Transmission with hydraulic coupling device and locking clutch suitable for a motor vehicle

The invention relates to a motor vehicle transmission of the kind incorporating a hydraulic coupling device such as a torque converter and a lock-up clutch. The transmission comprises, between an input shaft and an output shaft, a hydraulic coupling having impeller and turbine wheels and a clutch which provides direct drive between the shafts when engaged. The clutch has a friction coupling element for frictionally engaging an input element integral in rotation with the input shaft, and a torsion damping assembly. According to the invention, a tab connection is used between the friction coupling element an output element rotatable with the output shaft.

BACKGROUND OF THE INVENTION 
This invention relates generally to transmissions with a hydraulic coupling 
member and locking clutch, i.e. transmissions of the kind comprising, in 
parallel between an input element intended to be rotationally integral 
with a first shaft, (usually the drive shaft) and an output element 
intended to be rotationally integral with a second shaft, (usually the 
driven shaft) on the one hand a hydraulic coupling member, such as a 
torque converter or hydraulic coupler, which comprises an impeller wheel 
rotationally integral with the input element and a turbine wheel 
rotationally integral with the output element, and on the other hand a 
clutch which, on starting up and usually each time the gear ratio is 
changed, is idle in a first stage and thus first allows the hydraulic 
coupling member to intervene between the input element and the output 
element and which, in a second stage, puts this hydraulic coupling member 
out of action so as to prevent the slipping caused by the latter and thus 
improve the overall efficiency, by providing a direct mechanical coupling 
between the input element and the output element. 
The invention relates particularly to such transmissions which are intended 
to be fitted to motor vehicles. These may be either semi-automatic or 
automatic. 
In practice, in the transmissions of the kind in question, the clutch used 
comprises an axially-movable coupling element which is rotationally 
integral with the output element and capable of being made rotationally 
integral, by friction, with the input element. A clutch of this kind may 
be reduced to this coupling element. 
However, more often, although not necessarily, this clutch may also 
incorporate a torsion damping assembly, for smoothing out the vibrations 
inherent in the kinematic chain in which it is interposed, this torsion 
damping assembly comprising two coaxial parts mounted for relative 
rotation within the limits of a specified angular clearance and against 
elastic means acting circumferentially between them, one of said parts 
being rotationally integral with the coupling element whilst the other is 
rotationally integral with a rigid hub. 
For example, one of the rotary parts may comprise an annular flange and the 
other part may comprise two guide washers provided on both sides of this 
flange, parallel thereto, and integral with each other, whilst the elastic 
means provided circumferentially between these parts then consist of 
springs partly housed in apertures provided in the flange and partly 
housed in apertures provided in the guide washers. 
One of the problems to be solved in producing transmissions of this type 
stems from the fact that a rotational connection has to be provided 
between one of the rotary parts forming the torsion damping assembly, on 
the one hand, and the coupling element, on the other hand, whilst the 
latter should also be capable of moving axially. 
Two solutions are generally adopted to satisfy this requirement. 
In one method, a rigid connection is provided between the flange and the 
hub with which it is associated, and a grooved connection (such as a 
splined coupling) is provided between the coupling element and this 
flange. 
In a second arrangement, which is more often used in practice, a rigid 
connection is provided between the coupling element and the flange, and a 
grooved or splined connection is provided between this flange and the hub 
which is associated with it. In both cases, a grooved connection is used. 
A grooved connection of this kind can give rise to friction and slipping. 
Moreover, as a result of jamming or blocking, it is liable to operational 
breakdowns, thus jeopardising the engagement and/or disengagement of the 
clutch. 
It is also known to provide a rotational connection between two elements by 
means of tabs, this connection comprising a plurality of elastically 
deformable tabs usually known as tangential tabs, which are each formed by 
at least one leaf spring and which, being provided substantially 
tangentially, relative to a circumference of the assembly, in relation to 
one of the elements which they connect, permit relative axial displacement 
of these two elements relative to each other, whilst making them 
rotationally integral with each other. 
A tab connection of this kind is usually used, for example, in orthodox dry 
clutches, between the pressure plate and the cover. 
This invention relates generally to the application of a tab connection of 
this kind to transmissions having a hydraulic coupling and locking clutch 
of the kind described above, whether or not the clutch incorporates a 
torsion damping assembly. 
SUMMARY 
The invention provides a transmission, especially for a motor vehicle, of 
the kind comprising, in parallel between an input element intended to be 
rotationally integral with a first shaft, generally a drive shaft, and an 
output element intended to be rotationally integral with a second shaft, 
generally a driven shaft, on the one hand a hydraulic coupling device such 
as a torque converter or coupler, which comprises an impeller wheel 
rotationally integral with the input element and a turbine wheel 
rotationally integral with the output element, and on the other hand a 
clutch, which comprises an axially movable coupling element which is 
rotationally integral with the output element and capable of being made 
rotationally integral, by friction, with the input element, cooperating 
with a tab connection provided between two elements, said tab connection 
comprising a plurality of elastically deformable tabs hereinafter referred 
to as tangential tabs, which are each formed by at least one plate and 
which, being provided substantially tangentially, relative to a 
circumference of the assembly, with respect to one of the elements which 
they connect to the other, permit relative axial movement of these two 
elements relative to each other, whilst making them rotationally integral 
with each other, the tab connection acting between the coupling element, 
on the one hand, and the output element, on the other hand. 
If the clutch is reduced to its coupling element, the tab connection used 
according to the invention is established between, on the one hand, the 
coupling element, forming a first element, and, on the other hand, either 
the turbine wheel or output element, forming a second element. 
If, in an alternative embodiment, the clutch also comprises a torsion 
damping assembly, the tab connection used according to the invention is 
established between, on the one hand, any of the parts constituting this 
torsion damping assembly, forming a first element, and, on the other hand, 
either the coupling element or the turbine wheel, forming a second 
element. 
In every case, as a result of the tab connection according to the 
invention, engagement or disengagement of the clutch is not accompanied by 
friction, and therefore operational breakdowns are less likely to occur. 
It should be emphasised that in the transmission according to the invention 
the tabs of this connection operate under different conditions, in 
practice more severe conditions, than those to which tabs of this kind are 
usually subjected in dry clutches. 
In fact, in dry clutches, only part of the couple to be transmitted between 
the reaction plate or flywheel forming the input element, and its friction 
disc, forming the output element, passes through the tangential tabs used, 
whilst the remainder of this couple is transferred directly from this 
reaction plate or flywheel to this friction disc. 
As a result, there is no risk of buckling of the tangential tabs used in a 
dry clutch of this kind when the latter is operating in reverse or 
overrun, and the axial pressure of the pressure plate on the friction disc 
remains the same as it is during a pulling action; the couple to be 
transmitted is therefore always capable of passing directly from the 
reaction plate to the friction disc. 
This is not the case in the transmission according to the invention, in 
which on the one hand, all the couple to be transmitted passes through the 
tangential tabs used and, on the other hand, the coupling element of the 
clutch is simply applied against a reaction plate, without being clamped 
against the latter by a pressure plate. 
Thus, at the outset, there was no reason to suppose that tangential tabs of 
this kind could be used in a transmission of the type in question, all the 
more so because the absence of any axial clamping for the coupling element 
of the clutch in such a transmission makes it more difficult, owing to the 
resulting lack of equilibrium, for tangential tabs of this kind, and 
particularly the points of attachment thereof, to contain the stresses to 
which they are subjected during operation as a result of the cyclic 
vibrations and oscillations which, between the engine and the driven 
wheels, affect the entire kinematic chain of which they form a part. 
However, tests have confirmed that the tangential tabs used according to 
the invention in a transmission with a hydraulic coupling member and a 
lock-up clutch of the kind in question are completely satisfactory in 
practice. 
However, for increased safety, according to a further feature of the 
invention, it is proposed that there be provided, between the two elements 
affected by the tab connection in question, circumferential abutment means 
with some play, which are adapted to provide, if necessary, a direct 
rotational coupling of these two elements to each other after the 
corresponding play has been absorbed. 
Circumferential abutment means with play of this kind may, for example, 
comprise at least one abutment member carried in an axially projecting 
position on one of the elements concerned and engaging with play in a 
recess provided for this purpose in the other said element; this abutment 
member may either be formed simply by an axial extension of one of the 
rivets normally used for attaching tangential tabs to the corresponding 
element at one of their ends, or may be a part which is separate from 
these rivets. 
Whatever the case, these circumferential abutment means with play will 
automatically overcome the consequences of any buckling of the tangential 
tabs used, particularly during reverse or overrun operation of the 
transmission. 
Moreover, because of the resulting safety, these circumferential abutment 
means with play make it possible to use a minimal number of tangential 
tabs, under otherwise identical conditions, thus reducing the cost of the 
assembly accordingly. 
Finally, to increase safety still further, the tab connection used is 
associated with axial abutment means for limiting the axial displacement 
of the axially movable member affected by this connection, when the clutch 
is disengaged, and thus protecting the tabs of the connection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a transmission 10 with a hydraulic coupling member 11 and a 
lock-up clutch 12 of the type fitted to certain motor vehicles. It may be 
an automatic transmission or a semi-automatic transmission. 
Since this transmission 10 as a whole is not in itself the object of this 
invention, not all its details are shown in FIG. 1, particularly as 
regards the control means; instead, FIG. 1 shows only those components of 
the transmission which relate to this invention. 
The hydraulic coupling member 11 and the clutch 12 are provided in parallel 
between an input element on the one hand, formed by the rotating housing 
15 of the assembly, and an output element on the other hand, formed, in 
the embodiment shown, by a tubular hub 21. 
The housing 15 is intended to be rotationally integral with a drive shaft 
13, and a drive diaphragm 9 connects this housing 15 to the shaft 13 for 
this purpose. 
The tubular hub 21 is intended to be rotationally integral with a driven 
shaft 14, and for this purpose a splined coupling is provided between the 
tubular hub 21 and the shaft 14. 
In practice, the drive shaft 13 itself is intended to be rotationally 
integral with the output shaft of the motor of the vehicle in question, or 
even consist of this output shaft, whilst the driven shaft 14 is intended 
to be rotationally integral with the input shaft of a gear box, or even 
consist of this input shaft. 
In the embodiment shown, the hydraulic coupling member 11 is a torque 
converter and comprises an impeller wheel 17, a turbine wheel 18 and a 
reactor wheel 19; however, it could equally be a simple coupler. 
The impeller wheel 17 is directly fixed to the inner wall of the rotating 
housing 15; it is therefore rotationally integral with the latter, which 
forms the input element of the transmission. 
The turbine wheel 18, in contrast, is carried by a hub 20 which is 
rotationally integral, via a splined coupling, with the tubular hub 21 
forming the output element of the transmission. 
Finally, the reactor wheel 19 is itself carried, via a free wheel 22, by a 
tubular boss 24 which extends coaxially around the driven shaft 14, 
between the latter and a sleeve 25 integral with the rotating housing 15, 
and to provide a seal a seal 8 is provided between the tubular hub 21 and 
the driven shaft 14. 
Similarly, a bearing block 6 is provided between the driven shaft 14 and 
the tubular hub 24. 
As a whole, the clutch 12 comprises, in the embodiment shown in FIG. 1, a 
coupling element 26, on the one hand, and a torsion damping assembly 27, 
on the other hand. 
Overall, the coupling element 26 forms an annular cheek which is mounted, 
by means of a piston assembly rendered leaktight by means of a seal 7, in 
axially movable manner on a support ring 28; the latter, which has an 
L-shaped cross section, engages on the tubular hub 21 and, with its flange 
is centred by the latter; furthermore, it is axially braced between this 
tubular hub 21 and a transverse area 30 of the rotating housing 15 and 
comprises, in contact with the latter, axial extensions 31 which define 
between them radial passages 32 suitable for the circulation of fluid. 
In the embodiment shown, the coupling element 26 comprises annularly, on 
its outer periphery, opposite an annular area 33 of the rotating housing 
15, a friction lining 35 by means of which it is capable of being made 
rotationally integral by friction with this rotating housing 15 which 
forms the input element of the transmission; alternatively, the friction 
lining 35 may be carried by the rotating housing 15. 
In the manner known per se, according to constructional methods which will 
not be described in detail here, the torsion damping assembly 27 comprises 
two coaxial portions mounted so as to be rotational relative to each 
other, within specified angular limits, and counter to elastic means 
adapted to act circumferentially between them. 
In practice, one of these rotary portions comprises an annular flange 36 
which extends radially around the tubular hub 21, whilst the other rotary 
portion comprises two annular guide washers 37 which extend parallel to 
the flange 36, on both sides thereof, with the interposition of friction 
discs 38, and which are integral with one another by means of axial pins 
39 passing, with some play, through openings provided for this purpose in 
the flange 36. The elastic means adapted to act circumferentially between 
these rotary portions consist of springs 40 housed, substantially at a 
tangent to a circumference of the assembly, partly in windows provided for 
this purpose in the flange 36 and partly in windows provided for this 
purpose in the guide washers 37. 
In the embodiment shown in FIG. 1, the flange 36 is rotationally integral 
with the tubular hub 21, being carried by the latter, whilst the guide 
washers 37 are freely rotatable relative to this tubular boss 21. 
According to the invention, a tab connection is provided between the 
coupling element 26 and the output element of the transmission thus 
formed. 
In the embodiment shown in FIG. 1, a tab connection of this kind is 
provided between, on the one hand, the coupling element 26 forming a first 
element and, on the other hand, that one of the rotary parts constituting 
the torsion damping assembly 27 which comprises the guide washers, forming 
a second element, whilst the other of said rotary portions, namely the one 
comprising the flange 36, is integral with the output element which in 
this case is formed by the tubular hub 21. 
In practice, to provide a tab connection of this kind, one of the guide 
washers 37, the one nearest the coupling element 26, is fitted with an 
adjacent flange 42 made integral with the guide washers 37 by means of 
rivets 39 which interconnect these guide washers 37. 
On its periphery this flange 42 comprises a plurality of lugs 43 which are 
uniformly circularly distributed, and to each of which is attached, by 
means of a rivet 44, an elastically deformable tab 45. 
Each tab 45, which extends substantially tangentially relative to a 
circumference of the assembly and which is hereinafter referred to as a 
tangential tab, is formed by at least one leaf spring 46 and, in practice, 
a plurality of leaf springs 46, i.e. two in the embodiment shown in FIGS. 
1 and 2. 
At its other end, each tangential tab 45 is fixed to the coupling element 
26 via a rivet 47, with an interposed spacer 48 in the embodiment shown in 
FIGS. 1 and 2. 
In the manner known per se, due to their axial capacity for elastic 
deformation, the tangential tabs 45 are adapted to permit relative axial 
displacement of the two elements which they connect, namely the coupling 
element 26 and the rotary portion of the torsion damping assembly 27 
comprising the guide washers 37, whilst making these two elements 
rotationally integral with each other. 
Associated with the tab connection thus formed are axial abutment means, to 
limit axial displacement when the clutch 12 is disengaged, given that, 
when the clutch is engaged, this displacement is in any case limited by 
the abutment of the coupling element 26 against the rotating housing 15. 
In the embodiment in FIG. 1, these axial abutment means are formed by the 
flange 36, and the coupling element forms, towards said flange 36, an 
axial collar 50 by which it can bear against this flange 36 through the 
components of the torsion damping assembly 27 interposed between it and 
the hub flange 36, whilst it should be remembered that the tubular hub 21 
carrying the hub flange 36 is itself suitably axially controlled by the 
hub 20. 
A passage 51 is drilled axially through the output shaft 14. 
During disengagement of the clutch 12, pressurised oil is admitted through 
this passage 51 and through the radial passages 32, to penetrate into the 
space formed between the rotating housing 15 and the coupling element 26, 
thus forcing this coupling element to move away from this housing and thus 
become rotationally disconnected from the latter, owing to the leaktight 
seal provided by the seals 7 and 8 and the bearing block 6. 
After circulating through the hydraulic coupling member 11, the oil passes, 
through a passage 52 provided between the tubular hub 24 of the reactor 
wheel 19 and the sleeve 25 of the rotating housing 15, into a return 
space. 
On the other hand, when the clutch 12 is to be engaged, pressurised oil 
arrives through this passage 52 and circulates through the hydraulic 
coupling member 11 and the internal space of the rotating housing 15. 
Owing to the presence of this oil, the hydraulic coupling member 11 ensures 
that the driven shaft 14 is progressively made hydraulically integral with 
the drive shaft 13, with the normal slippage associated with such 
transmissions, whilst the turbine wheel 18 is integral with the driven 
shaft 14 and the impeller wheel 17 with the drive shaft 13. 
However, the oil which has thus circulated in the internal space of the 
rotating housing 15 and initially leaves it again through the radial 
passages 32 and the axial passage 51 progressively acts on the coupling 
element 26 by its flow, and finally comes to press it forcefully against 
the annular area 33 of the housing 15. 
Taking into account the leaktight seal provided by the seals 7 and 8 and 
the bearing block 6, this results, on the one hand, in an interruption in 
the return circuit for this oil, the supply of which is then reduced to a 
tapping-up supply of the leaktight space thus confined, and on the other 
hand in a direct rotational connection, by friction, of the driven shaft 
14 to the drive shaft 13, via the coupling element 26, the torsion damping 
assembly 27 and the tubular hub 21. 
In other words, the hydraulic coupling member 11 is then idle, and as a 
result there is no slipping between the driven shaft 14 and the drive 
shaft 13. 
According to the alternative embodiment shown in FIG. 4, the tangential 
tabs 45 forms an integral part of the flange 42, being cut out from this 
flange on the periphery thereof. 
In this case, each of these tangential tabs 45 normally consists of only 
one leaf spring 46, but these can be reinforced by one or more such leaf 
springs if desired. 
According to the alternative embodiment shown in FIGS. 5 and 6, between the 
elements involved in the tab connection according to the invention, 
namely, on the one hand, the coupling element 26 and, on the other hand, 
the rotary portion of the torsion damping assembly 27 comprising the guide 
washers 37, there are also provided circumferential abutment means with 
some play which are adapted to provide a direct rotational coupling of 
these two elements to each other in the event of buckling of the 
tangential tabs 45 which connect them. 
In practice, there is no danger of such buckling when the transmission is 
in the pulling state and the tangential tabs 45 are subjected to traction. 
However, there can be a danger of buckling when the transmission is 
operating in reverse or overrun, when the tangential tabs 45 are thus 
subjected to compression. 
The circumferential abutment means with play according to the invention 
comprise at least one abutment member 55 which projects axially from one 
of the elements concerned and which engages with play in a recess provided 
for this purpose in the other element. 
In the embodiment shown in FIGS. 5 and 6, each of these abutment members 55 
is individually formed by the axial extension of a rivet 47 by means of 
which a tangential tab 45 is fixed to the clutch friction coupling 26 at 
one of its ends. 
The abutment member 55 thus formed engages, with annular play J, in an 
opening 56 provided for this purpose in the flange 42, the latter then 
having a circular contour, in order to form the lugs 43 and also to extend 
at right angles to the rivets 47. 
If buckling of the tangential tabs 45 occurs, each abutment member 55 comes 
to bear against the edge of the opening 56 in the flange 42 through which 
it passes, thus ensuring a direct rotational coupling between the flange 
42 and the coupling element 26 and hence counteracting the effects of the 
buckling, which as a result does not have any damaging effect on the 
tangential tabs 45. 
Moreover, in the embodiment in FIG. 5, a reinforcing washer 57 is provided 
around each rivet 44, at the corresponding end of the tangential tab 45 in 
question. 
To achieve the minimum axial dimensions for the assembly, as shown in FIG. 
7, each rivet 44 by means of which the corresponding tangential tab 45 is 
attached to the flange 42, is mounted by means of a boss 58 on this flange 
42, projecting towards the coupling element 26 and formed, for example, by 
an embossed portion on the flange 42. 
At the same time, with the same purpose, there is formed, in the coupling 
element 26, opposite each rivet 44, a recess 59 adapted for axial 
penetration by this rivet 44 and formed, for example, by a boss on the 
coupling element 26. 
Besides the reduced axial dimensions obtained with this arrangement, this 
advantageously enables the bracing discs at the attachment ends of the 
tangential tabs 45 to be eliminated. 
Moreover, in this alternative embodiment, the axial abutment means 
associated with the tab connection consist of rivets 47, at least some of 
which comprise a shoulder 54 opposite the flange 42 for this purpose. 
In the alternative embodiment shown in FIG. 8, each rivet 47, by means of 
which the corresponding tangential tab 45 is fixed to the coupling element 
26, forms an integral part of this coupling element 26, and is made of the 
same material. Furthermore, according to this embodiment, at least one of 
the abutment members 55 used forms a part which is individually distinct 
from the rivets fixing the tangential tabs 45 in position. 
In this embodiment, the axial abutment means associated with the tab 
connection consist of rivets 44, whilst the heads of at least some of 
these rivets 44 are sufficiently prolonged axially towards the coupling 
element 26 to enable the latter to abut thereon during disengagement of 
the clutch 12. 
According to a further feature of this embodiment (not shown), one rivet 44 
may act as both circumferential and axial abutment means; the same may 
apply to an abutment member 55, in which case it is carried by the flange 
42 and not by the coupling element 26. 
In the embodiment shown in FIGS. 9 and 10, the coupling element 26, instead 
of extending beyond the torsion damping assembly 27 relative to the 
hydraulic coupling member 11, extends between this assembly 27 and the 
coupling member 11. 
The other components of the transmission are identical to those described 
hereinbefore. 
In the embodiment shown in FIGS. 9 and 10, for example, reinforcing discs 
48 and 57 are thus used at the ends of the tangential tabs 45. 
In an alternative embodiment, FIG. 11, and according to the details 
described hereinbefore, reinforcing discs of this kind are eliminated, 
thanks to the use of bosses 58 embossed in the flange 42 and bosses 61 
embossed in the coupling element 26, at right angles to the corresponding 
rivets. 
Moreover, in this variant, as shown diagrammatically by broken lines, the 
axial abutment means are formed by the abutment members 55 carried by the 
coupling element 26 and to this end comprise a shoulder 60 beyond the 
flange 42 through which they pass. 
In the embodiments shown in FIGS. 1 and 9, that one of the rotary portions 
constituting the torsion damping assembly 27 which forms one of the 
elements involved in the tab connection according to the invention is the 
one comprising the guide washers 37. 
However, in an alternative embodiment, according to an arrangement which is 
not shown, the portion in question could also be the one consisting of the 
flange 36, in which case the latter is mounted so as to be freely 
rotatable relative to the tubular hub 21, whilst the guide washers 37 are 
made integral therewith, according to arrangements known per se which will 
not be described in detail here. 
In the embodiment shown in FIGS. 12 and 13, the tab connection according to 
the invention is provided between, on the one hand, either of the rotary 
portions constituting the torsion damping assembly 27, forming a first 
element, and, on the other hand, the turbine wheel 18, forming a second 
element, whilst the other of these rotary portions is carried by the 
coupling element 26. 
Thus, this tab connection again acts between the coupling element 26 and 
the output element of the transmission which in this case is the hub 20 on 
the turbine wheel 18, this hub 20 being directly connected, via a splined 
coupling, to the driven shaft 14. 
In the embodiment shown, it is the flange 42, integral with the guide 
washers 37, which is made integral by the tangential tabs 45 with the 
turbine wheel 18, whilst the hub flange 36 is fixed by means of rivets 65 
to the coupling element 26, by means of bosses 66 formed for this purpose 
by embossing the coupling element. 
Alternatively, however, the flange 42 which is integral with the guide 
washers 37 could be integral with the coupling element 26, and the flange 
36 could be connected to the turbine wheel 18 by a tab connection. 
Whichever the case, in this embodiment of the invention, the torsion 
damping assembly 27 is suspended annularly by its outer periphery between, 
on the one hand, the coupling element 26 and, on the other hand, the 
turbine wheel 18. 
Since the tubular boss 21 previously provided for this torsion damping 
assembly 27 is now omitted, the support ring 28 of the coupling element 26 
engages on an axial extension of the hub 20 of the turbine wheel 18. 
A ring 68 forming a spacer between the guide washers 37 is provided 
annularly between the flange 36 and this axial extension of the hub 20 of 
the turbine wheel 18. 
On the inner periphery of the flange 36, on the one hand lugs 69 are cut 
out, which are alternately folded axially towards one or other of the 
guide washers 37 and which centre the ring 68 and ensure the axial 
positioning of the hub flange 36, and on the other hand teeth 74 are cut 
out, which ensure that this ring 68 is rotationally driven. 
Whichever the case, to ensure that the tangential tabs 45 are fixed, the 
turbine wheel 18 comprises on the outside, on its periphery, a collar 70 
forming in the transverse direction an annular area 71 by means of which 
these tangential tabs can be fixed, using rivets 72, FIG. 12, with the 
interposition of reinforcing discs 48. 
The axial abutment means associated with the tab connection used according 
to the invention, for disengaging the lock-up 12, are formed in this 
embodiment by a shoulder 75 of the ring 28 against which the coupling 
element 26 abuts during such disengagement. 
As will be seen, in this embodiment, the tab connection used according to 
the invention is beyond the torsion damping assembly 27, in the direction 
input element-output element of the transmission; this advantageously 
protects the tabs. 
This invention may also be applied to a transmission in which the lock-up 
clutch 12 does not comprise a torsion damping assembly and is therefore 
reduced to its coupling element 26, as shown in FIGS. 14 and 15. 
In FIG. 14, the tab connection is provided between, on the one hand, the 
coupling element 26, forming a first element, and on the other hand the 
hub 20 of the turbine wheel 18, forming a second element; in the 
embodiment shown, it is formed by leaf springs 46 cut out in the periphery 
of a flange 42, as shown in FIG. 4, these leaf springs 46 being fixed to 
the coupling element 26 by means of rivets 47, whilst the flange 42 is 
fixed to the hub 20 by rivets 77 which make it integral with the turbine 
wheel 18. 
In an alternative embodiment, FIG. 15, the tab connection is provided 
between the coupling element 26, forming a first element, and the turbine 
wheel 18, forming a second element, by means equivalent to those described 
with reference to FIG. 12. 
The present invention is not limited to the embodiments described and 
shown, but covers all alternative constructions and/or combinations of the 
various elements within the scope of the appended claims. 
In particular, the tangential tabs used may be curved in the usual way. 
Moreover, the circumferential abutment means described hereinbefore may be 
replaced by a second set of tabs arranged symmetrically to the first, with 
the tabs of these two sets forming a `V`, for example, in pairs, from one 
set to the other.