Abstract:
An actuator, connectable to and for adjusting a device, comprises a housing having a longitudinal passage extending between first and second ends and defining an opening at or adjacent to the second end, and a spindle supported in the housing and movable longitudinally in the housing passage. The spindle has two oppositely handed, longitudinally spaced threaded first and second portions respectively nearer to the first and second ends of the housing. A first threaded nut fixed relative to the housing is threadedly engaged with the first threaded portion. A handle rotatably mounted at the first end of the housing is coupled to the spindle for rotating the spindle in the first nut and thereby moving the spindle longitudinally relative to the first nut and the housing. A second nut fixed against rotation relative to the housing is threadedly engaged with the second threaded portion of the spindle and, in response to rotation of the spindle by the handle, is movable longitudinally in the housing passage relative to the spindle, in the same direction as movement of the spindle relative to the housing. Connecting means on or of the second nut is connectable, through the opening defined by the housing, to an adjustable device to be adjusted by the actuator. The spindle is rotatable by the handle for adjusting the adjustable device by longitudinal movement, in the same direction, of the spindle relative to the housing and of the second nut relative to the spindle.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to an adjustment device, hereinafter referred to as an actuator, suitable for adjusting the operating position of another device, such as a lumbar support, either directly or by means of a Bowden cable system.  
       BACKGROUND OF THE INVENTION  
       [0002]     Bowden cable systems are used in a wide variety of applications. One application is in adjusting a lumbar support built into a seat, such as a seat of an automotive vehicle. The Bowden cable system has a wire cable extending through a sleeve. The sleeve usually is held stationary at each end, enabling relative longitudinal movement between it and the cable. An actuator coupled to one end of the cable is able to move the cable reversibly, longitudinally through the sleeve, to enable reversible application of a force to a device, such as a lumbar support, coupled to the other end of the cable. The Bowden cable system is relatively inexpensive. Also, of importance in automotive applications, it is able to operate quietly, while its flexibility enables its use in situations of limited available space.  
         [0003]     A number of different forms of actuator have been proposed for use with a Bowden cable system. Examples are shown by U.S. Pat. No. 5,638,722 to Klingler; U.S. Pat. No. 6,053,064 to Gowing et al; and U.S. Pat. No. 6,520,580 to Hong. In each case, the actuator/Bowden cable system combination is disclosed in relation to a lumbar support for an automotive vehicle seat, a principal application for the actuator of the present invention.  
         [0004]     The actuator disclosed in U.S. Pat. No. 5,638,722 to Klingler has a threaded spindle which is guided in axial movement in a tubular housing, but with torsional strength on a guide. One end portion of the spindle projects from the housing and comprises a threaded ring with which a nut of an adjustment handle is in threaded engagement. At their ends remote from the handle, each of the spindle and housing respectively has a radial opening, an axial bore and a radial slot connecting the opening and bore. With the spindle moved axially to bring the radial openings into alignment, a nipple on the end of a cable of a Bowden system can be inserted into the spindle. As the slots are in a common plane, the cable then can be secured by moving it through the slots, into the aligned bores to retain the nipple within the spindle. At the remote end, the housing has an extension in which an end of the sleeve of the cable system is received and locked. The cable is able to be reversibly moved longitudinally with the spindle, by rotating the handle and its nut.  
         [0005]     In U.S. Pat. No. 6,053,064, Gowing et al discloses an actuator which, in terms of the disclosure of Klingler as detailed above, is essentially the same. However, Gowing et al proposes a separate barrel, fixedly coupled to the end of the housing remote from the handle, for fixing the Bowden system sleeve. This necessitates the cable being passed through a bore in the barrel before its nipple is fitted, while the barrel is simply abutted by the sleeve. The arrangement of Gowing et al differs further in proposing a thread stop coupled with its screw or spindle to prevent the screw from being moved completely out of the nut. Additionally, the nut has a tubular extension which projects away from the screw, with the tubular extension coupled to and rotatable with a handle by a spline coupling therebetween provided by inter-fitting key elements and slots.  
         [0006]     As with the actuator of Klingler, the actuator of Gowing et al has a threaded spindle or screw guided for axial movement, but with torsional strength on a guide. That is, in each case, the screw or spindle is constrained against rotation. In Gowing et al, this is shown by diametrically opposite feet or lugs on the spindle or screw locating in axially extending grooves in the housing. This of course prevents twisting of the cable, as is highly desirable, particularly as twisting in one direction would act to untwist the strands of which the cable is made.  
         [0007]     U.S. Pat. No. 6,520,580 to Hong discloses an actuator which essentially is the same as that of Klingler. As in Gowing et al, the express disclosure is of a nut and handle arrangement with a splined coupling therebetween. The arrangement of Hong proposes a coil spring within the housing and through which the cable of the Bowden system extends to the spindle or screw. As with the barrel of Gowing et al, this complicates coupling and uncoupling of the actuator and cable system.  
         [0008]     The present invention seeks to provide an improved actuator which, while retaining some of the benefits of the prior art discussed above, also enables additional benefits to be obtained.  
       SUMMARY OF THE INVENTION  
       [0009]     In accordance with the present invention, there is provided an actuator connectable to and for adjusting an adjustable device, wherein the actuator comprises: a housing having a longitudinal passage extending between a first end and a second end of the housing and defining an opening at or adjacent to the second end; 
        a spindle supported in the housing and movable longitudinally in the housing passage, the spindle having two oppositely handed, longitudinally spaced threaded portions of which a first threaded portion is nearer to the first end and a second threaded portion is nearer to the second end;     a first threaded nut fixed relative to the housing and threadedly engaged with the first threaded portion of the spindle;     a handle rotatably mounted at the first end of the housing, the handle being coupled to the spindle for rotating the spindle in the first nut and thereby moving the spindle longitudinally relative to the first nut and the housing;     a second nut fixed against rotation relative to the housing and threadedly engaged with the second threaded portion of the spindle, whereby in response to rotation of the spindle by the handle the second nut is movable longitudinally in the housing passage relative to the spindle, in the same direction as movement of the spindle relative to the housing; and     connecting means on or of the second nut and connectable, through the opening defined by the housing, to an adjustable device to be adjusted by the actuator,     wherein the spindle is rotatable by the handle for adjusting the adjustable device by longitudinal movement in the same direction of the spindle relative to the housing and of the second nut relative to the spindle.        
 
         [0016]     The connecting means on or of the second nut can take a variety of forms. In a first embodiment the actuator is connectable to an adjustable device by means of a Bowden cable system. That is, the actuator is indirectly connectable to the adjustable device, albeit in a manner which permits considerable freedom as to how the cable system is arranged and where the actuator is mounted relative to the adjustable device. In that first embodiment, the actuator further comprises: 
        an opening formed in the second nut and configured for receiving and securing an end of a cable of a Bowden cable system and thereby comprising the connecting means; and     the housing at the second end having an engagement member for fixing a sleeve of the Bowden cable system; 
 
 wherein the spindle is operable for moving the cable longitudinally through the sleeve for adjusting the adjustable device to which the other end of the Bowden cable system is connected. 
       
 
         [0020]     In a second embodiment, the actuator is connectable to an adjustable device by a direct coupling between the second nut and the adjustable device. Thus, the second nut may be coupled to the adjustable device by a projection which extends laterally of the second nut, through the opening defined by the housing, with that opening being in the form of an elongate slot extending longitudinally along the housing at the second end. Preferably there is a respective such projection and elongate slot at each of opposite sides of the second nut and housing.  
         [0021]     In the second embodiment, the connecting means may be at least one such projection. The projection may be formed integrally with the second nut, or be connected to the nut such as by screw threaded engagement in a lateral, threaded bore defined by the second nut. Where there is a respective projection at each of opposite sides of the second nut, the projections may comprise opposite end portions of a single member such as a pin, shaft or rod which extends through a diametral lateral bore defined by the second nut. The single member may be glued or welded to the second nut, or in threaded engagement in the lateral bore. In each case, the at least one projection is adapted to be coupled to the adjustable device exteriorly of the housing, such as by a pivotal coupling between the projection and the device.  
         [0022]     Alternatively, the at least one projection may be defined by the adjustable device, with the connecting means adapted to enable the projection to be connected to the second nut. In such alternatives, the connecting means may comprise a lateral bore defined by the second nut and in which an end of the projection is engageable, such as by screw threaded engagement or by being held captive in the bore against retraction therefrom.  
         [0023]     The actuator of the present invention is able to use a thread pitch for each threaded portion and the respective nut which makes the actuator easier to operate, or to enable a greater range of movement for the adjustable device per revolution at a given thread pitch, or to provide a combination of these benefits. This is because the distance the adjustable device is moved is the aggregate of the longitudinal distance moved by the spindle relative to the housing, and the longitudinal distance moved by the second nut relative to the spindle. Thus, for the same given thread pitch for each threaded portion of the spindle, the distance through which the adjustable device is able to be moved is twice the distance moved by the spindle relative to the housing. Thus, there is greater scope for selection of the thread pitch for ease of operation, or to achieve a required movement of the adjustable device per revolution of the spindle, or a combination of these results. Also, while it generally is beneficial for the thread of each threaded portion of the spindle to have a common pitch, this is not necessary. That is, for each revolution of the spindle, the longitudinal distance moved by the second nut relative to the spindle may be greater or less than the longitudinal distance moved by the spindle.  
         [0024]     The handle and spindle are rotatable in unison. The handle may be mounted to the housing and held against movement longitudinally with respect to the housing. In that case, a coupling between the handle and the spindle is to be such as to enable the spindle to adjust longitudinally relative to the handle as the spindle moves longitudinally with respect to the housing. To enable this, an end portion of the spindle at the first end of the housing preferably is movable longitudinally within a sleeve defined by the handle, with there preferably being a key and keyway or splined coupling between the handle sleeve and the spindle. However, the handle may be mounted to the spindle, rather than the housing, with the handle able to move longitudinally with the spindle, as the spindle moves longitudinally in the housing passage while being rotated by the handle.  
         [0025]     The first nut may be a friction fit in the housing, or it may be a snap-fit so as to locate behind a slight protrusion defined in the housing. In each case, the first nut preferably is insertable into the passage of the housing from the first end of the housing. The housing may define at least one radially extending shoulder, such as of at least part-annular form, against which the first nut locates when in its required position longitudinally of the housing. The first nut may have an outer periphery which is non-circular in cross-section, such as square or hexagonal, and which is complementary to the form of the cross-section of the part of the passage along which the first nut is movable to its required position, such that the first nut is constrained against rotation. However, both the first nut and that part of the passage preferably are of circular cross-section, with the nut having at least one radial projection which is slidable in a longitudinal slot defined by the housing along that part of the passage. The first nut preferably has at least two angularly spaced radial projections, each slidable in a respective slot defined by the housing.  
         [0026]     The second nut preferably has two longitudinally adjacent sections. The first of these sections is an internally threaded sleeve by which the second nut is engaged with the second threaded portion of the spindle. The second section of the second nut extends longitudinally beyond the spindle from the first section, towards the second end of the housing. In each embodiment, the connecting means preferably is provided in the second section of the second screw. Thus, for example, in the case of an indirect arrangement using a Bowden cable system, the opening in the second nut is formed in the second section and preferably opens laterally. Also, the second section preferably defines a radial slot extending from the lateral opening towards the second end of the housing whereby, with the nipple of the cable of the Bowden system received in the lateral opening, the cable can be adjusted so as to extend longitudinally from the second nut.  
         [0027]     The second section of the second nut, apart from defining an opening configured for receiving and securing the end of the cable of the Bowden system, may be of solid form. However, this is not essential and, for example, a passage defined by the internally threaded sleeve of the first section of the second nut may continue through the second section. Where the configured opening opens laterally, it may extend through to the passage.  
         [0028]     The second nut also may have an outer periphery which is non-circular in cross-section, such as square or hexagonal, and which is complementary to the form of the cross-section of the part of the passage along which the second nut is movable relative to the spindle, such that the second nut is constrained against rotation. However, both the second nut and that part of the passage preferably are of circular cross-section, with the second nut having at least one radial projection which is slidable along a longitudinal slot defined by the housing along that part of the passage. The second nut preferably has at least two angularly spaced radial projections, each slidable in a respective slot defined by the housing. The slot for a radial projection of the second nut preferably is the same radial plane as the slot for a radial projection for the first nut, although the respective slots preferably are not longitudinally in line with each other.  
         [0029]     Adjacent to its second end, the housing of an actuator for use with a Bowden cable system also may define a side opening communicating with the passage, and a slot extending from the opening to the second end. Thus, as the cable is adjusted so as to extend longitudinally from the second nut, it also is able to be adjusted to extend through the second end of the housing. For this, it is necessary that the respective side openings and slots of the second nut and the housing be brought into longitudinal and radial alignment, as taught by the disclosure of U.S. Pat. No. 5,638,722 to Klingler. However, other arrangements are possible. For example, prior to affixing a nipple to the end of the cable of the Bowden system, the cable can be passed longitudinally through the housing, from the second end to the first end, and the nipple then affixed to the cable before the cable is secured to the second nut.  
         [0030]     The housing may be of elongate form. It preferably is able to receive therein, from the first end, an assembly comprising the spindle with each of the first and second nuts screwed onto the respective first and second threaded portions of the spindle. Prior to installation of the assembly, the nuts may be at one or other of first and second extreme positions along the threaded portions. In the first, preferred one of those positions for installation, the assembly may be such that when installed in the housing the spindle is at its extreme position near to the first end of the housing with the first nut at the end of the first threaded section which is nearer to the second end of the housing, and with the second nut at the end of the second threaded section which is nearer to the first end of the housing. Thus, the second nut is at a minimum longitudinal spacing from the first nut. In the second position, the assembly is such that when installed in the housing, the spindle is at its extreme position nearer to the second end of the housing, with the first nut at the end of the first threaded section nearer to the first end of the housing and the second nut at the end of the second threaded section nearer to the second end of the housing, and the nuts at a maximum longitudinal spacing from each other. However, as will be appreciated, the assembly once installed, is reversibly adjustable between those extremes, with the second nut able to move relative to the spindle in the same direction as the spindle is moved relative to the housing.  
         [0031]     The housing may be of a form such that its passage, apart from longitudinal grooves for preventing rotation of the first and second nuts, is of a substantially uniform, preferably circular, cross-section. However, as detailed later herein, a region of the spindle between the two threaded sections may have at least one lateral projection. To accommodate this, and to minimise material usage, the housing may have a form such that its passage has a larger cross-section over that part of its length from the inlet end to a furthest longitudinal position from the inlet end travelled by such projection as the spindle moves longitudinally, than its cross-section from that position to the second end.  
         [0032]     The engagement member at the second end of the housing may be a small sub-housing adapted to receive therein a suitably shaped termination of the sleeve of the Bowden system. The sub-housing may have a part cylindrical peripheral wall which defines a lateral opening through which at least part of the termination is receivable, such as by a snap fit. Preferably such peripheral wall is provided with an inwardly extending flange or bead at its edge remote from the housing which serves to retain the termination from longitudinal disengagement from the actuator.  
         [0033]     The spindle is of elongate form, and has three principal longitudinal sections. These include the first and second threaded sections while a third section is the part of the spindle with which the handle is coupled. The handle remains coupled to the third section as the spindle moves longitudinally. Thus if, as preferred, the spindle moves longitudinally with respect to the handle, the third section needs to be of at least comparable length to the length of the first threaded section. Assuming the same thread pitch for each of the threaded sections, each of the three sections can comprise about one third of the length of the spindle. However, the third part can be shorter if the handle is attached to the spindle for both rotational and longitudinal movement with the spindle.  
         [0034]     The spindle is rotatable with the handle. However, in moving longitudinally relative to the first nut as it rotates, the spindle may either be movable longitudinally relative to the handle or the handle may be movable longitudinally with the spindle. Where the spindle is movable longitudinally relative to the handle, the handle preferably has a central hub in which the third section of the spindle is located and is longitudinally movable. The handle is coupled by the hub to the third section in a manner enabling relative longitudinal movement therebetween. Thus, the third section of the spindle may be of non-circular cross-section and be receivable in a passage defined by the hub which is of complementary cross-section, or the hub and third section may define longitudinally adjustable key elements and slots, or a splined coupling. Alternatively, one of the third section of the spindle and the hub may define an elongate longitudinal slot in which a pin or peg on the other of the third section and hub is located to enable the required extent of relative longitudinal movement. Where the handle and spindle are longitudinally movable together, they may be bonded together (after fitting the first nut), or permanently or releasably secured together by screw threaded engagement, lateral pins, or the like.  
         [0035]     In addition to its coupling to the spindle, the handle may have a sleeve which fits over the first end of the housing. Where the spindle is longitudinally movable relative to the handle, the sleeve may be a snap fit onto the first end of the housing in a manner which releasably retains the handle against longitudinal movement relative to the housing. However, where the handle is longitudinally movable with the spindle, the sleeve may simply be telescopically received over the first end of the housing for relative movement therebetween.  
         [0036]     In addition to the features detailed, the handle can take a variety of forms. It may include a transverse lever integral with the hub and sleeve. Alternatively it may be a wheel or disc co-axial with the hub and sleeve. Preferably the handle has a scalloped edge form to define a plurality of spokes extending radially outwardly around the hub and sleeve, with a respective arcuate web between each successive pair of spokes.  
         [0037]     With the actuator adjusted so that the assembly comprising the spindle and the first and second nuts is in the first extreme position, hereinafter referred to as the “on” position, the spindle is retracted away from the second end of the housing to the first end, and the second nut is similarly retracted along the second threaded section of the spindle so as to be in its position closest to the first nut. Thus, the cable of a Bowden system secured to the second nut will have been tensioned and pulled into the housing, through the engagement member and the second end. The actuator is in the “on” position because the cable tension will have moved a device to which the other end of the cable is connected from a rest position, or from a position to which it is biased, to an active or on position. Thus, where for example the other end of the cable is connected to a lumbar support, the actuator in the “on” position holds the support in its most forwardly advanced supporting position. Conversely, with the actuator in the other extreme position, herein referred to as the “off” position, the spindle and the second nut will have moved towards the second end of the housing, releasing tension on the cable and enabling the device to return to rest or biased position.  
         [0038]     The “on” position preferably is sharply defined, by an abutment surface at the end of the spindle near to the second end of the housing being contacted by an abutment surface defined within the sleeve section of the second nut. The abutment at the end of the spindle may be provided by an abrupt termination of the thread of the second threaded portion, rather than the usual threaded termination. The abrupt termination may extend substantially radially in a plane substantially parallel to the axis of rotation of the spindle, while the abutment surface of the second nut is similarly disposed and opposed to the thread termination when the “on” position is attained.  
         [0039]     The spindle may have a short unthreaded part of its length between adjacent ends of the threads of the first and second threaded sections. it is at this unthreaded part that it is convenient to provide abutment means which provides a sharply defined stop with the actuator in its “off” position. For this, the spindle may have a lateral projection at the unthreaded part, with the projection having an abutment face which makes surface to surface contact with an abutment face defined by the housing when the spindle reaches the “off” position. The abutment face of the spindle is somewhat radial and leads in the direction of helical advance of the spindle as it rotates and moves longitudinally towards the second end of the housing to its longitudinal location for the “off” position. The abutment face defined by the housing is similarly disposed but oppositely facing for good surface to surface contact between the abutment faces. While the respective abutment surfaces are substantially radially disposed, it is preferred that they are inclined slightly to the radial such that the outer edge of the spindle abutment surface leads in the direction of spindle rotation to the “off” position. This inclination brings the abutment surfaces into more positive face to face engagement in the event of excessive torque being applied to the spindle, thereby minimising the risk of the spindle abutment being able to be forced radially within the housing abutment and jamming of the actuator. This risk preferably is further reduced by the spindle having a spacer which projects laterally from the unthreaded part of the spindle, at a location diametrically opposed to the abutment face of the spindle. The spacer has a lateral extent such that it bears against the housing to prevent lateral displacement of the spindle sufficient to enable the spindle abutment to pass radially within the housing abutment.  
         [0040]     The foregoing explanation of operation of an actuator according to the first embodiment using a Bowden cable system, in terms of movement between “on” and “off” positions, is similarly applicable to an actuator of the second embodiment which is directly connectable to an adjustable device. Thus, with the connecting means connected to a location on the adjustable device, that location is caused to move with the second nut with adjustment of the actuator between the “on” and “off” positions. The nature of the adjustment of the adjustment device will vary with its form and its disposition relative to the longitudinal extent of the actuator. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0041]     The accompanying drawings illustrate preferred embodiments of the actuator of the present invention. The detailed description of the drawings is to assist with an appreciation of the construction and function of the actuator. In the drawings:  
         [0042]      FIG. 1  is a perspective view of a first embodiment of an actuator according to the present invention;  
         [0043]      FIG. 2  is a partly cut-away perspective view of the actuator of  FIG. 1 , but taken from the opposite side and showing the actuator in a first condition;  
         [0044]      FIG. 3  is similar to  FIG. 2 , but shows the actuator of the first embodiment in a second condition;  
         [0045]      FIG. 4  is a full sectional view of the device of  FIG. 1 , in the first condition shown in  FIG. 2 ;  
         [0046]      FIG. 5  is similar to  FIG. 4 , but shows the actuator in the second condition of  FIG. 3 ;  
         [0047]      FIG. 6  is a transverse sectional view taken on line VI-VI of  FIG. 5 ;  
         [0048]      FIG. 7  is a transverse sectional view taken on line VII-VII of  FIG. 5 ;  
         [0049]      FIG. 8  is a transverse sectional view taken on line VIII-VIII of  FIG. 5 ;  
         [0050]      FIG. 9  is a transverse sectional view taken on line IX-IX of  FIG. 5 ;  
         [0051]      FIG. 10  is a transverse sectional view taken on line X-X of  FIG. 5 ; and  
         [0052]      FIG. 11  is a perspective view of a second embodiment of an actuator according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0053]     With reference to FIGS.  1  to  5 , the actuator  10  shown therein has an elongate cylindrical housing  12 , of circular cross-section, which has a handle  14  at one end and receives one end of a Bowden cable system  16  at the other end. From its first end, at which handle  14  is provided, housing  12  defines a passage  13  which has a maximum diameter through to a first step  18 , an intermediate diameter from step  18  to a second step  19 , and a minimum diameter from step  19  through to the second end through which system  16  is received. Adjacent to handle  14 , housing  12  has two diametrically opposed lugs  20  by which actuator  10  is able to be mounted on a suitable support, such as a side frame of a vehicle seat. In the context of a vehicle seat, the end of system  16  remote from actuator  10  may be connected to an adjustable device to be adjusted or actuated through system  16  by actuator  10 . The device at the remote end may, for example, be a lumbar support mounted within the seat-back.  
         [0054]     As seen most clearly in  FIGS. 4 and 5 , actuator  10  includes an elongate spindle  22  within passage  13  of housing  12 . The spindle  22  has a handle engaging portion  24  at the first end of housing  12 , followed in turn by a first externally threaded portion  26  and a second externally threaded portion  28 . Of the threaded portions  26 , 28 , the first is nearer to the first end, while the second is nearer to the second end, of housing  12 . Also within housing  12 , there is a first nut  30  with which first portion  26  of spindle  22  is in threaded engagement, and a second nut  32  with which second portion  28  of spindle  22  is in threaded engagement. Preferably the thread of each of the portions  26  and  28  has substantially the same pitch.  
         [0055]     The handle  14  has a transverse end wall  34  around the circumference of which there is a skirt  36 . The skirt  36  has angularly spaced protrusions  36   a  which assist a user to grip and rotate handle  14 . Concentrically within skirt  36 , handle  14  has a sleeve  37  which is neatly received over the first end of housing  12 . Within sleeve  37 , handle  14  has a central sleeve  38  in which portion  24  of spindle  22  is received.  
         [0056]     The handle  14  is releasably and rotatably retained on the first end of housing  12 . This is by a peripheral groove  39  defined around the internal surface of sleeve  37  engaging on a continuous or discontinuous bead  40  defined around the external surface of housing  12 . The handle  14  also is coupled to spindle  22  in a manner such that rotation of handle  14  causes rotation of spindle  22 , while allowing spindle  22  to move longitudinally in passage  13  relative to housing  12  and handle  14 . As shown most clearly in the sectional view of  FIG. 6 , the portion  24  of spindle  22  has an angularly spaced array of longitudinal ribs  24   a  which are slidable in a complementary angularly spaced array of longitudinal grooves  38   a  defined by the inner surface of sleeve  38 . The inter-fitting ribs  24   a  and grooves  38   a  cause spindle  22  to rotate with handle  14 , while allowing the spindle to move longitudinally with respect to handle  14  to vary the extent to which portion  24  of spindle  22  projects into sleeve  38 .  
         [0057]     The first nut  30 , over a first part of its axial extent as it is received into passage  13  from the first end, is a neat fit within the intermediate diameter section of passage  13  of housing  12  between steps  18  and  19 . A trailing part of its axial extent as it is so received defines a flange  30   a  which is a neat sliding fit in the maximum diameter section of passage  13  up to step  18 . As seen most clearly in  FIG. 7 , nut  30  has longitudinal grooves  30   b  in its flange  30   a , in which longitudinal ribs  12   a  of housing locate. Thus, nut  30  is secured against rotation. Also, as seen most clearly in  FIG. 1 , housing  12  at each of diametrically opposite location, has a U-shape groove  12   b  cut therethrough to define a resilient tab  41 . Each tab  41  is deformed inwardly into passage  13  so that, once nut  30  has been longitudinally moved into position within passage  13 , from the first end of housing  12 , the tabs  41  locate behind flange  30   a  of nut  30  and hold unit  30  against a shoulder  42  defined in passage  13  at step  18  and also restrain nut  30  against unintended retraction. The situation is such that, in addition to being held against rotation, nut  30  is held against longitudinal movement. Thus, when rotated by handle  14 , spindle  22  is caused by its threaded engagement with nut  30  to move longitudinally along passage  13  in a direction determined by the direction of rotation.  
         [0058]     The second nut  32  is threaded onto the second threaded portion  28  of spindle  22  and is a neat sliding fit in the minimum diameter section of passage  13  between step  19  and the second end. The nut  32  has two longitudinally adjacent sections, comprising an internally threaded sleeve  43  by which nut  32  is engaged on portion  28  of spindle  22 , and a section  44  located beyond the free end of portion  28 . As shown in  FIG. 8 , nut  32  has a projection  32   a  at each of opposed sides, with each projection located in a respective groove  12   c  defined along the minimum diameter length of passage  13 . Thus, nut  32  is constrained against rotation relative to housing  12 , but is able to move longitudinally therein.  
         [0059]     The thread of the respective portions  26  and  28  of spindle  22  are of opposite hand. That is, when spindle  22  is viewed from one end, the thread of one of portions can be seen to be clockwise, while the other is anti-clockwise. Thus, with rotation of spindle  22  by handle  14 , spindle  22  moves longitudinally along passage  13  with respect to housing  12 , while the second nut  32  moves longitudinally relative to spindle  22  and in the same direction as spindle  22 .  
         [0060]     With rotation of handle  14 , the actuator  10  can be moved between two extreme positions. The first of those positions, shown in  FIGS. 2 and 4  is herein designated as the “off” position, while the other of the positions is shown in  FIGS. 3 and 5  and is designated as the “on” position. To attain the “off” position, spindle  22  is rotated so as to move longitudinally along passage  13 , relative to and towards the second end of housing  12 . Spindle  22  rotates relative to the fixed first nut  30  and, in being rotated by handle  14 , is caused by its threaded engagement with nut  30  to move longitudinally. As second nut  32  is constrained against rotation relative to housing  12 , spindle  22  rotates relative to nut  32 , while the threaded engagement between spindle  22  and nut  32  causes longitudinal movement of nut  32  relative to housing  12  and also relative to spindle  22 . As the threaded engagement between spindle  22  and nut  32  is of opposite hand to the threaded engagement between spindle  22  and nut  30 , nut  32  moves relative to housing  12  in the same longitudinal direction as spindle  22 . Thus, nut  32  also moves to the second end of housing  12 . The distance moved by nut  32  is the distance it moves relative to spindle  22  plus the distance spindle  22  moves relative to housing  12 .  
         [0061]     The “on” position, shown in  FIGS. 3 and 5 , is attained by reversal of the direction of rotation of handle  14 . This causes spindle  22  to move relative to housing  12  towards the first end, with nut  32  moving in the same longitudinal direction relative to spindle  22 .  
         [0062]     Movement of spindle  22  towards its “on” position may be terminated on attaining that position by the leading end of portion  24  of spindle  22  contacting the inner surface of end wall  34  of handle  14  (as shown in  FIG. 5 ). This, of course, is subject to spindle  22  not providing a force sufficient to displace handle  14  from housing  12  by disengaging groove  39  and bead  40 . Movement of spindle  22  towards its “off” position is terminated on attaining that position, shown in  FIG. 4 , by an arrangement best understood by reference to  FIGS. 9 and 10 . As can be seen from  FIGS. 4, 5 ,  9  and  10 , spindle  22  has a circumferential flange  45  located around the junction between its respective threaded portions  26  and  27 . At each of diametrically opposed locations, flange  45  has a respective outwardly extending tab  46 , 47  which serve respective purposes. The tab  46  has a side  46   a  which leads in the direction of rotation as spindle  22  is rotated towards the “off” position. At the “off” position, side  46   a  abuts against an end surface  48   a  defined by a short arcuate bead  48  formed around and against a shoulder  19   a  defined in passage  13  at step  19 . The side  46   a  is inclined slightly with respect to a plane containing the rotational axis of spindle  22 , such that the radial outer edge leads slightly in rotation to the “off” position. This assists in ensuring that the spindle  22  is not able to move longitudinally beyond the “off” position, by preventing lateral deflection of spindle  22  to permit tab  46  to pass radially within bead  48 . The tab  47  also assists in this regard, in that it limits the freedom for spindle  22  to deflect laterally.  
         [0063]     Rather than longitudinal movement of spindle  22  being terminated on attaining the “on” position by the end of portion  24  of spindle  22  contacting the inner surface of wall  34  of handle  14 , it is preferred that a gap be retained between that end of portion  24  and wall  34 . To enable this, longitudinal movement of spindle  22  on attaining the “on” position may be terminated by the threaded engagement between second nut  32  and second threaded portion  28  of spindle  22 . Thus, the end of the respective threads of nut  32  and portion  28 , at the end of each nearer to the second end of housing  12 , may define a respective end face similar in form and action to side  46   a  of tab  46  and surface  48   a  of bead  48 , with the end faces abutting to terminate longitudinal movement of spindle  22  at the “on” position.  
         [0064]     The section  44  of nut  32  has a transverse opening  50  extending diametrically therethrough. Also, as best seen in  FIG. 3 , and able to be appreciated from  FIGS. 4 and 5 , there is a radial slot  52  cut in nut  32  which extends from the outer surface to the centreline of nut  32  and from opening  50  to the free end of nut  32 .  
         [0065]     At the second end of housing  12 , there is a lateral opening  54 . The location of opening  54  is such that, with actuator  10  in its “off” position, opening  54  is laterally in-line with the end of opening  50  of nut  32  at which slot  52  is provided. Also, from opening  54 , housing  12  defines a slot  56  which extends to, and radially across, an end wall  58  of housing  12 . With actuator  10  in its “off” position, slot  56  is in line with slot  52  of nut  32 . Also, beyond end wall  58 , housing  10  has a part cylindrical extension  60  which has radial tabs  61  spaced around and extending inwardly from its free edge.  
         [0066]     With actuator  10  in its “off” position of  FIGS. 2 and 4 , Bowden cable system  16  is able to be connected to or disconnected from actuator  10 . For connection, a nipple  62  at the free end of cable  64  of the system  16  is able to be presented radially through opening  54  of housing  12  and into opening  50  of nut  32 . The cable  64  then is able to be moved through the slots  52  and  56  so as to extend longitudinally beyond the second end of housing  12 , with nipple  62  held captive in opening  50 . As the cable  16  is moved to this position, a termination  66  at the end of sleeve  68  of system is able to be located in and retained by an engagement member comprising wall  60  and its tabs  61 . As shown, the termination  66  has a peripheral flange  66   a  which is a snap fit within wall  60  from which it is held against longitudinal extraction by tabs  61 . With the system  16  secured in relation to actuator  10 , operation of actuator  10  by rotation of handle  14 , to change from the “off” position to the “on” position results in the cable  64  being pulled through sleeve  68  and longitudinally within housing  12 , along passage  13 . As spindle  22  moves along passage  13  towards the first end of housing  12 , with its portion  24  received further into sleeve  38  of handle  14 , nut  32  is drawn onto portion  28  of spindle  22 . Thus, cable  64  is drawn along passage  13  by the combined action of spindle  22  moving relative to housing  12  and nut  32  moving relative to spindle  22 . Accordingly, the distance cable  64  is able to be drawn along passage  13  is the total distance moved by nut  32  due to those combined actions.  
         [0067]      FIG. 11  shows a second embodiment of an actuator  110  according to the present invention. Parts of actuator  110  corresponding to those of actuator  10  of FIGS.  1  to  10  have the same reference numeral, plus  100 . Also, actuator  110  is substantially the same as actuator  10 , in both its form, operation and functioning, except as detailed herein. Thus, for actuator  110 , there is shown its housing  112  with lugs  120  and first nut retaining tab  141  defined by U-shaped slot  112   b , as well as its handle  114 .  
         [0068]     While the actuator  10  of FIGS.  1  to  10  is intended for connection to an adjustable device, such as a vehicle seat lumbar support. via a Bowden cable system, the actuator  110  of  FIG. 11  is adapted for direct connection to the adjustable device. As shown in  FIG. 11 , the housing  112  of actuator  110  is able to be closed at the second end by its end wall  158 . However, adjacent to the second end, housing  112  defines two diametrically opposed elongate slots  102 . Additionally, part  144  of the second nut  132  does not necessitate a lateral opening and slot, corresponding to opening  50  and slot  52  of actuator  10 , for receiving the nipple and cable of a Bowden system. Rather, part  144  of nut  132  has a respective projection  104  extending laterally through each slot  102 .  
         [0069]     The projections  104  provide means by which the actuator  110  is able to be operatively connected to an adjustable device. An end part D of such device is shown in broken outline in  FIG. 11 . In the arrangement illustrated, the second end of actuator  110  extends into an aperture A of device D, between side portions S. Each projection  104  is journalled in a respective portion S of device D. The arrangement is such that, as actuator  110  is operated to move its spindle (not shown) and nut  132  between the “on” and “off” positions, projections  104  move along slots  102  with movement of nut  132 . This results in the end part D of the adjustable device being moved, such as to apply or release tension in, and thereby adjust, the adjustable device. Where the device is a lumbar support. having one end connected to one side of a vehicle seat-back frame, and its other end D connected to an actuator  110  mounted on the other side of the frame, the support can be adjusted to increase or decrease, respectively, the level of lumbar support provided to an occupant of the seat.  
         [0070]     Operation with actuator  10  of FIGS.  1  to  10  can be similar. However, of course, adjustment of an adjustable device by actuator  10  is by movement transmitted via the Bowden cable system  16 .  
         [0071]     The projections  104  may be formed integrally with part  144  of nut  132 . However, this would require that part D of the adjustable device is split, to enable projections  104  to be received therein, in the arrangement illustrated. Alternatively, the projections  104  may comprise a respective or common pin, bolt or the like separable from part  144  and securable in a lateral bore defined by part  144  after being inserted through part D. Such separable projection  104  may be securable in part  144  by screw threaded engagement in the lateral bore, or by any other suitable means.  
         [0072]     In a variant on the embodiment of  FIG. 11 , the part  144  of nut  132  may have a lateral bore, or oppositely opening lateral bores, and not include projections such as shown at  104 . With that variant, each side S of end part D of an adjustable device may have an integral projection locatable in a respective lateral bore of part  144 . Alternatively, each side S may define a bore through which a pin or bolt is able to be secured, with the pin or bolt journalled in the transverse bore of part  144 . In that alternative, there may be a respective pin or bolt for each side S, or part  144  may have a single through bore in which a common pin or bolt for each side S is journalled. That is, the through bore may be similar to opening  50  of actuator  10  of FIGS.  1  to  10 , but there need not be a slot similar to slot  52  of actuator  10  associated with the through bore.  
         [0073]     Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention.