EP1222413A1

EP1222413A1 - Multiple speed orbital transmission

Info

Publication number: EP1222413A1
Application number: EP99970719A
Authority: EP
Inventors: Eric Paul Willmot
Original assignee: Aimbridge Pty Ltd
Current assignee: Aimbridge Pty Ltd
Priority date: 1998-10-19
Filing date: 1999-10-19
Publication date: 2002-07-17
Also published as: WO2000023727A1; AU1140400A; CN1375045A; AU762318B2; AUPP659498A0

Abstract

A multiple speed orbital transmission is disclosed which has orbit gear pairs (10-30, 220-230 and 220'-230'). One of the pairs (230-220 or 230'-220') form an orbit control by fixing stationary or otherwise controlling the outer gear (230 or 230') so as to cause the gear (30) to execute an orbit to drive gear (10) to provide output rotary power. A brake (80 or 80') is provided for fixing the gear (230 or 230'). The gear pairs have different gear ratios between them so that by selecting and braking one of the gears (230 or 230') so the gear pair to which that gear belongs controls orbital motion of the orbit gear (30) will set the drive ratio of the transmission. Thus, by selectively causing the brake (80) to brake one of the gears (230 or 230') the drive ratio can be changed.

Description

MULTIPLE SPEED ORBITAL TRANSMISSION

This invention relates to a multiple speed orbital transmission which may be used in a variety of environments where multiple speed output rotary power is required, such as in industrial transmission systems, transmission systems for vehicles and transmissions for other environments such as drills winches, hoists and the li e.

The invention may be said to reside in a multiple speed orbital transmission, including: an input; an output; an output orbital gear pair coupled to the output, the output orbital gear pair having an orbiting gear and a rotary gear so that when input power is supplied to the input, the orbiting gear can orbit relative to the rotary gear and drive the rotary gear to provide rotary output power to the output; orbit control means for maintaining orbital motion of the orbiting gear; at least one further orbit gear pair coupled to the input or the output and including a further orbiting gear and an orbit control gear; and ,.. speed switch means for controlling the orbit control means and the at least one further orbit gear pair so as to selectively maintain or release the orbit control exerted by the orbit control means or the orbital motion of the at least one further orbit gear pair, so that the speed of the output rotary power is selected dependent upon which of the at least one further orbit gear pair or orbit control means is controlled by the switch means to maintain orbital motion.

Thus, in order to provide multiple speed output, it is only necessary to select which of the orbit control means or further orbit gear pair are controlled or released so that input power to output power is transmitted through the selected orbit control means or at least one further orbit gear pair to thereby provide the required output speed. By simply changing the selection, the output speed can be changed. By providing a plurality of orbit gear pairs at the input or the output, three or more output speeds can be provided.

In one embodiment of the invention, the orbit control means comprises a first orbit control gear pair at the input including an inner orbiting gear and an outer control gear; the at least one further orbit gear pair being coupled to the input and comprising a further inner orbiting gear and a further outer control gear; and wherein the speed switch means comprises a brake means associated with each of the outer control gears for selectively maintaining the outer control gears stationary so that when one of the outer control gears is maintained stationary, the inner orbiting gear associated with that outer control gear controls orbital motion of the output orbital gear pair so output rotary power is transmitted to the output, and when the brake means releases the outer control gear, the outer control gear is able to rotate so that the orbital control is no longer maintained so that no __. power is transmitted via the orbit gear pair in which the orbit control is released.

Thus, by simply choosing which of the brake means is activated to maintain the respective outer control gear stationary, rotary power can be provided via the input through that orbit gear pair which acts to control the orbital motion of the orbiting gear of the output orbital gear pair so that output rotary power is supplied to the rotary gear of the output gear pair and then to the output . Thus, the ratio between the orbital gear pair at the input which is controlled so as to maintain its respective outer control gear stationary and the gear ratio of the output orbital gear pair will determine the output speed of the transmission. Each of the orbital gear pairs at the input will be provided with a different gear ratio between the respective inner orbiting gears and outer control gears so that different gear ratios can be provided by selecting which of the outer control gears are held stationary and which are released to release the orbit control by that orbit gear pair.

The brake means can be a mechanical brake which holds the outer control gears selectively stationary or releases them for rotary movement . Alternatively, the brake means can be a magnetic arrangement in which magnetic fields are used to selectively brake and hold the outer control gear stationary or release the outer control gear for rotary movement .

In the preferred embodiments of the invention, the orbit control means effectively forms one of the further orbit gear pairs at the input. However, in other embodiments, the orbit control means could include a stationary orbit control plate and pin arrangement whic is selectively released or controlled with at least one further orbit gear pair at the input or the output. In such embodiments, if ,.. the plate and pin arrangement is controlled to maintain the orbital control over the output orbital gear pair, the gear ratio of the transmission will be set merely by the gear ratio between the orbiting gear and rotary gear of the output gear pair. If the plate and pin arrangement is released so as to release the orbit control and orbit control is provided by the further orbit gear pair at the input, the gear ratio will be dependent upon the gear ratio of the further orbit gear pair and the output orbital gear pair.

Similarly, if the further output gear pair is provided at the output, the multiple speed output can be provided by controlling output through either the output orbital gear pair or the further orbit gear pair at the output so that different output speeds are provided by controlling either the output gear pair or the further orbit gear pair at the output. The orbit control can be maintained by an orbit control gear pair or stationary plate and pin assembly or by brake means arranged with the output orbital gear pair and further orbit gear pair at the output . In this embodiment of the invention, the gear pairs at the output would be coupled by a bevel gear arrangement so that output rotary power is transmitted to the output via the bevel gear connection between the selected output orbital gear pair and the output .

Preferably the input comprises a shaft having an eccentric and the further orbit gear pairs are arranged on the eccentric.

Preferably the output comprises a shaft coupled to the rotary gear of the output gear pair.

By providing a plurality of orbital gear pairs at the input and a plurality of orbital gear pairs at the output and controlling an appropriate one of the input gear pairs and an appropriate one of the output gear pairs, a multiple speed transmission can be provided having N x M speeds where N is the number of orbital gear pairs at the input and M is the number of orbital gear pairs at the output and with each of the orbital gear pairs having a different gear ratio.

The invention also provides a multiple speed transmission, including; an input for receiving rotary power; an eccentric coupled to the input; a plurality of orbit gear pairs each comprised of an inner gear mounted on the eccentric and having external teeth, and an outer gear having internal teeth for meshing with the external teeth of the respective inner gear; an output; an output orbit gear pair having an inner output gear mounted on the eccentric, the inner output gear having external teeth, an outer output gear having internal teeth which mesh with the external teeth of the inner output gear, the outer output gear being coupled to the output; and control means for controlling the outer gears so that drive is supplied from the input via one of the orbit gear pairs selected by the control means to the output orbit gear pair and therefore to the output.

The control means preferably comprises a brake means having a plunger spring biased towards said orbit gear pairs, the plunger being slideable so as to align the plunger with one of the orbit gear pairs for engaging the outer gear of said one of the orbit gear pairs.

Preferably the outer gears have grooves or recesses on an outer peripheral surface which are engageable by the plunger to fix stationary the outer gear of the selected orbit gear pair.

Preferably the input comprises a shaft portion coupled to or integral with the eccentric.

Preferably the outer gears have bearings arranged between them.

A preferred embodiment of the invention will be described, with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of a multiple speed orbital transmission according to one embodiment of the invention;

Figure 2 is a graph showing various gear ratios which can be used in the embodiment of Figure 1; and

Figure 3 is a schematic drawing showing various different gear pairs to provide the different gear ratios illustrated in Figure 2; and Figure 4 is a cross-sectional view of a second embodiment of the invention.

With reference to Figure 1 an input shaft 64 is provided with an eccentric 63. A balancer 201 is integrally formed with the shaft 64 as shown in Figure 5 to provide balance to the transmission. A cylindrical spline mount 203 is mounted on the eccentric 63 via bearing 205 so that the cylindrical spline mount 203 can rotate relative to the eccentric 63. The spline mount 203 is provided with spline grooves 207. Output gear 30 is provided with splines 221 on its inner circumference and slides onto the spline mount 203 so as to be fixed to the spline mount 203.

The gear 10 is coupled to an output shaft 10a for providing output rotary power.

Also arranged on the spline mount 207 is an inner orbit control gear 220. The orbit control gear 220 has splines 222 which mate with the splines 207 to fix the gear 220 on __. the spline mount 203. The orbit control gear 220 is provided with teeth 224 which are of the same profile as the teeth 34. Arranged about the inner gear 220 is an outer orbital control gear 230. The outer orbital control gear 230 has teeth 234 for engagement with the teeth 224. The teeth 234 have the same profile as the teeth 14 of the gear 10.

Thus, the orbit control gears 220 and 230 are generally the same as the gears 10 and 30, except the gear ratio between the gears 220 and 230 is different to the ratio between the gears 10 and 30. The gears 220 and 230 provide orbit control for the gears 30 and 10 .

The outer gear 230 is held stationary by a brake mechanism 80.

In view of the different gear ratio between the gear pairs 220, 230 and 10, 30, when the input shaft 64 rotates, the gears 220 and 230 will be moved in orbital fashion by the eccentric 63 and spline mount 203 and because of the fixed nature of the gear 230 and the different gear ratios, the gears 10 and 30 will be controlled to undergo orbital motion. In this regard, the orbit control gears 220 and 230 form a progressive or regressive orbit control. Whether the control be progressive or regressive depends on the gear ratio between the gears 220 and 230 compared to that between the gears 10 and 30. In the embodiment described, for example, the ratio of the gears 220 and 230 will be such that the gear pair 220 and 230 undergo an orbital motion which is somewhat slower than that provided to the gears 10 and 30 thereby providing a regressive orbit control. The output gear ratio of the transmission shown in Figure 1 will be dependent upon the gear ratio between the gears 220 and 230 and the gears 10 and 30.

In order for the transmission in Figure 1 to be placed in effective neutral condition, the brake 80 is released so as to release the outer gear 234 to allow the outer gear 234 to simply rotate with the inner gear 220. This brakes the orbital control over the gear pair 10 and 30 so that the gear pair 10 and 30 simply rotate rather than undergo orbital motion thereby effectively placing the transmission into neutral without output power being supplied to the output shaft 10a.

In order to provide a multiple speed transmission according to one embodiment of this invention, the spline 203 accommodates two or more orbital control pairs 220, 230. In the embodiment of Figure 1, a second orbital control pair 220', 230' is shown. The second pair 220', 230' is the same as the first pair 220 and 230 and primed reference numerals are used to designate like parts to the pair 220, 230. The only difference between the pairs 220, 230 and

220', 230' is that the gear ratio between the gear 220 and gear 230 is different to the gear ratio between the gears 220' and 230" .

By selecting which of the gear pairs 220, 230 or 220', 230' controls orbital motion of the gear 30, the output speed of the gear 10 and shaft 10a will be determined. For example, a first output speed can be provided by causing the brake 80 to maintain the gear 230 stationary whilst causing the brake 80' to release to enable the gear 230' to rotate. With this arrangement, the gear pair 220, 230 will control the orbit of the gear 30 and the output speed will be dependent upon the gear ratio between the gears 220, 230 and the gears 10 and 30 as described above and in the copending above mentioned provisional application.

However, if the brake 80 is released to thereby release the gear 230 so that the gear pair 220 and the gear 230 no longer controls the orbit of the gear 30, and the brake 80' is activated to hold the gear 230' stationary so that orbit control is maintained by the gear pair 220' and

230 ' , the output speed of the shaft 10a will be dependent upon the gear ratio between the gears 220' and 230' and the gears 10 and 30 thereby providing a different output speed. Thus, the output speed of the transmission can be determined by simply selecting which of the brake mechanisms 80 or 80' is used to control the orbital motion of the gear 30.

In the embodiment described above, a two speed transmission is provided by the two pairs of gears 220, 230. In other embodiments, further gear pairs could be arranged on the spline mounts 203 which are identical to the pairs shown in Figure 1 except that they would have different gear ratios between the inner gear 220 and the outer gear 230. By selecting the appropriate one of the brakes 80 and releasing the other brakes 80, a selected gear ratio can be provided. For example, if five orbital gear pairs 220, 230 are provided instead of two as shown, a five speed transmission can be provided.

In other embodiments (not shown) , the output 10a can be provided with a plurality of orbital output gear pairs each separately controllable to provide different output speeds . In this embodiment, if a plurality of orbital gear pairs 220 and 230 are provided at the input, and a plurality of output orbital gear pairs are provided at the output the number of output speeds can be increased with fewer gear pairs by controlling one of the input pair and one of the output pair to provide the desired speed. If N pairs are provided on the input and M pairs on the output, the number of speeds available is N x M. The output gear pairs would be coupled together and to the output shaft 10a by a bevel gear arrangement so that rotary output power is transmitted to the output shaft 10a via the selected one of the output gear pairs.

Figure 2 shows a graph illustrating gear ratios which can be obtained and Figure 3 shows schematically various gear pairs 220, 230 each having different ratios which could be mounted on the spline mount 203 to provide eight different output speeds . In Figure 3 , the second and subsequent gear pairs 220, 230 are designated by roman numerals I to VII.

By selecting an appropriate gear ratio between the gears of any pair 220, 230, a gear ratio anywhere on the line shown on the graph of Figure 2 can be obtained.

Figure 2 also shows the number of teeth on the gears 220, 230, the pitch circle diameter of the gears, the module of the gears and the circular pitch of the gears. The reference numerals WT44-47 etc are merely convenient references designating the various gears shown in Figure 3.

For example, the gears 10 and 30 are labelled WT44-47 and WT44-40 in Figure 2 and have 47 and 40 teeth respectively.

The gears 220' and 230' shown in Figure 3 and labelled WT44-V52 and WT44-V59 have 52 and 59 teeth and would provide a gear ratio for the transmission of 29.095:1.

The profile of the gear teeth 222 and 234 and also of the teeth 34 an 14 can be symmetrical. However, if an anisotropic gearbox is required as disclosed in our above mentioned provisional application, the gear teeth can be arranged to have different profiles as disclosed in our above mentioned provisional application.

Furthermore, the profile of the gear teeth 14, 34, 222 and 234 is preferably sinusoidal as disclosed in our international application No. PCT/AU97/00443. The contents of this international application, together with the contencs of our above mentioned copending provisional application are incorporated into this specification by this reference.

Figure 4 shows a second embodiment of the invention which is in the form of a transmission for an electric drill which can be battery or mains powered.

The drill has an electric motor 300 which is supported by inner casing 304 by bolts 306. The inner casing 304 is arranged within outer casing 308. A flange member 310 may screw or otherwise fit about the outer casing 308 adjacent the electric motor 300 to secure the inner casing 304 and outer casing 308 together. The motor 300 has a drive shaft 302 which is coupled to stem 303 which is integral with or otherwise connected to an eccentric 316. The eccentric 316 has a stub 317 which is journaled in a recess in output shaft 344. The stem 303 may carry a counter weight 312 for balancing the transmission to be described hereinafter.

A splined sleeve 318 is mounted on the eccentric 316 via bearings 315.

A first inner gear 320 is formed on the blind shaft 318 and may be integral with or otherwise connected to the spline shaft 318. The inner gear 320 has external teeth 326. A first inner orbit gear 330 with external teeth 327 is provided on splines 321 of the spline sleeve 318. A second inner orbit gear 334 is also provided on the splines 321 of the spline shaft 318. The gears 330 and 334 simple slide onto the spline shaft 318 as described in the earlier embodiment. The gear 334 has external teeth 331.

An outer orbit gear 322 surrounds the gear 320 and has internal teeth 324 for meshing with teeth 326 of the gear 320. A second outer gear 328 is provided around the gsar 330 and has teeth 339 for meshing with the teeth 327 of the gear 330. A third outer gear 322 surrounds the gear 334 and has teeth 329 for meshing with teeth 331 of the gear 334.

The gear pairs 320-322, 330-328 and 334-332 have different gear ratios from one another.

An inner output gear 336 is also provided on the spline 321 of the spline shaft 318 and the gear 336 has teeth 333. An outer output gear 338 is provided around the gear 336 and has internal teeth 335 which mesh with the teeth 333. The output gear 338 is fixed to flange 342 of an output shaft 344 by bolts 336. The output shaft 344 carries a chuck 346 for receiving a drill bit as is know. The output shaft 344 is supported in casing 308 by bearings 349.

The outer gears 332, 328 and 338 are slightly spaced from another and ball bearings 390 are disposed between the respective gears. End ball bearings 392 are also provided at the outer sides of gears 322 and 338. The end ball bearings 392 are supported by bearing tracks 393 which may be fixed to the gear 338 and track 358 which may be fixed to the gear 322. The ball bearings 392 are also supported by the casing 308 and the inner casing 304 as shown. The ball bearings 390 are retained in place by rings 390.

A slide housing 372 is fixed on the casing 308 and receives a plunger 360. The plunger 360 has a pin 361 to which is connected a handle 372. A spring 369 is provided within the housing 370 and against the plunger 360 so as to bias the plunger downwardly in Figure 4. The plunger 360 has end portion 371 which is dimensioned to fit within any one of a number of grooves 380 formed in the outer surface of the gears 322, 328 and 332.

In Figure 1 the plunger 360 is shown in engagement with the outer gear 322 so as to fix the outer gear 322 stationary. ,-

When input drive is supplied from the electric motor 300 to the eccentric 316 via shaft 302 and stub 303 the eccentric is rotated which causes the inner gears 320, 330 and 334 to orbit within their respective outer gears 322, 328 and 332. Because the outer gears 328 and 338 are not restrained they are simply able to rotate and in effect supply no output drive. Because the outer gear 322 is fixed by the plunger 369 the inner gear 322 is caused to execute an orbit within the outer gear 322 which controls orbital motion of the output inner gear 336 so the output inner gear 336 also executes an orbit within the gear 338 so as to in part drive to the gear 338 and cause the gear 338 to rotate about the central axis of the shaft 302, and stem 317 to rotate the upward shaft 344 and therefore the chuck 346 to drive a drill bit.

If it is desired to change the speed of the transmission the handle 372 is lifted to pull the end 371 away from the groove 380 in the outer gear 322 and the housing 370 is slid to the left in Figure 4 so as to engage one of the other outer gears 328 or 338. Figure 4 shows, in phantom, the housing 370 'moved into a position where the end 371 can engage in one of the grooves 380 of the outer gear 338 to thereby fix the outer gear 338 so that the orbital motion of the output inner gear 336 is controlled by the gear pair 338 and 334. The gear ratio of the gears 338 and 334 is different to the gears 320 and 322 so that different drive ratio is supplied to the output shaft 344. Similarly, the housing 370 can be slid so that the gear 328 is fixed and the gear 328 and 330 control the orbital motion of the inner gear 336 to supply yet a further drive ratio. Thus, by movement of the housing 370 any one of three output drive ratios can be selected for the drill.

The housing 370 is mounted on the casing 303 for sliding movement in grooves (not shown) or the like.

Once again, in this embodiment the orbital control is provided by fixing stationary one of the outer gears 322, 328 or 338 by a brake mechanism formed by the plunger 360. Whilst the control of the preferred embodiment is a fixing of one of these outer gears, the control could enable a controlled rotation of the outer gear rather than a fixing of the outer gear so that one of the gear pairs 322 320 or 330 328 or 334 338 ensures that the output inner gear 336 executes an orbit so as to drive the outer gear 338 in a rotary fashion to supply output rotary power. If there is no control over any one of the outer gears then the outer gears will simply freely rotate under the influence of the moving inner gears and no drive will be transmitted from the inner output gear 336 to the outer output gear 338 and hence the output shaft 344.

Thus, the embodiment of Figure 4 describes a very compact three speed transmission suitable for an electric drill or the like which is very strong and robust, able to transmit considerable torque and very compact compared to spur gear systems which would provide the same drive ratios.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiments described by way of example hereinabove.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A multiple speed orbital transmission, including: an input; an output; an output orbital gear pair coupled to the output, the output orbital gear pair having an orbiting gear and a rotary gear so that when input power is supplied to the input, the orbiting gear can orbit relative to the rotary gear and drive the rotary gear to provide rotary output power to the output; orbit control means for maintaining orbital motion of the orbiting gear; at least one further orbit gear pair coupled to the input or the output and including a further orbiting gear and an orbit control gear; and speed switch means for controlling the orbit control means and the at least one further orbit gear pair so as to selectively maintain or release the orbit control exerted by the orbit control means or the orbital motion of the at least one further orbit gear pair, so that the speed of the output rotary power is selected dependent upon which of the at least one further orbit gear pair or orbit control means is controlled by the switch means to maintain orbital motion.

2. A multiple speed orbital transmission as claimed in claim 1, wherein the orbit control means comprises a first orbit control gear pair at the input including an inner orbiting gear and an outer control gear; the at least one further orbit gear pair being coupled to the input and comprising a further inner orbiting gear and a further outer control gear; and wherein the speed switch means comprises a brake means associated with each of the outer control gears for selectively maintaining the outer control gears stationary so that when one of the outer control gears is maintained stationary, the inner orbiting gear associated with that outer control gear controls orbital motion of the output orbital gear pair so output rotary power is transmitted to the output, and when the brake means releases the outer control gear, the outer control gear is able to rotate so that the orbital control is no longer maintained so that no power is transmitted via the orbit gear pair in which the orbit control is released.

3. A multiple speed orbital transmission as claimed in claim 2, wherein the brake means is a mechanical brake which holds the outer control gears selectively stationary or releases them for rotary movement.

4. A multiple speed orbital transmission as claimed in claim 2, wherein the brake means is a magnetic arrangement in which magnetic fields are used to selectively brake and hold the outer control gear stationary or release the outer control gear for rotary movement.

5. A multiple speed orbital transmission as claimed in any one of the preceding claims, wherein the orbit control means forms one of the further orbit gear pairs at the input .

6. A multiple speed orbital transmission as claimed in any one of the preceding claims, wherein the orbit control means includes a stationary orbit control plate and pin arrangement which is selectively released or controlled with at least one further orbit gear pair at the input or the output .

7. A multiple speed orbital transmission as claimed in claim 6, wherein, if the plate and pin arrangement is controlled to maintain the orbital control over the output orbital gear pair, the gear ratio of the transmission is set merely by the gear ratio between the orbiting gear and rotary gear of the output gear pair.

8. A multiple speed orbital transmission as claimed in either claim 6 or 7, wherein, if the plate and pin arrangement is released so as to release the orbit control and orbit control is provided by the further orbit gear pair at the input, the gear ratio depends upon the gear ratio of the further orbit gear pair and the output orbital gear pair.

9. A multiple speed orbital transmission as claimed in any one of the preceding claims, wherein, if the further output gear pair is provided at the output, the multiple speed output is provided by controlling output through either the output orbital gear pair or the further orbit gear pair at the output so that different output speeds are provided by controlling either the output gear pair or the further orbit gear pair at the output .

10. A multiple speed orbital transmission as claimed in any one of the preceding claims, wherein the orbit control is maintained by an orbit control gear pair or stationary plate and pin assembly or by brake means arranged with the output orbital gear pair and further orbit gear pair at the output .

11. A multiple speed orbital transmission as claimed in any one of the preceding claims, wherein the input comprises a shaft having an eccentric and the further orbit gear pairs are arranged on the eccentric .

12. A multiple speed orbital transmission as claimed in any one of the preceding claims, wherein the output comprises a shaft coupled to the rotary gear of the output gear pair.

13. A multiple speed orbital transmission as claimed in any one of the preceding claims, including a plurality of orbital gear pairs at the input and a plurality of orbital gear pairs at the output, whereby, by controlling an appropriate one of the input gear pairs and an appropriate one of the output gear pairs, a multiple speed transmission is provided having N x M speeds where N is the number of orbital gear pairs at the input and M is the number of orbital gear pairs at the output and with each of the orbital gear pairs having a different gear ratio.

14. A multiple speed transmission, including; an input for receiving rotary power; an eccentric coupled to the input; a plurality of orbit gear pairs each comprised of an inner gear mounted on the eccentric and having external teeth, and an outer gear having internal teeth for meshing with the external teeth of the respective inner gear; an output; an output orbit gear pair having an inner output gear mounted on the eccentric, the inner output gear having external teeth, an outer output gear having internal teeth which mesh with the external teeth of the inner output gear, the outer output gear being coupled to the output; and control means for controlling the outer gears so that drive is supplied from the input via one of the orbit gear pairs selected by the control means to the output orbit gear pair and therefore to the output.

15. A multiple speed transmission as claimed in claim 14, wherein the control means comprises a brake means having a plunger spring biased towards said orbit gear pairs, the plunger being slideable so as to align the plunger with one of the orbit gear pairs for engaging the outer gear of said one of the orbit gear pairs .

16. A multiple speed transmission as claimed in either claim 14 or 15, wherein the outer gears have grooves or recesses on an outer peripheral surface which are engageable by the plunger to fix stationary the outer gear of the selected orbit gear pair.

17. A multiple speed transmission as claimed in any one of claims 14 to 16, wherein the input comprises a shaft portion coupled to or integral with the eccentric.

18. A multiple speed transmission as claimed in any one of claims 14 to 17, wherein the outer gears have bearings arranged between them.