CA2114549A1

CA2114549A1 - Toothed fastener

Info

Publication number: CA2114549A1
Application number: CA002114549A
Authority: CA
Inventors: Norman Leslie Matthews
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-07-29
Filing date: 1992-07-29
Publication date: 1993-02-18
Also published as: JPH06511538A; WO1993003283A1; EP0595952A1; EP0595952A4

Abstract

ABSTRACT OF THE DISCLOSURE

A toothed fastener having a threaded portion, and a head portion provided integral to the threaded portion, the head portion having a toothed outer periphery and a pressure transmitting surface. The fastener also has a friction reducing means comprising a first part having a first pressure transmitting surface and a second part having second and third pressure transmitting surfaces. The second part is located between the head portion of the fastener and the first part.
A solid dry lubricant material in the form of an annulus is located between the first and second parts to reduce friction therebetween, whereby the first part can be held stationary relative to the object to be fastened so that the dry lubricant material acts as a bearing between the head portion of the fastener and the fastened object when the fastener is tightened or loosened by engaging the toothed outer periphery. A
fastening tool having a toothed portion for tightening and loosening the toothed fastener, together with a modified automotive wheel incorporating toothed wheel fasteners is also disclosed. The toothed wheel fastener facilitates more efficient fastening and removal of a wheel as well as improved security against theft.

Description

W!? 93/03~ U92/003~3 211 A.~ 4 9 ......... 1 . .
TOOTHED FASTE:NER
~: i FIE~P OF THE I~VENTION
; The present invention rela~es to a toothed fas~ener r having a head portion with a too~hed ouCer periphery and frlc~ion reducin~ means ~or substantlally reducin~ the frictional res~s~ance normally encountered durLng ~lghtelling or loosening of a fastener. The inven~ion relates particularly, though not exclusively, to a toothed aulomotive --wheel fastener of thls kind.

~CKG~Q~D TO TH~ TNVE~TION
A conventional wheel nut or bolt comprlses a head ~;~portlon designed to recelve a wheel brace or spanner, a threaded portlon to screw onto the inner ~lange o~ the br~ke drum located on the wheel axle an~ a tapered cone portion shaped to eng~ge in a m~tchin~ shaped recess provlded in the f~, S wheel. In some arra~gements the cone portion is prov~ded separate rrom the head p~rtlon and somet~mes the ~astener t S
~-further provided w1~h a conventional washer ~ehind the cone.
In other arrangements, partlcularly on tru~k wheels the wheel -20 n~s or bolts have ~ ~lat surface rather than a cone portion.
`-Irrespectlve of the form o~ the ~heel fastener a ... . .
prlmary ob~ec~ive during tightening is to pre-load the bolt or ~5~wheel stud ~o as to lmprove both fatl~ue resistance and the lock~ng effect. When ~ conven~ion~l wheel ~astener ls -~25 tightened a hl~h de~ree o ~riction is encountered, comprlsin~, ~riction on the threaded portion, riction on the conlcal wheel recess and frlctlon on the cone or flat portion contacting t~e w~eel sur~ace or ~ecess. Thus it is necessary to apply signif~ cantly more torque than would theoretically be needed 3 0 to a conven~ional wheel nu~ or bol~ during f astenin~ ~ n order ~o overcome the ~rictional resistance and still obtain the necessary hold-~o~n or clamping pressure. Thi~ becomes very signlflcant on heavy vehicles where the torque requlred to ~i,iovercome friction and attain clam~ing pressure is typically ~, .
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ve y high, ~as~eller friction the~efore cause~ experJ~i~ure of wasteful energy both during tigh~ening and loosening.
Fur~hermore, fastener fric~lon also caUses inaccurate reading of the torqu~ ~ension of ~he fastener. In practise it ls extremely difficult to dls~nguish th~ torque required to overcome friction from the ~orque re~uired to attain the necessary clamPing pressure and this can lead o t~e wheel no~
being securely clamped to the wheel fl~nge.
conven~lonal ~asteners have evolved wlth a means to ~ 10 grip the fastener with a fastening tool, (spanner or wrench), ,, in the form of either a six sided head or in ~ome lnstances a ,~ twelve slded head. The hl~h tor~ue requlred ~o tigh~en high ~ tension load fasteners has dictated this head shape as the rll, flats and corners are able to take the load applied by the tool - 15 as well as provide a sure ~rip for the tool. Where reduced ~',`` torque loadings are all that is re~uirea to ti~hten or loosen ~,; the fastener the head shape re~ulred to grlp and turn the fastener can be different ~rom the conventlonal slx or twelve r-~l sided bead. This leads to ~he possibllity of also reduclng the size and altcrln~ Lhe nature of the ~astenin~ tool.
A fuxther problem wlLh con~entional wheel fastener~
is ~hat the flats on the head of ~he fa~tener mu~t be accesslble ~o allow tightenlng and loosenln~ o~ the fastener hy engaglng the flats wlth a astenln~ tool ~uch aç a spanner, wrench or wheel brace. A wheel brace or ring spa~ner is ~yplcally provided wlth a socket adapted to be received over the head of the ~astener so as to enga~e the flats on all sldes. Alternatively ~he ~astenln~ tool may be an open-ended ~3:', spanner adapted Lo en~aqe the flats on the head of the fastener on two or three sides. ~he~e ~radltional mean~ to sriP a fastener with a fastener tool also dictate how access is ?, ob~ained to turn the ~astene~.
Modern alloy wheels are typically provided with recessed aper~ures adapted to receive the wheel i~asteners ,~, 35 thereln, but unavoidably such recesses must also be large i~ enough to receive the socket o~ the fastening tool. Thus the wheel fasteners remain ~xposed and accessible to unau~horised ~' removal and theft. Various atte~np~s h~ve ~een made to overcome ~'.t t `` 'i ~`
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_ this probl~m including a lockable wheel nut, and a lockable . wheel hub that covers the wheel fasteners. These solutions ~f have had limite~ success in deterring thieves.
- The present invention was developed with a view to .~ 5 providing a fastener which is capable of improving on or over~o~nirlg one or Inor e oE L~le ~ove-note~ ~roblelns with conventional threaded fasteners. Although t~e invention will be described with particular reference to automotive wheel '~ ~asteners, it i5 to ~e under5lood l~hat the ~as~ener is not limited to automotive fasteners and can be used in any application to improve security and/or to enable rapid ~ tightening or loosening of a ~astener with less torque.
r ~ ~ SUMMARY OF THE Il!JVENTION
: According to one aspec~ of the present invc-ntion - 15 there is provided a toothed fastener compr-ising:
a tlireaded portion;
a head portion provided integral to the threaded .- portion and having a toothed outer pe~iphery and a pressure transmitting surface, and wherein the teeth o~ the toothed ~ 20 outer periphery ~re ~dapted to function like the teeth of a ., conventional ~earwheel whereby, in use, the toothed outer periphery can be engaged laterally for transmit~ing a tor~ue ~- to the fastener; and, a friction reducing means COmprising:
`~ 25 a first part having a ~irst pressuxe ` transmitting suxface adap~ed to rotatably xeceive i, said pressure transmitting surEace oE the head portion in facing relation thereto; and, a solid dry lubricant material provided to ~,9, 3~ reduce friction between said head portion and the ~: first part of ~he friction reducing means whexeby, in use, said first part can be held ,~ stationary relative to the fastened objec~ so tha~ s~id dry ;`.~ lubricant material can ac~ as a bearing for the ~eaa portion of the fastener when said fastener is tightened or loosened by engagin~ said toothed outer peri~hery.
Typically said solid dry lubricant material is in the form of a separate annulus located ~etween said Eirst pressure transmitting surf~ce and thc pressure tral~smi~ing surface o~
the head portion.
Pre~erably said first part is in the forln of an ;.
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q ~ annula~ memberllavirlg an annular recess pro~ided therein within `~ whic~l said solid dry lubrican~ annulus is ~on~ained.
dvaIItageously, said pressure trallsmitting surface of the head portion of the fastener is formed on an annular protrusion, said annular protrusion having an outside diameter slightly . smaller than the inside diameter o~ the annul~r recess provide~
in the annular member. The head portion of the fastener may be coated with a film of anti-friction material havirlg ~ low ~;, coefficient of friction.
~r . 10 In one embodiment said head portion of th~ f~stener has an outer circumferential surface o~ su~stantially ~' cylindrical shape having a plurality of gear teeth eY~tending over substantially the whole of said cylindric~l surface. In ~j another embodiment said outer cir~umferential surface has a plurality o~ gear testh extending over a portion only of said cylindrical surface, the remainder of said cylindrical surface having a plurality of ~lats arranged as in a conventional ~` fastener.
According to another aspect of the present invention there is provided a wheel having a plurality of apertures ~j provided therein each adapted to receive a wheel fastener ~' having a toothed head portion, wherein each of said apertures for the ~asteners is recessed to rotatably receive the ~ead portion of the fastener in a close fit therein whereby, in use, the teeth on the toothed head portion can only be engaged ~ laterally, the wheel ~urther comprising:
s~ a recess adapted to rotatably receive a fastening '~`~ tool inser~ed therein whereby, in use, a fastener received in one o~ said apertures can be tightened or loosened by inserting said fastening tool into said xecess and rotatiny the tool with the teeth of a toothed port~on of the tool mechanically coupled `~,, to the teetll on the head portion oE the fastener.
:~ In one embodiment said recess is one of several `^ recesses each provided adjacent a respective aperture for the wheel fasteners.
Advantageously, each o said apertures ~or the fasteners is xecessed to rotatably receive the head portion of the fastener in a close fit therein whereby, in use, the fastener head portion can onl~ be engaged la~erally by rneans of the fastening tool through an adjacen~ recess. The fastener can also be locked by leaving ~he tool engaged with the teeth o ~he ~astener head portion and making ~he tool immobile in , ~, E~ ' ` ~

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the recess adjacent the aperture.
Accordin~ to a still furlher aspect of the present invention there is provided a fastening ~ool for a fastener having a toothed head portion, the ~ool comprisln~:
s a shank having means ~or gripplng the tool; and, a toothed portion provlded on the shank, having teet~
adapted to engage the teeth of the toothed hea~ portio~ o the ~ fastener w}~erebY, ln use, the toothed he~d portion of the ~ool b, can be mechanicallY coupled to the head portion of the fastener r ~10 and ro~ated to loosen or ti~hten the fastener.
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,~In one embod~ment, said tool iG in the form o~ a key It'having sald ~rlppln~ means at one end of the ~hank and said too~hed por~lon proxima~e the other end of the shank.
~,Pre~e~ably, sald shank is in the form of a sha~ of ~`~lS circular cross-sect~on. Advantageously, said toothed portlon r~,~of the key has a diameter smaller than the di~neter of ~he ~,too~hed head portion of the fastener.
~'`A recess into whlch Ihe shank o~ the tool ls inserted may be provided ad~acent the aperture in the ob~ect to be fastened or may be provlded ln a separate key support.
~,The key ls partlcularly advantageous ~or use with a wheel fastener having a toothed head portion and incorporatlng friction reducin~ means as descr~bed a~ove. ln 1ts applicatlon to a wheel ~astener, the wheel may be provided wlth a recess adjacent esch fa~tener hole, for receiving the ~hank of the key. The low torque required to tlgh~en or loosen the fa6te~er lncorporating the iric~ion reducin~ means that a ~mall key can ~be used ~o loosen or ti~hten ~he fastener ~anually, snd being '~,,small the tool is able tO fit lnto space ~vallable ad~acent ~he t-.30 fas~ener. The toothed portion of the key belng of smaller ~`idiameter provideS a mechanlc~l advantage as determlned by the 'gear ratio.
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RIEF DESC~I~ION QF THE DR~WI~GS
~,In order to ~acillta~e a better unders~anding of t~e nature o~ the invention, several embodlments will now be desc~ibed, by way of ex~ple only, wl~h re~erence to ~he ia~ompanying dra~ings 1~ which:

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093~032~3 rcl/Au<>2/oo393 ~s"~`~
~ 6 ~ 9 . , i~ Figure 1 is a section view through one ei~odiment of a too~hed f~terle~- according to the invention;
~ Flgure 2 1~ a plan view of the too~he~ fastener of c~l Fig l:
~, s Figure 3 lllustrates one embodimen~ of an automotive wheel incorporatlng toothed wheel fasteners;
~ igures 4(a) (b), and (c) illustrate a fastening tool for tightening and loosening a toothed fastener: a~d, r~, Fi~ures S(a), (~) and (c) lllustrate a varianl of the arrangelllerl~ shown in Fi~ure 6.

~, ~ETAILED DES~RIPTION OF PR~FF.RRED ~M~OVIMENTS
b~ Figures 1 ~n~ 2 illustra~e a preferred e~oodiment of a toothed fastener 1~ accordlng to the inventlon in the form of a wheel nut. The wheel nut 10 comprlses a ~hreaded por~ion lS 12 for screw threade~d engagement wlth a matching thread of a bolt or stud prov~ded on ~he flange of the brake drum located . on a vehicle axle (not illus~rated) to whlch a wheel ls ~astened. The wheel nut 10 further comprise~ a head port1on 14 provided lntegral to Ihe threaded portlon 12 and havlng a toothed ou~er periphery 16 and a pressure transml~ln~ surface 18 formed on an annular protr~slon provl~ed coaxial wilh the threaded portion 12 of the wheel nut. The wheel n~t also compri~es a frlction reduclng means 20 comprlsing a first part 22 havin~ a first pressure transmlttlng sur~ace 24 adapted to ~25 rota~ably receive the pre~sure CransmlL~lng sur~ace 18 of the head portlon 14 in ~aclng relatlon thereto. In this embodlment ~he flrs~ part 22 is in the form of an annular member havlng an annular recess provlded therein, the wldth o~ the annular recess being sll~htly l~r~er than the wldt~ of che annular pro~rusion lB provlded on the head portlon 14 of the wheel nut.
" Thus, the annular member 22 is free to rotate wlth respect to the wheel nu~ 10 w~th the annular protrusion 18 of the head ';~ portion 14 slidably recelved wi~hin the annular recess of ~he L~1l annular member. Advantageously, the head por~ion 14 of the ~-! 35 wheel nu~ is provided with an annular llp 26 ad~acent a necked ~j~ portion 28 o~ ~he wheel nut on which the ~nnular member 2Z is rotatably supported. The annular lip ~6 can be bent outwardly .., . .
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''`~ , ' ' .: . . , ~ W093/03~3 rCr/AU92/00393 - ~ - 211 ~ a ~ 9 - ~s illus~ra~ed i~ Fis~re 1 ~o re~ain the annul~r member 22 on ~the w~eel nu~. If de~ired ~ washer o$ resilient material m~y .~ be provide~ adjacen~ the lip 26 ~o bias the firs~ part 22 ~; ~owards ~he ~lead portion 14 and to act as ~ sedl ac;ainst ~he S ingress of dust and o~her conta~inantS
The frictlon reducing means 20 fur-her comprlses a solid dry lu~ricant ma~erl~l 30 in the form of a separa~e ~`: annulus located between the first ~art 22 a~d the head portlon 14 to reduce friction ~herebe~ween. The solid dry lubricant annulus 30 is contained withln the annular recess of the firs~
`~ part 22 ad~acent the flrst pressure ~ransmitLing surface 24.
~`1 The annular recess contains the solid dry lubrlcant annulus and prevents cold flow o~ the lubrlcan~ ~aterial when subjected to ~i hi~h compressi~e load.
~-1 15 In this embod~ment, ~he friction red~cin~ means 2n ~;~ further comprises a second part 32 located be~ween the he~d portlon 1~ of the wheel nut and the flrst part 22 of the friction reducin~ means 20. As lll~strated in ~lgure 1, ~he second part 32 i~ in the form of a washer rotatnbly recelved withln the annular recess of the ~lrst part 22, and havlng 1 second and ~hlrd pressure transmitting ~ur~ace~ adapted to i~ recelve the respect$ve pressure transmlt~ing sur~aces of the ~lr~t part 22 and the head portion 14 ln aclng rela~lon thereto. Advanta~eously, the washer 32 is manufacrured from ~25 a ~inely gralned, non-corrosLve materiPl ~lan the head portlon i'14 of the wheel nut, for example, s~alnless steel, and provides ~,a smoo~h pressure transmitting surface for sliding engagement with the solld dry lubrlcan~ annulus 30. Hence, if the first -~par. 22 is held staclonary rela~ive to the fastened ob~ecc and -,30 the second part 32 rotaCes with the head portion 1~ of the ~,w~eeL nut 10, ~he solid lubrlcanl annulus 30 act~ as a bearing for the he~d portion of the wheel n~t when the wheel nut ls tightened or loosened by engaging the toothed outer periphery 16. The washer 32 also helps to contain the soli~ lubrlcant material wl~hin the annular recess of the ~ t part 22, an~
is manufactured to be rotatably received wlthin the annular recess to a close tolerance.
The head por~ion 14 of the wheel nut has an ou~er ~ ,, .

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3/032~3 ~ I /A IJ'~ )U393 F
- 2 1 1 ~ 9 ~.~ circumferen~lal surface of subs~an~ially cylill~ri.cal shape :. ~avincJ a plurality of gear ueeth 34 eYtendirl~J over f~ substantially the whole of the cylindl-ical sur~ace, as : lllustrated most clearly in Figure 2. ~s can be seen in ~igure r` ~`' 5 1, one end of ~he wheel nut 10 ls pro~lded wlth a chamfer 36;
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~; as on a conventional wheel nuc, to allow a socke~ of a ~, fas~ening tool (not illustrated) to be i~ted thereto more ` easily. However, the princi pal advantage of the toothed outer ~,-i periphery 16 of the wheel nut 10 is that the wheel nut can be ti~h~ened or loosened by engaging the teeth 34 la~erally ~lth ~1 a f~stening tool, rather than coaxially ~ wlth conventional v~ wheel fasteners. An embodiment of ~n ~utomotive wheel f~, incorporating ~oo~hed wheel fasteners will now be described ~, with reference to Fi~ure 3 Figure ~ illustr~tes a wheel 40, typically manufactured _rom magneslum/alu~in~um alloy material. The ~, wheel 40 i~ fastened to a wheel flange of the brake~drum on the ~ vehlcle axle by means of five too~hed fasteners 1~ the ~orm of .~
wheel bol~s 42 (see Pl~ure 4). Each o~ the toothed wheel bolts 42 comprise a threaded portion, and a head portlon provided lntegral to the Ihreade~ por~lon and h~vin~ a toothed outer periphery and a pressure transml~tlng surface. Each wheel bolt ~' 42 also comprises a fric~ion reduc~ng ~eans (not vislble~ w~ich ~' ls struc~urallY and functionall~ slmllar to the ~r1ctlon reducing mean~ 20 of the wheel nut 10 illustra~ed in Fig~res 1 and 2. The toothed outer periphery of the wheel ~olts ~2 i~
formed on an outer cyllndrical surface of the head portlon of the wheel bolts.
`' The wheel 40 ls provlded with flve recessed aper~ures 44 within whiCh each of the wheel bol~s 42 can be received.
ach o~ the recessed circular apertures 44 ls d~mensioned to rot~tably recelve the head portion of the wheel bolts 42 ln a close flt therein. Hence, the teeth on t~e head portion o~ the wheel stud can only be engaged la~erally for tlght-ening and 35. loosenin~, by means of a fastening tool 46 (~ee Figure 4).
~ h~ fa6tening tool 46 lllustrated irt Figure 4 comprlses a shank 48 h~ving means for g~ipping the tool in the form of a handle 50 at one end o~ ~he shank. The ~ool 46 ' .
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~r~her comprises a toothed por~ion 5~ intermediate the len~
~, of ~he shank 48 having teeth adapted ~o engage ~he ~eeth of ~he oolhed head portion of ~he wheel bol~s 42. E~ch of the ~, circular apertures 44 isl t he wheel 40 i~ provided wi~h an adjacen~ aperture 54 within which ~he shank 48 of the fastening ~- tool 46 can ~e xotatably recelved ~o ~h~ ~he tee~h of the tool can en~a~e ~ith the teeth o~ the toothed head portion of the , wheel boll.
,~`'' The provislon of fastenins ~ool 46 not'only enables ~, 10 more efflcien~ ti~htening and loosenin~ of thc- wheel bol~ 42, bu~ also provides improved securitY against theft, since would-~e-thleves must have a fastening tool wlth toothed head portion in order to remove the wheel bolts 42.
t ls lar~ely ~he provislon of ~riction reducing me~ns in each of the wheel bolts 42 that enables the torque required to tl~hten/loosen the wheel fasteners t~ be kept to a mlnimum. The frlctlon reduclng means signlflcantly reduces ~, the torque required ~o tighten the wheel fastener~ while 1 main~alning adequate clamPing pre~sure. Indeed, ~he reduc~ion i~ torque requlred to achieve the requlred clamping pressure ~,i facllitated by the pro~lsion of the f~ictlon reducin~ means in ~, ~he wheel fasteners, enables the number of wheel fasteners ~'~ require~ ~o ~asten the wheel Lo the vehlcle axle IO be reduced., Thus, ~ox example, ~he wheel may be desl~ned to recelve only ~5 three fasteners, rather than ~ive as i~ the illustrated ~'~ embodiment, and ~till -be able to achieve t~e same hold-down ~' pressure as ~ive conven~ional wheel fasteners. This i~
~,' partlculaxly true on wheels where most of the ~er~lcal load ls , ~1, ln fact carried by the wheel hub rather than the wheel '~, 30 fastener~.
Preerably, the number o~ teeth provlded on ~he hea~
~'- portion o~ the ~oothed fastener is designed ~o be a maximum to provide addi~ional ~echanical advantage, and is limited only by ~he di~neter of ~he head portion of the fastener and che ~ 35 need to keep the teeth large enough co withstand the load !`.'` applied during tighteninglloo~ening o~ the fastener.
'~? The wheel 40 ~ay be fu~ther provided with a security ,~ hub cap (not ~llustrated) which covexs all of the apertures 44 t ~.
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W093/0328~ `/AU92/~03~3 ~1~ 4 and thus ~ur~her inhibits un2uthorlsed access ~o ~he wheel ~'~asceners. The hub cap is provided wlth five pro~eclins Parts slidably received in the ~perture~ 54 and ad~p~ed ~o engage the eeth o~ the head por~lons of the wheel bol~s 42 and thus lock S ~llem irl posi~ion. The hub cap can be locked on ~he wheel usin~
a conven~ional key operated lock in ~lown fashi.on.
.Fl~ure 4(a). (b) and (c), lllustrate ln ~reater detail the arrangement ~or enablins secure loosening and ~itightenln~ ol the too~hed fastener 42 in the form of a wheel bolt incorporating friction reduclng ~eans simllar ~o ~hat illustrated in Figure 1. The fric~ion reduclng means o~ the ~,wheel bolt ~2 lllustrated in ~igure 4(a) is provided wi~h a ~lrst part 56 having a frusto-conical surface 58 which is received in ~he cone-shaped aperture 44 provided ln ~he wheel 40. In o~her ~espects, ~he fr~ction re~ucin~ ~eans is structurally and functionally egulvalent to that of ~he fastener lllustrated ~n Flgure 1. The ~irs~ part 56 is .provide~ with an ann~lar recess in whlch a solld dry lubricant annulus 60 ~s received, to~ether wlth a ~econd part 62 in the ~orm of a stalnless steel washer. In this embodiment the shank of the bolt coac~s with the annular recess to contain the solld lubr~cant annulus 60 The head portion of the fastener 42 ls provided wi~h "~,~
gear teeth 45 on lts outer perl~hery whereby, in use, the ~astener can be tightened or loosened by inser~lng a _as~ening ~-tool ~6 lnto the recess 54 provided ad~acent the head por~on i............ of the fastener 42 ln ~he wheel 40, and ro~atlng the tool 46.~' wi~h the ~oothed portlon 52 of the tool en~aging the tee~h 45 on ~he head por~ion o~ the ~astener ~2.
~, 30~he par~lcular embodlment of the f astening cool 46 .`.: lllustrated is in the form of a key comprlsing a shank 48 in ;- the form of a shaft of clrcular cr~ss ~ec~ion, and havin~ means for ~ripping ~he key in ~he f orm of a handle sn a~ one end.
. ~he toothed por~ion 52 of the astenin~ key is provided wl~h tee~h on its outer peripher~ adap~ed to engage the teeth 45 of the head of the fas~ener 42. The recess 54 in the wheel 40 is .~ provlded with a shoulder on whlch the toothed portion S2 slts i wlth the ~haf ~ 48 ex~endin~ into the bore of the recess 54 and .
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beins freely rotatable thereln. As can be seen most clearly ~,in Figure 5(c) ~he too~hed porcion 52 of the fastening lool 46 .is of s1n~11er diameter than the head of the f~stener 42 and '~therefore a mechanical adv~ge is provi~ed due ~o the di~erence in ~he n~m~er of ~ear teeth.
~, 1Obviously, l;}le griE~ping me~sls ol~ Lhe ~stening tool 46 need rot be in the Iorm of a handl~ 50 as ln ~he illus~rated ~,`embodimen~, but may be adapte~ to be received ln the chuck o~
a power tool to enable rapid tlgh~enln~ or fastenin~J of ~he 10 too~hed fastener 42. However, the pxlncipal ~dvanta~e o~ this arran~ement is that it enables manual tlgh~ening or fastenin~
;.,of the fas~ener 42 using a small fastenlng tool of the ~lnd ~illustrated. r~his is posslble due ~o the rela~ively low torque '~requlred to obtaln ~he necessary hold-down or clamping pressure lS with Lhe Ias~erler 42 on the w~eel, due ~o the provision oL the -friction reducin~ mean~ in Lhe fas~ener 42.
i~~igure 5ta~, (b) and (c) lllustrate a variant of ~he .arrangement illustrated in Figure 4, whlch opera~es ln a substantially identical manner, but doe~ not require t~e ~`20 provision of a recess a~acent the fastener aperture ln ~he actu~l ob~ect to be fastenea, for recelvin~ the shank of the fas~ening tool. ln this alternative arran~emen~, a key ~upport 110 is provide~ having a ~lrs~ aperture 112 through whlch the `lthreaded portlon of the fastener 42 is recelved, and a second ~:1 25 aperture 114 ln which the end of the shank 48 oL the fasten1ng ~, tool is rotatably received The key support lln i~ provlded ~-~ wlth an arcuate wall section 116 whlch acts as a gulde for the ~;~ fastening key 46 durlng rotatlon Or ~he latter ln the ap~erture ~ 114. ~ guide rlng 118 provide~ on the shank o~ the raStening c30 ~ey sl~dably engages the ~nner sux~ace of the arcuate wall ;`-section 116 and enables the fastenlng key ~6 to rotate freely wi~h the toothed portion 52 engaging the teeth on the periphery ..o~ the head por~on of the toothed fastener 42.
;As ca~ be seen clearly in ~igure 5(a), the first part ~-~5 120 of ~he friction reduc~n~ means is similar to the firs~ part .`22 of the firs~ e~bodiment descrihed above and lllustrated in `. .:
Fi~ure 1. Fur~hermOre the head portion of the fas~ener 42 ls also provided w~th a pressure transmltting surface 122 as ln ~ ' :
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WO 9~/032X3 rcr/A u~2/~)()3s3 2 ~

the embodiment o~ Fisure 1- l~he faste~lins key 46 in this ~,~alte~native arrangement funclio~ls in substan~ially identlcal manner to that in Figure 4.
~ as~eners of the above kind coul~ be used on mo~or s vehicles, fdrm mac~inerY, trac~ors, truck~ a~ld irldustriai machinery, and will be particularly advantaseous where Parts are regularlY chan~ed or replaced as t~e fas~eners can be `~~uickly removed and replaced. When used ln con~unction witl, ~`a fastening ~ool or key as descrihe~ ~bove, the toothed ~,lO fascener can be easily tlghtened or loosened wlth as llttle as ~`-A ~ingle revolution of the key The toothed head portion oJ
increased diameter also provides a positive gripping surface for manual fastenlng or loosenins. The head por~ion of ~he toothed fastener may also have a normal tool grlp, for exa~ple, ~15 an ln~ernal hexagon recess, or may incorporate a manual '~grlppin~ device of the kind disclosed in co-pending Internatio~l Appllcation No. PCT/AU91/~0420, to facill~ate manual tightening ~nd loosenlng. Thu~, for example, ~he fastener may be rap~dly turned manually, and thenjti~htened or loosened using a key or fas~en~ng tool as hereln described.
-The friction reducin~ means employed in the too~hed :fastener of the present inventlon substantlally reduces ~he ~turning r~ction encountered durl~g tlghtenlng and loosenil~g `-`o~ the fastener. ~here~ore the six or twelYe side~ head ~25 portion of a conven~ional fastener, dlctated by the high torque j~required to overcome frictlon, c~ be repl~ced with a toothed head ~ortlon in the present invention, whereln only one or two ~teeth of the head portion need be engaged durlng tightenlng or loosenlng of the fas~ener. Th1s would not be pos~ible wlthout the ~ricLion reduclng means, unless the slze o~ Ihe head por~ion ~as si~nificantly increased, ~ince the load on one or ~two teeth would be too great. Furthermoxe, the reduced torque -re~uired to ~urn the fastener enables the use of a ~oo~hed f~stening tool, prefexably of lesser diameter, which engag~s ~-3s at least one side o~ Ihe ~oo~he~ head portion. A mechanical -advantage can be ob~alned by selectln~ an appropriate gear ~ .
ratio between the teeth on the tool and on the ~astener.
The solid dry lubrican~ materlal employed in the ;, .
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Iric~ion reducing means in each of th~ a~ove ~escrlbed er~odimenls may ~e any suita~le materlal, for example, a fluoropol~ner plastic h~ving a low coe~iclent o~ ~riction suc3, , - 25 PTF~, com~only known as Teflon Advantageously, the PT~E
may be cor~ned with ~owdered glass in order ~o produce a dry ~; lubricant materlal havins a mirli~um coefficierl~ o~ friction and capable of withstanAing a large compressive ~orce. The mos~
preferred form of the solid dry lubricant ~aterial i~ ~eflon ~ or a composite incorporatlng Teflon. Teflon i5 par~icularly ,~ 10 suitable because lt is resilient, has a low coe~lcien~ of slidlng friction ~nd is wear resistant. Hence, w~len used in the frictlon reduclng means of the invention 1I can act as a ~' pressure absorblng element and may act to apply an axially directed pre-loadin~ force to the fastener. Thls pre-load~n~
` 15 provlded by the Teflon may coac~ wlth the normal pre-loading obtained by tensionlng the ~tud or bolt of the fastener.
Te~lon has other unl~ue characteristics whlch make i~
particularly sul~able for this a~plicatlon; i~ is inert, non-~` moisture a`bsorbing and thermally stable.
It ls not essen~ial that the solid dry lubricant material be provided as a separa~e inte~er in the friction '~ reducing means. I~ may, for example, be pro~lded lntegral ~o '~ said first p~r~, the first part being itself Jnade wholly or -~ partly of said dry luhricant materlal or in the orm of a cornposite. It ls essential that the dry lubricant material act to reduce fr~ction between the respective pressure ~ransmitting . . surfaces of the head p~rtlon of lhe fas~ener anA the firs~ par~
~, o~ the friction reducln~ means.
- It will be a~parent to persons skilled in the ~` 30 mechanical arts that numerous variatlons and modlf~cations may be made to the described embodiments o~ the toothed lastener, ~-- ln addition to those already descrihed, wit~out departing from .: the baslc invenrive concepts. For example, ~he ~oothed outer periphcry o~ the head portion need not have teeth provided over , 3S the entire periPherY, a~d ~ay have teeth over only a ~ractlon ~ of the circumference. ~urthermore, the teeth need not ex~end `~ over the whole of the perlphery in an axial direction, but may .

~. excend over only a porl~ion, the remalnder belng smoot21 or :.~
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WO 93/03283 PCI`/A U92/00393 ~ 9 1~
. havln~ flats a5 on a conventional fdstener. All such variations and modifications ar~ to be considered wl~hin tl)e scope of the }~resent in~ention, the nature of which is ~o be .: determined from the foregoing description and the appen~ed ~`' S claims.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-

1. A toothed fastener comprising:
a threaded portion;
a head portion provided integral to the threaded portion and having a toothed outer periphery and a pressure transmitting surface, and wherein the teeth of the toothed outer periphery are adapted to function like the teeth of a conventional gearwheel whereby, in use, the toothed outer periphery can be engaged laterally for transmitting a torque to the fastener; and, a friction reducing means comprising:
a first part having a first pressure transmitting surface adapted to rotatably receive said pressure transmitting surface, of the head portion in facing relation thereto; and, a solid dry lubricant material provided to reduce friction between said head portion and the first part of the friction reducing means whereby, in use, said first part can be held stationary relative to the fastened object so that said dry lubricant material can act as a bearing for the head portion of the fastener when said fastener is tightened ox loosened by engaging said toothed outer periphery.

2. A toothed fastener as claimed in claim 1, wherein said solid dry lubricant material is in the form of a separate annulus located between said first pressure transmitting surface and said pressure transmitting surface of the head portion.

3. A toothed fastener as claimed in claim 2, wherein said solid dry lubricant material is a fluoropolymer plastic having a low coefficient of friction.

4. A toothed fastener as claimed in claim 2, wherein said first part is in the form of an annular member having an annular recess provided therein within which said solid dry lubricant annulus is contained.

5. A toothed fastener as claimed in claim 5, wherein said pressure transmitting surface of the head portion of the fastener is formed on an annular protrusion, said annular protrusion having an outside diameter slightly smaller than the inside diameter of the annular recess provided in the annular member.

6. A toothed fastener as claimed in claim 1, wherein said friction reducing means further comprises a second part having second and third pressure transmitting surfaces, said second part being located between the head portion of the fastener and the first part of the friction reducing means, with said third pressure transmitting surface being adapted to receive said pressure transmitting surface of the head portion in facing relation thereto, and said second pressure transmitting surface being adapted to receive said first pressure transmitting surface in facing relation thereto.

7. A toothed fastener as claimed in claim 6, wherein said second part of the friction reducing means is in the form of a washer adapted to rotate with said head portion of the fastener.

8. A toothed fastener as claimed in claim 1, wherein said head portion of the fastener has an outer circumferential surface of substantially cylindrical shape having a plurality of gear teeth extending over substantially the whole of said cylindrical surface.

9. A wheel having a plurality of apertures provided therein each adapted to receive a wheel fastener having a toothed head portion, wherein each of said apertures for the fasteners is recessed to rotatably receive the head portion of the fastener in a close fit therein whereby, in use, the teeth on the toothed head portion can only be engaged laterally, the wheel further comprising:
a recess adapted to rotatably receive a fastening tool inserted therein whereby, in use, a fastener received in one of said apertures can be tightened or loosened by inserting said fastening tool into said recess and rotating the tool with the teeth of a toothed portion of the tool mechanically coupled to the teeth on the head portion of the fastener.

10. A wheel as claimed in claim 9, wherein said recess is one of a plurality of recesses each provided adjacent a respective aperture for the wheel fasteners and adapted to rotatably receive a fastening tool inserted therein whereby, in use, the teeth on the toothed head portion of each fastener can be engaged laterally by the fastening tool.

11. A fastening tool for a fastener having a toothed head portion, the tool comprising:
a shank having means for gripping the tool; and, a toothed portion provided on the shank, having teeth adapted to engage the teeth of the toothed head portion of the fastener whereby, in use, the toothed head portion of the tool can be mechanically coupled to the head portion of the fastener and rotated to loosen or tighten the fastener.

12. A fastening tool as claimed in claim 11, wherein said tool is in the form of a key having said gripping means at one end of the shank and said toothed portion proximate the other end of the shank.

13. A fastening tool as claimed in claim 12, further comprising a key support having an aperture in which an end of the shank of the tool is rotatably received for supporting the key during tightening or loosening with the threaded portion engaging the head portion of the fastener.