US1447263A - Grinding machine - Google Patents

Description

S. H. NORTON GRINDNG MAQHINE Fi l-ed May '7 sheets-sheet 2 INVENTOR A AA A S. H. NORTON GRINING MACHINE Filed May 4, 192Q '7 shets-sheet 5 Allarhey Mm. e, mz3. mm@ l S. H. NORTQN GRINDING MACHINE Filed May 4, 1920 7 sheets-sheet 4 INVENTOH lfarney' Mar. 6, 923. 1,447,253

S. H. NORTON 'GRINDING MACHNE '7v sheets-sheet 6 Mar. 6, 1923. Lwi

s. H. NORTON GRIND'ING MACHINE Filed May 4, 1920 '7 sheets-sheet 7' Fig/l Patented Man? 1923. Y

SAMUEL HARRY NORTON, or MnaDviLL, PENNspYLvAivIA.

Grammars- MACHINE'. l y

` '.fappnaeion `inea Maya; 1920. serial nojarsgze?.

through another `part of which a re-,loading of the'D means is accomplished'. j y

in carrying the invention forward itk is` desirable to provide `means by whichvv the work may herotatedand to have this means providedwith devices forvarying the speed at which the worlrj is rotated. It is also' desirable to vary the speed ofthevorbital movement of 'the' work-carrying means in different parts of its travel, .that is, in-that portion of the pat-hin which the-grinding is`done and in which the work is'changed the speed should be'comparatively slowgand in that part of the travel which vis carrying the work-carrying means to thel grinding 'wheel7 or in other words7 in the inter-k mediate portions ofthe travel the speed should loe comparatively rapid."v y Y `l Y vVarious adjustments for the`VV grinding wheel and for reversing the reciprocatingl movement thereof and forfeeding the wheel are also provided. l Other features of the invention willap pear from the specification and claims. l

The apparatus ofl the invention is illiis` trated inthe accompanying drawings as follows 1- Fig. l is a` plan view of thev machine,v partly in section.

Fig. 2 and end view of the grinding wheel and driving spindles of thework-carrying means showing-their relation.I

Fig. ,3 is a front elevation ofA the machine. Fig. el is a section onA the line 4*@ in Figi. Fig.=5 an end elevation of the machine.

Fig. 6 an enlarged plan view of the shift-y ing device for shifting the speed of the travel of the orbital work-carrying means. Fig. 6a a detail view of the shift handle.

Fig. 7 a sectionon the line 7 7 iny Fig. l; Fig. 8 a section on the line 8--8 in Fig l.

rames' ansection'onithe line inFig. 3. y

Fig. l() is adetail viewqof the shifting lever for reversing thefgrindingwheel Yearriage.

Fig. ll shows 'a section onth'elin'e `11-*11 inF-igl.

Fig..l2is a section-on the line y rig; 5.,

l 'marks thelhase 0f thebmachine.'i2 the shaft on which the workgcarirying 'means is.

mounted, an`d'2b bearings in ywhich the shaft n 2-is joiirnaled. 'f Heads .I8 and 4@are lmounted ony the-shaft 2. The yhead afcarriesgthercenf ters 5. i 'lhefcentersv are 4carried intheiisual spindles I `6--'6 in the tailj ystock v 'and "adapted toheadjusted hyany convenient mechanism y j.

(notsh'own) 'secured the clampsf. flfhe centers 8" arearranged in "the 'spindles 9' of the head stock on lthe head 3 and the spindles 9; are Vrotated and lprovided with anyfeon. vement/means for rotatively driving-the workf.. The spindles 9- arecarried in'yhea-rwings l0 preferably hall hearingsin'zthe head y l 3 vand they :are providedattheirrear ends n with gears l2' (see Figs. l and 4). The "gears l2 mesh withgears l'carried by `rock 14C, `the rock arms being-secured to the head by meansof pins 15..Jr'irms.lonthe rock-arms? are provided with camrollers 17',

which engage a :cam '18 in acasue-llf.7 i'Springs f 19 throw the rock1 arms to; .carry "the"'gear`s.

lf3 outwardly Vand the rollersl'ope'rate on Va surface 20fwithin the case 11 except where actuated by the cam`l8. During thepart'Of the `travel in lwhich the roller isfon the cam 18 the,y gear '13 'is'forcedz' intowmesh 'with Aa gear 211oiirnaled on the. vvshaft 2.

The gearx2l is driven h v-a gear '22 carried by a short shaftv 23 which is journaledin hearings 24.- A gearf25. is'fixed on theshaft 23 between thehearings 24k and 'meshes'vlwith a gear 26 (see Fig. 9); .A gejar26isxed s'l'idingly `mounted onfthe shaft 27lloiit locked "against rotation thereonby a spline 30.- A

andis adaptedfvto be thrown into mesh with '0a' esima-27; The shafi'eafagjaamaiea in hearings 28` in i the frame.- l' gear f 29 is any of thefgearsf whichf'gears vary in size. The gears 36v are mounted on a sha-ft` 377 the shafti being joiirnaledin hearings 38 inthe frame. "The" frame 81- i may be thrown todifferent positionsv sofas 'to engage the various gears ,36 by meansofthe, handle 34 which may be locked into the varying notches 35, 'thus accomplishing a variation in speed of the gear 26 and consequently of the rotation of the spindle 9. This speed changingdevice is one 'of ordinary construe tion and quite commonly used on machine tools. The largest of the gears 86 meshes with a gear 39 mounted yon a shaft 40 (see Fig. l2) and is fixed on the shaft by means of a pin 4l. The shaftl is mounted in the framey by v'bearings 42. A gear 43'ismounted on the shaft '119 and `meshes with a gear 44. The gear 44 is mounted on a vshaft 45 extending lengthwise 'of ythe machine and mounted in bearings (not sl-ioi'n) on the frame. lgea-r 46 is fixed on vthe shaft 45 and meshes with a gear 47. rlhe gear 47 is fixed on a shaft 46 carried in bear ings y49 mounted-on tlie frame. A pulley 50 islixed on the shaft 48. A bolt 5l drivesthe pulley from the pulley-52. The pulley 52 is fixed on a shaft 58. The shaft 53 is vmounted in bearings `53a on an upright` 53b extendingl upwardly lfrom Vthe frame. A chain-gear 54 is mounted on the shaft and `a vchain S5/extends from the gear 54 to a'gear 56. The gear 56 is mounted on a. rotor shaft V57 of a motor 5S. lThe .motor is mounted on a base 59 carried by mav be viven varifno` saeeds tlirouo'lithe .f D b b speed changing device as desired and that this rotation lis accomplished iiotwitlistanth' ing; the orbital movement of these spindles.

rbital movement is given to the spindles through the following -dniyina' -.iif.cliairisni which as before 'stated4 preferably caries the movement so that in that part of the travel 'in which the grinding is jdone and the work is changed ythe movement is very slow While in the intermediate parts of thetravel the movement is very rapid. A worm gear-60 is `fired on the end of the shaft 2. A Worin 6l meshes with this gear (See Fig. il) and is mounted on a Shaft62. "The shaft 62 is carried in bearings 63 in the frame. Gears 64 and 65 areijournaled on the shaft 62 and are adapted to ybe locked `r-,iiththe shaft by a clutchelernent 66 Which has the detents 6i' vand 66-1n'hich fare adapted to be thrown into engagement "with similar detents on the gears 64 and 465. The gear 64 forms the slow speed connection. It -meshes with a gfear 69 journaledonthe shaft 40. A Worin 'gear 70 is xedfon the hub of the lgear v69 and'meshes with a Worin '7-1. The Worm 7l 'is carried fby' a vshaft 72. The shaft 72 is journaled in bearings 73 `in the frame. A ivor'm gear''ll :(see :Figs '5 and l2) are fired on the shaft 72 'and a-Worm Z 5 :me-shes with on the frame. A friction disc 76 is fixed on the sli-aft T6 and is engaged a friction Wheel 9. The friction Wheel 79 is carried by a shaft 80. The shaft 8O is mounted on bearings 8l and 82 on the frame. A gear 83 is fixed on the shaft 89 and meshes with the gear 43 on the shaft 40. As before fdescribed the gear 43 gets its motion from the shaft 45 and through the connection heretofore described with the motor the orbital movement of the spindle is accomplished. This speed maybe varied by changing the flocation of the friction pulley 7 9 on the friction disc 78. An arm 84 carriesftlie friction pulley 7 9 and controls its position relatively to the yaxis of the disc. rlhe arm 84 is slidiiirly mounted on an upright shaft 86 (see Fig. 3) by means of the bearings 87. An arm 86 extends from this bearing through the front of the frame and a locking pin 89 is arranged in ythe arm 8S and is adapted to be inserted in the openings 9() on the frame so as to lock the friction pulley iii-its different adjustments to vary the speed at which the spindle is given orbital movement in that part of the path in which `the u Work @is accomplished.

[The intermediate orbital movement of the Work-carrying means should be, as before `described, rapid and of uniform speed.

This i., accomplished through the Tliisgear meshes with a gear 91 on the shaft 40 and this shaft is driven. as before describechby lthe gear 43 meshing with the roar 44 on the shaft 45. This completes vthe drive lfor this intermediate increment.

The shift mechanism for shifting; the drivingconnection to the shaft 62 and consequently to the Worl-carrying means is as follons: The friction kelement 66 has av groove 92 which is engagedlfiythe end of the lever 93 in the usual manner. The lever is mounted on a pin 94 carried 'by the frame. An arm 95fexten`ds from the ylever 93 and is liii'fotally connected therewith by a pin 96.

The extension 95 extends through a slot 9T in the cover plate`98 on the housing 1, the housingbeing` mounted on the frame '.(see Figs. il and 'A yielding locking device is provided by a sliding bloei; arranged on the top of the lever and pressed downwai'dljvP by a spring' 99, the spring' engaging a shoulder l0() on tlic lever i detent lli] which engi z W2 secured to the plaie f 03 is carri-.ml b; fuides L04 in the lioiisi .di cani .finger l .i extends forwardly 'laoin i'heslide lil into the path of a cam l06 earried by the Worin gear 60. rlie position lof the 'linger lllwinay be adjusted. The finger 3.05 slidingly mounted in the slide 103 and may be adjusted by a Screw 16S Wliic'his proif'idednith a shoulder 109 engagingthe rear wall il@ of tliefsli'de 103. The screw stein has ildei l enga o' the rear Wall of the a itndle lla is provided by means The bloei:

ell() CIY Cir

of which the screw may be adjusted;v ln this way the linger T 'may be fretiated or' movedlforwardso as to vary ythe"thrust:

which is accomplished by .the Cam 106,. A spring- 113 extends inte-'a seelet=1j14lm the rear end oftlie slide,l and engages. a plug 1142l quently throws the clutch.- to elifect the leighA speed connection; Neen `the @aml 106 en-y gages the .niger 105 it pushes tlie'fslide 103` te the rear.' A pin 115V engages the llever 'llns pinextends `nte azseeletg116.lnftlie slide and is pressed outwardly by a spring` 117. The yielding engagement 'olvtlienoteli l e r with the (fam 102'liolds the .leyer its forward position until the spring" 1171sA suftunentlfr depressed `-when it overcomes tliis yielding leek and throws thel lever sofas to reverse the clutch. The purpose of this yielding detent and the spring pressed-pin,

one engagement te the otlierfand' thus pre# vent the stallingof the device when inneu; tral positien. The leverlQ meygbe' thrown laterally between the guide su'rfaee's 11S into the notch between the' plates 1181-so as to leek thevlutch in'neut al `position andthus sto) the orbital movementl y rying' meansentirely. y n

A grinding Wheel-119 is m'ounted'en' a shaft 120.` Tlissliaftvris earriedV-inbeeri's 121 (see Fig. 1) extending' upW'erdly-trom theslding traine for the.fn'rrindingV` Wheel. A gear122 the bearings121 and meshes With a'gear 123. The rear 1223 is 'mennted on as'liaft124fsee Fig. The shaft 124 is carried in bear-` ings 125 on the lra'me.--` A pulley 126m lined ontlie snail-'t 124.'. Albelt`12 extends aroundr the 'pulley 126' and around a guidepulley,

126l`journaledgon asha'ft'lO? extending upwardly :freni the grinder frame.' 'llue'leeflt l 127 extends over av pulley 128011 `tlie sha-ft '53. lt is carried overa tightening pulley 129, the tightening pulley oeing earriedbyf` :l shalt 130. The.slialit' 130 ismounted on a' The amr- 131 .is

springaetuuted 4arm '1.31.5 y carried by a. pin 132 extendingv :trom-the Sula-,baise andwtllepulley is kept'nnder. ten? sion kby a...fs')r1n;3j. 133. .The oeltentendsk around a pulley mounted on a sha,tt-1134a on the grinding" Wheelbase and from thence to the pulley .126. lt willvbe readily seenf that this system' et belts permits the reciproeal movement oil: Vthe grindingavlieel: to earlyit te lecatevtlie Work; v The grinding; Wheel iframe .135 has the guide ribs -lflfwhieh ere Carried by the sul) :trame ,137. rlhe sub-treme 137 is Cerri-ed by guides 1238. en theadjusting frame 139' and is adaptef, to be mOi/ed backward 21nd 'fer- Ward to adjust the leed el the-"grinding Wheell The adgustingjjrnme .laas the ixed on the spindle 120 between guide rib v1l 0.wleieh operates 'invtlie guide grooves y1.41 ina-table" W42 arranged onfthe base 1. The adjustmg I along `its.undersidel Whielr engages a, pinion 144. `llielpinion 144 ris carried by shaft 145 journaled in'bearingsfonthe .frame and lies a' lrandfwlieel 146Qatzit's fer'ward endby means of whichl the'adjustingrame-m'ay 'be moyed along to any -pointldesired.` i The purpose of thisA to locate v'tliev. Wheel l generally with relation to 'the wor-ln' thereeipreeating motion `being accomplished" vby the grinding .Vlieel frame; W'

. The sub-'frame-is moyed oryvardand to effect 'thefeed'ing Vof Yalle grinding yfheeli bymeans ofthe following-.medianism@` Av rame has fa rack-143x l nut. 147prejectsffrom thev sub-trane: and

eng'eged` by-a' screw 14833 Thezsfcrewjyhaga stem' *149. 'jj ournaled at 150 Iin thvej-sub-rame. A' Wormgear 151 s fined on thejend-o the Vstem 149.y .A- ,Worm f152 meshes With. the

- wenn' ygear 151. Thefwerm is Carried by a thereto-re, 1ste carry the clutch acrossfromrv yshaft 153. `The shaft 153 isf'carried -ley bear.-

ings (not shown) on thev frame. -`Qmgear 154 is fined -on the shaft 153. llt meshes lWitlra 'gearfl'inla sliattl (see Figl) running to tl1e;front.` of :the machine. .,Axiratchei kWheel 157 llor providing'amicrometer feed ie secured to the front `endofthe sliat't1156.

159:-:scarried bygafshaft 160 and afflngerv 161l is in thepathofeam fingers.-161ak on the Work-Carrying means sothatthe'micrometer feed 4may be actuated automatically as the Workadvanees.

The .reciprocatingf motion" given' Ato the grinding wli'eel'trame is as follows; eene'` u pulley 162 .is Xed on'tlie spindle 120;! The.

leelt 163` coinmunieaijesr the v"movement .from

164 is mounted on menait-165 V(see Fig..7).

The'isha'ft 165 is mounted inzbearings166 ontlie frame. z n A cluteh element16"('A is slidingly mountedjontlie v.shaft 165 and isleeled therewith by a spline 168'. i,Clutelifelements-:169

yand 170 are adqatedfto'loeengagedfbyv the theipulley IGZ-to" apulley 164e vllhelpulleyiro velement 167 altennately.`l The element 1691s 1 the. element 169' the shaft 1651is driven,4 di:

rectly.- bythe pulley 4164, it b'eing'understood 165. A {,fgeark 172 vis -locked Witlrtlie"v element 5170 andv mesheswith; a-gear 173. The gear 'that the :pulley 164 is journaled vonthe shaft 173is Carriedby avl shaft 174.- f The-shaft 174 lis mountedein bearings 4175 'and.'1 ?6.0n the frame. 1 Tlhefgear 173 meshes 4.Witlrtlne gear .171. When, therei'ere;` theelutelif element j-16r' is' in 'engagement with the element ,1.70 tlie motion from thepull'ey. 164 is carriedby ,Wayofthe gear 171threugfh the geerl and gear" 172 and vthe clutchTtofthefshaftrll 57" lt .will befreadily seentliat ytlieslflait 165 will loefdriven in a reverse direetio;n"wl1en,the;

clutch element 167 is in engagement with the clutch element 170 'from the direction in which it is driven when the clutch element 187 is in engagement with tlie'element 169. Motion s delivered to the grinding iframe or carriage through theiiollovving mechanism: A Worin 177 is lined on the shaft 165. lt meshes with a gear 178 on a shaft 17 9. The shaft 179 is jonrnaled in bearings180 onthe frame. A gear 181 is fixed .on the shaft 17 9 and meshes with a gear 182. The gear 18:2 is lined on a shaft-'188. The shaft 188 is jonrnaled in bearings 184C on the traine. A 185 is' also tinted on the shaft 183 and this Lgear operates'in a racli 185, .carried by the grinder i'rame. Consequently as the gears are rotated through thel driving 'mechanism jnst heretofore described the frame is moved through the action ot' the gear mechanism on 'the rack- 186. .Y

. The clutch is reversed Jy the ollovving mechanism :-\n arm 187 entends into groove 188 on the clutch element 1677. The arm 187 is carried by a s iafit 189; the shaft heingnionnted in bearings 190 in the grinding Wheel i ame (see 10). in arm `191 is secured to the sho-.ft 189 (see .ll-ige. t and 19) and a spring pressed ringer 192 is arranged in the path of the arm =191soasto yieldingly hold it in -one'position or other locking the clutch 167 in one of its driving connections or the other. Cables 198 extend from the arm- 191 by Way foi: guide pulleys 19i;.195 and other pulleys (not shown) to the nront of the machine, the cable being carried alongthe front o iL the machine as clearly shown in Fig, 3 and being provided with stops 196l and 197 which are adj'ustably secured to the cable and engage a stop 198 on the trame 'lt ivill readily be seenk that the cable nieves with the grinding lWheel vtrame and .when one of the stops 196 or 197 engages tf e stop 198 it overcomes the yielding iin'u 15192 and reverses the clutch; thus reversing the movement of the grinding Wheel' carriage.'

The general operation ci the machine is as follows: The vvorl is placed in one of the Work carrying` means While the Workv carrying means is in (the slow part of its path and during the grin-ding' operation of the companion 'carrying means. lt will be noted tl' ivorli i iscarried forward accomplishes a. certain amount of feeding movementivhich is rlesirebley is the Work Vapprozmhes the grin ling Wheel 4the grinding Wheel is'recipiocated alongl the ivorl and the Work is rotated through the driving mechanism heretoi'ore described. After the carrying means has traveled carrying the Work` pastr the grinding 'Wheel the: orbital movement of 'the shifting' device operates speeding up" the rotation ci the Work carrying means to carry a new piece 01" Work into position relatively f" the arc-shaped movement of the to the .Grinding` `wheel and the finished piece of Worn into position to be removed. ln this Way the grinding action is not only expe-v dited butthe removal of the Work may be readily andconveniently accomplished While the Grinding; operation is taking place.

lllliat l claim as new is 1. ln a grinding machine, the .combination of a grindingv Wheel; a power-driven Work-carrying means having an orbital movement with a path carrying` the Work to the Wheel; and` mechanism varying the orbital speed of the means in the part of the path at the Wheel from the speed in other parts of the orbital path.

2. ln fa, grinding machine; the comb-ination o1e agrinding Wheel; a Work-carrying means comprising; aplurality otl Work securing devices, said means 'having an orbital path with a path carrying' the Werl; to the .vh'eel and to a loading position7 one device being` in the loadingv .position with another device at the Wheel; and mechanism varying the o-rbitalspeedy oi the means in the part of the path with the WorlrA at the Wheel and in loading' position from'the speed at intermediate points in the path. y,

3. ln a grinding machine, vthe combination of aI grinding Wheel; a power-driven Work-carrying means comprising1 a spindle; said means havingan orhital movement with a path carrying` the Work to 'the Wheel and to a loading; position; devices rotating the spindle in the part of the path at the Wheel; and means for dis-*engaging said devices in the part of the lpath at the loading' position.

4t. ln a grinding machine, the combination of a grinding Wheel; a power-driven Workcarrying means comprising al plurality of spindles' said means having an orbital movement with a path carryinp,` one spindle toa Wheel and another spindle to loading position. While said first spindle 'is at the Wheel; devices ro` ing' said spindles in that part of the path at the Wheel and means for disconnecting said devices at the loading position.v

5. In a grinding machine, the combination of a grinding Wheel; iWork-carrying means comprising` a shaft; a driving' means Yfor the shaft; head carried by the shaft; a spin lle carried orbitally by the head; driving connection for the spindle comprising means concentric With the shaft; and devices dis engagingl the connection in, parts of the travel of the spindle air/ay from the Wheel.

6. In a vgrindingY machine, the combination of a grinding Wheel.; a Work-carrying means comprisingv a shaft; a driving; means for the shaft; a head carried by the shaft; a spindle carried orbitally by the head; a gear connection for the spindle c-omprising` a `dear on the spindle; gear on the shaft; 'a float-ing intermedia-te and devices throwing the intermediate gear into and out of mesh -vvith dle carried orbitally by the` head; a gearc'on'-v nectioii for driving the spindle comprising a gear on the spindle; a gear on the shaft; an intermediate floating i gear; a mounting for the intermediate gear 1carried by .the head; and devices acting on' the mounting as the head rotates throwing-,the intermediate gear into and out of mesh with oneof theother gears tofmake and break the driving connection to the spindle at the grinding wheel' and other parts Yof the path respectively'.y

8. In a grinding machine,'tlie combination of a grinding wheel; a work-carrying means comprising a shaft; a driving means'y for the shaft; a head carriedv by thefs'haft; a plurality of spindles carried orbitallybvtlie head and disposed to Alocate one spindle in loading position as another spindle is at the wheel; a drivingconnectioiifor the spindles comprising means concentric with theshaft; and devices disengaging they connection at the loading position.

9; In afgrindino machine, the combination of a grinding wheel; a work-'carrying means comprising a shaft; a driving means for the shaft; a head carried by the shaft; aplurality of spindles 'carried orbitally by the headand disposed tolocate one spindle in loading position as another spindle isat the `wheel; a driving connection for the spindles; devices disengaging the connection at the loading position; a gear connection for driving said yspindles comprising gears on the spindles; a. gea-i'` on the shaft; intermedi,A ate iioating gears between the gears von the spindle and the shaft; and means for throw-v ing said intermediate gears intoand 'out of mesh with the other gears of its ltrain to make the driving connection with they spindle at the vwheel and to break thel driving connect-ion with position. I s I .10. In a grinding machine, the' combination of a grinding wheel; a'woriricaii'lyiiig tal movement with a path 'carrying the work to the wheel; .mechanism for varying the orbital speed lof themeans in the .part of the path at the wlieel. from the speed in other parts of the path; ydevices rotating the spin'- dle in that pait `of"the"path of the spindle at the wheel; and means for. disconnecting said devices in otherparts vof the path.` l s .11. Ina grinding machine, the combina# tion of a grinding` wheel; a work-carrying means .comprising plurality 4of 4rotating spindles having an orbital movement with a movable 4from the wheel.

vthe spindle at. the loading lp ath carrying then-vork to vthe .wheel i and to` a Y loadingl position.; mechanism. varying the v.orbital lspeed of the means with/one spindle "-'i 'I at the wheel and. another. atthe ...loading f posi-- -of the path; "devices, vfor rotatingj the,`

spindles; .andvmeans .for fdisengagingfsaid i devices at the loading position.

tion of a grinding'w-heel; a workrcarrying means having yan orbital movement witha path carrying the worlr` tothe wheel; devices giving to theorbital movement a slow 12.3In a grindinginachine, the combina` speed atl thegrindingposition and a fast.

intermediate yspeed and Vmeans rfor vv:trying 'b' the low speed.- -f

13. In a grinding machine, the combina-` tion of grinding wheel; ya work-carrying.`

means having an orbital movement with` a path carrying the work tothe wheel; devicesv giving to the orbitalinovementa slow speed?V at the grinding position` and' a ffastinterl f mediate speed; and Ameans for varying the low .speed ,comprising a gfrictiondriven speed changing device.

14. vIn a grinding-machine, the combination of a grinding wheel; a`rotating head;

a work-carrying means on thehead having a-n orbital 'movement" carryingv thel work `to Y the wheel a driving mechanism for the headv comprising a -fast speed connection anda slow speed connection ;'and al shift device.v

' automatically. ythrowing saidfjconiiections into .and `ont ofl operativey positionv to vary, n

the speed ofthe head ,giving the yhead a slow speed at thewheel anda tionof a grinding'wheel; arotating headg'a wheel; a driving .connection Vfortlie head .highspeed, away comprisinga fast speedfconnection and a slow speed@ connection; a'shiftdevice auto*- matically throwing ysaid connections `into .and out ofoperative positionto vvary the speed of Vthe head giving the' head a slows @speed atthe wheel and a higlrspeed away fromA the wheel, saidfdevice comprising .a lever for 'shifting-V said connection; vand a `cam on thehead acting on the leven I s 1,6. `'In grinding. machine,n the. coi'iibina-' l tionuo'l'` a grinding wheel; a rotating*headj` la means comprising a spindlehaving an orbiiin work-carrying means' on the headl having an,r i orbital movement `carrying'the'work to they' wheel; a V driving connection `for.,l the head comprising .a fast speed.connection-*and lal `.slow speed connection; f a shift device. com-, v

prising a cam on the head; clutch mechal -nisinforthrowing.in and out the high'aiid r: v low `speed connections a'lever actuatingl said clutch; a spring throwing said'lever yto set the clutchl .with .one connection; ajy'ielding

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