The present invention relates to transmission apparatus which will match the power input from a prime mover to provide a power output of equal value less the efficiency of the meσhanism. It is an object of the present invention to provide an improved form of transmission apparatus.

According to the present invention there is provided transmission apparatus comprising at least one system having driving means adapted to be driven about an axis of rotation by a prime mover, driver means rotatably driven by said driving means, and transmission means drivingly inter¬ connecting said driving and driven means characterised in that means are provided for generating a kinetic force on operation of the transmission means to cause a torque to be applied to control movement of the transmission means whereby the driven means can be rotated at a speed which is not directly related to that of the driving means.

According to a further aspect of the present invention there is provided a method of operating a transmission apparatus having driving means adapted to be driven about an axis of rotation by a prime mover, driven means rotatably driven by said driving means, and transmission means drivingly interconnecting said driving and driven means ' characterised in that said method comprises generating kinetic force on operation of the transmission means, and applying said force to provide torque to control movement of the transmission means whereby the driven means can be rotated at a speed which is not directly related to that of the driving means. The centrifugal force generated by a rotatable weight acts to prevent reciprocation of a reciprocating mechanism which in turn applies a torque to the transmission means to tend to rotate the driven means.

Preferably the transmission means comprises a planetary gear connected to the driving means and rotatable about an axis of rotation parallel to and offset from that of a driving wheel constituting the driving means, which planetary gear engages with a driven gear of the driven means.

Preferably the ^" planetary gear carries a crankpin offset from its centre of rotation which drives the reciprocating mechanism and causes the weight to rotate. An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 shows a cross-sectional view of a first embodiment of transmission apparatus illustrating the principle of the present invention;

Fig. 2 shows a schematic front view of the trans¬ mission apparatus of Fig. 1, and

Fig. 3 shows a cross-sectional view of a second practical embodiment of transmission apparatus in accordance with the present invention.

Referring to Fig. 1 of the accompanying drawings a transmission apparatus comprises a driving wheel or frame 10 which is rotatably mounted on a shaft 11 and is rotatably driven about the shaft 11 by a prime mover (not shown) . The shaft 11 is in turn mounted in bearings 11a and has keyed to it a driven gear 12 which engages with a planetary gear 13 rotatably mounted on the driving wheel 10. The shaft 11 is adapted to be connected to a load and as such it will be appreciated that the shaft 11 and the driven gear 12 keyed to it are not freely rotatable in the bearings 11a but rather will rotate only when the force exerted on the driven gear 12 exceeds the resistance of the load on the shaft 11. This will be elaborated on further hereinhelow. The planetary gear 13 carries a crankpin 14 radially offset from its centre of rotation and to the end of this crankpin 14 is keyed a gear wheel 15. Also mounted on the

crankpin 14, but freely rotatable thereon is a frame 16 which has rotatably mounted on it two gear wheels 17 and ^: 18. The gear wheel 18 is the same size as the gear wheel 15 and is, in fact, driven by the gear wheel 15 through a gear wheel 17 which is positioned between and engages with them both. The end of the frame 16 remote from the crankpin 14 is provided with an elongate locating slot 19 which is located over the end of the shaft 11 and ensures that movement of the frame 16 is limited to reciprocating back and forth with the motion of the crankpin 14.

Finally, a radially extending arm 20 carrying at its outer end a weight 21 (see Fig. 2) is secured to the gear wheel 18. The disposition of the radial arm 20 and the weight 21 on the gear wheel 18 ensures that they rotate in unison with crankpin 14, but that they lag the crankpin by approximately 90°.

The operation of the transmission apparatus of Figs. 1 and 2 will now be described.

As indicated previously hereinabove the load on the shaft 11 will usually be such that on start up of the prime mover (not shown) , the driven gear 12 is held stationary. As a result, it is the planetary gear 13 which is rotated as it moves around the driven gear 12 on the rotating driving wheel 10. As the planetary gear 13 rotates about its central axis, so too does the crankpin 14 and as the crankpin 14 rotates so too does the gear wheel 18 (through the action of gear wheels 15 and 17) and the weight 21 secured thereto by the radial arm 20. At the same time, the frame 16 is caused to reciprocate back and forth due to the motion of the crankpin about the central axis of the planetary gear 13.

The rotation of the weight 21 generates a centri¬ fugal force which is proportional to the angular accelera¬ tion of the weight 21 and which, because of its disposi- tion relative to the crankpin 14, tends to apply a torque to cause the frame 16 resist the movement of the crankpin 14. The effect of this is to cause the force required to

rotate the planetary gear 13 to be transmitted to the driven gear 12. As the σentrigugal force generated by the rotating weight 21 increases with its angular accelera¬ tion so too does the resistance to movement of the crankpin 14 and hence the torque tending to rotate the driven gear 12 until a point is reached where the resistance to movement of the driven gear 12 is overcome and it rotates in the same direction as the driving wheel and at a speed which matches the power input to the driving wheel with the power output from the shaft 11.

It will be understood that in the present invention as described above that as the rotation of shaft 11 increases^rotation of the planetary gear decreases but the weight 21 rotates about its axis at a speed which is the sum of the planetary gear and the driven gear. Finally, once the weight 21 reaches an angular acceleration at which the average centrifugal force is greater than the resistance to movement of the driven gear 12 then the planetary gear locks and causes the driven gear 12 to rotate at the same speed as the driving wheel 10.

The embodiment illustrated in Fig. 3 of the drawings illustrates a more practical form of the invention as compared with that shown in Figs. 1 and 2. The embodiment of Fig. 3 comprises a prime mover 30, e.g. a vehicle engine, having an output shaft 31. The outer end of the output shaft 31 has an integral flange 32 which is fixedly secured by bolts 33 to a driving frame or housing 34 whereby the driving frame 34 can be rotatably driven about a shaft 35 by the prime mover 30 on bearings 36. A -output gear 37 is integral with shaft 35. Planetary gear systems each designated by the references A and B are disposed at a spacing of 180° relative to each other on either side of the shaft 35 so that in operation the systems A and B result in a balanced

structure. The gear systems A and B are otherwise substantially identical.

Each system A and B comprises a planetary gear 38 which meshes with a driven gear 39 integral with shaft 35. As in the embodiment described in relation to Figs. 1 and 2, the shaft 35 and integral driven gear 39 are not freely rotatable but will rotate only when the force exerted on the driven gear 39 exceeds the resistance of the load on the shaft 35. The planetary gear 38 is carried rotatably on a hub 40 extending axially from an internal extension

41 of the driving frame 34 and the gear 38 has an integral crankpin 42 projecting therefrom and radially offset from its centre of rotation. The outer end of the crankpin 42 carries an integral gear wheel 43. Also carried by the crankpin 42 so as to be freely rotatable thereon is a connecting rod 44 which has rotatably mounted thereon a pair of gear wheels 45 and 46. The gear wheel 46 is the same diameter as the gear wheel 43 and is driven by the gear wheel 43 through the intermediary of gear wheel 45 which is in mesh with both gear wheels 43 and 46. The end of each connecting rod 44 remote from crankpin 42 is provided with an elongated slot 47 which closely surrounds one end of the shaft 35 to ensure reciprocation of the connecting rod 44 in accordance with the motion of the crankpin 42. Each gear wheel 46 has an axially-extending sleeve 48 freely surrounding a lateral extension 49 of its associated connecting rod 44 and each sleeve has an integral radially-extending counterweight 50. As in the embodiment of Figs. 1 and 2, each counterweight 50 rotates in unison with its associated crankpin 42 but is angularly spaced therefrom by around 90 .

It will be appreciated that the components of the gear system A are angularly spaced from their corresponding components of gear system B about the axis of shaft 35 by 180° thus ensuring a balanced force acting on the structure during operation.

It should be noted that in Fig. 3 the counterweights 50 are shown in the same plane as their associated crankpins 42. This is for ease of illustration only and it will be understood that in reality each counterweight 50 is angularly spaced from its associated crankpin 42 by approximately 90 in the same manner as illustrated in the embodiment shown in Fig. 2.

The assembly of Fig. 3 is shown associated with a gear box 51 of substantially traditional design. The output gear 37 of the transmission assembly meshes with gear wheel 52 carried by shaft 53. One or more gear ratios are engageable by suitable axial movement of gear sleeve 54 under the influence of gear selector lever 55 in order to transmit torque to output shaft 56. As can be seen from the drawings, the gear box 51 is housed within an extension 57 of the driving frame 34.

Operation of the transmission assembly of Fig. 3 is generally similar to that illustrated in Figs. 1 and 2. On start up of the prime mover 30, the driven gear 39 is held stationary to cause each of the two planetary gears 38 of the systems. A and B to be rotated as they move around the driven gear 39 on the rotating driving frame 34. Rotation of the planetary gears 38 causes corresponding rotation of the crankpins 42 about the axis of their associated gear 38 which in turn causes rotation of gear wheels 46 through the intermediary of gear wheel 43 and 45. As each gear wheel 46 rotates, corresponding angular movement of its associated counterweight 50 is effected. As in the previous embodiment, each connecting rod 44 reciprocates due to the motion of its associated crankpin 42 about the central axis of associated planetary gear 38.

As the counterweights 50 rotate, a centrifugal force is generated thereby which is proportional to the angular acceleration of the counterweights 50. A torque is thereby applied to cause the connecting rods 44 to resist movement of the crankpins 42. This causes the torque required to rotate the planetary gears 38 to be transmitted to driven

gear 39. As the centrifugal force generated by the rotating counterweights 50 increases with their angular acceleration so too does resistance to movement of their associated crankpins 42 and hence the torque tending to rotate the driven gear 39 until a point is reached where the resistance to movement of the driven gear 39 is over¬ come and it rotates ^' in the same direction as the driving frame 34 and at a speed which matches the power input to the driving frame 34 with the power output from the shaft 35.

In the same manner as described in the embodiment of Figs. 1 and 2, the angular movement of the counterweights 50 generate a torque which tend to cause the connecting rods 44 to resist the movement of their associated crankpins 42 and consequently driven gear 39. When the resistance to movement of driven gear 39 is overcome on an angular acceleration being achieved at which the centrifugal force is greater than the resistance to movement of the driven gear 39, the planetary gears 38 lock and the driven gear 39 rotates at the same speed as the driving frame34.

It will be appreciated that in the arrangements of the present invention, the torque is available to provide static force on the driven member and through the speed range until the driving member and driven member are rotating synchronously. '

Although the ^' above embodiments are described as employing one and two gear systems respectively, it will, be appreciated that three or more gear systems can be employed if desired. ^■ The present invention is applicable to many situations where a drive has to be taken up from a prime mover e.g. vehicles or cranes and may be substituted for a conventional flywheel and clutch with the advantage that the wear which takes place in such clutches can be obviated. ^' The apparatus can therefore be utilised as a clutch as well as a ^' continuously variable transmission, or a torque converter.

An additional advantage of the present invention is that for a given power output, a smaller power unit is required as compared with existing power units presently in use.