US2614372A

US2614372A - Valve grinder

Info

Publication number: US2614372A
Application number: US52441A
Authority: US
Inventors: Louis W Kelly
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-10-02
Filing date: 1948-10-02
Publication date: 1952-10-21
Anticipated expiration: 1969-10-21

Description

Oct. 21, 1952 w. KELLY 2,614,372

VALVE GRINDER 3 Sheets-Sheet 1 Filed Ooi-, 2l 1948 lNVENToR TTQQNEX L. W' KELLY VALVE GRINDER Oct. 2l 1952 s sheets-shagLV2 Filed Oct. 2, 1948 v Il@ www a 50a/.s W KELLY,

INVENTOR' Oct. 21, 1952 L, W, KELLY 2,614,372

VALVE GRINDER Filed Oct, 2, 1948 5 Sheets-Sheet 5 0a/.s FIZ-KELLY,

IN VEN TOR.

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Patented Oct. 21, 1952 I UNITED 'PATENT vOFFICEy GRI-NBER 'Louis 1W. iilly, nlhmbra, A4cani. y Aplil'icfaftion"October 2, 1948, Serial No. 52,441

1"3 Claims.

The present .invention-:relates'to valve grinders 'in which ,thelabrasive ,grinding wheel is driven l nby means of an .air motor Lwhich alsol provides power .fto `.fturn the ,grinder "head lino' bring 'fthe wheel'into contact with the .entire circumference of fthe valve seat, air sunderpressurefbeing fed to "the v motor .through "5a supporting "base unit mounted V.withinv the; steingu'ide vofthe valve seat 'being ground.

-It is .a characte'ristco po'p'pet Ivalve co'm- "-buston engines "thatlthir valve ,seats lrequire v'reriishing .romjtime "to time tofremove carbon and also .to .eliminate .the je'aifec'ts of "wear proaduced (by the 'repeated A,seating of the 'valve and "by .the passage of (gases. "In 'small ,enginfe'sg'the .`.,grin'der may be a hand .or power-*driven wheel 'the {zliarn'eter of which v.corresponds"'.t'o the diam- ;e'ter of the valveseat to berefnished. `In large'r rriotorsfhoweven the valve seat ytennishing :is more'suc'cessfuly performed-by 'a 'smaller "di'axnf- Veter grinding wheel rotating 'at Lhigh speed :and :traveling around the 'seatto contact `th'e .entire circumference '.'thereo'i tis to 'valve y"grim-1ers lio for 'this iias't "type 4that the `present "invention relates .a

motor vmovable with 'the 'grinder r`head "it 'revolves to bring thewh'eel "into'contact withthe circumference-of ythejvalv'e"'seaLt.

vIt :is 'an object fork-the invention to eliminate ithe "twisting of fan `air-c'ondu'oting conduit which would result wererit 14 connected''from-as'taticmaafy -source `directly to "the 'revolutie` fair-motor; .Acfco'rding 'to the yf-presentinvention the 'source -of fair-power connects *tothe stationary E;1'o'art of lthe supporting base-unit andiair is conducted upwardly therethrough to "the frotary head.

@It fis :another (obi-ect of V"the "invention ctoi-make 'ipossibie thefuse for Jagrinding"fwhelof increased `diameter fand so "tho supporting 74Abase; which includes ra :stationary jvpilot fseated-- within 'the rvalvestem guide, fprov'de'd with an fotfset isiand ato ,support `the revolublewgrinder head wat :one iside foi the "valve centerline. 'The flinrfcrcased :diameter fofitheigrli'rxding I wheel permits @or Junger use fwithout dressing 'and of greater eaccuraoy.v w A Azfurther iobjectfof the invention fis fto A.provide V:an1*irrrprotred grinderfeedx-in lwhioh`r the grinding @wheel ,and itsfactuating m'e'ans :are pivotally 'sup- .jfported for radial :adjustment "with :respect :'to athefcenteriofzthe valvezfseatT lteingfgroundi 'upon"the-'line'3H-3l of that figure; v

QA still further object of the invention "is I-t provide la valve grinding unit Yin 'which `the .grinding Wheel -is directly 4c'orin'ec'ted .to 'the'aotilating motor which also functions through means including a clutch 'to eiect the revolution of the grinding'head around `-the valve'seat, the 'presence of the clutch 'facilitatingtliedressing Aof the .grinding Wheel when necessary.

'Still another object ofthe`v invention is to `pro vide ga 'valve grinding "unit in 'which the revoiub'le grinding head is pivotall'y supported lupon ab'ase Tand i's 'anguiarly adjustable 'thereon to vary'the `eiective radius ofthe 'grinding 'wheel under the control of a manually operable micro adjustment. I c

A "still "further 'Ob'jt 'of 'the invention 'is' the vprovision of a 'valve'grinder in which the grinder headmounted for revolutionreiative'tothe valve .seat 'can be Vgiven `a quickrough adjustment Vfollowed by an 4accurate micro adjustment.

'These Jand other more `spec'ic objects Vvwill appear upon reading Ythe following spe'c'i'iication `and "claims and upon considering jt'he connection therewith the attached drawings to-whichthey frelate. I

-Referring `now to A'the drawings "in 'which a preferred lembodiment ofv the invention 'is ilis'- 'tratedz f g j 'Figure '1 illustra-tes a valve grinder constructed "inf'a-ccord'an'ce with the presentinventionseated in operative 'relationship `to the Vvalve 'Setif *an Vengine 'which is'partiall'y s hown in section;

Figure 2 lisa 'toppl'an View of the construction -sn'own inFigure-I'; f v

Figure :3 is va partial longitudinal" section through the construction of Figure l, being'taken 'Figure 'f4 iis-:a section through the gearbox or powerftake foi unit upon the lifne i4-H4 o'f `Figure i2 and sho-ws .the power transmitting means between the v-n'iotor--d'riven shaftorfthe ',fgrinding wheel v'and the velutclicontrolled shaft Vwhich yee'ct's'the'Ire'avolution 'of 'the fg'rindingfhead;

Figure 55 is -lavertical section through fthe :"gar "box unit upon the lin'e '5-5 of fFi-gur il Jand shows :the :mounting ofthe grinding 'wheel :sii-aft Figure f6 i'sa vertical section thro'ughithe I -ear .box :unit `upon the line 6-6 orFigureand :shows then'mountingof the drivenshaitiwhioh effects therevolution of the grinding'fhead I Figure t'? iis ahQr'izontal section upon it eline 1-1 of Figurefand shows thegearboxiloching 4boit rby vwhich rough vertical and l'angular fad'- justment of the grnding'lwheel isobtaine'd;

"Figurez is a vertical section ithrough'.' the suprportin'g base unit upon theline-: y'orfligurc;

Figure 9 is a vertical section through the manually adjustable cone cam by which the micro adjustment of the grinding head is obtained, the cone being shown in an initial position;

Figure l is a view similar to Figure 9 showing the cone in a lowered nally adjusted position; and

Figure A1-1 is a--view in perspective-of the gear box bolt'per se.

In the drawings a preferred form of the present invention is illustrated and may be divided into three major parts identifiable as the grinding head unit, generally indicated by the reference character 20 and including a grinding wheel proper 2|; a power take off or gear box unit 22, and a driving motor 23; a supporting base unit generally indicated by the reference character 25 including a base 26 revoluble with the head 20 and a stationary pilot 21; and a micro adjustment indicated generally by the reference character 36 by which the grinding wheel 2| is radially adjusted for use on different size valve seats and which includes among other parts to be described a irustoconical cam 3| carried by a vertical shaft 32 at the upper end of which is a manually rotatable knob 33. n

In Figure lof the drawings the grinding'head A,unit 20 kis shown positioned operatively with respect to the valve seat of a poppet-type motor in ywhich the block is indicated by the reference character 35, the valve chamber by the character 36, the stem guide for the unshown valve by the reference character S1, and the valve seat which is to be ground by the reference character '38, its internally threaded retaining ring .bearing the reference character 39.

Directing our attention first to the grinding head unit 2B, it is seen that the grinding wheel 2|, whichV may be irustoconical and formed of a suitable abrasive, is secured at the lower end of a rotatable shaft 4| which extends vertically downwardly through a passage 42 in the gear box 22, being supported by ball bearings 43 and 4prospectively rA packing gland 46 is positionedl below the lower bearing 44 and. a` worm .gear 41 is iixed to the shaft between the bearings for a purpose to be related. The upper end of shaft 4| carries a slotted head 48 seating `the rectangularly sectioned lower end of the shaft 49 of air motor 23. The lower portion of the motor casing seats in threaded relationship at 5| in a supporting sleeve mounting 52 itself threaded at 454 in the casing of gear box unit 22 immediately above the ,bearing 4 3. The air motor 23 may be of any conventional type adapted to be actuated by air under pressure and is supplied through a eXible conduit 56 to which it is connected by a connector 51. The'opposite end Vof hose 56 extends to a suitable IConnector 58 opening into the base 26 of the supporting base unit .25. When the motor is supplied with air under pressure the rotation of its shaft 49 effects the rotation of the directly connected shaft il and of the grinding wheel 2| carried at the lower end thereof.

Grinding wheel 2| and its actuating motor 23 rare supported by the gear box unt22, also referred toas the power takeen unit, which is itself mounted for angular adjustment about a vertical axis above a horizontal platform 6I:

tioned Within the. .valve stem guide 31 the base.

26, also a part of the base unit 25, extends into valve seat 38, the oiset island 62 being displaced at one side of the longitudinal axis of the valve seat to permit of the use of a grinding wheel 2| of larger diameter than would otherwise be possible. Gear box unit 22 is angularly adjustable upon the base 26 and its platform 6| by means which will subsequently be described. Attention is .here directedphowevento the vsupporting base unit 25 by'which the grinding lhead unit-20 is rotatably supported.

As Stated, supporting base unit 25 includes the rotatable base 25 and a stationary pilot 21. The latter extends through the valve stem guide 31 in which the engine valve reciprocates vertically in the normal operation of the engine. The upper end of the pilot is expanded conically at El so that it will center itself and seat within stem guides of Varying internal diameters. Its lower end lis threaded at 68 toseat a pilot nut 59 formed with a knurled enlargement at '1| for ease in manual rotation and with a tapered upper end at 12. The latter functionsv in the manner of surface 6? and enables it to seat and to center itself within stem-guides or" various" internal diameters. The tightening of the nut 69 draws the pilot 21 downwardly and positions it'xedly and non-rotatably with respect to the stern guide 31 so thatv its upper end provides a fixed support for the base 23. The latteris rotatably supported upon the pilot 21 by meansof upper and lower ball bearings 13 and 14, respectively.

Incoming air to thedriving `motor 23 isfed upwardly through the supporting base unity 25 lentering the pilot 'nut 69 at a rotatable connector 15 connected at its outer' end by an L connectorll tov an incoming air conduit 18. Pilot 21 isitself provided withalcen'tral bore 19 functioning as an air conduitinto the upper end of which 4a nozzle 8| 'extends downwardly fromthe rotatable Y base 26, being seated with respect thereto by a sealing gland 82. vAt its upperfe'nd nozzle 8| connectsl through a transverse passage 84 in base 26 to the lthreadedly seated connector 53..' As Vpreviously described, connector 58'isitself connected to the flexiblecond'uit 56 leading to the air motor 23. It is seen,"then, that the motor actuatingv air enters the lower end of thepilo't 21 to be conducted upwardly therethrough tothe rotatable base 26, thencethrough the nozzle 18` toconduit 56, and so .to the motor 23.

The construction described'mounts the grinding wheel 2| with respectto the valve seat 38 and providesrfor its rotation about its ownairis. vIt is additionally necessaryrto provide for thetravel of the wheel around the` circumference ofthe valve seat. This is raccomplished byfeI-lecting the rotation of the base y25 ofthe supporting/base unit 25 upon its supporting pilot 21 by means which will now be described. f l

Within the gear box unit 22 a transversepas.- sage 9| is provided'lin which-extends a shaft 92 rotatably supportedin bearings `93 and 94 retained against longitudinal displacement" v by threaded positioning, spacersswand 91, respectively. Adjacent the worm 41 carried by grinding wheel shaft 4| v.transverse sha-ft192 carries a pinion 98 so that upon the'operationv or" the: air motor shaft' 92 is rotated. Adjacent its opposite end shaft 52 carries a worm 99 engaging a pinion `10| positioned in a second vertical passage |02 similar and parallel topassage 42. Pinion |0| is fixed on the lower end of a hollow sleeve l|03 rotatable in a bushing' |104 lthreaded into the vend of passage 02 and' carries at its own. upper .end

vsleeve I8. .carries a nut |24 which, Awhen tightened,j draws a; transversely slotted femalefclutch member |06. vnfvertical shaft |01extendsthrough the sleeve |03', its vupper end being irregular in section, -as for example squar-e, and-slidably seats a male iclutchelement |08 adapted to `engage the vvfirstmentioned clutch element |06 to clutch the shaft tothe vsleeve |03. As is shown most clearly in Figure 8` the Vlower end ofshaft |01 carries a pinion Within the base` 26-of supporting base unit "25 irl-mesh with a -centergear ||'2 xedto the; `upper yend of non-rotatable pilot shaft 211. Theirotation of shaft |01 causes the` pinion to travel Vas a planet gear about-the center gear |12 as' kasun 'gear to effect the rotation' off'basefZS and with it'the `grinding 'head unit -20 carried thereby. v y In 'addition to the rotation of grinding wheel -2|- and its revolution about the longitudinal axis of the valve seat mechanism it is also necessary to provide for the vertical and radial adjustment of vthe wheel to enable it to functionin-'diiferent vvalve seats. According tothe present-.invention this adjustment means comprises an initial rough adjustment and a final micropadjustment. The

lower endof shaft' |01 extends throughanfelon- -gatedSvertically extending bored post ||6 rseated threadedly in the island 62 of base 26. The .pla-t,.- form 6|,.previouslyireferred to, is clamped-between'a shoulder ||`1 on the post :and the island. vA. concentric sleeve ||8 encloses' post Ij|6 within y'the vertical passage |02 of: unit 20 Vand is; rotat- 4passage |02 in. gear box unit is intersected by a .horizontally extending bore |2| in which is positioned a lockingv bolt |22 formed with a cut-out sector v|23 shaped to conform to the curvature of The threaded outer end of bolt |22 the bolt |22 outwardly as to lock thesleeve |18 and the gear box 22 against relative longitudinal oryarcuate displacement. :With nut |24 loosened .gear box unit 22 may be adjusted angularly with .respectwto the s1eeve n .s to vary the radial ex'- tension of wheel 2|. v,Itlmay also,v be adjusted vertically to vary the Vertical` lposi/tion Vof vthe wheel.

e The micro adjustment of the grinding wheel v r2|l-is` accomplished by the 4manual adjustment of Vthe frustoconical cam- 3|, the vsupporting shaft 32 ofV which seats threadedly for vertical adjustment upon a fixed threaded post |26 clamped by a nut .|21 in its threaded relationship to thebase Vformed: at the outer end of lever |2| vfixed: to

sleeve, H8. Coil spring |32 tends at all times .to

force the end ofA lever |2| against the surface of "cam 3| and the angular position of thelever is 4determined by the vertical radjustment ofthe rcam which is manually' positi'onablejby the rotation-of shaft 32Y under a torque exerted` at its 'knurled upper end 33. With the nut |24` tightened. upon the' locking bolt |22gear box unit22 is xed with respect to sleeve I I8 and any -further langular adjustment thereof, `and so of lthe grindingr wheel 2| carried thereby,A is accom- (..plishedl by the rotation of thesleeve l|18. y'relative tothe posti |6 under the'actuation of "the" cam 3|.

jcf'looo or 1500 to 1.

j In the operation ^Io'f thegrinding unit constructed in'"accordance with -the' present invention the unit would-be positioned relative'to-"the blo-ck of the motor as illustrated in Figure 1, the pilot-21 being extended downwardly through the valveguide stem 31. Pilot nut 69 would then lbe threaded uponthelower-end of the pilot'to. draw they conicalupper 'end 61 thereof downwardly into seating relationship with theupper end of the guide 131. Theair conduit .18 at the lower end ofV thelpilotvr couldv then be connectedcto a sourceof air under pressure. It isl assumed that the 'grinding wheel 2l vvhas. been suitablydressed contactwith Vva diamond stone. The `operator then rotates the .coneshaft 32 by turning -itsl knurled top. 33 until the small end. of the cone just engagesthe top of the lever |2|, as illustrated in Figure 9'... He thenloosens the gearbox locking bolt .|22 by vunscrewing its nut |24 `and 'angularlyadjusts as Well as raises or lowers the box with. respect to the sleeve |18 'and the supporting post |l6 which it surrounds. The gear box unit 22 is lowered until the grindingwheel 2;| ,almost touchesthe valve seat face in therelationship illustrated in Figure 1. Gearbox lock.; ling bolt |22 is then tightened by its nutA |24and the box'unit is fixed with respect to the vsleeve I8 and its attached lever |2|. The fine micro ladjustment is then accomplished` by the manual rotation of the cone ,shaft 32, the air to the actuatingmotor 23 first being turned on. Cam 3| is .lowered on its supporting stud |26` bythe rotation of shaft 32 effecting the pivotal movement of the gear box unit about the supporting stud H6 until the grinding wheel 2| makes satisfactory contact withthe valve seat. f

.The rotation ofthe Wheel 2| "under povver supplied by motor 23 is accompanied. 'bythe Isimultaneous revolution# of the grinding head unity y20, the` rotation ofl the wheel-connected shaft 4| Vbeing transmitted vthrough thelgears 41,v 9B to the ftransversesh'aft '9-2, driving the vertical shaft |01 through gears 9:9.and- IDI., sleevel|03 and the. clutchv |06, |08. The grinding head unitrevolves at a speed muchless than that of Wheel 2|, the speedsv being in. the ratio If itis desired to discontinue the revolution of `the grindingheadfunit itis `only necessary :to liftfthe clutch." element |08 upon shaft |01 as to disengage itffrom the angle for grinding a narrow seat.

lWhile the particular apparatus herein show and described in detail. is fully capable affattaining theY objects and providing the advantages hereinbefore stated, it is to be Aunderstood .that it is merely illustrative of the presently preferred embodiments of the invention andthat no llimitations are 'intended to thedetails- 'fof construction or design herein shown'other than `asdefine'd in theappendedclaims.

. 1. A Avalve grinder comprising a revoluble grinding head unit including a rotary grinding Wheel and an air motor connected thereto, a supporting base unit including a base supporting `said head unit and itselfl revolubly mounted upon a stationary pilot adapted to extend into v'the' stem guide of the valve the seat of which '1s being ground, and an air conduit system to supply actuating air to said air motor including an air passage in said base and a connected passage extended through said pilot including the portion thereof adapted to extend through said stem guide.

2. A valve grinder comprising a revoluble grinding head unit including a rotary grinding wheel and an air motor connected thereto, a supporting base unit including a base supporting ,said head unit and itself revolubly mounted upon a stationary pilot adapted to extend into the stem guide of the valve the seat of which is being ground, said base and said pilot below said base and through said stem guide being provided interiorly with air-conducting passages including a joint having relatively rotatable parts, and an air conduit connected to said base to-conduct air therefrom to said air motor.

3. A valve grinder comprising a grinding head unit including a rotary grinding wheel, a driving motor direct connected thereto, and a power take oif unit, a rotatablev supporting base unit including a base supporting said head unit for pivotal movement about a pivotal axis parallel to and displaced from a central axis to vary the radial distance of said wheel from said central axis, and a stationary pilot in said central axis rotatably supporting said base adapted to seat in the stem guide of the valve the seat of which is to be ground, a rotary shaft extended between said power take oi' unit and said base and connected to said power take ofi unit through means including a clutch, and means to effect the rotation of said base :about said pilot upon the rotation of said shaft.

4. A valve :grinder comprising a grinding head unit including a rotary grinding wheel, a' driving motor direct connected thereto, and a power take oi unit, a supporting base unit including a base supporting said head unit for pivotal movement about a pivotal axis parallel to and displaced from a central axis and a stationary pilot in said central axis rotatably supporting said base and adapted to seat in the stem guide of the Valve the seat of which is to be ground, a rotary shaft extended between said power take off unit and said base connected to said power take off unit through means including a clutch, and means to effect the rotation of said base comprising a planet gear on said shaft and a sun gear fixed to said pilot.

5. A valve grinder comprising a grinding head unit including a rotary grinding wheel, a driving motor direct connected thereto, and a power take off unit, a supporting base unit including a base supporting said head unit for pivotal movement about a pivotal axis parallel to and displaced from a central axis and a stationary pilot in said central axis rotatably supporting said base and adapted to seat in the stem guide of the'valve the seat of which is to be ground, a rotary shaft extended between said power take oi unit and said base in said displaced axis, means to effect the rotation of said base upon the rotation of said shaft, and cooperative means upon said base and said head unit to adjust said head unit angularly about saidvdisplaced axis to vary the radial extension of said grinding wheel from said central axis.

6. `A valve grinder comprising a grinding head unit including a rotary grinding Wheel, a driving motor connected thereto, and a power take off unit, a supporting base unit including a base Ysupporting said head unit for pivotal movement about a pivotal axis displaced from a central axis and a stationary pilot in said central axis rotatably supporting said base adapted. tovseat in the stem guide of the valve theseat of which is to be ground, a rotary shaft extended between said power vtake off unit and saidbase, a planet gear fixed to Athe lower end of said shaft in said base, a sun ring gear fixed tothe upper end of said pilot in said base, the rotation of said planet gear with said shaft causing said base and head unit to revolve around said central axis, a lever forming a part of said head unit extended laterally adjacent a platform rigid with said base, spring means urging said lever and head unit in one direction about said pivotal axis, and manually adjustable means to move said lever and said head unit in the opposite direction about ,said pivotal axis to varyvthe radial extension of vsaid grinding wheelfrom said central axis.

7. The construction recited Vin claim 6l characterized in that said pilotand base form a part of the air conduit system to convey air to actuate said driving motor and in that a nut threadedly seated on the lower end of said pilot draws the upper end thereof downwardly against the upper end of said valve sternguide through which it extends.

8. -A valve grinder comprising a grinding head unit including a rotary grinding wheel, an1air motor direct connected thereto, and a'power take 01T unit, a supporting base unit including a base supporting said head unit'for pivotal movement about a pivotal axis displaced from a central axis and a stationary pilot supporting said base for rotation about said central axis and adapted to seat in the stem guide of the valve the seat of Which is to be ground, a rotary shaft extended between said power take off unit and said base, said power take off unit including speed reducing means connecting said shaft to said driving motor to effect the rotation thereof at reduced l speed, means to effect the rotation of said base upon the rotation of said shaft, and an air conduit system to feed actuating air to said air motor including an air passage insaid base and an air passage extended interiorly through the portion Vof said pilot ladapted to seat in said stern guide, said pilot being adapted to connect to -a source ofY air under pressure below said guide.

9. A valve grinder comp-rising a, grinding head unit including a rotary grinding wheel anda driving air motor therefor, a source of actuating air for said motor including a rigid air fco'nduit adapted to seat` non-rotatably in the stem guide of a value the seat of which is to be ground, means mounting said head unit for rotation about said rigid conduit as an axis, and air-conducting means to conduct air from said rigid air conduit to said air motor in all rotational positions of said motor around said rigid conduit.

10.'A valve grinder comprising a grinding head unit including a rotary grinding wheel and a driving air motor therefor, a source of actuating air for said motor including a rigid air conduit adapted to seat non-rotatably in the stem guide of a valve the seat of which is to be ground, means ymounting said head unit for rotation about said rigid conduit as anfaxis, means to revolve said Y head unit around the axis of saidrigid air conduit upon thev actuation of said motor, and vairconducting means to conductair from vsaid rigid air conduit to said air motor in all rotational positions of said motor around said rigid conduit.

yl1. A valve grinder comprising a grinding head unit including a rotary grinding wheel and a driving motor therefor, a supporting base unit including a base revolubly supporting said head unit and a non-rotatable pilot adapted to seat in a valve stem guide rotatably to support said base, means supporting said grinding head unit for selective angular adjustment on said base to vary the radial extension of said Wheel relative to the axis of a Valve seat including means supporting said head unit on said base for relative rotation about a parallel axis spaced from the axis of said pilot, and manually operable micro adjusting means to pivot said head unit about said parallel axis, characterized in that said micro adjusting means includes a lever arm movable with said head unit and a manually rotatable cam to pivot said lever arm.

12. A valve grinder comprising a grinding head unit including a rotary grinding wheel and a driving motor therefor, a supporting base unit including a base revolubly supporting said head unit and a non-rotatable pilot adapted to seat in a valve stem guide rotatably to support said base, means supporting said grinding head unit for selective angular adjustment on said base to vary the radial extension of said wheel relative to the axis of a valve seat including means supporting said head unit on said base for relative rotation about a parallel axis spaced from the axis of said pilot, and manually operable micro adjusting means to pivot said head unit about said parallel axis, characterized in that said micro adjusting means includes a lever movable With said head unit urged in one direction by a spring abutting said base and in contact with a manually adjustable cam carried by said base and adapted to be moved thereby in the opposite direction.

13. A valve grinder comprising a grinding head unit including a rotary grinding wheel and a driving motor therefor, a supporting base unit including a base revolubly supporting said head unit and a non-rotatable pilot adapted to seat in a valve stern guide rotatably to support said base, means supporting said grinding head unit for selective angular adjustment on said base to vary the radial extension of said Wheel relative to the axis of a valve seat including means supporting said head unit on said base for relative rotation about a parallel axis spaced from the axis of said pilot, and manually operable micro adjusting means to pivot said head unit about said parallel axis, characterized in that said micro adjusting means includes a lever movable with said head unit spring-urged in one direction into contact with a cone cam carried by a manually rotatable shaft mounted for rotation on and for movement toward and from said base.

LOUIS W. KELLY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS