CA1056269A - Push-pull, cable-type actuator - Google Patents
Push-pull, cable-type actuatorInfo
- Publication number
- CA1056269A CA1056269A CA262,346A CA262346A CA1056269A CA 1056269 A CA1056269 A CA 1056269A CA 262346 A CA262346 A CA 262346A CA 1056269 A CA1056269 A CA 1056269A
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- Prior art keywords
- sheath
- strands
- actuator
- abutting
- cable
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A push-pull cable-type actuator comprises a sheath compris-ing a plurality of sheath strands arranged in side edge-abutt-ing, long-lay helices, the abutting side edges of the strands being wedge shaped, and a motion-transmission core member moun-ted for guided longitudinal movement within the sheath.
A push-pull cable-type actuator comprises a sheath compris-ing a plurality of sheath strands arranged in side edge-abutt-ing, long-lay helices, the abutting side edges of the strands being wedge shaped, and a motion-transmission core member moun-ted for guided longitudinal movement within the sheath.
Description
10562~9 PUSH-PULL~ CABLE-TYPE ACTUATOR
This invention oertains to push-oull cable-tyoe actuators of the class used as remote control dsvices It pertains parti-cularly to ?ush-pull type remote control devices which may be us over long distances in tortuous runs and which may include eithQr a sliding or a ball bearing-mounted power transmission element of simplifi~d construction .
Although th2re are many types of ?ush-pull cable actuators known to the prior art, there is nead for an actuator of this class which is adaptable for the transmi3sion of high loads with-out the occurrence of backlash or other mechanical problems.There also is ne~d for a low friction ball bearing-ty?Q push-pu~
cable control of simplified construction which is flexible in a~
pli~9S, A typical orior art bearing type push~pull cabla control is characterized by the pr~sence of tracks laid inside a tightly wound coiled wire flexible sheath. ThP tracks provide a smooth `
surface on which the ball bearings roll. They are undesirable bacause of their added cost, the difficulty in adjusting the con-trol to different planas of bending, and the need for complicated fittings to secure the ends of the sheath.
: Stated in greatsr detail~ th~ pre7sence of the tracks causes difficulties whPn bending the conduit bPcause as the bend plane of the conduit is chang~d, the tracks must move circumferentially within the sheath to allow the motion transmission core msmber to align with the bent plane. Also, the tracks must be sacured at -: thair ends to tran3mit axial load to the sheath. Since bending crsates a differential length betwQen the two tracks, the extent of bending of the sheath i 5 restrictsd correspondingly. Still further, the securing m~ans for th~ tracks creates a gap in the ball bearings at the full ~xtension of the motion transmission cor~ m~mber. This in turr. reducas the compression capability of thP core member.
. ~ .: , :, ' ' ~ - ~ lOS62~69 As a substitute for the tracks of tha above doscribrd ball bearing type control the U32 of a plastic shaath has been sugg-~s~ed. The use of such a sheath provides 2 smooth surface for the operation of the ball bearings, and allows unlimited flex-ing. However~ th~ low bearing stress caDability of plastics severely limits the allowable load that may be transmitted by such a control.
The use of a metal tube as the sheath will overcome the latter problem and permit high loads to be transmitted. How-ever, a metal sheath is not suffici~ntly flexibla to alloweasy installation and Pfficient op~ration.
It is the genPral purpose of the prosent invention ~o pro-vide a push-pull~ cable-type actuator which overcomes the fore-going problems and which permits the ~fficient use of a ball bearing-moùnted central corP, or power transmission member, :~ while rataining a high de~ree of actuator flexibility and stren-gth.
i~ It is another object of the present invention to provide a ,"
r~`~ push-pull~ cable-type actuator which is universally applicable for usa with both ball bearing type and sliding type core mem-!
bers, or with combinations of both, Another important object of the present invention is the provision of a ball bearing type push-pull actuator which is of simplified construction and which accordingly is of relatively low cost.
Still a further ob;ect of the present invention is the pro-vision of a push-pull cable-tvpe actuator which may be usPd to transmit high loads over great distanc_s; which is universally applicable to both straight line and devious courses of appli-cation; and which is free from backlash and other operatingdifficulties.
Basically considered, the push-pull cable-type actuator of my invention comprises a flexible sheath comprising a plur-~056~'69 ality of sheath strands arranged in side edge-abutting, long-lay helices, the abutting side edges of the strands being - wedge-shaped in transverse cross section. This provides a smooth, uniform bore which per se provides a tracking surface - for the ball bearings of a ball bearing-type power transmission core member, thereby eliminating the need for separate tracks.
It also provides a sliding surface for core members of the sliding type. t ,, The sheath assembly includes at least one binder strand of a shorter lay than the sheath strands. This is wrapped helically about the sheath strands in counter rotation thereto. The resulting sheath assembly resists both tension and compression stresses. In tension, the sheath is prevented from collapsing inwardly because of the keystone effect of its component wedge-shaped strands. In compression, the sheath strands are prevented from buckling outwardly by the retaining ` effect of the binder strand.
~d, In accordance with one aspect the invention `" relates to a push-pull cable-type actuator comprising a hollow sheath having a core-guiding inner surface comprising a plurality of sheath strands wedge-shaped in cross section and i arranged in side edge-abutting, long lay helices, whereby to prevent their inward collapse, and a motion-transmission core member mounted for guidedlongitudinal movement within the sheath.
In accordance with yet another aspect, the invention relates to a push-pull, cable-type actuator comprising a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in transverse cross section, the sheath strands comprising from 6 to 15 flat metal wires having lay lengths of from 6 to 15 times the outside diameter of the sheath and swaged into a smooth ~' I
.. , .: . ~ , ' . ~
bore annulus the component wires of which each comprise 24 to 60 included sectors of the annulus, the sheath including at least one binder strand of a shorter lay than the sheath strands, helically wrapped about the sheath strands in counter-rotation thereto, the binder strand having a lay length of from ; 1/6 to 3 times the outside diameter of the sheath, and a motion-transmission core member mounted for guided longitudinal movement within the sheath.
In accordance with another aspect, the invention relates to a push-pull, cable-type actuator comprising a sheath comprising a plurality of sheath strands arranged in side edge-~` abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in transverse cross section, and a motion-transmission core member mounted for guided longitudinal movement within the sheath and comprising a flexible ~ar, a coil spring encircling the bar, and a plurality of ball bearings retained in spaced relation in the convolutions of the spring in bearing relation to the sheath.
; In accordance with a further aspect, th~ invention ;~ 20 relates to a push-pull, cable-type actuator comprising a : plurality of sheath strands arranged in side edge-abutting long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in transverse cross section, and a motion-transmission core member mounted for guided longitudinal move-ment within the sheath and comprising a round, flexible bar having in its peripheral surface three substantially parallel, ; longitudinal guideways arranged at angles of about 120 to each other, a plurality of ball bearings positioned in the guideways and bearing against the sheath, and ball bearing retaining means mounted on the bar for retaining the ball bearings in longitudinally spaced relation to each other.
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` lOS6Z~9 Considering the foregoing in greater detail and with particular reference to the drawings wherein: t Fig. lA is a fragmentary view in longitudinal section of the hereindescribed push-pull, cable-type actuator ; in a first embodiment, and in particular with a sliding type motion transmission core member.
Fig. lB is a continuation of Fig. lA being partly in side elevation, partly broken away, and partly in longitudinal section.
Fig. 2 is a fragmentary view in longitudinal section similar to Fig. lA, but illustrating the actuator of the invention in a second embodiment, and in particular with a ball bearing type motion transmission core member.
Fig. 3A and Fig. 3B are continuation views in side elevation, partly in section, illustrating a push-pull cable-type actuator of the invention in a third embodiment, and in partic-.,', .
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: 1056Z69 ; ular one In which a combin2tion ball be2rina, type and sliding type motion tr~nsmission core member is em~loy3d.
Fig, 4 is a transverse sectional view taken along lines 4-4 of Fig. 2.
Fig, 5 is a fragmentary view in longitudinal section illus-trating a second form of ball bearing typR motion transmlsslon core msmber which may be used in the actuator of the ~resent invention.
Flg, 6 is a fragm~n~ary transverse section taken along line ~i; 10 6-6 of Fig, 5, ,~ Flgs, 7 and 8 are views in transverse section simîlar to ~,; Fig, 6 but illustrating~ respectivPly, altarnate ty~es Qf ball bearing typa motion transmiss~on core members which may be used in the hereindPscribed push-pull, cabls-typs actuator assembly, '~ Figs, lA and lB illustrate a push-pull~ cable-type actuator of the invantion incorporatin~ a sllding type of motion-trans-~,~ mis3ion cors member, ,; The actuator broadly comprises a novel external sheath in-dicated generally at 10 and a sliding type motion transmission .,, core member indicated generally at 12, Sheath 10 is characterized by having a hard~ uniform, smo-oth surfaced bore which of itself provides a guiding surface for the core member, To this end the sheath includes an internal sheath component indicated generally at 14 which is made up of a plurality of sheath strands arranged in side adge-abutting, long-lay helices, the abuttin~ side edges of the strands being inwardly wedge shaped~ or tapered, in transverse cross section, The sheath strands preerably comprise flat wires of orig-inally rectangular cross section, A suitable stock from which the wires originate may comprise a stainless hard drawn or pla-ted steel wire which provides a hard surface to resist the bear-ing stresses applied by the components of the core member, In fabricating the in~ernal shea~h ccmponent 1~ th~re are ~562~i;9 emplo~ed from 6 to 15 of such flat wires, The use of fewer than six wir~s results in the fabrication of a v~ry stiff sheath wh-; ich is not satisfactory for many ap~lications, The use of more than about 15 wires will result in a reduction in sheath tensile ; strength caused by inward colla~se of the wires under stress.
Additionally, it will create an internal sheath surface of e~-cessive roughness, which will in.erf~re with the proper action of the inner motion-transmission core member housed within the `~ sheath, Accordingly, thP number of flat wires used to form the annulus is selected as a compromise between bending stiffness ; of the conduit, tensile capability of the conduit~ and s~oothness of the bore.
In the fabrication of internal sheath component 14 th~ sel-ected number of sheath wires 16 are formad into long lay helices and swagPd into a cylindrical shell, or annulus. Swaging is p~rformed over a mandrel in a rotary swager. During the swag-ing operation, the component wirPs ara curved and compacted into their final shape. Also, their side edges become w~dge-shaped or i~wardly tapered~ as is seen partlcularly in the sectional views of Figs. 4~ and 6-8 inclusive.
The an~le of bevel of the wire sids edges will be a func-tion of the nu~ber of wires amployed in the fabrication of the inner sheath member. Thus~ where the inner sheath mPmber is a com?ositP- of six wires, each of the wires will comprise a 60 included ~ector of th~ annulus, Where there are 15 wires in the sheath, each wire will reprasent a 24 included sector of the annulus.
Although the degree of splralling of the sheath wires is variable~ depending upon such factors as the application to which the actuator is to be put, and the identity and nature of ths other actuator components, it is pref~rred to lay the wires into a helix wherein the individual wires have lay lengthsof - : ' ' ' ': . ' '. . 1~56Z169 from 6 to 15 times tne outsidc diamets-r Oc the sheath.
The net result of the wire lc~Jin~ ~nd swaging o~eration is . . -th fabrication of ~n int gral sheath com?onent having a hard, smooth continuous bore fully capable of wlthstanding the s~rsssæ
* ., and bearing forces exerted upon it by the action of a contained ~; motion ransmission core member of oither the sliding or ball bearing classes.
The internal sheath component 14 is maintained in its oper-ativ~ formed condition by the application of at least one binder strand 18. This strand holds the sheath strands together and prevents the outward axpansion of the sheath when it is under a compression load.
~, .................................................................... . .
' Binder strand 18 preferably com~risas a stiff, strong wir~
of either rectangular or circular cross section. It is wrapped about the internal sheath com~onent in helical manner and prefer-ably in counter rotation to the strands of the internal sheath - component. Also, it is characterized by a lay length which is :. .
shorter than the lay lengths of the strands of the sheath compo-nent. In a typical instance it may have a lay length of from ; 20 1/6 to 3 times the outside diameter of the sheath. As a result, when the sheath is in compression, the stif, strong, counter-rotated binder wira resists the tendency of the internal sheath strands to ~xpand, thereby preventing buckling of the latter and = destruction of the actuator.
If desired~ the entire sheath assembly consisting of inter-nal sheath component 14 and binder strand 18 may be housed or contained in an external tube 20 of polyethylene or other plastic.
This ~rotects the assembly from damage occasioned by impact. It also seals the actuator against the entrance of moisture.
The sliding motion transmission core m~mbQr 12 may ba vari-ously constitut~d~ but in the illustrated embodiment comprises a stranded wire cable 22 wrapped with a closely spiralled flat wirP
covering, or armor~ 24. The cors assembly then may be encased in ' - ~0s6Z~j9 a plastic tube 26 ~referzbly fabricatsd from a ~lastic having self-lubricating charact~ristics to ~ac litats slidln~ of the core msmber wlthin the external sheath The construction of a flexible terminal fittin~ assembly which may bs employ~d in the use of thP actuator is illustrated - in Fig. lA.
Th end of sh2ath 10 is fitted with a ferrule 28, the inner portion of which receives a s~irallad sl~eve 30 and i5 swa~ed tc the 0nd of sheath 10. The outer end of ferrule 28 is provided with an outwardly pro~ecting extQnsion 32 havirg an nterior an-nular detent 34.
: Core member 12 sxtends outwardly through ferrule 28. Its outsr and is received in th~ hollow inner end of a po~Jer take- -off or application rod 36 and bushing 37. It is secured by sr~ag-ing or other suitable means, ; An external sleeve 38 is couplsd to ferrule extension 32 b~
means of an interlocking, outwardly flared end 40. The end fit-ting thus permits a certain amount of flexing through a flex an-gle indicated by the dashed lines and arrows of Fig. lA, thereby improving the p0rformance of the unit.
; Fig. 2 illustrates the application of the novel actuator sheath of the invQntion to an assembly including a bzll-b~aring ;~ type of motion transmission cors member.
In this form of the invention the sheath, indicated genPral-ly at lOa, is substantially identical in construction with sheath 10 of the previously described embodiment.
Thus, it includes an internal sheath component 14 comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices with the abutting side edgQs of th~ strands be-ing inwardly w~dge-shaped in transverse cross section. It also includes a binder wire 18a which is similar in application and function to binder wire 18 previously described, with the excep-tion that it is of circular cross ssction rather than rectangular.
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`.` ~C~56Z69 :`,- .
It, too, may include a protective 31astic cover 20 of the char~c-; ter and function above dcscribod.
The sheath assemblv thus constituted hous2s 2 ball bearing ty~2 motion transmission core member indicat~d gener~lly at 42.
- Ths latter ssrves the same ,~eneral pur?ose a3 does corC m~mber 12 ,- of the previously described embodiment, but incor~orates ball bearing~,the low friction characteristics of which make possible US2 of the actuator ov~r great distances.
Core membsr 42 includes as its powGr transmission com~onent a flat bar or tape 44 having on its o?posits facas continuous, regist~ring, longitudinally extanding oroovss 46, Grooves 46 serve as tracks for a plurality of ball bearings 48, Thesa are maintain~d rotatablv in s?aced relation by a spir-,, al spring 50.
In the operation of the actuator, ball bearin~s 48 rotatC
; fr2ely b~tween the convolutions of the sprin~ and track in ~roov~
46. Their outer surfaces bear against thP hard~ continuous~ in-, ner surfac~ of internal sheath com~onent 14 without the nece~sity of providing spacial tracks for this purpose.
The end fitting as3embly of the actuator of Figs. 2 and 4 includes a f~rrule 52 and spiralled bushing 54 which are swaged ,' over the out~r end of sheath assembly lOa. The ferrule has an outwardly extending terminal ?ortion 56 which is threaded for at-tachment to an operating element.
,' A control rod 58 h~ving a cleft inner lnd is swaged to theouter snd of flat bar 4~ theraby attaching the motion transmiss-ion al~ment to th~ control rod.
Figs, 3A and 3B illustrate zr. embodiment which employs as a po~er transmission core element a combination of the sliding core, ; 30 el7m2nt and ball bearir.g core element above described. It is useful in long run situa~ions in which pzrt of the run is straight and part charact~rized by bends and turr.s. The relatively lo~
.friction ball b~arin~ typ cors olement 1s useful ln the strai,~
` 1~56;~69 -- ` , runs where flexin~ oE +he actuator in diverse planes is not re-~uired. It r~ill be ap?arent that the ball bearing ty?e actuator includin,~ flat ba~ 44 can flex in ~he ?læne o~ the bar only, l~ow~ver, the sliding ty?e of core member incor~orating armor2d cable 22 is flexible universally in all directions, and henc2 is used in the devious parts of the run.
Accordinglv, the composite actuator of Figs, 3A and 3B in-cludes a sheath ass~mbly 10 which is identical to that prev~ous-ly described. Alor~g its straight runs it includes a ball bear-ing type motion transmission cor~ member 42 and along i~s twist-ing runs a sliding type motion transmission cors member 12 both of which also may be identical with these elements of the actua-tor assembly, previously described.
The two motion transmission core members are coupled end to end by means of a swiveled connection which includes a first fer-rule 60 swag~d to the end of the flat bar component 44 of the ball bearing type motion transmission core element 42 and a SC-ond ferrule 62 s~aged to the end of the sliding ty~e motion trans-mission core element 12.
' 20 The outer end of ferrule 60 has a pocket 64 which receives a head 66 on the adjacent end of ferrule 62 in swivel-forming re-.;: : . .
lation. This prevents the transmission of twists from the sec- ~, tion of the actuator containing the universally flexible sliding , core element to the section of the actuator containing the ball ' bearing type core element of limited flexibili*y.
Alternate forms of ball bearing type motion transmission ~'!' core elements having s~ecial usefulness are illustrated in Figs.
5 to 7 inclusive.
Whereas the embodim~nt of Figs. 2 and 4 utilizes a spiral 30 s~ring S0 to retain the ball bearings, that of Fis, 5 and 6 em-ploys for this purpose a pair of p~rforated metal tapes, lndica-ted generally at 68, Each tape 68 comprises a stiff, flat me*al body 70 having _g_ .
56;~69 ., .
i,^~ at spacad intervals alon~ its len~th cer~tr~ J loc~ted, punch~d out perforations 72. These ~re deflned b~ side w211s having ~; shaped îbut~ents 74 and are d mansioned to receive ball bearings 48 in a r~tzined, frealy rotating condition. The ball bearings ; track in grooves 75 in flat bar 70 ~nd bear against the hard, continuous, inner surface of in'err.al sheath component 14. They are hold in po3ition by the s d~ walls of erforations 72 and in oarticular by the abutment portions 74 thereof, The novel ball baaring type core elements illustratod in Fi$s. 7 and 8 ar~ fullv flexible in all planes, thereby over-coming the inherent deficiency of the ball bearing type cor~ ele-ment of Figs, 2 and 4 previously describ_d, the flexibility of which is limited to a single plane by the pr~sence of its rlat bar compon~ont 44.
In the embodimsnt of Fig. 7~ a round rod 76 is substituted for flat bar 44, Rod 76 has in its outer surface three longltu-dinally extending surface grooves or tracks 78. Thsse are arrang-ed at approximately 120 to each other and are dimensioned to re-.,, ceive ball bearings 48, A spiral spring 50 receives the rod and ball b2arings~ rstaining the latter in spaced freely rotatingcondition ~ithin the annular sheath compon~nt.
In the embodiment of Fig. 8 a longitudinally cleft rod 80 is usad in place of the solid rod of the embodiment of Fig, 7.
Tha cleft rod is divided into three substantially equal segments 82 having included angles of approximat21y 120 each. Each seg-ment is provided on its outer surface with a c ntral longitudinal-ly extending groove 83 in which track ball bearings 48~ retained in coil spring 50, This form of the inv_ntion is even more eas-ily flexed than that of Fig, 7, because of the slip planes pre-sent between core rod seg~ents 82.
The operation of the hersindescribad push-pull cable-typ2 actuator is as follows:
In the form of th~ invention illustrated in Figs, lA and lB, pushing or pulling on rod 36 tr~nsmits ~ correspondin~ ~otion to the sliding t~J~ motion transmission core member 12 which slides wlthin sheath assembly 10.
In *he form of the invention illustrated in Figs. 2 and 4, pushing or Pulling on rod 5 8 transmits the movement to the ball bearing type mo~ion transmission core member 42. In such motion, ball bearings 48 rotate freely within retaining spring 50 and bear against the smooth, continuous, hard surface of the bore of helically wound sheath com?onent 14 In the form of the invantion illustrated in Fi~. 3, actua-tion of the control rod trzns~its motion to sllding core member 12, which is universally flexible and is applled in tortuous stretchos. Core member 12 in turn transmits the driving force through a swivel connection to low friction ball bearing ty7e core m0mber 42. The latter flexes only in the plane of flat bar 44 and accordingly i5 applied in long, straight stretches.
In the form of the invantion illustrated in Figs. 5 and 6, application of pushing or pulling force to flat bar 44, produces low friction movemsnt of the bar through long stretches of a~pli- -cation because of the action of ball bearings 48 retained in thewall~d perforations of perforated ta~es 68.
In the for~ of th~ invention illustrated in Figs. 7 and 8, a similar low friction asplication is cbtained usin ball bear-ings tracking in solid rod 76 and split rod 80~ respectivelv, for universally flexible application of the ball bearing type of mo-tion transmission core member.
In all of the forms of the invention, use is made of a sim-plified construction incorporating an external sheath assembly comprising a plurality of sneath strands arranged in side edge-abutting~ long lay helicas~ the abutting side edges of the strandsbeing inwardly wedge-shaped in transverse cross s~ction as i9 particularly a~parent in Figs 4 to 8 inclusive.
This construction imparts a keystone effect to the sheath .
1056;Z69 so that ~t is inh~rentl~r s~rong ancl resists appl7'~d tension for-ces. Appliad com?ression forces in turn are resisted by the counter-rotated binder wire 18 and 18A with which the internal sheath is wra?~ed.
Other adva~tages stam from this novcl construction.
i; Usln,g it, it is possible to cons'ruct 2 control havin~ ver~J
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low backlash due to the close tolerar.ces made poss1ble by the method by which the actu2tor is fabricatcd. If a ~lastic co-t-Ing is employed on the core member~ the be2ring surface of the plastic sliding on m~tal ~'s ,greatsr thar. if the metal inner mem-' ber were sliding insida the plastic tube.
'` Tha outside diametar of the ?12stic coated core memb~r may ; be made about ~qual to that of the end fitting. The elimination '~ of a diarneter difference at this joint allows the core mamber to ~, transmit greater compression load withQut column buckling.
;; The actuator is ?articularly well adapted to u9e employing ', a combination of ball bearing and sliding type cors members. For ,~ very long controls, the ball bearing type core membsr may be em-ployed in straight sections with very little increass in fricti~.
This reduces the cost of the control. Also, use of the armored strand, sliding type core member at each end of the ball bearing core member will allow the associated snd fittings to swivel a-bout the actuator centsr line~ a result not ~ossible with actua-tors including conventional ball bearing type core memb~rs.
This invention oertains to push-oull cable-tyoe actuators of the class used as remote control dsvices It pertains parti-cularly to ?ush-pull type remote control devices which may be us over long distances in tortuous runs and which may include eithQr a sliding or a ball bearing-mounted power transmission element of simplifi~d construction .
Although th2re are many types of ?ush-pull cable actuators known to the prior art, there is nead for an actuator of this class which is adaptable for the transmi3sion of high loads with-out the occurrence of backlash or other mechanical problems.There also is ne~d for a low friction ball bearing-ty?Q push-pu~
cable control of simplified construction which is flexible in a~
pli~9S, A typical orior art bearing type push~pull cabla control is characterized by the pr~sence of tracks laid inside a tightly wound coiled wire flexible sheath. ThP tracks provide a smooth `
surface on which the ball bearings roll. They are undesirable bacause of their added cost, the difficulty in adjusting the con-trol to different planas of bending, and the need for complicated fittings to secure the ends of the sheath.
: Stated in greatsr detail~ th~ pre7sence of the tracks causes difficulties whPn bending the conduit bPcause as the bend plane of the conduit is chang~d, the tracks must move circumferentially within the sheath to allow the motion transmission core msmber to align with the bent plane. Also, the tracks must be sacured at -: thair ends to tran3mit axial load to the sheath. Since bending crsates a differential length betwQen the two tracks, the extent of bending of the sheath i 5 restrictsd correspondingly. Still further, the securing m~ans for th~ tracks creates a gap in the ball bearings at the full ~xtension of the motion transmission cor~ m~mber. This in turr. reducas the compression capability of thP core member.
. ~ .: , :, ' ' ~ - ~ lOS62~69 As a substitute for the tracks of tha above doscribrd ball bearing type control the U32 of a plastic shaath has been sugg-~s~ed. The use of such a sheath provides 2 smooth surface for the operation of the ball bearings, and allows unlimited flex-ing. However~ th~ low bearing stress caDability of plastics severely limits the allowable load that may be transmitted by such a control.
The use of a metal tube as the sheath will overcome the latter problem and permit high loads to be transmitted. How-ever, a metal sheath is not suffici~ntly flexibla to alloweasy installation and Pfficient op~ration.
It is the genPral purpose of the prosent invention ~o pro-vide a push-pull~ cable-type actuator which overcomes the fore-going problems and which permits the ~fficient use of a ball bearing-moùnted central corP, or power transmission member, :~ while rataining a high de~ree of actuator flexibility and stren-gth.
i~ It is another object of the present invention to provide a ,"
r~`~ push-pull~ cable-type actuator which is universally applicable for usa with both ball bearing type and sliding type core mem-!
bers, or with combinations of both, Another important object of the present invention is the provision of a ball bearing type push-pull actuator which is of simplified construction and which accordingly is of relatively low cost.
Still a further ob;ect of the present invention is the pro-vision of a push-pull cable-tvpe actuator which may be usPd to transmit high loads over great distanc_s; which is universally applicable to both straight line and devious courses of appli-cation; and which is free from backlash and other operatingdifficulties.
Basically considered, the push-pull cable-type actuator of my invention comprises a flexible sheath comprising a plur-~056~'69 ality of sheath strands arranged in side edge-abutting, long-lay helices, the abutting side edges of the strands being - wedge-shaped in transverse cross section. This provides a smooth, uniform bore which per se provides a tracking surface - for the ball bearings of a ball bearing-type power transmission core member, thereby eliminating the need for separate tracks.
It also provides a sliding surface for core members of the sliding type. t ,, The sheath assembly includes at least one binder strand of a shorter lay than the sheath strands. This is wrapped helically about the sheath strands in counter rotation thereto. The resulting sheath assembly resists both tension and compression stresses. In tension, the sheath is prevented from collapsing inwardly because of the keystone effect of its component wedge-shaped strands. In compression, the sheath strands are prevented from buckling outwardly by the retaining ` effect of the binder strand.
~d, In accordance with one aspect the invention `" relates to a push-pull cable-type actuator comprising a hollow sheath having a core-guiding inner surface comprising a plurality of sheath strands wedge-shaped in cross section and i arranged in side edge-abutting, long lay helices, whereby to prevent their inward collapse, and a motion-transmission core member mounted for guidedlongitudinal movement within the sheath.
In accordance with yet another aspect, the invention relates to a push-pull, cable-type actuator comprising a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in transverse cross section, the sheath strands comprising from 6 to 15 flat metal wires having lay lengths of from 6 to 15 times the outside diameter of the sheath and swaged into a smooth ~' I
.. , .: . ~ , ' . ~
bore annulus the component wires of which each comprise 24 to 60 included sectors of the annulus, the sheath including at least one binder strand of a shorter lay than the sheath strands, helically wrapped about the sheath strands in counter-rotation thereto, the binder strand having a lay length of from ; 1/6 to 3 times the outside diameter of the sheath, and a motion-transmission core member mounted for guided longitudinal movement within the sheath.
In accordance with another aspect, the invention relates to a push-pull, cable-type actuator comprising a sheath comprising a plurality of sheath strands arranged in side edge-~` abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in transverse cross section, and a motion-transmission core member mounted for guided longitudinal movement within the sheath and comprising a flexible ~ar, a coil spring encircling the bar, and a plurality of ball bearings retained in spaced relation in the convolutions of the spring in bearing relation to the sheath.
; In accordance with a further aspect, th~ invention ;~ 20 relates to a push-pull, cable-type actuator comprising a : plurality of sheath strands arranged in side edge-abutting long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in transverse cross section, and a motion-transmission core member mounted for guided longitudinal move-ment within the sheath and comprising a round, flexible bar having in its peripheral surface three substantially parallel, ; longitudinal guideways arranged at angles of about 120 to each other, a plurality of ball bearings positioned in the guideways and bearing against the sheath, and ball bearing retaining means mounted on the bar for retaining the ball bearings in longitudinally spaced relation to each other.
,~ ..
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` lOS6Z~9 Considering the foregoing in greater detail and with particular reference to the drawings wherein: t Fig. lA is a fragmentary view in longitudinal section of the hereindescribed push-pull, cable-type actuator ; in a first embodiment, and in particular with a sliding type motion transmission core member.
Fig. lB is a continuation of Fig. lA being partly in side elevation, partly broken away, and partly in longitudinal section.
Fig. 2 is a fragmentary view in longitudinal section similar to Fig. lA, but illustrating the actuator of the invention in a second embodiment, and in particular with a ball bearing type motion transmission core member.
Fig. 3A and Fig. 3B are continuation views in side elevation, partly in section, illustrating a push-pull cable-type actuator of the invention in a third embodiment, and in partic-.,', .
` ~
~' -3b-.~ ., .
: 1056Z69 ; ular one In which a combin2tion ball be2rina, type and sliding type motion tr~nsmission core member is em~loy3d.
Fig, 4 is a transverse sectional view taken along lines 4-4 of Fig. 2.
Fig, 5 is a fragmentary view in longitudinal section illus-trating a second form of ball bearing typR motion transmlsslon core msmber which may be used in the actuator of the ~resent invention.
Flg, 6 is a fragm~n~ary transverse section taken along line ~i; 10 6-6 of Fig, 5, ,~ Flgs, 7 and 8 are views in transverse section simîlar to ~,; Fig, 6 but illustrating~ respectivPly, altarnate ty~es Qf ball bearing typa motion transmiss~on core members which may be used in the hereindPscribed push-pull, cabls-typs actuator assembly, '~ Figs, lA and lB illustrate a push-pull~ cable-type actuator of the invantion incorporatin~ a sllding type of motion-trans-~,~ mis3ion cors member, ,; The actuator broadly comprises a novel external sheath in-dicated generally at 10 and a sliding type motion transmission .,, core member indicated generally at 12, Sheath 10 is characterized by having a hard~ uniform, smo-oth surfaced bore which of itself provides a guiding surface for the core member, To this end the sheath includes an internal sheath component indicated generally at 14 which is made up of a plurality of sheath strands arranged in side adge-abutting, long-lay helices, the abuttin~ side edges of the strands being inwardly wedge shaped~ or tapered, in transverse cross section, The sheath strands preerably comprise flat wires of orig-inally rectangular cross section, A suitable stock from which the wires originate may comprise a stainless hard drawn or pla-ted steel wire which provides a hard surface to resist the bear-ing stresses applied by the components of the core member, In fabricating the in~ernal shea~h ccmponent 1~ th~re are ~562~i;9 emplo~ed from 6 to 15 of such flat wires, The use of fewer than six wir~s results in the fabrication of a v~ry stiff sheath wh-; ich is not satisfactory for many ap~lications, The use of more than about 15 wires will result in a reduction in sheath tensile ; strength caused by inward colla~se of the wires under stress.
Additionally, it will create an internal sheath surface of e~-cessive roughness, which will in.erf~re with the proper action of the inner motion-transmission core member housed within the `~ sheath, Accordingly, thP number of flat wires used to form the annulus is selected as a compromise between bending stiffness ; of the conduit, tensile capability of the conduit~ and s~oothness of the bore.
In the fabrication of internal sheath component 14 th~ sel-ected number of sheath wires 16 are formad into long lay helices and swagPd into a cylindrical shell, or annulus. Swaging is p~rformed over a mandrel in a rotary swager. During the swag-ing operation, the component wirPs ara curved and compacted into their final shape. Also, their side edges become w~dge-shaped or i~wardly tapered~ as is seen partlcularly in the sectional views of Figs. 4~ and 6-8 inclusive.
The an~le of bevel of the wire sids edges will be a func-tion of the nu~ber of wires amployed in the fabrication of the inner sheath member. Thus~ where the inner sheath mPmber is a com?ositP- of six wires, each of the wires will comprise a 60 included ~ector of th~ annulus, Where there are 15 wires in the sheath, each wire will reprasent a 24 included sector of the annulus.
Although the degree of splralling of the sheath wires is variable~ depending upon such factors as the application to which the actuator is to be put, and the identity and nature of ths other actuator components, it is pref~rred to lay the wires into a helix wherein the individual wires have lay lengthsof - : ' ' ' ': . ' '. . 1~56Z169 from 6 to 15 times tne outsidc diamets-r Oc the sheath.
The net result of the wire lc~Jin~ ~nd swaging o~eration is . . -th fabrication of ~n int gral sheath com?onent having a hard, smooth continuous bore fully capable of wlthstanding the s~rsssæ
* ., and bearing forces exerted upon it by the action of a contained ~; motion ransmission core member of oither the sliding or ball bearing classes.
The internal sheath component 14 is maintained in its oper-ativ~ formed condition by the application of at least one binder strand 18. This strand holds the sheath strands together and prevents the outward axpansion of the sheath when it is under a compression load.
~, .................................................................... . .
' Binder strand 18 preferably com~risas a stiff, strong wir~
of either rectangular or circular cross section. It is wrapped about the internal sheath com~onent in helical manner and prefer-ably in counter rotation to the strands of the internal sheath - component. Also, it is characterized by a lay length which is :. .
shorter than the lay lengths of the strands of the sheath compo-nent. In a typical instance it may have a lay length of from ; 20 1/6 to 3 times the outside diameter of the sheath. As a result, when the sheath is in compression, the stif, strong, counter-rotated binder wira resists the tendency of the internal sheath strands to ~xpand, thereby preventing buckling of the latter and = destruction of the actuator.
If desired~ the entire sheath assembly consisting of inter-nal sheath component 14 and binder strand 18 may be housed or contained in an external tube 20 of polyethylene or other plastic.
This ~rotects the assembly from damage occasioned by impact. It also seals the actuator against the entrance of moisture.
The sliding motion transmission core m~mbQr 12 may ba vari-ously constitut~d~ but in the illustrated embodiment comprises a stranded wire cable 22 wrapped with a closely spiralled flat wirP
covering, or armor~ 24. The cors assembly then may be encased in ' - ~0s6Z~j9 a plastic tube 26 ~referzbly fabricatsd from a ~lastic having self-lubricating charact~ristics to ~ac litats slidln~ of the core msmber wlthin the external sheath The construction of a flexible terminal fittin~ assembly which may bs employ~d in the use of thP actuator is illustrated - in Fig. lA.
Th end of sh2ath 10 is fitted with a ferrule 28, the inner portion of which receives a s~irallad sl~eve 30 and i5 swa~ed tc the 0nd of sheath 10. The outer end of ferrule 28 is provided with an outwardly pro~ecting extQnsion 32 havirg an nterior an-nular detent 34.
: Core member 12 sxtends outwardly through ferrule 28. Its outsr and is received in th~ hollow inner end of a po~Jer take- -off or application rod 36 and bushing 37. It is secured by sr~ag-ing or other suitable means, ; An external sleeve 38 is couplsd to ferrule extension 32 b~
means of an interlocking, outwardly flared end 40. The end fit-ting thus permits a certain amount of flexing through a flex an-gle indicated by the dashed lines and arrows of Fig. lA, thereby improving the p0rformance of the unit.
; Fig. 2 illustrates the application of the novel actuator sheath of the invQntion to an assembly including a bzll-b~aring ;~ type of motion transmission cors member.
In this form of the invention the sheath, indicated genPral-ly at lOa, is substantially identical in construction with sheath 10 of the previously described embodiment.
Thus, it includes an internal sheath component 14 comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices with the abutting side edgQs of th~ strands be-ing inwardly w~dge-shaped in transverse cross section. It also includes a binder wire 18a which is similar in application and function to binder wire 18 previously described, with the excep-tion that it is of circular cross ssction rather than rectangular.
. ............ : ................ . ~ , . :
, . .
`.` ~C~56Z69 :`,- .
It, too, may include a protective 31astic cover 20 of the char~c-; ter and function above dcscribod.
The sheath assemblv thus constituted hous2s 2 ball bearing ty~2 motion transmission core member indicat~d gener~lly at 42.
- Ths latter ssrves the same ,~eneral pur?ose a3 does corC m~mber 12 ,- of the previously described embodiment, but incor~orates ball bearing~,the low friction characteristics of which make possible US2 of the actuator ov~r great distances.
Core membsr 42 includes as its powGr transmission com~onent a flat bar or tape 44 having on its o?posits facas continuous, regist~ring, longitudinally extanding oroovss 46, Grooves 46 serve as tracks for a plurality of ball bearings 48, Thesa are maintain~d rotatablv in s?aced relation by a spir-,, al spring 50.
In the operation of the actuator, ball bearin~s 48 rotatC
; fr2ely b~tween the convolutions of the sprin~ and track in ~roov~
46. Their outer surfaces bear against thP hard~ continuous~ in-, ner surfac~ of internal sheath com~onent 14 without the nece~sity of providing spacial tracks for this purpose.
The end fitting as3embly of the actuator of Figs. 2 and 4 includes a f~rrule 52 and spiralled bushing 54 which are swaged ,' over the out~r end of sheath assembly lOa. The ferrule has an outwardly extending terminal ?ortion 56 which is threaded for at-tachment to an operating element.
,' A control rod 58 h~ving a cleft inner lnd is swaged to theouter snd of flat bar 4~ theraby attaching the motion transmiss-ion al~ment to th~ control rod.
Figs, 3A and 3B illustrate zr. embodiment which employs as a po~er transmission core element a combination of the sliding core, ; 30 el7m2nt and ball bearir.g core element above described. It is useful in long run situa~ions in which pzrt of the run is straight and part charact~rized by bends and turr.s. The relatively lo~
.friction ball b~arin~ typ cors olement 1s useful ln the strai,~
` 1~56;~69 -- ` , runs where flexin~ oE +he actuator in diverse planes is not re-~uired. It r~ill be ap?arent that the ball bearing ty?e actuator includin,~ flat ba~ 44 can flex in ~he ?læne o~ the bar only, l~ow~ver, the sliding ty?e of core member incor~orating armor2d cable 22 is flexible universally in all directions, and henc2 is used in the devious parts of the run.
Accordinglv, the composite actuator of Figs, 3A and 3B in-cludes a sheath ass~mbly 10 which is identical to that prev~ous-ly described. Alor~g its straight runs it includes a ball bear-ing type motion transmission cor~ member 42 and along i~s twist-ing runs a sliding type motion transmission cors member 12 both of which also may be identical with these elements of the actua-tor assembly, previously described.
The two motion transmission core members are coupled end to end by means of a swiveled connection which includes a first fer-rule 60 swag~d to the end of the flat bar component 44 of the ball bearing type motion transmission core element 42 and a SC-ond ferrule 62 s~aged to the end of the sliding ty~e motion trans-mission core element 12.
' 20 The outer end of ferrule 60 has a pocket 64 which receives a head 66 on the adjacent end of ferrule 62 in swivel-forming re-.;: : . .
lation. This prevents the transmission of twists from the sec- ~, tion of the actuator containing the universally flexible sliding , core element to the section of the actuator containing the ball ' bearing type core element of limited flexibili*y.
Alternate forms of ball bearing type motion transmission ~'!' core elements having s~ecial usefulness are illustrated in Figs.
5 to 7 inclusive.
Whereas the embodim~nt of Figs. 2 and 4 utilizes a spiral 30 s~ring S0 to retain the ball bearings, that of Fis, 5 and 6 em-ploys for this purpose a pair of p~rforated metal tapes, lndica-ted generally at 68, Each tape 68 comprises a stiff, flat me*al body 70 having _g_ .
56;~69 ., .
i,^~ at spacad intervals alon~ its len~th cer~tr~ J loc~ted, punch~d out perforations 72. These ~re deflned b~ side w211s having ~; shaped îbut~ents 74 and are d mansioned to receive ball bearings 48 in a r~tzined, frealy rotating condition. The ball bearings ; track in grooves 75 in flat bar 70 ~nd bear against the hard, continuous, inner surface of in'err.al sheath component 14. They are hold in po3ition by the s d~ walls of erforations 72 and in oarticular by the abutment portions 74 thereof, The novel ball baaring type core elements illustratod in Fi$s. 7 and 8 ar~ fullv flexible in all planes, thereby over-coming the inherent deficiency of the ball bearing type cor~ ele-ment of Figs, 2 and 4 previously describ_d, the flexibility of which is limited to a single plane by the pr~sence of its rlat bar compon~ont 44.
In the embodimsnt of Fig. 7~ a round rod 76 is substituted for flat bar 44, Rod 76 has in its outer surface three longltu-dinally extending surface grooves or tracks 78. Thsse are arrang-ed at approximately 120 to each other and are dimensioned to re-.,, ceive ball bearings 48, A spiral spring 50 receives the rod and ball b2arings~ rstaining the latter in spaced freely rotatingcondition ~ithin the annular sheath compon~nt.
In the embodiment of Fig. 8 a longitudinally cleft rod 80 is usad in place of the solid rod of the embodiment of Fig, 7.
Tha cleft rod is divided into three substantially equal segments 82 having included angles of approximat21y 120 each. Each seg-ment is provided on its outer surface with a c ntral longitudinal-ly extending groove 83 in which track ball bearings 48~ retained in coil spring 50, This form of the inv_ntion is even more eas-ily flexed than that of Fig, 7, because of the slip planes pre-sent between core rod seg~ents 82.
The operation of the hersindescribad push-pull cable-typ2 actuator is as follows:
In the form of th~ invention illustrated in Figs, lA and lB, pushing or pulling on rod 36 tr~nsmits ~ correspondin~ ~otion to the sliding t~J~ motion transmission core member 12 which slides wlthin sheath assembly 10.
In *he form of the invention illustrated in Figs. 2 and 4, pushing or Pulling on rod 5 8 transmits the movement to the ball bearing type mo~ion transmission core member 42. In such motion, ball bearings 48 rotate freely within retaining spring 50 and bear against the smooth, continuous, hard surface of the bore of helically wound sheath com?onent 14 In the form of the invantion illustrated in Fi~. 3, actua-tion of the control rod trzns~its motion to sllding core member 12, which is universally flexible and is applled in tortuous stretchos. Core member 12 in turn transmits the driving force through a swivel connection to low friction ball bearing ty7e core m0mber 42. The latter flexes only in the plane of flat bar 44 and accordingly i5 applied in long, straight stretches.
In the form of the invantion illustrated in Figs. 5 and 6, application of pushing or pulling force to flat bar 44, produces low friction movemsnt of the bar through long stretches of a~pli- -cation because of the action of ball bearings 48 retained in thewall~d perforations of perforated ta~es 68.
In the for~ of th~ invention illustrated in Figs. 7 and 8, a similar low friction asplication is cbtained usin ball bear-ings tracking in solid rod 76 and split rod 80~ respectivelv, for universally flexible application of the ball bearing type of mo-tion transmission core member.
In all of the forms of the invention, use is made of a sim-plified construction incorporating an external sheath assembly comprising a plurality of sneath strands arranged in side edge-abutting~ long lay helicas~ the abutting side edges of the strandsbeing inwardly wedge-shaped in transverse cross s~ction as i9 particularly a~parent in Figs 4 to 8 inclusive.
This construction imparts a keystone effect to the sheath .
1056;Z69 so that ~t is inh~rentl~r s~rong ancl resists appl7'~d tension for-ces. Appliad com?ression forces in turn are resisted by the counter-rotated binder wire 18 and 18A with which the internal sheath is wra?~ed.
Other adva~tages stam from this novcl construction.
i; Usln,g it, it is possible to cons'ruct 2 control havin~ ver~J
. . .
low backlash due to the close tolerar.ces made poss1ble by the method by which the actu2tor is fabricatcd. If a ~lastic co-t-Ing is employed on the core member~ the be2ring surface of the plastic sliding on m~tal ~'s ,greatsr thar. if the metal inner mem-' ber were sliding insida the plastic tube.
'` Tha outside diametar of the ?12stic coated core memb~r may ; be made about ~qual to that of the end fitting. The elimination '~ of a diarneter difference at this joint allows the core mamber to ~, transmit greater compression load withQut column buckling.
;; The actuator is ?articularly well adapted to u9e employing ', a combination of ball bearing and sliding type cors members. For ,~ very long controls, the ball bearing type core membsr may be em-ployed in straight sections with very little increass in fricti~.
This reduces the cost of the control. Also, use of the armored strand, sliding type core member at each end of the ball bearing core member will allow the associated snd fittings to swivel a-bout the actuator centsr line~ a result not ~ossible with actua-tors including conventional ball bearing type core memb~rs.
Claims (19)
1. A push-pull cable-type actuator comprising:
a) a hollow sheath having a core-guiding inner surface compri-sing a plurality of sheath strands wedge-shaped in cross section and arranged in side edge-abutting, long lay helices, whereby to prevent their inward collapse, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath.
a) a hollow sheath having a core-guiding inner surface compri-sing a plurality of sheath strands wedge-shaped in cross section and arranged in side edge-abutting, long lay helices, whereby to prevent their inward collapse, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath.
2. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath wires forming a substantially continuous, smooth bore annulus, the wires be-ing arranged in side edge-abutting, long lay helices, the abutting side edges of the wires being inwardly wedge-shaped in transverse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath.
a) a sheath comprising a plurality of sheath wires forming a substantially continuous, smooth bore annulus, the wires be-ing arranged in side edge-abutting, long lay helices, the abutting side edges of the wires being inwardly wedge-shaped in transverse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath.
3. The actuator of claim 1 wherein the sheath comprises from 6 to 15 wire strands shaped into an annulus.
4. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, the sheath being annular in cross sec-tion and each strand comprises an included 24° to 60° sector of the annulus, and b) a notion-transmission core member mounted for longitudinal movement within the sheath.
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, the sheath being annular in cross sec-tion and each strand comprises an included 24° to 60° sector of the annulus, and b) a notion-transmission core member mounted for longitudinal movement within the sheath.
5. The actuator of claim 1 wherein the sheath strands have lay lengths of from 6 to 15 times the outside diameter of the sheath.
6. A push-pull cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, the sheath comprising from 6 to 15 flat metal wires having lay lengths of from 6 to 15 times the outside diameter of the sheath and swaged into a smooth bore annulus the component wires of which each comprise 24°
to 60° included sectors of the annulus, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath,
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, the sheath comprising from 6 to 15 flat metal wires having lay lengths of from 6 to 15 times the outside diameter of the sheath and swaged into a smooth bore annulus the component wires of which each comprise 24°
to 60° included sectors of the annulus, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath,
7. The actuator of claim 1 wherein the sheath includes at least one binder strand of a shorter lay length than the sheath strands, helically wrapped about the sheath strands in counter-rotation thereto.
8. The actuator of claim 1 wherein the sheath includes at least one binder strand of a shorter lay than the sheath strands, heli-cally wrapped about the sheath strands in counter-rotation there-to, the binder strand having a lay length of from 1/6 to 3 times the outside diameter of the sheath.
9. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, the sheath strands comprising from 6 to 15 flat metal wires having lay lengths of from 6 to 15 times the outside diameter of the sheath and swaged into a smooth bore annulus the component wires of which each com-prise 24° to 60° included sectors of the annulus, the sheath including at least one binder strand of a shorter lay than the sheath strands, helically wrapped about the sheath strands in counter-rotation thereto, the binder strand hav-ing a lay length of from 1/6 to 3 times the outside diameter of the sheath, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath.
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, the sheath strands comprising from 6 to 15 flat metal wires having lay lengths of from 6 to 15 times the outside diameter of the sheath and swaged into a smooth bore annulus the component wires of which each com-prise 24° to 60° included sectors of the annulus, the sheath including at least one binder strand of a shorter lay than the sheath strands, helically wrapped about the sheath strands in counter-rotation thereto, the binder strand hav-ing a lay length of from 1/6 to 3 times the outside diameter of the sheath, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath.
10. The actuator of claim 1 wherein the flexible, motion-trans-mission core member comprises a metal-armored stranded cable.
11. The actuator of claim 1 wherein the flexible motion-trans-mission core member comprises a plastic sheathed stranded cable.
12. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a ball-bearing mounted flexible bar.
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a ball-bearing mounted flexible bar.
13. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a flex-ible bar, a coil spring encircling the bar, and a plurality of ball bearings retained in spaced relation in the convol-utions of the spring in bearing relation to the sheath.
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a flex-ible bar, a coil spring encircling the bar, and a plurality of ball bearings retained in spaced relation in the convol-utions of the spring in bearing relation to the sheath.
14. The actuator of claim 1 wherein the flexible, motion-trans-mission core member comprises a flexible bar having a plurality of perforations spaced along its length and a plurality of ball bearings retained one in each perforation in bearing relation to the sheath.
15. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a round, flexible bar having in its peripheral surface three substan-tially parallel, longitudinal guideways arranged at angles of about 120° to each other, a plurality of ball bearings positioned in the guideways and bearing against the sheath, and ball bearing retaining means mounted on the bar for re-taining the ball bearings in longitudinally spaced relation to each other.
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a round, flexible bar having in its peripheral surface three substan-tially parallel, longitudinal guideways arranged at angles of about 120° to each other, a plurality of ball bearings positioned in the guideways and bearing against the sheath, and ball bearing retaining means mounted on the bar for re-taining the ball bearings in longitudinally spaced relation to each other.
16. The actuator of claim 15 wherein the retaining means com-prises a coil spring receiving the ball bearings between its con-volutions.
17. The actuator of claim 15 wherein the bar is divided into three longitudinal segments of substantially equal cross section.
18. A push-pull, cable-type actuator comprising:
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a length of metal-armored stranded cable, a length of ball bearing-mounted bar, and coupling means coupling the cable and bar in end-to-end relationship to each other.
a) a sheath comprising a plurality of sheath strands arranged in side edge-abutting, long lay helices, the abutting side edges of the strands being inwardly wedge-shaped in trans-verse cross section, and b) a motion-transmission core member mounted for guided longi-tudinal movement within the sheath and comprising a length of metal-armored stranded cable, a length of ball bearing-mounted bar, and coupling means coupling the cable and bar in end-to-end relationship to each other.
19. The actuator of claim 18 wherein the coupling means comprises ball and socket coupling means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA262,346A CA1056269A (en) | 1976-09-30 | 1976-09-30 | Push-pull, cable-type actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA262,346A CA1056269A (en) | 1976-09-30 | 1976-09-30 | Push-pull, cable-type actuator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1056269A true CA1056269A (en) | 1979-06-12 |
Family
ID=4106966
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA262,346A Expired CA1056269A (en) | 1976-09-30 | 1976-09-30 | Push-pull, cable-type actuator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1056269A (en) |
-
1976
- 1976-09-30 CA CA262,346A patent/CA1056269A/en not_active Expired
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