motor vehicle.
The present invention relates to the use of wedges in the actuation of the release bearing of a single plate dry clutch or for any clutch (both single plate or multi-plate) employing a diaphragm spring.
This invention reduces the clutch actuation effort on the part of the driver. The known actuation system, however, involve the use of a clutch fork release system, which applies the &rce for clutch actuation directly on the bearing.
The advantages of this invention are:
• Clutch actuation force requirements reduced.
• Ease of operation improved, hence user effort reduced.
• Life of actuation components improved.
The use of wedge principle is known in brakes as well as in
clutches.
Comparing the known art on wedges in clutches and the
present invention the following differences can be noted;
• The known art is intended for use with multi-plate
clutches but this inavention is meant for use with single
plate dry friction clutches as well as any other clutch

employing diaphragm springs (both single plate as well as multi-plate).
• The clutch actuator in the known art makes use of a gear rack and pinion arrangement for actuation but this invention makes use of a jaw mechanism to achieve the required actuation.
• The known system is for optional engagement of the secondary driveline in four wheel drive vehicles whereas this invention is intended for use in the primary driveline
• In the known system the wedge Is placed on the clutch-actuating fork and a corresponding mating fork to transmit the force but in this invention the wedges are placed on a semicircular disc, which in turn transmits the force to the corresponding wedge placed on the release bearing which is cylindrical.
Comparing the known actuation system with this invention the following differences can be noted:
• In the known system the initial force is applied on the release bearing from the axial direction hut in case of this invention the force comes in radially.
• The known actuation system makes use of a lever and fork type mechanism to achieve release bearing displacement but this invention proposes to use a
•

• wedge mechanism to achieve the necessary bearing displacement.
• In the known system the force magnification depends on the type of lever ratio used but in this invention the force magnification depends upon the wedge angie used.
This invention will now be described in further detail by referring to the accompanying drawings which illustrate, In Fig 1 the known dry clutch actuation system In Fig. 2 an embodiment of this invention by way of example and not by way of limitation.
Referring to figure 1 the mode of working of the known dry clutch actuation system is now described.
The force required to actuate the clutch is applied on the lever (LI). This lever (LI) has its fulcrum on ttie rod (FV). The force from the lever LI is transmitted on to the release bearing (rb) by means of the secsond lever (L2). The second lever (L2) also called the dutch release fork moves the release bearing (rb) on the spring in the clutch assembly (CA) and hence clutch actuation is achieved.
In the embodiment illustrated in figure 2 instead of the force being applied axially directly on the release bearing (rb) it is applied in the radial direclion Instead by means of a pair of

wedges (wl). The wedges are actuated by means of a jaw type mechanism (j1). These wedges meet another wedge (w2) resting on the release bearing (rb) and hence convert the radial force to an axial one and because of the wedge angle we also get a multiplication in force. When the jaw mechanism (jl) closes it moves the wedges against each other, which results in the force and displacement being transmitted to the release bearing (rb) and hence achieving clutch actuation on the clutch assembly (CA).
The major drawbacks encountered in the known dutch actuation of single plate dry friction clutches are considerable effort from the driver during actuation as we}] as reduced durability of chutch actuation components due to high efforts involved. Also the force is not uniformly distributed on the release bearing but acts at two points only.
In relation to the above-mentioned drawback the use of wedges in the actuation of the release bearing reduces clutch actuation effort considerably. Thus the driver comfort in clutch operation is improved as well as the durability of the clutch actuation components is ensured. Also the actuating force is applied uniformly on the release bearing.
The system illustrated in figure 2 is devised in order to reduce the force required to move the release bearing and

hence bring down actuation effort and enhance user comfort. Also in reducing the force requirements on the actuation systems the durability of the actuation components can be effectively improved, it involves two wedges (wl), which are moved in the radial direction by help of a jaw mechanism jl. This wedge pair (wl) comes in contact with another wedge (w2) cut into a cylinder and resting on the release bearing (rb). This wedge (w2) moves axially and transfers the force onto the release bearing to achieve clutch actuation on the clutch assembly (CA.). The wedges are supported by means of a sleeve S1 .This sleeve provides the necessary rigid support to achieve the required function. Rollers (rl)have been provwied between the wedges as well as between the sleeves to reduce wear dne to friction by converting sliding friction to rolling Motion.
In relation to the known actuation systems where the force is directly applied on the release bearing by means of levers, the force here is applied by means of wedges whose movement is controlled by a Jaw mechanism.

We Claim:
1. A clutch, actuation system for a motor vehicle comprising
a pair of wedges actuated by a jaw type mechanism, said
wedges meeting a third wedge resting on the release bearing,
to convert the radial force to an axial force, while also
resulting in a multiplication in force, by reason of the wedge
angle, the arrangement being such that the wedges are moved
against each other when the jaw mechanism closes, to cause
the force and displacement to be transmitted to the release
bearing, and thus actuate the dutch.
2. A clutch actuation system as claimed in Claim I wherein the wedges are supported by means of a sleeve, said sleeve providing the necessary rigid support,
3. A dutch actuation system m daimed in Claim 1 or Claim 2 wherein rollers have been provided between the wedges as well as between the sleeves to reduce wear due to friction, by converting sliding Motion to rolling friction.
4. A clutch actuation system for a motor vehicle substantially
as herein described and illustrated.