WO2008044049A2

WO2008044049A2 - Actuator arrangements

Info

Publication number: WO2008044049A2
Application number: PCT/GB2007/003898
Authority: WO
Inventors: Jonathan C. Wheals; Keith Ramsay; Andrew Turner; James Mcmickin
Original assignee: Ricardo Uk Ltd.
Priority date: 2006-10-13
Filing date: 2007-10-15
Publication date: 2008-04-17
Also published as: WO2008044049A3; GB0720153D0; GB2442878A

Abstract

A vehicle transmission has an actuator with an output shaft, which is movable for independent operation of two gear shift devices and a clutch. The output shaft is movable in an axial direction and in a rotary sense. The gear shift devices and the clutch each have an associated input member. The output shaft includes a selection finger, which is movable for engagement with a respective input member. The gear shift devices are located at one end of the actuator and the clutch is located at the opposite end of the actuator. The input member for the clutch includes a shaft which extends back through the output shaft and actuator. An electromagnetic latch, is used to hold the clutch in a closed state.

Description

Actuator arrangements

The present invention relates to actuator arrangements, more particularly, but not exclusively, to actuator arrangements for use in vehicle transmissions.

Conventional multi-speed gear transmissions for vehicles are well-known and generally comprise multiple gear pairs selectable on demand by the vehicle driver via a gearshift lever. Ratio selection is generally via a 'rail' which is movable axially from a neutral position to engage a loose gear via a synchroniser hub. Typically, a transmission having five forward ratios and one reverse ratio will include three double acting rails.

In recent years transmissions have been developed in which clutch engagement and gear ratio change is controlled using actuators, typically with each clutch and gear shift rail being operated by its own actuator.

There is a constant demand within the transmission industry to minimise parts and assembly costs. Also, there is an increasing emphasis on minimising the size of transmissions. Therefore, there is a need for an improved transmissions which addresses one or more of the above issues.

According to one aspect of the invention, there is provided an actuator arrangement for operating two or more controllable devices independently of one another, including an actuator having an output member, wherein the output member is movable in an axial direction and in a rotary sense for selective communication with the controllable devices.

According to another aspect of the invention, there is provided a vehicle transmission including an actuator for operating two or more controllable devices independently of one another, wherein the actuator includes an output member, which is movable in an axial direction and in a rotary sense, for selective communication of the output member with the controllable devices. The transmission will typically include a casing and the actuator may be located within the transmission casing. However, in other embodiments the actuator may be mounted on or adjacent the transmission casing, e.g. in a dedicated housing mounted on an outer wall of the casing.

According to a still further aspect of the invention, there is provided a vehicle transmission including an actuator having an output member which is movable for operating two gear shift devices and a clutch, brake or other device, wherein the gear shift devices and clutch/brake/other device are operable independently of one another using said output member.

Such arrangements are advantageous in that they reduce the number of actuators that would otherwise be required for operating the transmission. This can have a beneficial effect in reducing the number of components and/or the weight and/or the assembly time for a vehicle transmission. The space occupied by the transmission can also be reduced.

According to another aspect of the invention, there is provided an actuator arrangement having an actuator with an output member which is movable to provide an output force, and the arrangement further having two or more controllable devices arranged for cooperation with said output member for receiving said output force, wherein the arrangement is configured for the selective actuation of said controllable devices.

The arrangement is preferably configured for controlling the devices independently of one another via said output member.

The actuator arrangement is preferably configured for use with a vehicle transmission.

The actuator preferably includes a linear actuator (e.g. of the kind referred to in PCT/GB2006/003521)j which is arranged for operating two or more gear engagement devices (e.g. gear shift rails) and at least one additional controllable device within a vehicle transmission. It may be preferred to utilise a rotary actuator for the selection of gear shift rails and the or each additional device.

The additional controllable device(s) may include one or more additional gear or clutch engagement devices, park brake devices (e.g. of friction or positive engagement type), a valve (e.g. a spool type valve) or valve controller, a piston, or a diaphragm pump arranged for providing local oil flow for lubrication, cooling or other hydraulic supply within a vehicle, including for suspension, PAS etc.

In a preferred embodiment, the actuator arrangement forms part of an automated manual transmission or a dual clutch transmission, and is preferably used to modulate the force applied to open or close at least one clutch, in addition to operating gear shift rails.

In a preferred embodiment, the arrangement includes an additional actuator for selectively controlling the position of the output relative to an operative connection with each of said controllable devices. The additional actuator preferably takes the form of a rotary actuator for rotating a drive member between a first position in which the drive member is arranged for operating a first controllable device, and a second position in which the drive member is arranged for operating a second controllable device. The arrangement preferably includes one or more additional positions for said drive member, preferably intermediate the first and second positions, whereby in each additional position the drive member is arranged for operating a respective additional controllable device.

It may be preferred for the drive member to have an additional position on either side of the first and second positions, as well as or as an alternative to the intermediate position. The additional positions may be associated with separate controllable devices or the same device. Hence, in one embodiment the drive member defines five radial positions, wherein positions one, three and five are associated with driving the same clutch, and wherein positions two and four are associated with separate gear shift forks or rails. In another embodiment, the additional actuator may take the form of a linear actuator, wherein the drive member is movable in a linear direction, e.g. using a slide arrangement between its various operative positions.

There is also provided a vehicle transmission, preferably an automated manual transmission (AMT) or a dual clutch transmission (DCT), including an actuator arrangement according to the above aspect of the invention.

According to another aspect of the invention, mere is provided a latching arrangement for an actuator of any of the above aspects of the invention, e.g. for holding a clutch in a closed state so that the actuator can be used to perform additional tasks, such as gear shift operations, whilst the clutch is closed. The latching arrangement preferably includes an electromagnet arrangement.

According to a further aspect of the invention, there is provided an monostable latching arrangement (e.g. electromagnetic) or bi-stable latching arrangement (e.g. electromagnet plus permanent magnet or a known mechanical flip flop device), for holding a clutch in a closed state, e.g., in a dual clutch transmission.

According to another aspect of the invention, there is provided an actuator arrangement for use in controlling multiple gear shift rails, the arrangement including an actuator having an output member and a selection mechanism for selectively coupling said output member wifh a respective gear shift rail, e.g. for operating a first gear shift rail independently of a second gear shift rail.

In one embodiment, each gear shift rail has an input member, and the output member of the actuator includes a selection member for engagement with the shift rail input members. The output member is preferably rotatable so as to position the selection member for operative engagement with a respective input member. In another embodiment, a pivot member is coupled to the output member, wherein the pivot member can be pivoted between a first position in which one rail is engaged, and a second position in which another rail is engaged. The pivot member preferably has a passive position in which neither rail is engaged. Solenoids are preferably included for controlling movement of the pivot member, e.g. to drive the pivot member into engagement witii a respective rail.

In a simple embodiment of the above aspect of the invention, there is provided a linear actuator arrangement for use in driving first and second input members, wherein the arrangement has an output member and a selection mechanism, preferably including a pivot control, for selectively coupling said output member with a respective input member, e.g. for operating a first input member independently of a second input member.

According to still a further aspect of the invention, there is provided an actuator arrangement for operating multiple controllable devices, the arrangement including a linear actuator having an output member and a selector device arranged for selectively transmitting load from the actuator to one or more of the controllable devices.

The output member preferably includes an array of fingers arranged for transmitting load from the output member to the selector device.

The selector device preferably includes an array offeree transfer members for selective alignment with the fingers of the output member, e.g. for selectively defining a load path between the actuator and one or more of the controllable devices.

The selector device is preferably in the form of a rotatable barrel, which defines an array of axial bores, and wherein the transfer members consists of rods, which are axially movable within bores,, e.g. for transmitting load from the actuator to a controllable device. The transfer members may be configured for positive engagement with an input member of a controllable device, e.g. for bi-directional shunting of the input.

According to another aspect of the invention, there is provided a coupling arrangement for selectively coupling a controllable device to a linear output member.

The arrangement preferably includes a rocker member, which is selectively engagable with a linear output member. The rocker member is preferably mounted on a device intended for axial movement with said output member, e.g. a gear shift fork in a vehicle.

The output member preferably includes a notch, detent or other formation with which the rocker member is intended for positive engagement, e.g. for coupling the device for movement with the output member.

In a preferred embodiment, a solenoid is used for controlling movement of the rocker member relative to the output member. Under normal operating conditions, it is preferred if the rocker member is biased into engagement with a stop on an adjacent ground surface, e.g. an aperture or recess in a transmission casing, to prevent axial movement of the rocker and hence the associated device. The rocker member is preferably selectively movable from engagement with the stop and into engagement with the output member, e.g. by a solenoid.

A plate is preferably arranged between an output of the solenoid and the rocker member. The plate preferably has an axial length, which is at least as long as the intended axial travel of the rocker member once coupled with the output member, e.g. so that the rocker is able to maintain contact with the plate during axial movement of the output member, so as to be held in engagement with the output member.

The rocker member preferably includes a first portion arranged for engagement with the stop and a second, portion arranged for engagement with the output member. Many of the above aspects are described with reference to one or more 'rails^*. However, it will be understood that the actuators and arrangements can be used for controlling other devices or linkages capable of transmitting force in a single or bi-directional sense, whether linear or rotary.

Other aspects and features of the invention will be readily apparent from the following description of preferred embodiments of the invention, made by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective view showing a preferred actuator arrangement for a vehicle transmission;

Figure 2 is a different perspective view of the arrangement of Figure 1;

Figure 3 is a schematic side view of a control rod for operating a clutch or other controllable device using the arrangement of Figures 1 and 2 and an exploded view of a preferred latch arrangement;

Figure 4 is a schematic part cross-sectional perspective view of an alternative selection mechanism;

Figure 5 is a plan view of the mechanism from Figure 4;

Figure 6 is a schematic side view of a modified actuator arrangement;

Figure 7 is a schematic side view of a coupling arrangement for a linear actuation mechanism for use with a vehicle transmission;

Figure 8 is a schematic cross-section through a portion of the arrangement in Figure 7; and

Figure 9 is similar to Figure 8, showing the arrangement in an operative condition. Referring to Figures 1 and 2, an actuator arrangement for use in a vehicle transmission is indicated generally at 100. The arrangement 100 is operable to control the actuation of first and second gear shift rails 102, 104 and a clutch 106, only a portion of the latter being shown in the Figures. The clutch 106 is provided on the opposite side of the arrangement 100 to the gear shift rails 102, 104, although the clutch could be provided on the same side as the shift rails, if desired.

The arrangement 100 includes an actuator housing 108 for a linear actuator 110 and a rotary actuator 112. The actuators 110, 112 are operable to control the movement of a shaft, a portion of which is shown in an extended position relative to the housing 108 at 114, to the left of the housing 108 as viewed in Figure 1. The drive shaft 114 is simply supported in bearings (not shown) within the housing 108, and is movable in an axial direction under the influence of forces generated by the linear actuator 110, as well as in a rotary direction under the influence of forces generated by the rotary actuator 112, Hence, the drive shaft 114 can be moved axially from left to right (and vice versa) as viewed in Figure 1, as well as in clockwise and anti clockwise directions.

In this embodiment, the drive shaft 114 forms part of a moving magnet armature which is displacable within a tubular stator housing, for example of the kind shown in PCT/GB20067003521. Of course, other forms of actuator can be used, as appropriate.

A drive finger 116 is provided at the end of drive shaft 114 and is movable to engage one of three selection members 118, 120 and 122, Each selection member 118, 120, 122 includes a jaw 119 into which the drive finger 116 can be engaged, for transmitting output forces from the actuators to the respective selection members 118, 120, 122. The jaw 119 is two sided, so as to be capable of receiving push or pull forces from the drive finger 116. Single sided drive members may also be applied. Selection member 118 forms part of a fork 124 which is operable to provide linear push/pull actuation of gear shift rail 102. Selection member 120 forms part of a similar fork 126 arranged to provide corresponding actuation of gear shift rail 104. Selection member 122 forms part of a clutch rod 128 for controlling actuation of the clutch 106. The clutch rod 128 is shown most clearly in Figure 3 and includes an elongate portion 130 configured to extend back through the actuator housing 108 and drive shaft 114, concentric therewith, for operating a controllable device on the opposite side of the actuator 110.

The arrangement 100 is shown in a neutral position in Figures 1 and 2, wherein the drive shaft 114 is in a de-energised non-force transmitting state, such that neither gear shift rail 102, 104 or clutch 106 are experiencing actuation forces via the drive shaft 114.

As mentioned above, the drive shaft 114 is rotatable in the actuator housing 108 via the rotary actuator 112, Hence, with the drive shaft 114 in the neutral position shown in Figures 1 and 2, the drive finger 116 can be rotated clockwise or anti clockwise into engagement with the jaw 119 of either selection member 118 or 120. An operating force can then be transmitted to the respective gear shift rail 102 or 104 by subsequently displacing the drive shaft 114 in an axial direction via the linear actuator 110. It will be understood that the rails 102, 104 are therefore operable independently of one another, unless an interlock device is included. However, the arrangement 100 is preferably always configured so that the two gear rails 102, 104 are prevented from simultaneous gear engagement.

In this embodiment, the clutch rod 128 is permanently arranged with its selection member 122 in an intermediate position of angular displacement between the selection members 118 and 120. In this position, the clutch rod selection member 122 is offset axially from the selection members 118 and 120 (to the left as viewed in Figure 1 and 2). Therefore, to drive the clutch rod 128₃ the drive shaft 114 has to be axially displaced via the linear actuator 110 in order to bring the drive tooth 116 into a position capable of engagement with the clutch rod selection member 122. Rotation of the shaft 114 may be required to bring about a mechanical coupling between finger 116 and the jaw 119 on the clutch rod selection member 122, after said axial displacement. Once engaged, the clutch rod 128 can then be axially displaced via the linear actuator 110, so as to operate the clutch 106.

It is preferred if the clutch is naturally open, e.g. in a DCT transmission, whereby the clutch has to be operated via the clutch rod 128, in order to move to a closed state. For reasons of efficiency or to enable the linear actuator to perform additional tasks, it may be desired to hold the clutch in a closed state, independently of the linear actuator.

A pivot rod 136 acts a movable input for controlling the clutch 106. One end of the rod 136 is mounted in a block 142. A spring (which in this embodiment is a cone or Belville or fingered diaphram spring 144) is mounted between the block 142 and a ferrous armature 138, preferably in a generally relaxed state. The block 142, spring 144 and armature 138 are movable together in an axial direction, as a single unit, in order to operate the clutch 106 via rod 136.

An electromagnet 140 is arranged for cooperation with the armature 138, for latching the clutch in a closed state, as described below.

In this embodiment, the electromagnet 140 is annular and the block 142 is configured for movement within the bore of the electromagnet 140, whereas the diameter of the armature 138 exceeds the diameter of the bore, such tiiat movement of the armature 138, e.g. to the left in Figure 3, is inhibited by the electromagnet 140.

When the clutch rod 128 is displaced axially to the left as viewed in Figure 3 (i.e. by the linear actuator), plate 132 on the end of rod 128 urges the armature in an axial direction, whereby load is transferred to the pivot rod 136 through the block 142, thereby causing the clutch 106 to close. When the clutch has 106 has been moved to a closed state, any further travel of clutch rod 128 to the left as viewed in Figure 3 compresses spring 144 and the armature 138 is brought into abutment with the electromagnet 140.

The electromagnet 140 is controlled by the transmission ECU and can be energised (prior to or upon abutment by the armature 138) so as to hold the armature 138 against the electromagnet 140. The spring 144 is therefore held in its compressed state, and the clutch 106 is held in its closed state by rod 136, independently of the linear actuator or rod 128.

The electromagnet is preferably energised before abutment to assist the linear actuator in compressing the spring 144.

The spring 144 preferably has a non-linear over centre characteristic. Slip control of the clutch once substantially engaged can then be achieved via the linear actuator. This can be useful in modulating the control of the clutch, e.g. to damp against torsional vibrations from the engine.

The clutch 106 preferably incorporates a self adjusting bearing or other such adjustment device to account for wear within the clutch.

The arrangement 100 can be used to operate an AMT or DCT. In a preferred embodiment, there are provided two of said arrangements 100, wherein each actuator housing 108 is independently operable. Such dual actuator arrangements can be configured for full operation of the gears and clutches in a dual clutch transmission.

For AMT applications the latch should maintain state upon failure, and so may be of a bi-stable type such a biro-type latch or bi-stable magnet, e.g. of the kind shown in GB0521036.4, in order to hold the clutch in its closed state. In such designs no energy is expended except during state transitions.

In the embodiment of Figures 1 to 3, the arrangement 100 is configured for operating two controllable devices on one side of the actuator (e.g. gear rails) and a single controllable device on the opposite side of the actuator (e.g. a clutch), using only one end of the movable output member of the actuator 100. Indeed, in this embodiment the output member only projects from one end of the housing 108. This arrangement can be used for operating two clutches or two brakes, for example, rather than two gear rails. The rod 128 which passes back through the actuator housing 108 can then be used to operate another form of controllable device within the transmission, such as a valve or a pump, in particular when the clutches or brakes are not in operative communication with the actuator 110.

In another embodiment, a selection arrangement may be provided at the output end of the clutch rod 128, wherein the clutch 106 and/or one or more additional controllable devices can be selectively operated when the selection member 122 on the clutch rod 128 is in operative engagement with the drive finger 116.

It may be useful for the drive shaft 114 to incorporate a plurality of drive fingers 116, e.g. radially spaced fingers 116, so as to minimise the degree of movement required to bring the drive shaft 114 into operative association with an input member (e.g. selection members 118_» 120, 122) of a controllable device.

Ih a further embodiment, the drive shaft 114 can project from both ends of the actuator housing 108, with each end having one or more drive fingers 116 arranged for operative engagement or association with one or more controllable devices, wherein each controllable device has some form of input member or drive slave arranged adjacent a respective end of said actuator housing, for receiving drive or output from the drive fingers 116.

An alternative arrangement for selecting between gear shift rails is indicated in Figures 4 and 5, wherein a linear actuator 200 includes an output shaft 202 arranged in communication with a pivot member 204, which is movable for operative engagement with a respective gear shift rail 206, 208.

Each gear shift rail 206, 208 includes a detent 210. A pair of opposing solenoids 212 are arranged to act on levers 214, for selectively moving the pivot member 204 into engagement with a detent on a respective rail 206, 208. Once engaged, the output 202 of the linear actuator 200 can be moved axially so as to drive the selected rail 206, 208 via the engagement with the pivot member 204. Hence, the two rails 206, 208 are movable independently of one another. The pivot member 204 is disengaged from the selected rail when the associated solenoid is deenergised.

In this embodiment, the levers 214 move about pivots 216, so as drive against curved surfaces 218 on the inner end of the pivotable selector member 204, so that the pivot member pivots about pin 220, The arrangement is such that actuation of a first solenoid causes the pivot member to engagement the rail 206, 2OS which is on the same side as the solenoid.

A modified actuator arrangement 300 is shown in Figure 6. This embodiment may be used as a replacement for the arrangement in Figures 1 to 3, or in other actuator applications requiring at least one linear input.

The arrangement 300 includes an actuator 302 having an output shaft 304, which is reciprocable in a housing 306. The shaft 304 is axially movable, right to left as viewed in Figure 6. The actuator 302 may also include means for rotating the shaft 304, e.g. a rotary actuator coupled therewith or included in the housing 306.

Although shown extending from only one end of the housing 306, the output shaft 304 may extend from both ends of the housing, e.g. for use in actuating one or more devices on each side of the actuator. The linear actuator is preferably, but not exclusively, a moving magnet armature, e.g. of the kind shown in PCT/GB2006/003521. In other embodiments the actuator may be hydraulically controlled. The output member 304 may form part of any other linear actuation mechanism, e.g. a motor driven ratchet type device.

The shaft 304 includes an output adaptor 308, which includes an array of fingers 310.

In this embodiment, the actuator 302 is arranged for use with multiple controllable devices, in the form of a selection of linear gear shift rails 312, arranged in parallel with one another, and which are intended for movement in an axial direction, e.g. left to right as viewed in Figure 6. In other embodiments, the rails may be replaced by input members for other controllable devices, e.g. devices requiring an input force from the actuator, such as pistons, pumps, brakes or clutches.

A selector device 314 is arranged, between the actuator 302 and the rails 312, the selector device including an array of force transfer members 314. Li use, the actuator drives the output member, so as to drive the selection fingers in the direction of the selector device, to the right as viewed in Figure 6. Dependent upon the relative position between the fingers, force transfer members and the rails, a load path may be defined between the actuator and one or more of the rails.

Actuator sequences and combinations can be easily defined by a simple change of the array of fingers and/or transfer members.

The selector device 314 may be axially movable, so as to be displaceable by the selection fingers 310 and for transmitting load from the actuator 302 to the rails ^• 312. However, in a preferred embodiment, the selector device is in the form of a barrel, which is fixed against axial movement, but which is rotatable about a centreline of the actuator for locating the transfer members 314 in a desired position relative to the selector fingers 310 and/or the rails 312. In such embodiments, the barrel defines an array of axial bores 316 and the transfer members consists of rods, which are axially movable within bores, for transmitting load to the rails.

The barrel may be of plastic material with inherent bearing properties (for supporting the movement of the rods). The barrel may be rotated directly by any form of actuator, but preferably electromagnetic type actuators/motors.

Coupling means for permitting bi-directional movement of the rails may be included, for example a jaw formed on the end of each rod for positive engagement with the input device (rail). Engagement may also be via detents either spring or magnetic type, for example. The rods may be used for operating or forming part of an hydraulic connection, e.g. for operating a piston or a pump, in which case, the bores may include seals, which may preferably be configured to compress and prevent leakage under the first portion of linear travel of the actuator.

Referring now to Figures 7 to 9, there is shown an arrangement 400 for selectively coupling one or more controllable devices 402 to a linear output member 404.

The linear output member 404 is axially movable, left to right as viewed in Figure 7, and may form part of the output member from a moving magnet armature device, e.g. as shown in PCT/GB2006/003521 , or any other linear drive mechanism.

In this embodiment, the output member 404 is arranged for use with multiple controllable devices, in the form of a selection of linear gear forks 402, which are intended for movement in an axial direction, e.g. left to right as viewed in Figure 7. m other embodiments, the forks may be replaced by input members for other controllable devices, e.g. devices requiring an input force from the output member, such as pistons, pumps, brakes or clutches.

The output member 404 includes an array of notches or detents 406. A coupling arrangement, as most clearly indicated in Figures 8 and 9, is provided for selectively coupling a fork 402 with the output member 404, via a detent 406 in the output member, to enable axial movement of the fork with the output member.

The coupling arrangement includes a rocker 408, which is pivotably mounted on a respective fork 404, A linear actuator, which in this embodiment is a solenoid 410, is arranged to act on the rocker via a plate 412. Under normal operating conditions, the rocker 408 is biased by a spring 414 into engagement with a stop on an adjacent ground surface, e.g. an aperture or recess 416 in a transmission casing 418. The fork 402 is held against axial movement through the engagement of the rocker 408 with the stop 416. In any case, the rocker is held away from the output member by the action of the spring (see Figure 8). However, the solenoid can be operated to urge the plate against the rocker, so as to disengage the rocker from the stop and pivot the rocker in the direction of the output member, against the bias of the spring, for engagement of the rocker member with the detent on the output member.

The plate 412 has an axial length, as best viewed in Figure 7, which is at least as long as the intended axial travel of the fork 402, so that the rocker 408 is able to maintain contact with the plate 412 during axial movement of the fork under the action of the output member 404.

In this embodiment, the rocker 4OS is generally L-shaped, wherein the end of one limb is arranged for engagement with the stop and the end of the other limb is arranged for engagement with the notch or recess,

Although the above embodiments have been described with particular respect to then- use in vehicle transmissions for operating gear rails, clutches, brakes and the like, the invention may be applicable to other mutli device arrangements requiring a single master actuator arranged for selective actuation of two or more controllable devices- such as pistons, pumps and valves, not necessarily transmission or vehicle related devices.

Claims

1. An actuator arrangement for a vehicle transmission, wherein the arrangement is configured for operating two or more controllable devices independently of one another, the arrangement including an actuator having an output member, which is movable in an axial direction and in a rotary sense, for selective communication with the controllable devices.

2. An actuator arrangement according to claim 1 wherein each controllable device includes an input member which is drivable to operate the associated device, and wherein the arrangement includes a drive member in association with said output member, which is movable for selective engagement with a respective input member.

3. An actuator arrangement according to claim 1 wherein the output member is rotatable in order to position the drive member for engagement with a respective input member.

4. An actuator arrangement according to claim 3 wherein the output member is rotatable, for movement of said drive member between a first position in which the drive member is arranged for operating an input member of a first controllable device, and a second position in which the drive member is arranged for operating an input member of a second controllable device.

5. An actuator arrangement according to claim 4, including one or more additional positions for said drive member, preferably intermediate the first and second positions, whereby in each additional position the drive member is arranged for operating a further controllable device.

6. An actuator arrangement according to claim 5 wherein first and second controllable devices are arranged on one side of actuator and wherein a further controllable device is arranged on an opposite side of the actuator.

7. An actuator arrangement according to claim 6 wherein the further controllable device is operable using a drive rod which extends back through the actuator.

8. An actuator arrangement according to any preceding claim wherein the output member is arranged for operating two gear shift rails and at least one of a gear or clutch engagement device, a park brake device, a valve or a pump.

9. An actuator arrangement according to any preceding claim wherein the actuator arrangement forms part of an automated manual transmission or a dual clutch transmission, and is arranged for modulating the force applied to open or close at least one clutch, in addition to operating gear shift rails.

10. A vehicle transmission and an actuator for use therewith, the actuator having an output member which is movable to provide an output force for operating two gear shift devices and a clutch or brake device independently of one another.

11. A vehicle transmission according to claim 10 wherein the output member is movable in an axial direction and in a rotary sense, and wherein the actuator includes a linear actuator for controlling the axial movement of the output member, and a rotary actuator for controlling the rotary position of the output member.

12. A vehicle transmission according to claim 11 or claim 12, wherein the gear shift devices and the clutch/brake each have an associated input member, and wherein the output member includes a selector member which is movable for selective engagement with a respective input member, in order to operate the associated gear shift device or clutch/brake.

13. A vehicle transmission according to claim 12 wherein the output member is arranged for engagement of the selector member with the input members at one end of the actuator.

14. A vehicle transmission according to claim 13 wherein the gear shift devices are located at one end of the actuator and the clutch/brake is located at the opposite end of the actuator.

15. A vehicle transmission according to claim 14 wherein the output member includes a central bore and wherein the input member for said clutch/brake includes a shaft which extends back through the output member and actuator, so as to be movable to operate the clutch/brake on the opposite side of the actuator, if the input member of the clutch/brake is in engagement with the selector member.

16. A coupling arrangement for selectively coupling a controllable device to a linear output member, the arrangement including a rocker member, which is selectively engagable with the linear output member, wherein the rocker member is mounted on a device intended for axial movement with said output member, once engaged therewith.

17. A coupling arrangement according to claim 16, including a linear actuator, e.g. a solenoid or stepper motor, for controlling movement of the rocker member relative to the output member between non-engaged and engaged states.

18. A coupling arrangement according to claim 17, including a plate arranged between an output of the solenoid and the rocker member, wherein the length of the plate corresponds at least to the intended axial travel of the rocker member once coupled with the output member.

19. A coupling arrangement according to any of claims 16 to 18 wherein the rocker is arranged for engagement with a stop, so as to be held against axial movement.

20. An actuator arrangement including an actuator having an output member, a plurality of controllable devices, each device having an input arranged for receiving load from the output member, and a selector arranged between the actuator and the input members, wherein the selector includes two or more load transfer members arranged in a predetermined array for transmitting load from the output member to the input members, and wherein the selector device is movable for selective alignment of the load transfer members with one or more of said input members.

21. An actuator arrangement according to claim 20 wherein the selector is a rotatable device, and wherein the transfer members extend in an axial direction for providing axial drive for one or more of the input members in response to linear movement of the actuator output member,

22. An actuator arrangement according to claim 21 wherein the load transfer members are received in bores within the selector member, for reciprocable movement therein in response to movement of the output member,

23. An actuator arrangement according to claim 22 wherein the output member includes an array of axial fingers, and is rotatable for selective alignment of the fingers with the load transfer members or input members.

24. An actuator arrangement for operating a controllable device, including an actuator for providing an output force for use in operating the device, an input member which is movable to control the device, and a link member for transmitting load from the actuator to the input member, wherein an electromagnetic latch is provided for holding the link member in a load transmitting position.

25. An actuator arrangement according to claim 24, including an annular electromagnet having a central bore, and wherein the link member is arranged for movement within the bore, and for electromagnetic co-operation with the electromagnet for preventing movement thereof.