in a con-

  edition which allows a gear change operation

normal.

  As mentioned above, the arrangement of the input shaft 14 in the upper region of the casing 12 and the

  relative movements which exist between the pinion 28 of small

  speed, gear 44, speed change

  gnon 36 of high speed and the input shaft 14 make

  It is desirable that additional means of lubrication be provided by the oil pump 98. The oil pump 98 can be a conventional lubrication pump either of the vane type or the gear type, but a gear type pump has been specifically used in the operating mode.

  realization of the preferred transfer boot 10. As re-

  presented in Fig. 3, the pump 98 comprises a drive shaft

  drag 162 which has a fluted extension 164 direct

  towards the input shaft 14. The input shaft 14 has an axial bore 164, and it has at its rear end an internally fluted region 166. A hollow plug 168 through which a central bore extends axially is adapted to be rigidly received inside the internally fluted region 166. The plug 168 has in the surface of its end a slot which receives the fluted extension 164 for coupling the input shaft 14 and the shaft drive 162 of pump 98. Consequently, the pump

  98 is made to operate during any ro-

  tation of the shaft 14 and is thus capable of ensuring the

  the various elements associated with the input shaft 14. During the rotation of the input shaft 14, the pump

  98 oil sucks in the supply line 102 the oil

  the lubrication and the pressurized pressure at an orifice

  170. The outlet 170 communicates with the

  térieur of a projecting part 172 of the casing 12 which surrounds the rear end 100 of the input shaft 14. The interior of the projecting part 172 has its sealing essentially ensured for lubrication purposes thanks to the presence on

  the rear end 100 of the input shaft 14 of a device

  sealant 174 (more particularly shown in Fig. 4). The sealing device 174 comprises a collar 176 which surrounds the rear part 100 of the input shaft 14,

  to which he is keyed. A ring 178 is firmly attached

  fixed between the bearing 26 and the projecting part 172 so that

  lesson in tightly surrounding the necklace 176. A watertight seal

  180 is mounted on the collar so as to be in con-

  waterproof sliding contact with ring 178 to retain effective

  cement the oil under pressure inside the sail part

  lante 172 by effectively preventing any leakage, however small, around the outside of the input shaft 14 towards the bearing region 26 and towards the inside itself

housing 12.

  Therefore, the oil pressure can rise to

  the inside of the projection 172, and the lubricating oil

  fication is forced to flow through the central hole of the

  hollow plug 168 and in the bore 164 formed in the interior

  input shaft 14. A series of orifices 182 extend

  tend radially from bore 164 and provide lubrication of the various elements associated with the input shaft

  14. Specifically, it can be seen that the lubricating fluid

  tion introduced inside the synchronizer 126 ensures that its correct operation will not be interrupted for lack

  lubrication. Due to the high friction which is

  gendré between surfaces 146 and 148, as described above, several grease grooves 184 extending axially

  are provided for each synchronization ring 128, 130.

  To ensure that the pressure of the lubricating oil does not exceed a desired operating pressure at the various elements associated with the inlet shaft 14, a safety valve 186 communicates with the interior of the

  projection 172 through pipe 188 and is capable of

  drain the oil through a drain 190. If the pressure

  sion exceeds the nominal pressure, oil is evacuated via line 190 into the interior of the casing 12 to effectively maintain the oil pressure inside the part

  protruding at the desired operating level.

  As can be seen in FIG. 5, the transfer control mechanism 200 of the preferred transfer boot 10, comprises a connecting rod or transfer rod 202 which is mounted so as to be able to effect an axial movement inside the casing 12. A fork 204 is rigidly mounted on the transfer link 202, to which it is

  fixed by means of a locking member 206. The end extending

  gée 208 of the fork 204 is received inside a circumferential groove 210 of the clutch 86 with clutch, so that the displacement of the transfer rod 202 produces a corresponding axial displacement of clutch 86 with clutch. In the position shown in Fig. 5, the clutch clutch 86 has been moved to a front position in order to couple the output shaft 18 and the output shaft 20, so that the energy of exit from the boot of

  transfer 10 is supplied to the two output shafts 18, 20.

  The transfer link 202 is moved towards the a-

  vant to achieve the desired coupling by the action of a piston 212 mounted in the cylinder 214 of a cylinder which is

  mounted on the rear wall 104 of the casing 12. Compressed air

  mé is introduced by the inlet port 216 of the cylinder 214

  of the jack to push the piston 212 against the rear end

  218 of the transfer link 202. A spring 220, which is mounted in compressed state around the link 202

  between the front wall 94 of the casing 12 and the fork 204, ap-

  applies a biasing force to the transfer rod 202

  which is directed backwards and which uncouples

  normally the output shafts 18, 20, unless the pis-

  your 212 is activated to move the transfer link

  202 forward in order to couple the shafts. By con-

  sequent, when during the operation of the transfer boot 10, it is desired to decouple the shafts 18, 20, the supply of compressed air to the cylinder 214 is interrupted

  of the jack, so that the spring 220 can move the rod

  rear transfer lens 202.

Claims (8)

R E V E N D I C A T I 0 N S   1 - Advanced transfer boot (10), of the type   which is capable of receiving input energy from a source   this energy transmitting a couple and providing energy   output to a rear axle configuration and to a front axle configuration, and which comprises a casing (12),   an input shaft (14) rotatably mounted inside the car-   ter and coupled to the energy source, a pinion (28) of pe-   a high speed and a high speed pinion (36) mounted so as to be able to rotate independently around the input shaft, means (44) for selectively coupling one of the low speed and high speed pinions to the tree   input so that it turns with it and for the disengagement   of the input shaft, an intermediate shaft (16) mounted, parallel to the input shaft, to rotate inside the casing and on which are fixed an intermediate gear (68) of low speed and a high speed intermediate gear (70), low speed intermediate gear   and the high speed intermediate gear being respec-   constantly in alignment and meshed with the pi-   gnon of low speed and the pinion of high speed for   cause the intermediate shaft to rotate.   re in response to the rotation of that of the small sprockets   speed and high speed which is coupled to the drive shaft   trée, this transfer boot being characterized in that it comprises: a rear output shaft (18) mounted, parallel to the input shaft and the intermediate shaft, to rotate inside the housing, a output pinion (76) fixed on   this output shaft being constantly in alignment and   grained with the intermediate speed gear; the rear output shaft having a rear end   which extends out of the casing to be coupled to the configuration   rear axle ration, a first support bearing (74) being fixed to a rear wall (104) of the casing between said rear end and the output pinion; the rear output shaft having a front end (82) disposed inside the housing, a second support bearing (72) being fixed to an interior partition (73) of the housing between said front end and the output gear; a front output shaft (20) coaxially aligned with the rear output shaft and rotatably mounted in an intermediate region of its length by means of a bearing (78) carried at a front wall (94) of the housing ; the front output shaft having a front end which   protrudes out of the housing to be coupled to the confi-   front axle guration; the front output shaft having a rear end (80) which is formed into a sleeve mounted around the end   front (82) of the rear output shaft so as to be sup-   carried by it while being able to rotate relative   port to rear output shaft; and   coupling means (86) mounted axially sliding   sants on the rear output shaft so as to rotate with it and to be selectively coupled to a portion of   the rear end of the front output shaft and release ples of this part.   2 - Advanced transfer boot as claimed   cation 1, characterized in that the rear output shaft (18) comprises a region located between said front end (82) and the second support bearing (72) and which comprises splines (89) aligned axially, and in that the coupling means comprise a clutch (86) traversed by an internally grooved orifice (88) suitable for being received   on this region of the rear output shaft.   3 - Improved transfer case according to the claim   cation 2, characterized in that said part of the extremi-   rear tee (80) of the front output shaft (20) extends   outwardly facing to carry teeth (84)   tending axially towards the rear, and in that the clutch   (86) has teeth (85) extending axially towards the a-   who are capable of performing aligned meshing   with the teeth (84) and said part of the rear end   of the front output shaft to cause the front output shaft to rotate together with the rear outlet.   4 - Advanced transfer boot according to the resale   dication 3, characterized in that said part of the end   rear half (80) of the front output shaft (20) and said region of the rear output shaft (18) are arranged medially inside the casing (12) in a lower part of the latter which includes a tarpaulin (92) of oil   lubrication, between the intermediate pinion (68) of pe-   speed and the intermediate gear (70) of high speed   size, so as to be subjected to lubrication by pro-   jection from the latter during operation of the transfer case (10).   - Transfer boot perfected according to the revena. dication 4, characterized in that the teeth (84) extending   axially backward collect lubricating oil   cation from said spray lubrication for   supply a lubricating oil supply to the ex-   front end of the rear output shaft (18) and at the end   rear half of the front output shaft (20) formed into a   sleeve, mounted on the latter.   6 - Improved transfer case according to the resale   dication 4, characterized in that it comprises means (200) for axially positioning the clutch (86), these means comprising a transfer link (202) mounted so as to be able to move axially inside the   casing (12) and provided with a fork (204) which is rigid therein   dementia, this fork having an elongated end   which is received in a circumferential groove (210) formed mée around the clutch.   7 - Advanced transfer case according to the claim   cation 6, characterized in that the means (200) for axially positioning the clutch (86) comprise means (220) for urging the transfer link (202)   backwards and means (212 to 216) for pushing selectively   the forward transfer rod against   of the action of these means of solicitation.   8 - Improved transfer case according to the resale   dication 7, characterized in that said biasing means   citation include a spring (220) positioned around the transfer link (202) and held under compression   between the front wall (94) of the housing and the fork (204).   9 - Improved transfer case according to the resale   dication 7, characterized in that the means serving to   selectively push the transfer link include   a jack (212 - 214) mounted on the rear wall (104) of the car   ter in line with the rear end of the link   transfer (202) to apply force to it.