US2913920A

US2913920A - Window lift assembly

Info

Publication number: US2913920A
Application number: US571722A
Authority: US
Inventors: Ralph H Wise
Original assignee: Anderson Company of Indiana
Current assignee: Anderson Company of Indiana
Priority date: 1953-11-13
Filing date: 1956-03-15
Publication date: 1959-11-24
Anticipated expiration: 1976-11-24
Also published as: DE1208215B

Description

R. H. WISE WINDOW LIFT ASSEMBLY 5 Sheets-Sheet 1 original Filed'no'v. 15. 1953 INVENToR. RALPH H. WISE AT RNEYs Nov. 24, 1959 R. H. wlsE 2,913,920.

wINnow L IFT ASSEMBLY original Filed Nov.1s. 195s 5 Sheets-Sheet 2 IN VEN TOR. RAljHPH. WISE RN EY Nov. 24, 1959 R. H. WISE WINDOW LIFT ASSEMBLY 3 Sheets-Sheet 3 Original Filed Nov. 13, 1953 INVENTOR. RALPH H. wlsE AT 0R a# NEY I Patented Nov. 24, v1959 Unitef Safes Parete 2,913,920 wlNnow Lnrr ASSEMBLY Ralph H. Wise, Gary, Ind., assignor, by mesne assign-V ments, to The Anderson Company, `a corporation of Indiana application March 15, 1956,

of the armature of the motor and to the rigidity of the' connecting parts. In` the present invention the driving is .accomplished through the driving means, each of which` has some torque resilience. Therefore, when either theupper or lower abutment which limits window travel is reached, the shock upon the motor and the t'oan improved powered lifting apparatus for raising and lowering a window in the door of an automotive vehicle.y

The present application is a' division of my prior ap# plication entitled Window Lift Assembly tiled Novem-h ber`13, 1953, and assigned Serial No. 391,8`51,wh`ieli was abandoned -in favorof continuation application Serial No. 721,043 filed March 12, 1958. .This prior application is a continuation-in-part of a stillearlier ap-` plication iiled May 11, V1953 and issued on July 26, v1955 as Patent No. 2,714,004. The majority of conventional window-lifting devices now currently being used by the automative industry comprises a lift arm assembly and a control assembly` operatively connected to the lift armassembly. The lift arm assembly includes one or more lift arms, a plurality of `channel guides therefor, and a bracket for attaching the assembly to the inner panel of a vehicle door.` The control assembly, among other things, includes a sector` gear and pinion, a counterbalancing spring, a clutched.

drive shaft provided with a crank, and a bracket for supporting the assembly on the door. A

Thisconventional type of lifting device and those having a power unit, such as an electric motor for operating: the arm assembly are mounted adjacent the central portion or area of the inner panel. This disposition or center point location of the operating means has a disadvantage in that the weight and thrust of such meansl is not properly distributed, and as a consequence the inner panel will buckle or breathe when the operating means is actuated.

Window-lifting devices or apparatus ofthe above character are relatively heavy, cumbersome andrequire considerable space for their operation. Devicessof `this type are also expensive to and difficult to install.

Window-lifting devices now in general use require'precision in installation yto minimize Vmisalignment offuncl-I,

tional components. Such misalignment is diicult to prevent because surrounding structure of the door, onwhich the apparatus must be mounted,` is not precisely constructed. As a result, misalignrnentof componnt parts of well-known `types of window lifts creates a` great deal"` of malfunction requiring adjustment, repairs, and replace-- ments. Often the excessive load caused by mislignf. ment creates damage to electric motors used to drive Misalign'ment creates binding and cramping which produces notonly excessive loads onf the powerunit but also creates excessivefwearon func-lfV tioning parts and often stalls the mechanism to the very considerable embarrassment of the driver of the vehicle;

One of the problems prevalent in the window lift mechanisms presently generally `employed is that, sincef' the movement of the window, particularly-to top'p'osi` the mechanism.

tion, is stopped abruptly upon `impact with'the upper abutment carried by the door, the`shock tothe convenrnanufacture and assemble balance ofthe mechanism is cushioned and reduced by the torque of the driving members. t

'With the foregoing in mind, one of the principaleA objects of the invention is to provide a window lift 'asseinbly embodying entirely new and improved principles ofr design and construction and which overcomes practically all `of the disadvantages inherent in conventionalapparatus of the'kind above referred to.-

other things, a pair of corresponding threaded shafts,

actuated means preferably in the form of rollerassenzi?` blies respectively carried by the shafts, connection means operatively connecting the actuated means to a window,

n a pairfof corresponding flexible elements or cables connected to the shafts, power means preferably in the form, of a Vreversible electric motor connected to the elements,l a control-r for reversing the flow of current through the motor, and switchmeans for operating the control. The

- shafts and cables may be referred to as driving means'. y

An object of the invention is to provide roller assemblies, each of whichis preferably comprised of a pair of retainer members and three rotatable elements pivotallyA mounted between the members for cooperation with one Mor: more threads of a threaded shaft or screw. Thevin? vention Vcontemplates the utilization of dilierent forms or modifications of roller bearings for various installa tions and load requirements. A particular object of the invention is to provide an assembly in which the rotatable elements or roller bear` ings are preferably equally spaced apart circumferentially.,

and longitudinally with their axes in parallel relation. The assembly may be used with a shaft provided with one or more threads but is preferably usedwith a shaft having a' double thread so that two of the bearings will cooperate with one thread and the other bearings will cooperate with the other thread in a manner whereby to afford a stabilized connection between the assembly 70 tional-type mechanismeis heavy due to the momentumI and shaft. This arrangement has proven very satisfactory in use and provides a thrust of considerable force or ypower unit` with increased speed of operation as compared to a setup, in which the assembly is associated witha single threaded screw.

Another' object of the invention is to provide a rollerf which is preferably formed with toroidal bearingV sur' faces which straddle a portion of the thread of a shaft for engagement with such portionat points betweenitsY b'a`se'and crest;r 'Otherwise expressed, the multiple points" of contact between each roller and a threaded portion are the root diameter ofthe threads.

pr-eferablyl located between the crests of the threads and e be moved,1such as a window, in anyposition to which ithas been 4moved after. the means for actuating the shaft= is `.rendered inoperative; l s.

Another featurefresides in providing improved; means.:

for yieldablyfor resiliently supporting the lower extremi ties ofthe shafts and-,the upper extremities of the ,cables` Mattached to the shafts so as to facilitate installation of v the structure and reduce noise or vibration to a Aminimurn.A .Moren'specifcally in this respect, the s haftsandv ilexible elemehtsfare detachably secured together by,` couplings and these`couplings are respectively carriedby'jthel yieldable extremities of an elongated support, whichfis" preferably detachably connected to the door by a bracket,

More particularly, an important object ofthe inverttion is to provide a lift assembly comprising, among The bracket is attached to the door substantially midway between the shafts and to the center ofthe support lso thatl the extremities of the support may yield or oat. This support offers advantages with respect to installationsthat cannot` be obtained, when for example, theA couplingslare,

more. or less rigidly mounted on the door by a of, separate brackets. as in the assembly described? inthel earlier application. A resilient abutment; or stop-iscritried by therbracket to support the windowinit'slower.- most position.

An important object of the invention is to provide a lift assembly in. which provision is made to compensate forl anyv structural variations or. misalignments oflthe. components constituting the door and particularly with.

respect to any variations in the distance between th'ewindow and' driving means therefor.

'An important object of the invention is to provide-a.

new lift assembly. which is preferably adapted to be mounted on one of the panels of a vehicle doorA so that the, supporting means for the driving means are located at appropriate locations adjacent the vertical rigid edges off-the door so as to distribute the weight of'the` driving;

means and at the same time completely alleviate any tendency of the panel to buckle. The power means for thek driving means is preferably carried by the lower-horizontal edge flange of the inner panel of the door at a point substantially midway between the planes.` formedf bythe vertical edges of the window to provide a wellbalanced assembly. Y

A signicant object of the inventiony is to, providev a unique liftassembly comprised of a minimum number ofA components which can be economically manufactured'and` assembled on a production basis and which canbe easily and quickly installed. f

A particular object of the invention is to provide a-` lift assembly of a size and arrangement which will permit its installation in a much smaller space or area than any' of the conventional lifts, and thereby provideaddition'al' space which might be utilized for other. equipment. or

put lto other use. In fact, use of the inventionwill permita reduction in the thickness of a car door at-y or adjacent its-centralarea so as to provide additional space or room in the car. V

Also, an object of the invention is to provide a -lift assembly which is relatively light in weight and substantially noiseless in operation.

Another object of the invention is to provide a'lift assembly having novel tubular means associated with, the,

Figure 1 is an elevational view of the inner side. ofa` vehicle door showing the application of theinventionrto.- the. window structure thereof; .Y Figure 2 is an enlarged vertical section takenasubstantially on line 2 2 of Figure 1 illustrating, among-other? things, the relative positions of certain componentsofzthe operating assembly;

Figure 3 is an enlarged partial sectiontakensubstantially on the line -S of Figure 1, showing the-manner of supporting the upper ends of the shaftseor screws-toy the door and the window to such shafts;

Figure 4 is an enlarged partial section showing one of` afpair-of unique couplings connecting ther lower-ends of theA shafts and the flexible cables; j y

Figure 5 is a top view of one of a pair of roller4 as'- s'embles as applied to a shaft shown in cross section;v

Figure 6 is an elevational view of one o'lth'e. roller.

assemblies; l

lFigure 7 is an' elevational, view of a roller, assembly,

connected -to a shaft and the connection means employed for attaching the assembly to a Window;

Figure 8 is a vertical section taken through an appropriate part of the structure disclosed in Figure 7 to illustrate certain details;

Figure 9 is an enlarged vie'w showing the operative relationship between a. roller. and the thread of a shaft;

Figure 10 is a view showing the mode of supporting the-ends of the shafts;4

Figure 1'1 is a partial perspective view of a component shown in Figure 10;

Figure 12 is` an elevational view showing the manner-. o'f. supporting the couplings on the yieldablev support above referred to; and

Figure 13 is a view, partially in section, of one of the couplings that is utilized todetachably secure the shafts and cables together and detachably secure the cables to the motor.

The window lift assembly as exemplified in Figures 1 and 2 comprises, among other things, a resiliently mountedl reversible electric motor 1, a pair of corresponding,

threaded

shaftsor screws

2 and 3, a pair of roller assemblies 4.`and 5` carried and actuated by the shafts, a pair ofconnection means 6 operatively connecting the roller* assemblies with a window 7, a pair of flexible elements' or cables. 8 and 9 having ends connected to the shafts' andend's connected to the motor; a control 10 connected tothe motor, and switch means 11 for actuating the control" to rotate the armature of the motor and shafts and'y Icables to cause the roller assemblies to move lengthwise of theshaftsand thereby raise or lower the window.

The manner of supporting the upper endsof the shafts" 2 andV 3 which carry the window will be described first'.4

As; clearly exemplifiedV in Figures 2, 3, l0, and ll, the upper'extremity of an inner panel 12 of the door which constitutes a support or mounting is provided with an upper horizontal portion 13 and a depending fiange which form a channel. ingmeans' are provided for lthey shafts, and each means, among other things, includes a block of rubber 14.. or the equivalent seated in the channel, and a cup 15 having ball bearings' therein. openings in the horizontal portion 13 of the inner panel, through the rubber block 14 and threadedly connect with ears on'each cup; A member 17 is interposed between each of the rubber blocks and each cup and as shown in FigureI 10 this member is provided with curved resilient end portionswhichV are adapted to engage the threads ofv the screws to lock the screws against accidental displacement. Each of the members is further provided with an indent' forming an abutment which the upper endV of a shaft may engage lto reduce friction when there is anupward thrust on thevshaft. Each of the shafts extend through a hole in the bottom Wall of each cup and'. isx

provided with a portion having a circumferential groove I8 therein within which ball bearings are confined so. that l theshafts may freely rotate substantially about vertical aXeS;

As clearly shown in Figures 2, 4, 12' and 13 the lower.l

end of' each shaft is preferably detachably connected, with` the upper end of aflexible element by couplingseach. having a connector 19. The connectors are respectively rotatably mountedin housingsA 20 carried by the extremi-.

-ties'of an elongated support 21V detachably mounted. byL

shown in. Figures 1 and 2, resilient members arel carried by the bolts` and, interposed between the couplings and support'toresiliently mounty the couplings on the' support,.-

-The .b racket; 22 isA also provided with a bumper or stop` as.-illustrated to. resiliently support the window: 7 inritsl` A pair of uppercorresponding support-l Screws 16 extend through clearance.

lowermost position. The connectors 19 are preferably anchored or permanently fixed to the lower endsof the shafts and the upper end of each flexible element, as shown in Figure 4, is provided with a squared portion 23 which detachably ts in a socket of corresponding configuration in the lower extremity of the connector. In `order to assist in reducing noise and alleviate the tendency of the exible elements to produce a whipping action when the motor is operated the elements are pref erably encased in a tube of rubber or suitable resilientor pliable material 24. The upper extremities of the connectors extend through clearance holes provided in horizontal legs of the brackets 21. Within each of the-hous-` ings 20 there is disposed a rubber bushing25 and a pair of corresponding rings 26 located within an internal groove provided in the bushing. The rings engage one another and cooperate to provide a race or retainer for ball bearings 27 which ride in a circumferential groove 28 provided in the connector, when the connector, flexible element and shaft are rotated as a unit. The connector and bearings therefor are thus resiliently supported by the rubber bushing. The upper end of each of the tubes 24 surrounding an element is provided with a rabbeted enlargement so that portions of the end extend into` and against the lower part of the housing 20, and is held in place by a spring clip 29 shown in Figures 4, 12 and 13; Each clip is of a form to encircle the tube and has ends which project into apertures provided in ears 30 on the housing. Each clip serves to hold the bushing, rings, bearings, connector and tube to the housing, as well as maintain the flexible element in interlocking relation `with the connector. With this novel coupling arrangement, each connector and associated flexible element and shaft is mounted for free and silent rotation. The connectors 19 and supporting means therefor are located to promote balance and afford stability for the flexible elements and shafts and position them in spaced relation to the inner and outer panels of the door. It will also be noted that` the flexible elements are more or less curved with slack or play to afford suilicient maneuverability in operation as' well as locate their upper ends in axial relationship to the shafts.

but due to `the character of the flexible elements, connectors and resilient supporting means therefor themotor can be mounted in an olf-centeror angular position with respect to the supporting means and the inner and outer,` panels of the door, without affecting the eciency of the ends of the shaft of the motor 1 as mentioned above.,

More particularly in this regard, each end of the motor shaft is provided with` a squared socket similar to the socket 23 in each of the connectors 19 so that the lower squared ends of the cables 8 and 9 will nt into the sockets.

Thus, installation of facilitated.

The roller assemblies 4` and 5 respectively connected to. the

shafts

2 and 3 may be constructed in various ways and as shown most clearly in Figures through 8, each the assembly is simplified and It is of course desirable' to locate the` various components in a balanced operative relationship,

assembly preferably includes a pair of retainer members` 31 and 32 which are secured together by any suitable means, such as by rivets 33 to provide a support, housing or cage for three

roller bearings

34, 35 and 36. The retainer member 32 will be referred to as the inner member and member 31 as the outer member because theyuare` assembled in a nesting relationship. The innerA member.

l their side walls.

With this'r setup the members are positively held againstdisplacement to` provide what -can be termed Aa supporting means, carriage or housing. As depicted in Figures 5, `6 and-7 the base '39 of the outer member is provided with three offset

formations

41, 42 and 43 and the base 37 `of the inner member is provided with threesimilarformations. The base portions of the formations on lthe inner member are arranged in opposed predetermined spaced parallel relationship with the base portions of the formations on the other member to provide pockets for the roller bearings. The base portion provided with a concave' of each of the formations isseat 44. v Each rollerV or rotatable element preferablyA includes a pairof corresponding bead formations or

units

45 and 46 and a pair of corresponding axle or pivot portions 47 extending therefrom whichv register with theseats 44. The `design or shape of the formations may be' varied to suit `different requirements, but as herein illustrated each formation is preferably constructed to provide an annular convex bearing portion having` opposed corresponding toroidal -contact or bearing surfaces as clearly exemplified.v

More particularly in this regard, the rotatable elements each `have one or more thread-contacting units., `which have, normal to their axes, cross-sectional areas circular in form and diminishing progressively in either direction from. the cross-section medial thereto, said units having parallel vertical cross-sectional `areas elliptical in form,

and diminishing progressively in area in either direction from thel cross-sectional area takeny through the axis` of said unit; whereby to provide, inward from the `crest of the threads, substantially a pointor points of contact between the vrotatable elements and portions of the threads. It will be noted, that when the rotatable elements` are secured in the retainer members that they are preferably equally spaced longitudinallyA and circumferentially. More specifically, the rotatable elements are prefe'rably Varranged in astepped or generally axially spaced relationship so that they will rotate in equally spacedapart planes disposed transverse to the longitudinal axes ofthe carriage formed by the retainer members.

The threaded

shafts

2 and 3 shown in the drawingare preferably of the multiple-thread Itype.

More particu#V larly, each shaft includes double threads 48 and49, pref` erably formed by a well-knownrolling method. As depicted in Figure l, the exible elements 8 and 9 are op'- eratively connected with the shafts and the motor H1 in a manner whereby the

shafts

2 and 3 will be respectively simultaneously rotated clockwise and counterclockwise to force the roller assemblies upwardly to raise the window.

When operated in another way the shafts will be rotated in reversed directions to cause the roller assemblies to' travel downwardly and lower the window. The arrangement as illustrated in Figures 5 and 7 is preferably such that the rollers such as 34 and 35 are disposed to engage the thread 48 and the roller 36 is disposed for engaging the thread 49 on theshaft 3. The rollers on the assembly 4 are arranged to similarly engage the right-hand threads on the vshaft 2. l

Rollers of multiple-contact form add stability to the roller assembly; increase the resistance to deformation of the assembly and functional parts thereof under higher loads; reduce frictional resistance of the assembly; give longer life to the drive screw and all other functional parts of the assembly; retard the development of-noise in operation; minimize cramping o1' bendf minimize Ehe rollerassemblies. may be.. operatively connectedwith a window or other deviceto be actuated inl any portions 50 of at hanger by a: pair of rivets 51. The upper extremities of the portions 50- are. preferably connectedfto depending arms=52y of a bracket 53: by rivets.

54; The. bracket S3, is preferablyy permanently secured to thel lowerpartl of a window frame member 55. as shown in Figures 3, 7 and 8'. As shown in Figures 7 and: 8, a resilient` means S6, preferably in the form of a rectangular piece ofv rubber, is interposed between thefbracket and' the. bridge portion ofthe hanger. resilientmeans 56 is-preferably held betweenl the-bracket and the hanger by providing the hanger with an opening and the resilient means with a projection disposed inthe opening. Thel sidefportons 50 of the hanger are provided with corresponding offset portions 57 which are'located a'djacent to the depending arms S2 of the bracket so as to control, Within` practical limits, the pivotal movement between thehanger and the bracket. The lower extremities of the side portions 50 are further provided with inturned end portions 58 which serve to control pivotal movement of the roller assembly with respect to the hanger. serve tostab'ilize the operative connection between the screw and theA Window or a device to be actuated andl th'e resilient means S6 functions to reduce noise andotherwise cushion the movement between the' hangerv and' thebracket. The connection illustrated also affords an improvedf arrangement for automatically holding the window in any position to which it has been moved after" thev means for rotatingthe screw is rendered inopera tive. More particularly in this-regard, the construction of." each connection and' itsv operative relationship with the windowl andl ascrew is such that the rollers: will cramp onl the screw' and automaticallyv hold the Window in any verticall position to which it has been movedlafter` the means foractuating the shafts are rendered inopera- VC;

`In view of the foregoing, it will be manifest' that by merely' manipulating the switch means 11, the control various` other modifications may be made in the same.

without departingfrom the spirit of my invention; .hence I, do not Wish to be understood as limiting myself tol thevexact form, construction, arrangement and combination. of parts herein. shown andV described--or uses: mentioned.

I-c'laim: I ILA torque-convertingr assembly comprising; a: longif tudinal. rotatable primary, torque-transmitting `member having a plurality of continuous helical surfacesty remote;

from. the axis thereof,. a. load-bearingl driven member operatively related to said transmitting member, said loadfbearingrnember; embodying disclike. rollers having toroidal surfaces disposed to engage; said helical' sur facesraud to: roll thereon. while being driven thereby,

saidrollers each, having. axis portions adjacent opposed.

surfaces. thereof,. abutment; means carriedy by' said axis portions, said abutment means disposedA to engage portions.- o=said; loadfbearing' member in freel turning relationship thereto, whereby saidy disclike. rollers revolve:

Thev

These controlled movements- 82 ina a; plane substantially transverse to the axis of. said torque-transmitting member.

2, A. torque-converting assembly-comprising a. longutudinal. rotatable primary. torque-transmitting member;-

havinga plurality of continuous helical surfaces remote'.

from the axis thereof, a load-bearing driven memberA operatively related to said transmitting member, saidv load-bearing member embodying disclike rollers having: toroidal surfaces disposed to engage said helical sur.- faces and to roll thereon while being driven thereby,. said rollers each having axis portions adjacent opposed' surfaces thereof, the maximum lateral dirnensionof. said; axis-portions being less thanthe maximum lateral dimension of the said roller to which they relate, abutment. meansl carried=by said axis portions, said abutment'means': disposed to engage portions of said load-bearing member.` in free turning relationship thereto, whereby said disc'-v like: rollers revolve in a plane substantially transverse.l to the axisv ofy said torque-transmitting member.

3. In a.device of the class described, a driving member. having a multithreadedy surface, a driven member including a housing and a plurality of freely rotatable elements disposed to guidingly embrace said driving member and be driven thereby, said rotatable elements having opposed ends pivoted in a load-bearing housing, said rotatable elements each having one or more threadcontacting units, said units having, normal'to their axes, cross-sectional areas circular in form and diminishing progressively in either direction from the cross-section medial thereto, said units having parallel vertical crosssectional areas elliptical in form and diminishing progressively'in area in either direction from the cross sectional area taken through the axis of said' unit, whereby'to provide, inward from the crest of said threads,V substantially a point contact between said rotatable elements and portions of said threads.

4. In a device of the class described, a driving member having a multithreaded surface, a driven, member engaging said driving member for reciprocal propulsion thereby, said. driven member including a housing and, a plurality of freely rotatable elements disposed to guidingly embrace said driving member and be driven thereby, saidrotatable elements having opposed ends pivoted. in a load-bearing housing to be driveny thereby,

" said load-bearing housing having a load-receiving portion spacedY from said driving memberA inv a single direction therefrom whereby to provide acramping. action between said driving. member and said driven member for the prevention of movement therebetweenwhen saidy driving member is idle.

5. In combination, a multithreaded shaft, an assembly comprising a pair of members secured together, each of the members having an aperture, the apertures being aligned and receiving the multithreaded shaft, each member havinga plurality of offset portions, the offset portions; on the respective members being opposed andl cooperating with one another to provideformations disposed in different planes, and rotatable elements journaledA between opposed offset portions for engaging the threads of the shaft, at least one elementy engaging each thread of the multithreaded shaft.

6. Inl-a device of the class described,l a driving and driven member, one of said members being Ia screwhaving a continuous thread of appreciable pitch and root depth; the other member being a housing member encompassing said screw member and carrying in' spaced relation to each other, and` spaced away from the root area of said threads, a plurality of freely and independently rotatable elements disposed to operatively engage and be engaged by saidA screw member continuously on the ank of. the thread and in a path remote fromV said root area andi from the crest of the thread, each of said elements being maintained by said housing member in substantially a predetermined axial disposition with re- 9 lation to the axis of said screw member, each of said elements having one or more toroidally shaped threadengaging portions extending outwardly from the axis of the element, said portions being disposed to rotatably engage and drive or be engaged and driven by said screw at said path when either` member is rotated with relation to the other.

7. In a device of the class described, a driving member and a driven member, one of said members having spirally shaped threads formed thereon, said threads having a crest area and a root area dening a contacting path therebetween, the other of said members having a housing encircling said spiral member, independently rotatable elements carried by said housing and spaced apart to embracingly engage said screw member, each of said elements having a plurality of portions adapted and disposed to engage said path in limited spot or point contact therewith to deliver to said path, or to receive from it, driving thrust, said portions having a progressively lesser cross-sectional area in the direction of the axis of said spiral member than it has normal to said axis.

8. In a device of the class described, a driving member and a driven member, one of said members having a plurality of spirally shaped threads formed thereon, said threads having a crest area and a root area defining a contacting path therebetween, the other of said members having a housing encircling said spiral member, independently rotatable elements carried by said housing and spaced apart to embracingly engage said screw member, each of said elements having a plurality of portions adapted and disposed to engage said path on said threads in limited spot or point contact therewith to deliver driving thrust to said spiral member, said portions having a progressively lesser cross-sectional area in the direction of the axis of said spiral member than it has normal to said axis.

9. In a device of the class described, a driving and a driven member, a screw having a continuous thread of appreciable pitch and root depth, a housing encompassing said screw and carrying in spaced relation to each other, and spaced away from the root area of said threads, a plurality of freely and independently rotatable elements disposed to operatively engage said screw continuously in a path appreciably remote from said root area and from the crest of the thread, each of saidV elements being maintained by said housing in substantially a predetermined axial disposition with relation to the axis of said screw, each of said elements having one or more toroidally shaped thread-engaging portions extending outwardly from its axis, said portions being disposed to rotatably engage said screw at said path and drive or be driven in the direction of the axis of said screw as rotative power is applied to one or the other.

10. In a device of the class described a screw having :a plurality of continuous threads of appreciable pitch and root depth, a housing encompassing said screw and carrying in spaced relation to each other, and spaced away from the root area of said threads, a plurality of freely and independently rotatable bearing elements, each of said elements being maintained in said housing in substantially a predetermined axial disposition with relation to the axis of said screw, each of said elements having one or more toroidally shaped thread-engaging portions extending outwardly from its axis, said toroidally shaped portions being disposed to rotatably engage said screw continuously in a path appreciably remote from said root area and from the crest of the thread whereby rotation of the screw or housing will move the screw or housing along the axis of the screw.

11. In a device of the class described, an elongate member having disposed lengthwise thereof a threaded surface, a second member embodying in a housing, a plurality of freely and independently rotatable elements spaced apart to guidingly embrace said rst member and disposed to operatively engage continuously a predetermined portion of the threaded surface of said member, and means associated with said housing adapted to maintain substantially a predetermined axial disposition of said elements with relation to the axis of said elongate member and being adapted to maintain said elements substantially in predetermined spaced relationship with each other and with the innermost root area of the groove defining said threads, said elements each having one or more thread-engaging portions extending outwardly from its axis, said portions having, normal to their axes and respectively coaxial therewith, parallel cross-sectional areas circular in form and diminishing progressively in either direction from the cross-section medial thereto, said portions having noncircular crosssectional areas parallel to the axis of the element and to each other and diminishing progressively in area in either direction from a cross-sectional area lying in the plane of the axis of said element, said portions of said elements being disposed with relation to said threads so as normally to prevent simultaneous operative contact between said portion and more than one of the two opposed lateral surfaces that define a groove between threads, whereby to provide substantially a continuous point or spot Contact between said portions of said rotatable elements and normally confined within a thrust-receiving path on said thread lying inward from its crest and outward from the innermost part of said thread, whereby to avoid excessive friction and abrasion between such elements and such threaded member.

12. In a device of the class described, an elongate member having disposed lengthwise thereof a threaded surface, a second member embodying, in a housing, a plurality of freely and independently rotatable elements spaced apart to guidingly embrace said first member and disposed to operatively engage continuously a predetermined portion of the threaded surface of said member, and means associated with said housing adapted to maintain substantially a predetermined axial disposition of said elements with relation to the axis of said elongate member and being adapted to maintain said elements substantially in predetermined spaced relationship with each other and with the innermost root area of the groove defining said threads, said elements each having one or more thread-engaging portions extending outwardly from its axis, said portions having, normal to their axes and respectively coaxial therewith, parallel cross-sectional areas circular in form and diminishing progressively in either direction from the cross-section medial thereto, said portions having noncircular cross-sectional areas parallel to the axis of the element and to each other and diminishing progressively in area in either direction from a cross-sectional area lying in the plane of the axis of said elements, each said portion of said elements being disposed with relation to said threads so as normally to maintain operative contact between said portion and not more than one of the two opposed lateral surfaces that define a groove between threads, whereby to provide substantially a continuous point or spot contact between said portions of said rotatable elements, said contact being normally confined within a thrust-receiving path on said thread lying inward from its crest and outward from the innermost root area of said thread, whereby to avoid excessive friction and abrasion between such elements and such threaded member.

References Cited in the file of this patent UNITED STATES PATENTS 2,441,168 Richardson May 11, 1948 2,445,384 Bousky Iuly 20, 1948 2,714,005 Wise Iuly 26, 1955 FOREIGN PATENTS 995,011 France Nov. 26, 1951 UMEED STATES PATENT UEEEEE CERTIFICATE @F CORECTIN Patent Noo 2,913,920 November 24. 1959 Ralph EL, wis@ EEEEE It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correction and thatJ the said Letters Patent should read as corrected below.

Column l, line 15, fer "resists" read m relates we; line 25, ,after "1953" insert a comme; seme line after "1955" insert a come; column 9v line '72, after ".housttgl strike outJ the comma; column 1G, line 33, after "embodying" strike `out bittev comma; ,same line ,after "houaingY strike' out the' Colmaxi Signed' and sealed. this 10th day of May 19610.,

(SEAL) Attest:

KARL I-I.. `.AXTJIMEI ROBERT C. WATSON Attestingl Ocer Commissioner of Patents