US2532346A - Mechanical silent tappet - Google Patents

Description

DeC- 5, 1950 c. L. sTANcLlFF `2,532,346

MECHANICAL SILENT TAPPET Filed June 18, 1946 3 Sheets-Sheet l INVENTOR.

C; IFTON LS1-ANCI.. H-F

BY M,

ATTORNEYS Dec. 5, 1950 c. L.. s'rANcLlFF 2,532,346

MECHANICAL SILENT TAPPET Filed June 18, 1946 3 Sheets-Sheet 2 IVIIIIIIIIIIIIIL INVENTOR. CLIFTON L .STANCLIFF AT ToRNEYs Dem 5, 1950 c. l.. sTANcLlFF 2,532,346

MECHANICAL SILENT TAPPET Filed June 18, 1946 5 Sheets-Sheet 3 1. -13.1 r v l, f N 47 ZV TTU.

46 l 51 39* f 2V Y a: l l 9 S 40 L mw@ V1' INVENTmL CLU-TON L .STANCLJFF mm l 'P AT TOR NEWS,

Patented Dec. 5, 1950 UNITED STATES PATENT GFFIC MECHANICAL SILENT TAPPET Clifton L. Stancliif, Bakersfield, Calif.

Application June 18, 1946, Serial No. 677,552

13 Claims. l

An object of my invention is to provide a mechanical silent tappet which is an improvement over the form of my invention shown in my Patent No. 2,493,783, dated January 1G, 1950. In the copending case, I disclose the spring means for rotating the two parts of the silent tappet as being disposed exteriorly of the parts. In the present form of the invention the spring means for rotating one part with respect to the other is confined within the area occupied by the two parts.

In all of the modiiications illustrated in the present case, the two parts of the device have centering means for holding them in proper relation `with the valve stem and with the valve tappet. The mechanical silent tap-pet is waferlike in appearance and can be slipped between the valve stem and tappet or between the push rod and rocker arm, or between the valve stem and rocker arm, and will remain in position Witnout any auxiliary fastening means being necessary.

The device is extremely simple in construction and is designed to be stamped out from sheet metal.

Other objects and advantages will appear in the following specification, and the novel features of the device will be particularly pointed out in the appended claims. i

My invention is illustrated in the accompanying drawings forming a part of this application, in which:

Figure l is a top plan view of the silent tappet;

Figure 2 is a top plan view of the upper plate;

Figure 3 is a top plan view of the lower plate;

Figure 4 is a section taken along the line IV-IV of Figure 1;

Figure 5 is a section taken along the line V--V of Figure l;

Figure 6 is a transverse section taken along the line VI-VI of Figure l;

Figure 7 is a view similar to Figure 6, but shows the two parts of the device in a slightly separated position; i

Figure 8 is a top plan view of a modified form of the invention;

Figure 9 is a transverse section taken along the line IX-IX of Figure 8;

Figure l0 is a top plan view o the lower plate; Figure ll is a top plan view of the upper plate;

Figure 12 is a section taken along the line .XIL-XII of Figure 8;

Figure 13 is a top plan View of another modified form of the invention;

2 Figure 14 is a transverse section taken along the line XIVXIV of Figure 13;

Figure 15 is a top plan View of the lower plate; Figure 16 is a section taken along the line XVI- XVI of Figure 13;

Figure 17 is a section taken along line XVIL-XVII of Figure 13;

Figure 18 is a view similar to Figure 17 but shows the parts slightly separated; and

Figure 19 is a top plan View of the upper plate.

While I have shown only the preferred forms of my invention, it should be understood that various changes or modiiications may be made within the scope of the appended claims without departing from the spirit and scope of the invention.

In carrying out my invention, I provide a mechanical silent tappet comprising two disc-shaped plates, an upper plate indicated at A in Figure 2, and a lower plate indicated at B in Figure 3. The device is designed to be stamped out by means of a punch press and both Figures 1 :and r2 show the upper plate provided with a plurality ofA raised portions I when looking at the top of the plate, these portions being provided with camshaped undersurfaces 2 as illustrated in Figure 5. It willbe noted that these cam-shaped surfaces have a gradual arc portion 2a and an abrupt curved portion 2b. The raised portions l are arranged in a circle about a common center 3 and as many of these portions as desired may be provided. In Figure 2 I show twelve of the raised portions, although I do not wish to be conned to any exact number.

Within the boundary deined by the circle of raised portionsA l, I provide a second group of semi-cylindrical raised portions t. In Figure 4 the interior of the raised portions 4 are designed to receive the upper halves of coil springs 5. Each interior forms the upper half of a spring housing 6. The housing has a shoulder l' formed at one end against which an end of the spring 5 contacts and the other end of the housing 6 has an inclined wall li. rlfhe raised semi-cylindrical portions i are arcuate in shape and are arranged in a circle whose center is the same center 3 for the raised portions I, see Figure 2. Referring to Figure 6, it will be seen that the upper plate A has a circumferential ange 9 that extends downwardly and this flange has an inwardly turned rim iii fora purpose presently to be described. It will be seen that the entire upper plate is designed so that it can be punch pressed.

Figure 3 shows the top of the lower plate and this plate s provided with a plurality of depressions or recesses Il of a number equal to the number of raised portions I. The recesses I I have cam-shaped inner surfaces I2 designed to cooperate with the cam-shaped surfaces 2, see Figure 5. Each surface I2 has a gradual arcuate portion I2a and an abrupt curve IZb. Figure 5 indicates how the gradual arc portion 2a, is disposed at the opposite side of a ball C from that oi the gradual arc portion 52a. When the disc A is rotated in thev directionA or the arrov-.zy shown in Figure iand'the disc B` rotated in the opposite direction, the ball C will act on the curved cam surfaces 2a and Ia for separating discs A and B a slight distance One from the otheri Again referring to Figure 3, it will be seen thatthe plate B has a plurality of elongated and arcuate shaped recesses I3 that are semicircular in cross section. These recesses cooperate with the` spring-receiving housings to accommodate the lower.A halves of: the coil springs 5. Each recess I3 has a shoulder i against whichwthe'adjacent endof. the spring 5 contacts andthe opposite end ofy eachv recess is provided with an inclined wall I5. Figure 4 illustrates how the; springs 5 are received within the cooperating portions 5 and I3 and how the ends of the springs contact with the shoulders 'I and Ill for yieldinglyv urging the discslA and B in oppositek directions.

n In; assembling the parts, the. balls C areplaced inl the recesses. Hand the springs 5 are placed in, the recess I3, The upper plate A is now moved down upontheilower plate, and the springs are received in-l the upper` spring'hcusing 6V while the balisgare received inthe cavities 2. Therim Il is formed on the ange 9 after the plate A is mounted onthe plate B. A felt washer I6 may be,` placed in a. groove il that extends around theperiphery of .ther pla-teB. This washer is for the. purpose;A of retaining; any oil that; may' be forced between -twoplates. Itwill be notedrfrom- Figures 3, 6 and '7 that the lower plateA has a centraloil opening I8 and this opening registers with an axial bore I9` provided in the tappet pli-1g D.-

From'the foregoingdescription of thevarious partsof thedevice, the*operation thereofmay be readily understood.

The wafer thin device is placed between the tappet plugvor lift D and the lower end of a valve 'f stem E, or between theppush rod'` and rocker arm, orf-.sternA and rocker arm on an overhead` valve motor. The. outersurfaces on the-lower plate B which form the recesses i3 act as a centering meansforthe plateB- on thetappet plug or lift as clearly shown in Figures-l 6.and 7. In like manner the projections or, raised portions Iv on tha upper: plate` Av act as a centering means for correctly positioning the device with respect to the valve sternE. In mounting the device in place all thatis, necessaryv istolinsert it between-r the tappet-Dandvalve stern E. No fasteningmeans of any-kind is necessary.

During-the operation of theengine itis asfsurnedsthat ,during the interval ci" y rest whenl the Valve isseated and the tappet plugk is in its lower.- most, position', theitwo plates A and` B; will have their central portions.v spaced slightly apart. When the tappetliftsfthevalve -stem thev springs 5i wllrstyield andnpermit thetop plateAV to rotatewi-th-respect to thebottom plate B until the,centralportionsAI and BI contact with each other. The ballsC ,will roll downl to the. lowest portions of,lthe cam surfaces I2, while` at the same time thehighest,portionssot the cam sur-` faces 2 will Contact with the tops of the balls to permit this movement. The two plates A and B will contact with each other at the central portions AI and Bl before the valve starts to lift. No metallic sound has been created during the movement of the central portions Ai and BI into contact with each other because these portions already contact with the tappet and with the valve stem and the initial movement really consists` in the. closing. of theespaceibetween the central pla-teportions and aslight rotational movement between the two plates. rIhis is accompanied without any metallic noise because of the gradual cam surface portions 2a and I2a causing the central plate portions to come together with a nlm ofoil therebetween.

During the lifting of the valve by the tappet, the springs 5 are not used to lift the valve because the central plate portions A! and BI contact each other and carry the entire load. As soon as the valvehas completed its opening and closing moyement` and should the tappet continue to, move away from the valve stem end so as to forma space therebetween, the plate A will instantly lotate with respect to the plate B dueto the action of the springs 5 and will move thearcuate cam surfaces 2a, and I2a in the. directions of the arrows shown in Figure 5 for causing the balls andv the. cam portions to spread the central plateportions apart. Since this movement instantly.4 takes place, there is no time period when the valve stemY end will, be spaced fromA the plate` A and therefore there will be no tappet noise.

The bore Iii: communicateswith a forced feed lubricating system, and the separation ofthe two central plate portions, asin Figure 7, will permit lubrication under pressure to be` forced between the plates A` and B and lubricate the balls.V and the springs. A thin lm of lubricant W-ill form on the inner surfaces, of the two plates and this will permit relative rotation between` theplates the instant there is any separation between the tappet and the valve stem end.

In the drawings ofFigures 1 to '7, inclusive, the

' device is shown on a greatly enlarged scale for clarity. Inactual practice the material willbe to als ofY an inch thick. The tappet screw is adjusted to take care of the` thickness of' the two plates, so that the total distance between the tappet and valve stem will be .072 to .077; No-other changes arenecessary to be made; The valve stem'is'raised to insertthe device.

The form shown in Figures 8 to 12, inclusive, is designed primarily for a Ford motor car engine. This -formis also of the punch press type; The lower plate Vl?? is shown in Figures 9 and 10 and it will be seen that this plate is provided with a plurality of hemispherically shaped recesses 20.' In addition thek rimY 2l ofthe platehas struck up portions '22 provided with radially extending shoulders 23; The top plate G has a'centralportion 24 designed to rest on the central portion of the lower plate. Figure 11 shows the top plate provided with a plurality of spherical shaped recesses 255 that are designed to overlie andnor- Inally register with the, recessesY 2Q in the lower plate. Balls H are placed in the, alignedirecesses and when the topA plate is rotatedwith respect to the bottom one, the sphericalsurfaces of there/- cesses will ride on'theiballs to cause them togseparatel the plates and automatically takeup any spaceithat might existbetween the Ford lift'J'and the valve stem K.

The-top platehas an annular springfreceiving channel 21 formed adjacenttdits rim, this chan@l nel overlying the rim 2| of the lower plate. Figure 11 shows projections 28 extending inwardly into the channel, these projections providing flat radially extending shoulders 2i) against which the ends of springs 30 bear. Figure 12 shows a portion of the channel 2l with its inwardly ex tending projection 28 and the spring 3G is indicated as contacting with the nat shoulder 2S. The other end of the spring contacts with the shoulder' 23 formed by the upwardly extending projection 22.

Figure 8 illustrates the assembled device while Figure 9 shows how the rim 3l of the upper plate G extends beyond the channel 2l and encloses the periphery of the lower plate F. The portions 32 are struck inwardly from the rim 3l and prevent the plate G from being entirely removed from the plate F. If desired, a felt washer 33 may be placed adjacent to the rim 2 I, this washer or seal bearing against the rim 3l of the upper plate.

Ihis device operates in the same manner as that disclosed for the device in Figures 1 to 7, inclusive. The springs Si) are placed outside of the balls H in this device rather than inside of the balls. The springs tend to rotate the two plates F and G with respect toeach other and to cause the balls H to act on the spherical surfaces 20 and 26 to move the two plates apart as indicated in Figure 12 by the dash lines. The Ford valve stem K has a bushing 34 and a keeper 35. The silent mechanical tappet is placed between the Ford lift and the valve stem. The flange of the keeper 35 is received within the circular portion formed by the outer surface of the spring receiving channel 2l. The lower plate F has a depression 35 on its under surface that will fit the conical top of the Ford lift J. No fastening means is necessary to secure the silent tappet in place. The device will clear the valve lifter guide shown at 3'?.

In Figures 13 to 19, inclusive, I show another modified form of silent tappet which makes use of cams rather than balls. In this form, the lower plate L has a central depression 38 on its under surface for receiving the top of the tappet plunger or lift M. The upper plate N has a central def pression 39 in its upper surface that receives the end of the valve stern P. The two plates L and N have the same outer diameter and a retaining ring 4i! is secured at di to the top plate and rotatably and slidably receives the bottom plate. The ring di! has an inwardiy extending flange d2 that prevents the entire removal of the plate N from the plate L.

Referring to Figure l5, it will be seen that the bottom plate L has a circle of arcuate-shaped recesses 113 that are semicylindrical in cross section. The top plate N has complimentary re cesses i4 that register with the recesses i3 in the manner shown in Figure 16. A coil spring 45 is placed in each pair of registering recesses and one end of each spring will bear against the shoulder t5 in the lower plate while the other end of the spring will bear against the shoulder 4l in the top plate. The springs tend to rotate the two plates with respect to each other and to cause depending cams 48, that are carried by the under surface of the top plate, to ride on cam surfaces 49 provided in the upper surface of the lower plate. Figure il illustrates the position of one of the cams 48 when the two plates L and N are in contact with each other. Figure l5 shows the lower plate provided with a plurality of cam surfaces 49, while Figures 13 and 19 illus 6 trate the top plate as being provided with a plurality of cams 48. In Figure 18 the two plates L and N have been moved apart a slight distance by the cams 48 riding up on the cam surfaces 49.

In operation this form of the invention performs in the same manner as the other two forms, except that the cams 8 are integral with the top plate N and slide over the cam surfaces 49 in the lower plate. Any spacing that might exist between the top of the tappet M and the bottom of the valve stem P will be automatically taken up by the instant movement of the two plates away from each other, because of the springs 45. This form of the device may be lubricated by a central bore 5l! in the tappet conveying a lubricant through an opening 5l provided in the bottom plate L. When the plates are spaced apart, the lubricant will iiow therebetween and will lubricate the opposed surfaces as well as the cam# shaped recesses 49 and the projections 48.

I claim:

1. A mechanical silent tappet comprising two disc-shaped members arranged in confronting relation and adapted to be placed between an operating part and an operated part of a valve-operating mechanism, the confronting faces of the members having registering recesses with camshaped surfaces that extend from the said faces to spaced distances therefrom, a ball bearing placed in each pair of recesses, the pairs of recesses being arranged in a circle about the center of the members and the cam surfaces of each pair being such that a relative rotation between the members in one direction will cause the balls to ride on the cam surfaces to separate the mem? bers, and spring means confined within the perimeters of the members for yieldingly urging them in the direction just mentioned, said spring means being disposed within the area dened by the ballbearing recesses and including a plurality of arcuate-shaped cavities formed in each member, the cavities in one member cooperating' with those in the other to provide pairs of cavities, and a coil spring mounted in each cavity pair, each cavity having a face against which an end of the spring bears, the faces in each pair contacting opposite ends of the spring, the springs yieldingly exerting a rotative force on the members for causing the balls to ride on the cam surfaces to separate the members.

2. A mechanical silent tappet comprising `two disc-shaped members made of sheet metal and having central portions arranged in confronting relation, each member having portions formed into cam-shaped recesses, the recesses in one member registering with those in the other to form pairs of ball-receiving compartments that are arranged in a circle whose center is the aligned centers of the members, balls placed in the compartments, each member also having semi-cylindrical arcuate-shaped cavities formed therein, the cavities in one member registering with those in the other to form pairs of springreceiving compartments arranged in a circle that lies within and is concentric to the Iball-receiving compartments, springs mounted in the spring-receiving compartments, the cavities in one member having shoulders bearing against one end of the springs and the cooperating cavities in the other member having shoulders bearing against the other end of the springs., the` springs yieldingly exerting a rotative force on the members for causing the balls to ride on the cam surfaces to separate the members.

t. A mechanical silent tappet comprising two atsasae 'ifr disc-shaped membersmade of sheet-metal :and having centralv portions arranged in 'confronting relation, each member having portions `formedV into-fcamshaped recesses, the recessesinone member registering with those' in the other to form pairs of ball-receiving compartments that are arranged in a circle whose centerl is the aligned centers of the members, balls -placediin the compartments, each member also having-1 semi-cylindrical arcuate-shaped cavities formed therein, the cavities in one member registering with those in the other to form pairs of spring-receiving compartments arranged in a circlethat lies within and isconcentric tothe ball-receiving compartments,y springs mounted" in thefspring-receiving compartments, the` cavities in one member having shoulders bearingv against one end of the springs and thecooperating cavities in the other member having shoulders bearing against the other endof the springs,

the springs yieldingly exerting a rotativey force on 'themembers Vfor causing the balls to -ride on the -cam surfaces to separate the members, one member having a peripheral rim for slidably` receiving: the periphery of the other member, l

and means carried by the rim for limiting the separation between the members.

`4.,A- mechanical silent tappet comprising two disc-shaped. members made of sheet metal andl having central portions arranged in confronting. relation, each member having partial sphericalshaped recesses, the recesses in one member registeringwith those in the otherlto form-pairsof ballfreceiving compartments that are arranged in a circle whose center is the aligned centers 0f themembers, balls placed in the compartments, onemember having a circular spring,- receiving channel that surrounds the circle of ballreceiving compartments, the channel having inwardly-extending stops, the other memberllhaving a portionforming a closure for the channel with stops extending inwardly into the. channel for cooperating with the other stops to provide pairs of` stops,.and coil'springslplaced inthe channel and having their ends bearing against the pairs of stops for yieldingly exerting airotative force on the members for causing the balls to ride on the cam surfaces of saidV recesses to separate the members.

5. A mechanical silent tappetv comprising two disc-shaped members made of sheet metal and having central portions arrangedin confronting relation, eachmember having partial sphericalshaped recesses, the recesses in one member registering with those in the other to form pairs of ball-receiving compartments that arearrangedy in a circle whose center is theV alignedv centers of the members, balls placed in the compartments, one member having a circular springreceiving channel that surrounds the circle' of ball-receiving compartments, the channel having inwardly-extending stops, the other member having a portion forming a closure for the channel with stops extending inwardly into the channel for cooperatingwith the other stops to provide pairs of stops, coil springs placed in the.y

channel and having their ends bearing against the pairs of stops for yieldingly exerting a rotative force on the members for causing thev balls to ride on the cam surfaces of said recesses` tov separate the members, the channel having an` extended circular side for slidably receiving the periphery of the other member, and means carried by the circular side for limiting the separation between the twomembers.

6i Aim'echancal silent tappetl comprising two Vii) til)

8; disc-shaped4 members yand having centra'lfporf' tions adapted to contact each other so asto' transmitthrust from one member to `theother,` the membershaving centrally disposed recesses in their outer'surfaces adapted toreceive an op;- erating and anoperated part of aIvalve-actuating mechanism, both members having arcuate and semi-cylindrical recesses in their confronting surfaces, theY recesses in one' memberY regl istering with those in the other substantially.-v

throughout their lengths to form pairs-otrecesses, coil springs received in the pairsof-frecesses and extending into both, one recess of each pair having an end wall contactingwithv an end of the spring received in the recess Yand the other recess of the same pairl having an end wall contacting with the other end of thefsame spring; one member having a plurality of cams arranged in a circle `that encloses the pairs of; recesses, the other member having a plurality, of cam-shaped concave surfaces that receive theV cams, said cams when at the lowest points ofthe concave surfaces permitting the central-portions of said members to contact each other, said' springs yieldingly exerting a rotative forceon the, members for causing the cams-to rideonthe-con-` cave surfaces for separating the members.

7. A mechanical silent tappet comprisingtwo disc-shaped members and having central portions adapted to contact each other so as to transmit thrust from one member to the other,

the members having centrally disposed-recessesl in their outer surfaces adapted to receive an operating and an operated part of` a valve-- actuating mechanism, respectively, both mem/- bers having arcuate and sehn-cylindrical recesses in their confronting surfaces, the recesses in one member registering with those-inthe other substantially throughout-their lengths to form pairs of recesses, coil springs received in the pairs of recesses and extending into both, one recess of each pair having an end wall contacting with an end. ofthe springireceived in the recess and the other recess of the same pair having., an end wall contacting with the other end of the same spring, one member having a. plurality of cams arranged in a-circle that encloses the pairs of recesses, the other member having aplurality. of cam-shaped concave surfaces that receive the cams, said'cams when at the lowest points ofl the concave surfaces permitting the central portions of said members to contact each other, said. springs yieldingly exerting arotative force on the members for causing the cams to ride on the concave surfaces for separating the membersa ring carriedA bythe periphery of one member and slidably receiving the periphery ofY theother, and means carried by the ring for limiting the separation between the members.

8. A mechanical silent tappet comprising two disc-shaped members arranged in confronting. relation, the members having centrally disposed recesses in their outer surfaces adapted to receive an operating and an operated part ora Valve-actuating mechanism` recesses in their confronting surfaces, the' re cessesA in one member registering with those in the other substantially throughout their lengths to form pairs of recesses, coil springs received in the pairs of recesses and extending intov both, one recess of'each pair having an end Wall contacting with an end of the spring received inv the recess and the other recess oi thesame pair' having an end wall contacting with the other endloi-v the same'spring, one'member having a respectively, both' members having arcuate and semi-cylindrical` plurality of cams arranged in a circle that encloses the pairs of recesses, the other member having a plurality of cam-shaped concave surfaces that receive the cams, said springs yieldingly exerting a rotative force on the members for causing the cams to ride on the concave surfaces for separating members, a ring carried by the periphery of one member and slidably receiving the periphery of the other, and means carried by the ring for limiting the separation between the members, the member contacting with one of said parts of said mechanism having a lubricant receiving opening therein that registers with a lubricant bore in that part.

9. A. mechanical silent tappet comprising two wafer-like members arranged one above the other in confronting relation and movable into face-to-face contact so as to transmit thrust from one member directly to 'the other, and adapted to be interposed between operating and operated parts of a valve-actuating mechanism; the upper member having a depending annular iiange on its periphery having a dust-tight and sliding telescoping iit with the periphery of the lower member; the flange dening a downwardly-facing opening at its bottom through which the lower member is insertable; camming means connned within the peripheries of the members for separating them when one member is rotated relative to the other in one direction; the camming means being shaped to gradually bring the members into sliding contacting relation with a spiral movement when the direction of rotation is reversed; and spring means for rotating the members in the direction to separate the members to maintain them continually in engagement with the operated and operating parts, respectively, of the valve-actuating mechanism.

l0. A mechanical silent tappet comprising two wafer-like members arranged one above the other in confronting relation, and adapted to be interposed between operating and operated parts of a valve-actuated mechanism; the upper member having a depending annular flange on its periphery having a dust-tight and sliding telescoping nt with the periphery of the lower member; the flange defining a downwardly-facing opening at its bottom through which the lower member is insertable; camming means confined within the peripheries of the members for separating them when one member is rotated re1- ative to the other in one direction; the camming means being shaped to gradually move the members into sliding contacting relation with a spiral movement when the direction of rotation is reversed; and a plurality of independent springs arranged around the extended axes of the operating and operated parts of said mechanism, and anchored to the members to provide rotary thrust between the members at several points around said axes.

1l. A mechanical silent tappet comprising two wafer-like members arranged one above the other in confronting relation, and adapted to be interposed between operating and operated parts of a valve-actuated mechanism; the upper member having a depending annular flange on its periphery having a dust-tight and sliding telescoping t with the periphery of the lower member; the flange defining a downwardly-facing opening at its bottom through which the lower member is insertable; camming means confined within the peripheries of the members for separating them when one member is rotated relative to the other in one direction; the camming means being shaped to gradually move the members into sliding contacting relation with a spiral movement when the direction of rotation is reversed; and a plurality of independent springs arranged around the extended axes of the operating and operated parts of Said mechanism, and anchored to the members to provide rotary thrust between the members at several points around said axes; said camming means including ball bearings disposed between the members and around the extended axes of the operating and operated parts of said mechanism and providing substantially uniform ball bearing support between the members.

12. A mechanical silent tappet comprising two disc-shaped members movable into face-to-face contact so as to transmit thrust from one member directly to the other, and adapted to be placed between an operating part and an operated part of a valve-actuating mechanism; the confronting faces of the members having registering recesses with cam-shaped surfaces that extend from said faces to a spaced predetermined distance therefrom; a ball bearing disposed in each pair of recesses; the pairs of recesses being arranged about the center of the members; the cam surfaces of each pair of recesses being sloped oppositely so that a relative rotation between the members in one direction will cause the balls to ride upon the cam surfaces to separate the members; and spring means for yieldingly urging the members in the direction just mentioned; the recesses having suiiicient depth to entirely receive the balls and thus allow the members to come into face-to-face contact with one another when the members are rotated into a predetermined position relative to one another and thus relieve the balls from thrust.

13. A mechanical silent tappet comprising two disc-like members arranged one above the other, and adapted to be placed between an operating and an operated part of a valve-actuating mechanism; the upper member having a depending annular flange on its periphery having a dust-tight and sliding telescoping fit with the periphery of the lower member; the flange deiining a downwardly-facing opening at its bottom through which the lower member is insertable; the confronting faces of the members having registering recesses with cam-Shaped surfaces that extend from said faces to a spaced predetermined distance therefrom; a ball. bearing disposed in each pair of recesses; the pairs of recesses being arranged about the centers of the members; the cam surfaces of each pair of recesses being sloped oppositely so that a rotation between the members in one direction will cause the balls to ride up on the cam surfaces to separate the members; and a plurality of independent springs for yieldingly urging the members in the direction just mentioned to separate the members.

CLIFTON L. STANCLIFF.

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

UNITED STATES PATENTS Number Name Date 1,452,276 Jerdone Apr. 17, 1923 1,631,563 rlitus June 7, 1927 1,790,999 Perkins Feb. 3, 1931 1,903,078 Woolman Mar. 28, 1933 1,913,241 Kuse June 6, 1933

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