GB1567406A

GB1567406A - Shifting mechanism for shifting a power-dividing transmission for motor vehicles

Info

Publication number: GB1567406A
Application number: GB3818077A
Authority: GB
Original assignee: Steyr Daimler Puch AG
Current assignee: Steyr Daimler Puch AG
Priority date: 1976-09-15
Filing date: 1977-09-13
Publication date: 1980-05-14
Also published as: DE2739870C3; FR2364780A1; AT344516B; PL200858A1; ATA685276A; JPS5337272A; FR2364780B1; PL111370B1; JPS5623170B2; CH621975A5; YU39133B; DE2739870A1; YU216377A; DE2739870B2; IT1085391B

Abstract

The control device serves for switching the front axle drive on in addition to the rear axle drive and at the same time for switching on a transmission stage of an auxiliary range transmission for road travel or for off-road travel. The device has two parallel selector plate slots each with a shift fork (2, 3). A common manual shift lever (1) serves for operation of the two shift forks (2, 3). The latter are coupled by a bridge (14), which has a longitudinal guide (13) for the shift finger (1a), so that they can swivel about parallel axes (4, 5). The bridge (14) is connected to the shift forks by way of a swivel pin (15) or by way of a pivot-slot coupling (17, 18). For a simple design construction, this allows the desired transmission stage and the desired axle drive to be selected as required. <IMAGE>

Description

(54) A SHIFTING MECHANISM FOR SHIFTING A POWER-DIVIDING TRANSMISSION FOR MOTOR VEHICLES (71) We, STEYR-DAIMLER-PUCH AKTIENGESELLSCHAFT, an Austrian Company, of Kärntnerring 7, Wien, Austria, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a gear selection mechanism of the kind (hereinafter referred to as the kind set forth) for selecting a power-dividing transmission for motor vehicles, which transmission is operable selectively to transmit power to the front axle drive in addition to the rear axle drive and constitutes also a range selector comprising a road travel gear and a cross-country travel gear, said transmission comprising two shift mg forks and a common manual selector lever that is movable along two paths each of which is associated respectively with one of said shifting forks.

In known mechanisms of the kind set forth the two shifting forks are mounted on parallel shifting rods and the shifting finger of the manual selector lever selectively engages mating recesses, which face each other and are formed in the two parallel shifting rods.

To engage the road and cross-country travel gears of the range selector and selectively to connect and disconnect the front axle drive, one or the other shifting rod is shifted in the longitudinal direction of the vehicle by means of the manual selector lever, which engages the recess of the respective shifting rod. When, however, the front axle drive has been connected, so that the all-wheel drive is in operation, and the shifting finger of the manual gearshift lever is disengaged from the associated shifting rod, e.g. because the range selector is to be shifted, that shifting rod may be displaced because the shifting sleeve is loaded by the torque which is exerted. If a conventional gate is provided, the driver is unable, in such case, to couple the shifting finger of the manual selector lever with the shifting rod so as to connect the front axle drive and the latter cannot be connected. The vehicle may even become entirely inoperative if the shifting finger of the manual selector lever is in engagement with the shifting rod for connecting the front axle drive and the road travel gear which is initially engaged is unintentionally disengaged so that a no-load position between the road and cross-country travel gears is assumed. Even when there is no gate, it is very difficult to move the shifting finger into the recess of the respective other shifting rod in case of a change of the path, i.e. when the manual selector lever is pivotally moved from one shifting rod to the other, and this will excessively divert the driver's attention.

All these difficulties are due to the difference between the power-dividing transmission and a conventional change-speed transmission that one shifting rod must be disengaged when the other is to be shifted and the transmission elements coupled to said disengaged shifting rod are partly under load when the vehicle is travelling so that an undesired shifting of that shifting rod or a disengagement of the corresponding shifting sleeve can easily occur.

It is known to provide conventional mechanical means, such as locking pins or locking balls (German Patent Specification 1,530,713) or locking levers (German Patent Specification 462,512) for axially holding each shifting rod in position during a shifting of the other shifting rod. Such mechanical locking of the shifting rod is unobjectionable in the conventional transmissions only when they are under no load but in the transmission according to the invention would result in a constant loading of the respective shifting fork when the gear is shifted under load and the respective shifting sleeve tends to become disengaged. The resulting wear will not be noticed by the driver until the trans mission has eventually suffered severe damage.

It is also known to provide a powerdividing transmission in which the shifting sleeve associated with the two gears of the range selector is connected by a two-armed lever to the shifting sleeve for connecting the front axle drive (German Patent Specification 1,405,858). This arrangement has the disadvantage that the cross-country travel gear must always be engaged when the front axle drive is to be connected so that the road travel gear cannot be utilized when both axles are driven.

It is important to eliminate these disadvantages and so to improve a gear selection mechanism of the kind set forth that after a disengagement of the clutch members for the front axle drive or of the cross-country and road travel gears the manual selector lever can readily be returned to that position which enables a renewed engagement of the desired range gear or of the cross-country and road travel gears the manual selector lever can readily be returned to that position which enables a renewed engagement of the desired range gear or the desired axle drive.

It is also desired to provide a relatively simple structure in which the free selection of the modes of operation of the transmission is not unfavourably restricted.

Accordingly we provide a gear selection mechanism of the kind set forth wherein the two shifting forks are pivoted on spaced apart parallel axes in the transmission housing and are coupled by a bridge that extends transverse to the shifting paths and is provided with a longitudinal guide for engagement by the shifting finger of the manual selector lever and is connected directly or indirectly to each shifting fork by a separate pivot pin.

The invention is now described by way of example in relation to the figures of the accompanying drawing, in which: Figure 1 is a vertical selection view showing the essential parts of a gear selection mechanism for shifting a power-dividing transmission.

Figure 2 is a top plan view showing part of the transmission when the cover and manual selector lever have been removed and Figure 3 is a diagram illustrating the paths of the hand lever for actuating the mechanism used for selecting the gears and is directly related to Figure 2. (It is to be noted that the shift finger moves in reverse to the hand lever).

Figure 3 shows that there are two paths I and II. Path I includes the positions assumed by the handle knob of a manual selector lever 1 when only the rear axle drive is connected (position La) and when the front axle drive is also connected (position Ib). Path II includes a position Ila for the road travel gear, a position IIb for the cross-country travel gear, and an intermediate no-load position IIc. In accordance with the diagram of Figure 3, left-hand shifting fork 2 in Figures 1 and 2 is associated with path I and right hand shifting fork 3 serves to control the range selector when the manual selector lever 1 as positioned on path II. The shifting sleeves and transmission shafts are not shown, for the sake of clearness. In the embodiment shown the two shifting forks 2, 3 are pivoted respectively to a transmission housing 6 on pins 4' 4"; 5' 5" spaced apart and forming parallel axes 4 and 5.

The manual selector lever 1 is pivoted in a bell-shaped member 8 on a pivot 7, which is parallel to the paths I, II (see line 7' 7" Figures 2 and 3). The bell-shaped member 8 is pivoted in the cover 10 of the transmission housing 6 on a pivot 9 transverse to pivot 7.

The pivot 9 extends through a suitable aperture in the manual selector lever 1 and is formed with notches 11 that are engageable by a spring-loaded detent pin 12, which is mounted with its spring 1 2A in the stem of the manual selector lever 1 so that the positions La Ib IIa lib IIc of the manual selector lever 1 associated with the paths I and II are defined.

A shifting finger la of the manual selector lever 1 extends into a longitudinal guide or groove 13 of a bridge 14 that extends transversely to the paths I, II of Figure 3. The bridge 14 is connected at one end by a pivot pin 15 to a pivoted lever 16 and has at the other end a slot 17 that receives a pin 18 that protrudes from the right hand shifting fork 3.

The pivoted lever 16 is mounted on the same pin 4' as the left hand shifting fork 2. The left hand shifting fork 2 is provided with an upright extension 19, and the pivoted lever 16 has a depending extension 20. A shifting spring 21 consisting of a compression spring is held between the upright extension 19 and the depending extension 20. The pivoted lever 16 carries also a locking pawl 22 that is biased by a spring, not shown, and carries a pin 23 that extends into a bore 24 of the pivoted lever 16.

When it is desired by the driver to connect the front axle drive (position Ib) and for this purpose the manual selector lever 1 is moved to the rear and the shifting finger forward along path I (from position La to position Ib in Figure 3), the bridge 14 is pivotally moved in the clockwise sense (of Figure 2), the pivoted lever 16 connected to the bridge 14 is pivotally moved in the counterclockwise sense, and the pivoted lever 16 acts by means of the shifting spring 21 on the left hand shifting fork 2 and tends to carry the said fork 2 along in the counterclockwise sense. If it is not yet possible to engage by means of right hand fork 3 the cross-country travel gear (position IIb), the shifting spring 21 will be stressed. At the same time the locking pawl 22 is pivotally moved in the counterclockwise sense and is locked behind a stop 25, that is rigid with the housing, so that the pivoted ever 16 is held in the springstressing position even when the driver has released the manual selector lever 1. When the front axle drive can be engaged under the continued pressure of the shifting spring 21, the shifting fork 2 is pivotally moved to the position shown in Figure 2 and by means of the pin 23 carries the locking pawl 22 along and pulls it away from the stop 25 so that the transmission is again ready for disengagement of the front axle drive.

When the manual selector lever 1 is pivotally moved into the path II, the shifting finger la moves to the right in Figure 2 in the longitudinal groove 13 of the bridge 14. Thereafter, a movement of the manual selector lever 1 along the path II will result in a pivotal movement of the right hand shifting fork 3 in one direction or the other so that one gear or the other of the range selector is engaged while the bridge 14 is pivotally moved about the pin 15. The bridge 14 has a locking nose 26, with which two stop faces 27, 28 of the transmission housing 6 are associated. In the position shown in Figure 2, in which the front axle drive (position Ib) is connected, the bridge 14 can be freely pivotally moved to cause one or the other gear of the range selector to be engaged. When the bridge 14 is pivotally moved about the pin 15 in the clockwise sense to cause the crosscountry travel gear (position IIb) to be engaged, the locking nose 26 will engage the stop face 27. When the shift lever is again moved into the gate I, and the driver tries to disconnect the front axle drive, the nose 26 bears against the face 27, thus preventing the bridge 14 from pivoting on the pin 18 and hence the fork 2 from pivoting in the clockwise direction to disconnect the front axle drive.

As stated above the bridge 14 is provided with a locking nose 26 and the transmission housing 6 has a stop face 27 which is engaged by the locking nose 26 when the bridge 14 is in the position in which the front axle drive (position Ib) is connected and the crosscountry travel gear (position IIb) is engaged.

As a result, when the cross-country travel gear is engaged so that a higher torque is available the vehicle cannot be driven only via the rear axle drive (position 1a), which would have to be stronger in that case. When the front axle drive (position Ib) is connected and the cross-country travel gear (position Ib) is engaged and the front axle d48s to be disconnected (position Ib) the road travel gear (position l'a) must be engaged first so that the locking nose 26 is disengaged from the stop face 27 and the transmission can then be shifted as desired.

The transmission housing 6 may have a second stop face 28, which is engaged by the locking nose 26 before the cross-country travel gear (position IIb) is engaged when the front axle drive (position Ib) is disconnected.

In that case the driver can shift the transmission from the road travel gear (position IIa) only to the no-load position (IIc) of the range-selecting transmission but not to the cross-country travel position (IIb), so that excessively high torque on the rear axle drive is avoided. When the front axle drive is disconnected and it is then desired to engage the cross-country travel gear (position IIb) by a pivotal movement of the bridge 14 in the clockwise sense, that pivotal movement will be prevented by the engagement of the locking nose 26 with the stop face 28.

More generally the modus operandi is as follows: During a shifting of the manual selector 1 the shifting finger la which performs the shifting operation engages the bridge 14 in guide 13 at one end or the other of the longitudinal guide 13 so that the bridge 14 is pivotally moved about pivot 15 or 18 and the shifting fork 2 or 3 disposed at that end which is moved by the shifting finger la follows the movement to the desired position. When the shifting finger la is then moved to the other end of the bridge 14 or guide 13 to perform a shifting operation there and this causes the initially shifted sleeve or the like to become disengaged, that end of the bridge 14 which is connected to the respective shifting fork 2, 3 will follow the movement which is due to the disengagement and the shifting finger la can easily be moved back in the longitudinal guide 13 to the respective path or the corresponding end of the bridge 14 and be operated to re-engage the disengaged gear or the axle drive clutch. The connection of the two shifting forks 2, 3 by the bridge 14 and the longitudinal guide 13 provided in the bridge 14 for guiding the shifting finger la thus enable the latter to move to each of the paths I or II or gearshift fork 2, 3 or the end of the bridge 14 to perform or repeat a shifting operation regardless of the position of the shifting fork 2, 3 or bridge at the other end.

WHAT WE CLAIM IS: 1. A gear selection mechanism of the kind set forth wherein the two shifting forks are pivoted on spaced apart parallel axes in the transmission housing and are coupled by a bridge that extends transverse to the shifting paths and is provided with a longitudinal guide for engagement by the shifting finger of the manual selector lever and is connected directly or indirectly to each shifting fork by a separate pivot pin.

2. The gear selection mechanism as claimed in claim 1, wherein the bridge is provided with a locking nose and the transmission housing has a stop face which is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. stressed. At the same time the locking pawl 22 is pivotally moved in the counterclockwise sense and is locked behind a stop 25, that is rigid with the housing, so that the pivoted ever 16 is held in the springstressing position even when the driver has released the manual selector lever 1. When the front axle drive can be engaged under the continued pressure of the shifting spring 21, the shifting fork 2 is pivotally moved to the position shown in Figure 2 and by means of the pin 23 carries the locking pawl 22 along and pulls it away from the stop 25 so that the transmission is again ready for disengagement of the front axle drive. When the manual selector lever 1 is pivotally moved into the path II, the shifting finger la moves to the right in Figure 2 in the longitudinal groove 13 of the bridge 14. Thereafter, a movement of the manual selector lever 1 along the path II will result in a pivotal movement of the right hand shifting fork 3 in one direction or the other so that one gear or the other of the range selector is engaged while the bridge 14 is pivotally moved about the pin 15. The bridge 14 has a locking nose 26, with which two stop faces 27, 28 of the transmission housing 6 are associated. In the position shown in Figure 2, in which the front axle drive (position Ib) is connected, the bridge 14 can be freely pivotally moved to cause one or the other gear of the range selector to be engaged. When the bridge 14 is pivotally moved about the pin 15 in the clockwise sense to cause the crosscountry travel gear (position IIb) to be engaged, the locking nose 26 will engage the stop face 27. When the shift lever is again moved into the gate I, and the driver tries to disconnect the front axle drive, the nose 26 bears against the face 27, thus preventing the bridge 14 from pivoting on the pin 18 and hence the fork 2 from pivoting in the clockwise direction to disconnect the front axle drive. As stated above the bridge 14 is provided with a locking nose 26 and the transmission housing 6 has a stop face 27 which is engaged by the locking nose 26 when the bridge 14 is in the position in which the front axle drive (position Ib) is connected and the crosscountry travel gear (position IIb) is engaged. As a result, when the cross-country travel gear is engaged so that a higher torque is available the vehicle cannot be driven only via the rear axle drive (position 1a), which would have to be stronger in that case. When the front axle drive (position Ib) is connected and the cross-country travel gear (position Ib) is engaged and the front axle d48s to be disconnected (position Ib) the road travel gear (position l'a) must be engaged first so that the locking nose 26 is disengaged from the stop face 27 and the transmission can then be shifted as desired. The transmission housing 6 may have a second stop face 28, which is engaged by the locking nose 26 before the cross-country travel gear (position IIb) is engaged when the front axle drive (position Ib) is disconnected. In that case the driver can shift the transmission from the road travel gear (position IIa) only to the no-load position (IIc) of the range-selecting transmission but not to the cross-country travel position (IIb), so that excessively high torque on the rear axle drive is avoided. When the front axle drive is disconnected and it is then desired to engage the cross-country travel gear (position IIb) by a pivotal movement of the bridge 14 in the clockwise sense, that pivotal movement will be prevented by the engagement of the locking nose 26 with the stop face 28. More generally the modus operandi is as follows: During a shifting of the manual selector 1 the shifting finger la which performs the shifting operation engages the bridge 14 in guide 13 at one end or the other of the longitudinal guide 13 so that the bridge 14 is pivotally moved about pivot 15 or 18 and the shifting fork 2 or 3 disposed at that end which is moved by the shifting finger la follows the movement to the desired position. When the shifting finger la is then moved to the other end of the bridge 14 or guide 13 to perform a shifting operation there and this causes the initially shifted sleeve or the like to become disengaged, that end of the bridge 14 which is connected to the respective shifting fork 2, 3 will follow the movement which is due to the disengagement and the shifting finger la can easily be moved back in the longitudinal guide 13 to the respective path or the corresponding end of the bridge 14 and be operated to re-engage the disengaged gear or the axle drive clutch. The connection of the two shifting forks 2, 3 by the bridge 14 and the longitudinal guide 13 provided in the bridge 14 for guiding the shifting finger la thus enable the latter to move to each of the paths I or II or gearshift fork 2, 3 or the end of the bridge 14 to perform or repeat a shifting operation regardless of the position of the shifting fork 2, 3 or bridge at the other end. WHAT WE CLAIM IS:

1. A gear selection mechanism of the kind set forth wherein the two shifting forks are pivoted on spaced apart parallel axes in the transmission housing and are coupled by a bridge that extends transverse to the shifting paths and is provided with a longitudinal guide for engagement by the shifting finger of the manual selector lever and is connected directly or indirectly to each shifting fork by a separate pivot pin.

engaged by the locking nose when the bridge is in the position in which the front axle drive is connected and the cross-country travel gear is engaged.

3. The gear selection mechanism as claimed in claim 2, wherein the transmission housing has a second stop face, which is engaged by the locking nose before the cross-country travel gear is engaged when the front axle drive is disconnected.

4. The gear selection mechanism as claimed in any of claims 1 to 3, wherein the bridge is connected by the pivot pin to a pivoted lever and a shifting spring is interposed between that pivoted lever and the shifting fork for connecting the front axle drive.

5. The gear selection mechanism as claimed in claim 4 wherein the pivoted lever carries a spring-loaded locking pawl, whixh is pivotally movable in a limited range and which, when the shifting spring is stressed, moves behind a stop that is rigid with the housing so that the pivoted lever is thus held in the spring-stressing position.

6. A gear selection mechanism for a power-dividing transmission, substantially as described hereinbefore and as shown in the figures of the accompanying drawings.

7. A power-dividing transmission comprising a gear selection mechanism as claimed in any of claims 1 to 6.

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