Discussion of the prior art Centriugal friction couplings are known in many variations with the use of draw-out and swinging jaws, which are due to the centrifugal force forced with the clutch lining to the inner surface of a drum and in such way they transmit the rotational movement to a driven unit.

According to the Czech patent No. 250407 the driven unit of a coupling consists of a dish-shaped disc with a friction lining on the inner cylindrical surface in the proximity of which press segments on the pins of a plate disc of the drive unit of the coupling are turnable arranged. On the free ends of of the press segments tension springs are hanged up and the other end is fixed on the plate disc. The disadvantage of this arrangement is that the pendant eyes of the springs are too strained and they breaks too often.

In the German patent No. 41 27 540 a centrifugal coupling is provided with three sliding jaws, which due to the centrifugal force overcome the stiffness of the press springs arranged in the hollows of the sliding jaws, which are provided with clutch lining for the friction contact with the drum linked to the driven shaft. Not appropriate positioning of the longitudinal axes of the springs causes by the reotation change of their characteristics because they are loaded by the centrifugal force in dependance on its own weight and turns of the engine. To achieve the pre-set moment for the activation of the coupling it is necessary to use a spring with greater or smaller stiffness, it means usually springs with different diameters. Because of the limited inner space of the coupling is the assembly of bigger springs difficult. The change of the activation moment of the coupling can be achieved only by the change of the springs with various characteristics. It means higher costs. An other frequent problem of known coupling is a nonuniform wear off of the clutch lining due to a nonuniform load of ot the turning pins and holes in the swinging jaws. This problem occurs by the couplings where the axe of the spring hanged up on the swinging jaw is not symmetrical with the width of the cluch lining. Cluch lining has to be changed too often.

Summary of the invention The above mentioned disadventages are substantially eliminated by providing centrifugal friction coupling where the carrier plate is provided with holders with sattle pins and between the sattle pins and the projections of the swinging jaws press springs are arranged. The characteristics of the press spring and such the precise moment of the activation of the coupling in dependance on a certain engine speed can be modified by turning of the ajustable pins.

In a preferred embodiment at least one of the pins is ajustable along its axe.

In another embodiment spring is so arranged on the inner surface of the swinging jaw that the longitudinal axe of it is perpendicular to the radial component of the centrifugal force. This ensures an elimination of the influence of the centrifugal force on the characteristics of the press spring.

In another embodiment a projection is on the contact surface for the press spring provided by a foot pin and the projection is on the contact surface provided with a sattle for fixation of the front surface of the press spring. This ensures good fixation of the spring on the projection.

In a preferred embodiment the longitudinal axe of the spring is parallel to the carrier plaste in the plain of the half width of the cluch lining. This ensures an uniform wear off of the clutch lining.

Detailed description of the drawings The preferred embodiment will be more clearly illustrated in reference to the drawing where the figure illustrates a front view of a centrifugal friction coupling according to the invention in the direction from the drum.

Detailed description of the preferred embodiment A centrifugal friction coupling according to the invention illustrated in the figure consists of a drive unit linked to an engine unit and of a driven unit, which is linked by use of a chain e. g. to a driven wheel of a small motor cycle.

The drive unit of the coupling consists of a hub 2 which is fixed to a carrier plate 1 the shape of which is determined by the number of carried swinging jaws 4. On the inner surface of the carrier plate 1 main pins 3 are arranged. Around these main pins 3 the swinging jaws 4 are turnable arranged and secured with retaining rings 5.

Swinging jaws 4 are provided on the outer round face with clutch lining 6. The other end of the swinging jaws 4 is just under the main pin 3 provided with a projection 7 orientated to the centre of the coupling. The contact surface of the projections 7 is provided by a foot pin 9. Against the projections 7 holders 8 in the"L"shape are arranged and these are fixed to the carrier plate 1. On the shorter shoulders of the holders 8 sattle pins 10 are screwed in. Between them and the projections 7 press springs 11 are arranged. The outer surface of the longer shoulders is in contact with the inner surface of the swinging jaws 4.

The drive unit of the coupling is positioned inside of a drum 12 which is the driven unit of the coupling.

By starting of the engine and turning of its shaft also the carrier plate 1 with the hug 2 is rotated. Also the swinging jaws 4 with the clutch lining 6 are brought into the rotation and due to the radial component of the centrifugal force the springs 11 are effected by the swinging movement of the projections 7. At a certain engine speed the stiffness of the sprigs 11 is overcome and a friction contact between the clutch lining 6 and the drum 12 is enabled. By turning of the screwed sattle pins 10 it is possible to set the precise moment of the activation of the coupling in dependance on a certain engine speed. By decline of the engine speed to an idle run or by its switching off or when the force of the spring 11 overcome the radial component of the centrifugal force, due to the force of the spring 11 the projection 7 is forced away and also the clutch lining 6 is out of contact with the drum 12 and the drive wheel of a motor cycle is not driven any more.

Of cource the principle of the invention is not limited only to the above mentioned embodiment.

The coupling according to the invention can be used for engines for small motor cycles, scooters, minibikes, go-karts, power saws or other smaller garden equipment.