GB1574067A - Speed-responsive engaging mechanisms for hydraulic torque converters - Google Patents

Description

(54) SPEED-RESPONSIVE ENGAGING MECHANISM FOR HYDRAULIC TORQUE CONVERTERS (71) We, BORG-WARNER CORPORA TION, a corporation duly organized and existing under and by virtue of the laws of the State of Delaware, United States of America, having its principal office and place of business at 200 South Michigan Avenue, Chicago, Illinois 60604, United States of America, 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 is concerned with speedresponsive engaging mechanisms for hydraulic torque converters.

It is known to provide lock-up clutches for hydraulic torque converters. More particularly, it has been proposed to provide clutch mechanisms for torque converters having a shoe assembly engaged by centrifugal force and, in addition, engaged by a wedging effect of cam surfaces, such clutch mechanisms serving to lock together the impeller and the turbine elements of the converter to improve efficiency by eliminating slippage.

Previous designs of such torque converter clutches are capable of being improved in the area of engagement between the shoe assemblies and the cam itself.

Previous designs had a sliding engagement between the shoe assemblies and the cam surface. This type of construction induces a certain amount of frictional resistance to movement of the shoe assemblies along the cam surface. The ideal shoe assembly in a clutch of this type would have no frictional resistance to the movement of the shoe assemblies upon the cam surface. In addition, there remains the problem of minimizing the machining to be done on each shoe and of providing a simplified assembly.

We have now developed an improved clutch mechanism for hydraulic torque converters in which there is minimal frictional resistance to movement of the shoe assemblies along the cam surface of the clutch.

According to the present invention, there is provided a speed-responsive engaging mechanism for a hydraulic torque converter, comprising first and second relatively rotatable members, which engaging mechanism comprises an annular disc fixed to the second member, the disc being provided with cam means and with shoe assemblies which have a frictional surface thereon and which are retained on the disc by retaining means including spring means secured to respective assemblies and having portions engaging slots in the disc, centrifugal force being operative to urge the shoe assemblies into engagement with the first member at a given speed of rotation and the shoe assemblies then being adapted to roll along the cam means until they become wedged between the disc and the first member.

In order that the invention may be more fully understood, preferred embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 is a cross-sectional view through a clutch mechanism for a hydraulic torque converter; FIGURE 2 is a sectional view taken along the lines 2-2 of FIGURE 1; FIGURE 3 is a bottom view of the shoe assembly in FIGURE 2; FIGURE 4 is a partial view of the shoe and spring of FIGURE 2 taken in the plane of lines 4-4 in FIGURE 2; FIGURE 5 is a view of the shoe taken in the plane lines 5-5 of FIGURE 3; and FIGURE 6 is a sectional view taken along the lines 6-6 of FIGURE 2; FIGURE 7 is a sectional view of an alternative construction; FIGURE 8 is a sectional view along the lines 8-8 of FIGURE 9; and FIGURE 9 is a bottom view of the shoe assembly.

Referring to FIGURE 1, an improved lock-up clutch or engaging mechanism 10 is disclosed. Clutch 10 is shown in a hydraulic torque converter 12 having a drive shell 14 connected to drive a vaned impeller member 16. Torque converter 12 includes a vaned turbine member 18 driven hydrodynamically by impeller 16 and includes a stator member 20. The improved lock-up clutch 10 is operative to lock the turbine to the impeller by means of frictional engagement between clutch 10 and an inner annular surface 22 in shell 14.

Turbine 18 includes an outer radial vaned portion 26 which is connected to a hub 30 by rivets 28. Hub 30 is splined at 24 to be connected to a transmission input shaft as is known in the art. Drive shell 14 includes a radially extending portion 32 connected to a central hub 34 which is driven by the engine of the vehicle. Hub 30 of turbine 18 includes an axially extending bearing portion 38. A bearing 40 is provided mounting hub 30 within hub portion 34.

Turbine 18 is thus mounted for concentric rotation within shell 14 to provide for concentric rotation between the turbine and impeller 16.

The clutch 10 comprises an annular curved disc 42 and friction devices or shoe assemblies 44. Disc 42 is concentrically mounted upon turbine hub 30 and is secured thereto by rivets 28. Annular disc 42 is curved to conform with the shape and curvature of turbine 18 and radial portion 32 to provide minimum space requirements for clutch mechanism 10 within torque converter 12. As illustrated in FIGURE 2, disc 42 has a series of apertures or ramp areas 50 in which shoe assemblies 44 are mounted. Provided within each aperture 50 is a cam surface or ramp 56. The cam surfaces 56 have a relatively slight curvature for purposes to be described later.

Shoe assemblies 44 are particularly illustrated in FIGURES 2, 3, 4, 5 and 6. Shoe assemblies 44 comprise a rectangular friction shoe 60 being generally arcuate in cross-section to conform with the arcuate shape of surface 22. Assembled to shoe 60 is a spring 62 at either end thereof and a friction lining 64. Also assembled to the shoe is a roller mechanism 66. Roller mechanism 66 comprises a roller pin or axle 70 upon which a roller 72 is mounted.

Roller 72 is centrally mounted in shoe 60 in a rectangular slot 74 upon axle 70. Axle 70 is received in a cylindrical bore or journal 76 extending through shoe 60.

The shoe 60 is preferably formed of sintered metal by a powdered metal technique such that the shoe is cast to nearly its finished shape. The roller assembly 66 is assembled to the shoe by placing the roller 72 in slot 74 and then pressing the axle or pin 70 through the center of the roller.

Thus, the roller will turn with axle 70 within shoe 60. In this way, the roller is supported in its rotation over the entire length of the pin 70 and the force acting on the roller is over a large area within the shoe 60.

The friction lining 64 is bonded to an external arcuate surface 80 on shoe 60.

The lining may be of paper (which is preferred) or any of the other known types of friction material used in friction engaging devices.

The spring 62 is of continuous wire and is preformed such that two of the springs 62 serve to retain the shoe 60 upon the disc 42 and also resist outward movement of the shoe 60 under centrifugal force. Shoe 60 is designed to accommodate the spring 62 and for this purpose includes a pair of lips or ears 82 at either end thereof which have an outer angular surface 84 thereon. Provided centrally of shoe 60 are a pair of slots 86 on either side of the center of shoe 60 and, in addition, on either side of the roller assembly 66 such that there are four slots 86.

As illustrated in FIGURES 5 and 6, the slots 86 open into a cast in opening 88 within the center of the shoe in the area of the slot 74 which accommodates roller 72.

Shoulders 90 are formed within opening 88 on each side thereof. The opening 88 has the shape illustrated in FIGURE 5 on both sides of the roller assembly 66 such that the pair of springs 62 for each end of the shoe 60 are accommodated and secured at their inner ends within openings 88. Also extending centrally of the shoe and longitudinally thereof is a groove 92 which receives the edge of the disc 42 such that groove 92 serves as a guide for arcuate movement of the shoe with respect to disc 42. While restricting axial movement of the shoe relative to the disc thereby providing axial or longitudinal location of the side.

Also provided in disc 42 near the periphery thereof are a series of equally spaced slots or openings 96, there being an opening 96 at either end of each of ramp areas 50. Spring 62 has a U-shaped section 100 which is received within slot 96 such that the spring will be retained within disc 42.

Spring 62 has widened portion 102 which run along either side of the shoe 60. A transverse section 104 extends at right angles to and joins portions 102 with section 100 on either side of spring 62. Terminal section 106 extend inwardly at right angles to portions 102 and are located within slots 86 in the central area of shoe 60.

Terminal portions 106 have end section 108 thereon which extend radially outwardly as pictured in FIGURE 6, the ends 108 being received within the areas of shoulders 90.

Sections 104 of the spring engage with angular surfaces 84 on ears 82, the surface 84 thus being a reaction surface for the spring as will be explained.

Springs 62 are assembled to the shoe by first inserting the spring through the slot 96 and then snapping the spring within the shoe 60 by having sections 104 in engagement with angular surface 84, then bending sections 102 of the spring down until portions 106 and end portions 108 clear the bottom of the shoe such that they can be snapped into slots 86 and opening 88 and end portions 108 move into the area of shoulders 90 as illustrated in FIGURE 6.

Thus the springs 62 snap over the shoe 60 on either end of the shoe 60, thus eliminating any need for welding or riveting or other securing techniques.

When springs 62 are in position, as illustrated in FIGURE 2, they serve to hold the shoe 60 in place with the roller 72 engaging cam surface 56, since the portions 104 will react on surface 84 and section 100 will act on the upper part of openings 96 to pull the shoes radially inwardly since the spring 62 is bent to assume the position illustrated in FIGURE 2 and has an inherent resliency tending to straighten the spring out. Chamfers 110 are provided on each corner of shoes 60 in the area of ears 82 to facilitate assembly of spring 62 to shoe 60.

Further, as can be seen in FIGURE 2, section 100 of springs 63 may move arcuately relative to disc 42 within slot 96 to accommodate radially outward and arcuate movement of shoe 60.

As described above, the roller mechanism 66 rolls on cam surface 56 as assembly 44 moves arcuately and thus provides a relatively frictionless engagement between cam 56 and shoe assembly 44.

The operation of the engaging mechanism 10 is that initially the shoe assemblies will be in their retracted position, i.e., the shoe 60 not in engagement with surface 22.

As impeller 16 is rotated, as would be the case when the vehicle is to be moved forward from a stopped position, turbine 18 will begin to rotate and, as the speed increases, shoe assemblies 44 will move outwardly in response to centrifugal force against the force of springs 62. When shoes 60 and, in particular, friction material 64 engage surface 22, assembly 44 will move arcuately with respect to disc 42 along cam 56 in a clockwise direction, as illustrated in FIGURE 2. The roller assembly 66 rolls along surface 56, section 100 of spring 62 moves arcuately within opening 96 and, due to the wedging action of cam surface 56, shoes 60 will be wedged into engagement with surface 22 to lock turbine 18 to shell 14 so that impeller 16 and turbine 18 rotate together as unit. The engaging force is multiplied as a function of the cam angle to increase torque carrying capacity.

Referring now to FIGURES 7, 8 and 9, an alternative shoe assembly comprises a disc 42' having a series of apertures 50' in which shoe assemblies 44' are mounted.

Apertures 50' includes a series of T-shaped projections 52' which define tabs 54' extending radially toward the center of apertures 50'. Tabs 54' have cooperative engagement with shoe assemblies 44' to retain same on discs 42'. Also provided centrally of apertures 50' is a cam surface 56', also referred to as a wedge or ramp surface.

The cam surfaces 56' have a relatively slight curvature for purposes to be described later.

Shoe assemblies 44' are particularly illustrated in FIGURES 8 and 9. Shoe assemblies 44' comprise a rectangular friction shoe 60' which is generally arcuate in crosssection to conform with the arcuate shape of surface 22'. Assembled to the shoe is a roller mechanism 66' and a roller retainer 68'. Roller mechanism 66' is comprised of a roller pin or axle 70' upon which a roller 72' is mounted. Roller 72' is centrally mounted in shoe 60' in a rectangular slot 74' upon axle 70'. Axle 70' is received in partly cylindrical bearing supports or journals 76' defined within a raised portion 78' on retainers 68' on either side of slot 74'.

Roller assembly 66' is mounted securely within retainer 68' such that the roller will roll on pin 70', pin 70' serving as a nonrotatable axle. Optionally, the pin 70' may be rotatable in journals 76' and be press fitted in roller 72' whereby the roller and axle turn as a unit.

Friction lining 64' is bonded to the external arcuate surface 80' on shoe 60'.

Friction lining 64' may be of a paper or other known type.

Spring 62' and retainer 68' are secured to shoe 60' in the preferred embodiment by a special riveting process. As illustrated in FIGURE 9, retainer 68' has four apertures 84' therein, and spring 62' has a similar series of four apertures 86' therein. Assembly 44' is secured together by locating the retainer and the spring together on shoe 60' with the roller assembly and its axles 70' mounted in journals 76', and four rivets or opposite portions 88' are formed or forced out of the material of shoe 60'.

Rivets 88' extend through apertures 84' and 86' on retainer 68' and spring 62' respectively, the rivets upset or deformed over the retainer 68', thus securing the assembly tightly together. The economies of this type of assembly are obvious in that the rivets are formed from the material of the friction shoe itself.

It will readily be apparent that although a particular type of riveting process and assembly is described, the assembly may be secured together by known techniques such as spot welding, or the normal type of rivets, or by screws.

Spring 62' includes a central body por tion 9y having S-shaped sections 92' and 94' adjoining the body 90' at either end thereof. A corner portion 96' of S-shaped section 92' and a corner portion 98' of section 94' engage the undersurface of tabs 54' and retain shoe assemblies 44' within apertures 50' and resist outward movement of shoe assemblies 44' induced by centri fugal force.

Friction shoes 60' have longitudinal cen trally located slots 100' on either end there of. Slots 100' are slightly larger than the thickness of disc 42' and receive the T shaped portions 52' of the disc therewithin when shoe assembly 44' is mounted in place in apertures 50'. Thus, the shoe assembly 44' is guided by the T-shaped sections 52' of the disc 42' as it moves arcuately and along the cam surface 56' when in oper ation. Thus, slots 100' and their cooper ation with T-shaped sections 52' prevent the shoe assembly 44' from cocking or moving at an angle with respect to the axis of rota tion as it moves arcuately.

As described above, the roller mechan ism 66' rolls on cam surface 56' as assembly 44' moves arcuately and thus provides a relatively frictionless engagement between cam 56' and shoe assembly 44'.

The operation of the engaging mechan ism of FIGURES 7 to 9 is that initially the shoe assemblies will be in their retracted position. As the impeller is rotated, as would be the case when the vehicle is to be moved forward from a stopped position, the turbine will begin to rotate and, as the speed increases, the shoe assemblies will move outwardly in response to centrifugal force against the force of the springs 62'.

When shoes 60' and, in particular, friction material 64' engage surface 22', assembly 44' will move arcuately with respect to disc 42' along cam 56' in a clockwise direction, as illustrated in FIGURE 7. The roller assembly 66' rolls along surface 56' and, due to the wedging action of cam surface 56', shoes 60' will be wedged into engagement with surface 22' to lock the turbine to the drive shell so that impeller and turbine will rotate together as a unit.

The engaging mechanism of the present invention, when installed in a hydraulic torque converter as used in an automative automatic transmission, will release under several conditions which are desired in an Cenviponment of this type. The release and reengagement of the clutch occurs due to the inherent structure of the device without the requirement of any outside controls.

It is to be understood that the use of the terms "disengaged" herein is meant to indicate a condition in which shoes 60, 60' move radially inwardly out of contact with surface 22, 22'. When the term "released", as applied to the clutch is used herein, it is intended to include a condition in which shoes 60, 60' may still be in contact with surface 22, 22', but the engaging forces are such that slipping of surface 22, 22' with respect to shoes 60, 60' may take place or, in other words, the turbine and impeller may rotate at different speeds.

Due to the design of the clutch, when the clutch is locked up during operation of the vehicle and the throttle of the vehicle is suddenly depressed to demand higher torque, the drive-line torque will rise to a greater value than the torque capacity of the clutch causing the clutch to release and allowing the hydraulic torque converter to return to slipping condition, which is desired at such times. This condition may also occur on upshifts in the transmission when a sudden surge or increase in torque will occur momentarily.

When a torque reversal occurs in the drive-line, due to the inherent characteristics of the clutch, the wedging effect is removed and the torque capacity of the clutch drops to a lower value. Thus, the clutch momentarily releases on down shifts since a torque reversal may occur at such times. As known in the art, during shifting, release of the clutch is desired to allow the converter to return to its shock absorbing characteristics.

It has also been found during test work that upon shifting or ratio changing in an automatic transmission with the present device installed, the torque pulse or reversal which occurs during a shift allows the lockup clutch to release under these conditions.

This inherent feature of the present design is extremely important in that automatic shifts are much smoother when a hydraulic torque converter is operating in its released or normal manner; if a torque converter is locked up, for example by a conventional lock-up clutch, at the time of the shift, the shift could be much harsher than desirable.

It is to be noted that upon engagement of shoes 60, 60' with surface 22, 22', the shoe assemblies can rock on the cam surface 56, 56' about roller assembly 66, 66' to self-align with respect to the clutch surface 22, 22'.

As mentioned above, cam surfaces 56, 56' are curved, and since the surface on roller 72, 72' is cylindrical, there is line contact between the roller and cam surface 56, 56'.

The purpose of having the cam surface curved is to maintain a uniform wedge angle regardless of the position of the friction shoe along the cam surface. As will be recognized by those skilled in the art, the wedge angle is the angle between a radius drawn from the center of curvature of surface 56' through the point of contact between surface 56, 56' and roller surface 72, 72' and a radius drawn from the center of rotation of internal clutch surface and the point of contact between the roller surface and surface 56, 56'. It will also be recognized by those skilled in the art that if cam surface 56, 56' is a flat surface, the wedge angle will vary significantly as the friction shoe moves along the surface. It will be readily apparent that for the device to function best, it is important to have a constant wedge angle to maintain constant torque capacity even with dimensional variation of the parts.

The wedge angle used, which can be established by varying the curve of surface 56, 56', may be selected from a wide range of angles, the major requirement being the wedge angle must be greater than the angle of friction for the device to engage and disengage properly. As is known, the friction angle is a speclfic angle for particular types of material in engagement, being the angle of inclination to an inclined plane on which a body will just overcome its tendency to slide, the inclined plane and the body being of the materials for which the friction angle is to be established.

It has been appreciated that if the cam surfaces do not have the proper low coefficient of friction characteristics, the shoe can bind or stick rather than move freely along cam surface 56, 56', which can produce a poorly operating clutch unit. The shoe assembly 44, 44' of the present invention solves the frictional characteristic problem in that the shoe assembly rolls along the surface 56, 56' rather than sliding to create a minimum of frictional resistance to movement of assembly 44, 44' along the cam surface. The shoe assembly as described above is very simple and economical in structure having a sheet metal retainer riveted to the shoe capturing the axle of the roller mechanism in the assembly.

It is to be noted that although the shoe assembly 44, 44' with roller mechanism 66, 66' is shown as used with a clutch having a disc 42, 42' with cams 56, 56' therein, the shoe assemblies 44, 44' could also be used with a clutch having a formed sheet metal type of support having ramps formed therein. Further, it is contemplated that more than one roller assembly 66, 66' could be used in each assembly 44, 44', although the single roller assembly described above is preferred. It is further contemplated that although a roller 72, 72 of cylindrical form is shown and described, the present invention contemplates any type of friction relieving rolling device which may for example include a ball bearing assembly around axle 70, 70' or a single diameter cylindrical roller extending nearly the whole width of the shoe.

WHAT WE CLAIM IS: - 1. A speed-responsive engaging mechanism for a hydraulic torque converter, comprising first and second relatively rotatable members, which engaging mechanism comprises an annular disc fixed to the second member, the disc being provided with cam means and with shoe assemblies which have a frictional surface thereon and which are retained on the disc by retaining means including spring means secured to respective assemblies and having portions engaging slots in the disc, centrifugal force being operative to urge the shoe assemblies into engagement with the first member at a given speed of rotation and the shoe assemblies then being adapted to roll along the cam means until they become wedged between the disc and the first member.

2. An engaging mechanism as claimed in Claim 1, in which the cam means comprises a curved surface whereby a uniform wedge angle of engagement between the surface and the shoe assemblies is provided regardless of the position of the assemblies along the surface.

3. An engaging mechanism as claimed in Claim 1, or 2, in which the retaining means comprises spring means extending through holes in the disc and having end portions received within a central portion of the shoe assemblies.

4. An engaging mechanism as claimed in Claim 3, in which a separate spring is provided for each end of each shoe assembly, the spring being releasably connected to the shoe assembly.

5. An engaging mechanism as claimed in any of Claims 1 to 4, in which each shoe assembly includes a shoe made of sintered metal.

6. An engaging mechanism as claimed in any of Claims 1 to 5, in which each shoe assembly includes a shoe and a roller assembly, the shoe having a central slot and the roller assembly including an axle and a roller, the axle being mounted in the shoe and the roller being mounted on the axle and received in the slot.

7. An engaging mechanism as claimed in Claim 1 or 2, in which a single spring retains the shoe assemblies on the disc.

8. An engaging mechanism as claimed in Claim 7, in which each shoe assembly includes a friction shoe having a retainer including a journal means and a roller assembly including a roller and an axle, the axle being mounted in the journal means

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

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. angle regardless of the position of the friction shoe along the cam surface. As will be recognized by those skilled in the art, the wedge angle is the angle between a radius drawn from the center of curvature of surface 56' through the point of contact between surface 56, 56' and roller surface 72, 72' and a radius drawn from the center of rotation of internal clutch surface and the point of contact between the roller surface and surface 56, 56'. It will also be recognized by those skilled in the art that if cam surface 56, 56' is a flat surface, the wedge angle will vary significantly as the friction shoe moves along the surface. It will be readily apparent that for the device to function best, it is important to have a constant wedge angle to maintain constant torque capacity even with dimensional variation of the parts. The wedge angle used, which can be established by varying the curve of surface 56, 56', may be selected from a wide range of angles, the major requirement being the wedge angle must be greater than the angle of friction for the device to engage and disengage properly. As is known, the friction angle is a speclfic angle for particular types of material in engagement, being the angle of inclination to an inclined plane on which a body will just overcome its tendency to slide, the inclined plane and the body being of the materials for which the friction angle is to be established. It has been appreciated that if the cam surfaces do not have the proper low coefficient of friction characteristics, the shoe can bind or stick rather than move freely along cam surface 56, 56', which can produce a poorly operating clutch unit. The shoe assembly 44, 44' of the present invention solves the frictional characteristic problem in that the shoe assembly rolls along the surface 56, 56' rather than sliding to create a minimum of frictional resistance to movement of assembly 44, 44' along the cam surface. The shoe assembly as described above is very simple and economical in structure having a sheet metal retainer riveted to the shoe capturing the axle of the roller mechanism in the assembly. It is to be noted that although the shoe assembly 44, 44' with roller mechanism 66, 66' is shown as used with a clutch having a disc 42, 42' with cams 56, 56' therein, the shoe assemblies 44, 44' could also be used with a clutch having a formed sheet metal type of support having ramps formed therein. Further, it is contemplated that more than one roller assembly 66, 66' could be used in each assembly 44, 44', although the single roller assembly described above is preferred. It is further contemplated that although a roller 72, 72 of cylindrical form is shown and described, the present invention contemplates any type of friction relieving rolling device which may for example include a ball bearing assembly around axle 70, 70' or a single diameter cylindrical roller extending nearly the whole width of the shoe. WHAT WE CLAIM IS: -

1. A speed-responsive engaging mechanism for a hydraulic torque converter, comprising first and second relatively rotatable members, which engaging mechanism comprises an annular disc fixed to the second member, the disc being provided with cam means and with shoe assemblies which have a frictional surface thereon and which are retained on the disc by retaining means including spring means secured to respective assemblies and having portions engaging slots in the disc, centrifugal force being operative to urge the shoe assemblies into engagement with the first member at a given speed of rotation and the shoe assemblies then being adapted to roll along the cam means until they become wedged between the disc and the first member.

2. An engaging mechanism as claimed in Claim 1, in which the cam means comprises a curved surface whereby a uniform wedge angle of engagement between the surface and the shoe assemblies is provided regardless of the position of the assemblies along the surface.

3. An engaging mechanism as claimed in Claim 1, or 2, in which the retaining means comprises spring means extending through holes in the disc and having end portions received within a central portion of the shoe assemblies.

4. An engaging mechanism as claimed in Claim 3, in which a separate spring is provided for each end of each shoe assembly, the spring being releasably connected to the shoe assembly.

5. An engaging mechanism as claimed in any of Claims 1 to 4, in which each shoe assembly includes a shoe made of sintered metal.

6. An engaging mechanism as claimed in any of Claims 1 to 5, in which each shoe assembly includes a shoe and a roller assembly, the shoe having a central slot and the roller assembly including an axle and a roller, the axle being mounted in the shoe and the roller being mounted on the axle and received in the slot.

7. An engaging mechanism as claimed in Claim 1 or 2, in which a single spring retains the shoe assemblies on the disc.

8. An engaging mechanism as claimed in Claim 7, in which each shoe assembly includes a friction shoe having a retainer including a journal means and a roller assembly including a roller and an axle, the axle being mounted in the journal means

whereby the roller assembly is secured to the shoe assembly.

9. An engaging mechanism as claimed in Claim 8, in which the retainer is secured to the shoes by rivets which are formed from the material of the shoe.

10. An engaging mechanism as claimed in any of Claims 1 to 9, in which the each shoe assembly includes a guide slot at either end thereof adapted to receive the disc whereby the shoe assembly is guided in its movement with respect to the disc.

11. A speed-responsive engaging mechanism for a hydraulic torque converter substantially as herein described with reference to FIGURES 1 to 6 or FIGURES 7 to 9 of the accompanying drawings.