US2176895A - Vibratory mechanical linkage - Google Patents

Description

3 Sheets-Sheet l INVENTOR.

M ATTORNEYS Oct. 24, 1939. H. H. ENGEMANN VIBRATORY MECHANICAL LINKAGE I Y lei'ariii'rzymzmzrz M1? Oct. 24, 1939. H, ENGEMANN 2,176,895

VIBRATDRY MECHANICAL LINKAGE Filed Dec. 2, 1936 s Sheets-Sheet a XM/a ATTORNEY-5' Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE Claims.

This invention relates to a cal linkage and in some respects is an improvement upon the patent to myself and H. H. Burdick 1,972,447, September 4, 1934. The invention is particularly applicable to the poppet valve mechanism of an internal combustion engine and herfce it will be disclosed and discussed in that connection.

Internal combustion engines are usually provided with poppet valves, which are spring biased into closed position. The opening of the valve is accomplished by means of a cam actuated tappet which engages the end of the valve stem and moves the valve open against the biasing action of the valve spring. In the usual engine practise, the tappet has a slightly longer range of movement than the valve, so that during the valveclosed portion of the cycle there will be a small clearance between the valve stem and the tappet. Some operating clearance is usually necessary to insure proper seating of the valve, though the clearance is usually only a few thousandths of an inch. Since the purpose of the clearance is to insure proper seating of the valve, the value to which the clearance can be reduced is determined by the accuracy with which the adjustment of the linkage can be maintained. By the maintenance of perfect adjustment the clearance could be reduced (theoretically at least) to a so-called zero clearance. In general, however, there will be some clearance, though it be an infinitesimal one. Accordingly, it is convenient to refer to an effective operating clearance, but it will be understood that in the limiting case this may become a so-called zero clearance.

For best engine performance, it is necessary that the operating clearance selected be maintained within close limits; and difllculty has long been experienced in this connection, due not only to the wear of parts, but also due to the expansion and contraction of the valve stem, tappet, and other parts as the temperature of the engine changes during operation. To take care of changes which are caused by variations in engine temperature, it is necessary that the clearance be adjusted automatically during the operation of the engine; and automatic devices have previously been proposed for this purpose.

50 The general object of the present invention is to provide an improved and reliable mechanism for automatically and continuously maintaining the desired effective operating clearance in a vibratory mechanical linkage. Another object of the invention is to provide such a mechanism vibratory mechaniparticularly applicable to the valve linkage of an internal combustion engine.

A further object of the invention is to provide automatic clearance adjusting means applicable to an internal combustion engine and capable of 5 satisfactory manufacture and installation on a quantity production basis.

Various other and detailed objects of the invention will be apparent to those skilled in the art mm the following disclosure.

In the forms of the invention disclosed, the valve is opened by a cam driven tappet and the automatic adjusting means is incorporated in the linkage between the cam and the valve stem. The clearance regulating mechanism embodies an adjusting element, such as a screw, cam, wedge, or eccentric. Spring means are arranged to so bias the adjustment element as to tend to move it in clearance-diminishing direction; and spacing means are provided to arrest the adjusting. element in the position of predetermined desired clearance. Each time the valve is closed the adjustment element is momentarily moved in the direction to increase the clearance, and is then immediately restored to the standard clearance 25 by the blasing spring. Thus, adjustment is made to the predetermined standard clearance prior to each operation of the tappet to open the valve. The momentary increase in the operating clearance is effected by an inertia element which is set 0 in motion during the movement of the valve in closing, the inertia element then moving freely to impinge on the adjustment mechanism and expend its kinetic energy in momentarily overcoming the bias of the adjustment element. I 5

Fig. I of the drawings is a largely diagrammatic view of an internal combustion engine valve and associated parts showing the present invention in elevation.

Fig. II is a largely diagrammatic view similar to Fig. I but showing the structure of the present invention primarily in central section. The section is taken in general on the line 11-11 of Fig.

Fig. III is a detailed view taken in general on the line III-III of Fig. II.

' Fig. IV is a plan view of the contact button which engages the valve stem- Fig. V is a, detail sectional view taken on the line V-V of Fig. I.

Fig. VI is a plan view of a spring locking wire used in the assembly.

Fig. VII is a plan view of spring locking ring, used in the assembly.

Fig. VIII is a largely diagrammatic view, partiaily in section, showing a second form of the invention.

Fig. IX is a detail view showing in elevation a portion of the structure of Fig. VIII as viewed from the right hand side of that figure.

Fig. X is a largely diagrammatic view showing a third form of the invention.

Fig. XI is a detail section, taken in general on the line XI-XI of Fig. X.

Structure of Figs. I to VII A valve designated as a whole by A, has a head i and a stem 2, the stem being guided as usual by any suitable means (not shown). A heavy helical spring 3 biases the valve toward its seat. As usual the valve is adapted to be operated periodically by upward movement of a tappet B, which is actuated by a valve cam C that is driven in timed relation to the engine. Interposed between the valve A and the tappet B there is an organization of movable parts D. This organization D includes an effective operating clearance which is closed each valve cycle by movement of the tappet B while the valve A is at rest; and means are included to automatically adjust and regulate such operating clearance.

I'he taDDet B has a bore which is internally threaded at 5, and an externally threaded adjusting screw 6 cooperates with the threads 5. At its upper end the adjustment screw is provided with contact button 1, beneath which is the eifective operating clearance 8. As shown on the drawings the screw 6, has a central bore fi and the button 1 has an integral shank 9 which depends into this bore. Directly beneath the bore 6 is an anchor stud II), which is screw threaded as shown into the base portion of the of the tappet B. A helical spring II is positioned in the bore 5' and has one end fixedly secured to the anchor Ill and the other end fixedly secured to the shank 9.

Viewed from above the button I has the form shown in Fig. IV, having an upwardly projecting boss portion 1, flat sides l 1, and segmental flange portions 1 and I The flange portion I is hotched from top to bottom as shown at 1=. At its top the screw 6 is provided with two diametrically positioned portions 6, 6 which extend outwardly and upwardly and are provided at their upper surfaces with inturned flanges li 6 The outer surface of portions i i is provided with an annular groove to receive locking wire it (Fig. VI); and a hole is provided to enable finger I! to project beneath one of the flanges li (Fig. 11).

Beneath the portions 6, 8 the screw is provided with a cylindrical body portion 6', on which there are two steep male threads 6, 6 A movable weight l2 has a bore which makes a sliding flt with the body portion 6" and has two female threads which cooperate with the steep male thread 6', 6 At its lower end the body portion 8 is provided with an annular groove adapted to receive a spring retainer ring ll.

Assembly procedure In assembling, the weight I! may be telescoped onto the body 8' of the screw before the screw has been inserted into the tappet, and then spring retainer ring Il may be forced into place, thus retaining the weight I I in the zone between retainer l4 and portions 6. Spring H may be attached to shank 9 and the spring and shank telescoped from above into the bore 6' of the screw 6. Then anchor Ill may be secured to spring ll, after which the adjustment screw 8 may be screwed well into the tappet. By rotating the button I the anchor Ill can be screwed into the base of the tappet, after which the head 1 is further rotated to torsionally bias spring ll. When the desired torsional bias of spring II has been effected, button 1 is forced down to longitudinally compress the spring. With the button 1 in the proper rotative position the flat sides 1'", I can be passed between the opposing edges of flanges 6 6 and then the button can be rotated 90 to bring it to the position shown in Fig. 11. In this position, the flanges 6 6 limit the vertical movement of the button I (relative to screw 6) to the distance provided by clearance 8; and to permit this slight vertical movement of the button while preventing rotative movement of the button, spring wire I3 is snapped into the annular groove in part 6, 6 with the finger l3 projecting into the notch 1 of-the button. It will be apparent that the torsional bias of spring H may be varied by moving spring wire I3 and rotating button 1 and then resorting the spring wire it.

The foregoing assembly procedure is merely suggestive, as any suitable assembly procedure may be used. And it will be apparent to those skilled in the art that various modifications of the structure may be made to facilitate assembly by somewhat different procedures.

Operation Assume theparts to be in the position shown in the drawings, in which the valve A, tappet B. and adjusting mechanism C are at rest with the valve closed. As rotation of the cam continues, the tappet B is elevated until the clearance 8 has been closed; then further upward movement of the tappet causes an opening movement of the valve A. As long as the tappet is gaining speed during its upward movement, the weight l2 remains in its bottom position against the retainer it. However, as the tappet loses speed in coming to rest at its uppermost position, the inertia of weight I2 causes it to maintain its upward speed for a moment, with the result that the weight slides upwardly on body portion 8" to the upper position indicated in dotted lines in Fig. II. As the Weight moves upwardly the threads 6', 6 cause it to rotate, so that part of the kinetic energy of translation of the weight is converted into kinetic energy of rotation, which tends to slow down the weight. If desired the upper ends of thread 6', B may be given a special curvature and inclination to stdp the weight without any substantial rotative impact against portions 6. 6". Additionally, the lower horizontal surface of parts Ii", 8 may be provided with a cushioning surface (such as felt, rubber, or a spring) to absorb the impact of the weight at its upper limit of movement. a

The fit of weight I! on body portion 6* and the pitch of threads 6', 6 is such that with body portion 8' at rest, the weight can descend under the action of gravity. However, such descent is a relatively slow movement, and in actual operation the valve is not open long enough to permit any substantial descent of the weight at this time. In any event, as soon as the valve starts to close the inertia of the weight tends to hold it against portions 6, 6, due to the increasing speed of the tappet in a downward direction. However, as the tappet loses speed in coming to rest in its lowermost position, the inertia of the weight causes it to maintain its downward speed, with the result that the weight moves downwardly on body portion 6 and threads 8', 6 cause the weight to rotate. The lower ends of the threads 6 6 are so designed that the weight strikes retainer I4 and imparts a torsional force to the screw 6 in the direction to move the screw 6 into the tappet 13. Thus the upper end of adjusting mechanism D is moved a short distance downwardly from the lower end of the valve stem 2.

As soonas the tappet reaches its lowermost position, the longitudinal force exerted by spring H is effective to elevate button I and reestablish clearance 8. Additionally this spring'exerts a restoring torsional force on screw 6 to unscrew the screw from the tappet until such movement is arrested by contact of button I with the lower end of the valve stem 2. Of course, the force exerted by spring I l is sumciently small to have no efl'ort in opening the valve or obiectionably diminishing the valve biasing force of spring 3.

It will be apparent that the operation would be substantially the same if the clearance at I were reduced to zero. Upon closing of the valve, the weight l2 would introduce a clearance between button I and the valve stem. Then spring ll would close up this clearance without disturbing the proper seating of the valve.

The inward screwing of the screw 6 due to the inertia of weight l2 and the restoring of the screw by spring II will not be accomplished in absolutely zero time. Accordingly the present invention operates best in a linkage where the driving link (e. g., the tappet) is at rest for an interval during which the readjustment of the operating clearance can be effected. The valve of an internal combustion engine is closed for approximately half of the valve cycle, and hence the tappet is at rest for an ample time during which the regulation of the operating clearance is effected by the present invention. It will be apparent that each time the valve closes the inertia of weight l2 becomes efiective to automatically increase the effective operating clearance by momentarily overpowering the bias of spring Ii, and that spring I I then restores the parts to position of desired operating clearance (which is. set at 8) Where the invention is applied to a linka e in which the driving link has little or no periods of dwell accurate timing of the weight I2 is necessary for proper functioning of the device. In such case the impact of the weight (to increase the clearance) should become effective at the instant when the linkage has reached its minimumspeed. In certain cases the timing of the weight may be advantageously modified by attaching a spring to it.

Structure of Figs. VIII and IX The lower end of a valve stem is shown at 22; and it will be understood that, as usual, the stem is suitably guided and that the valve is biased in there is an organization'DD for regulating the effective operating clearance.

A body portion, designated as a. whole by I6, is provided at its upper end with a bore it and is provided at its lower end with a bore l6". Between the upper and lower bores, there is a transverse passage IS. The bore l6"- telescopes freely over the lower end of the valve stem 22,

and the bore lB receives a hollow plug II that makes an easy sliding fit with the tappet BB. An adjustment button 21 is positioned in the upper portion of the bore I8 and has a shank portion that projects, as shown, into the transverse passage lii. Beneath the adjustment button is a leaf spring II which is separated from the upper end of the tappet by a disc It. Plug I1 is inserted such distance into the bore l5 that the desired efiective operating clearance will be established at 20. This operating clearance is the distance between the lower surface of button 21 (when the button is in the position shown in the drawing) and the top surface of disc 18 minus the thickness of the spring l8. The plug I! may be securedin the desired position in any suitable manner. As shown, the plug is screw threaded into the lower end of bore I6; and the threaded connection may be a fit which is suiilciently tight to prevent accidental rotation of the plug, or a lock-nut or other suitable locking means may be used to hold the plug in its adjusted position.

A wedge 26 projects through the transverse opening it and has one of its wedging surfaces in contact with the lower end of valve stem 22 and the other of its wedging surfaces in contact with adjustment button 21. Suitable means such as a leaf spring 2| biases the wedge in a direc-,

tion tending to decrease the clearance at 20. Supported by the body It is a pivot 28 on which is mounted a weight 22. An arm 33 is fixedly attached to the body l6; and a helical spring 34 may have one end connected to the arm 33 and the other end connected to the weight 32.

As the tappet moves upwardly to open the valve, the clearance at 20 is firstclosed and then further movement of the tappet is imparted to the valve. The inclination of wedge 26 is such that the wedge and associated parts are self-clamping under the pressure between the tappet and the valve stem, so that the wedge does not move laterally while the valve is being opened. As the valve comes to rest in its open position, the speed which has been imparted to weight 32 during the upward movement causes the inertia of the weight to be effective to swing it into the position shown in dotted lines. As the valve starts to close and the parts pick up speed in a downward direction, the weight remains in the dotted line position. However, as the valve and tappet lose speed in coming to rest in valve-closed position, the inertia of weight 32 is effective to swing it against wedge 26 and move the wedge to the right. This movement of the wedge momentarily increases the effective operating clearance. The clearance at 20 is reestablished by leaf spring l8, and spring 2| moves the wedge to the left until all lost motion has been taken up, i. e., until the eiiective operating clearance has been diminished to that established at 20 by the leaf spring I8. 01' course, spring 3| is not strong enough to have any effect in opening the valve or obiectionably diminishing the bias of the valve into closed position.

It will be seen that the operating principle is similar to that of Figs. I'to VII; and that once each valve cycle, the eflective operating clearance is momentarily increased and then immediately diminished to the desired value. Adjustment of the timing and action of weight '32'can be effected by changing the strength of spring 2|, or by shifting its angle of pull, or both. For

example spring 34 may be shifted from arm 33 to arm 33 which is also attached to body It.

rocker arm 62. The rocker arm is part of an organization of parts DDD which automatically regulates the effective operating clearance oi the linkage.

The valve end of the rocker arm is provided with a threaded bore 44, in the bottom of which isa contact button 45 which projects from the rocker arm and engages the end of the valve stem. A plug 46 is positioned in the bore 44; and between the lower surface of the plug and the upper surface of button 45 there is a leaf spring 41 which establishes the desired operating clearance at 48. Of course, the effective operating clearance is the distance between plug 46 and button 45 minus the thickness of leaf spring 41; and plug 46 is inserted the necessary distance to fix the operating clearance at the des red value. To prevent accidental rotation of plug 4'8, the screw threaded connection of the plug with the bore may be a very tight one, or the plug may be locked by means of a lock-nut or other suitable locking means. The rocker arm is supported indirectly by a shaft 49 on which is mounted an eccentric 60. An oscillating weight 5| makes a bearing fit with the outer surface of the eccentric 50; and the rocker arm also makes a bearing fit with the outer surface of the eccentric 50, the rocker arm and weight being positioned in sideby-side relationship, as shown in Fig. XI. Springs 52 and 53 rotatively bias the eccentric 50 and weight 6| respectively, as shown in the drawings. Projecting laterally from the eccentric 60 is a pin 60; and the weight 5| has a projection ii that is adapted to engage the pin 50'. Similarly, a pin 5| projects laterally from the weight. and the rocker arm has a projection. 62'' which is adapted to engage the pin Bi Assuming the parts to be in the position shown in the drawings, continued rotation of the cam causes the tappet to be moved upwardly and the rocker arm to be moved in a clockwise direction to close up the clearance at 48 and open the valve. The degree of eccentricity of the eccentrlc 50 is such that during this valve opening movement the parts are self-locking and there is no slippage between the eccentric and the rocker arm 52. When the valve closes, the spring 41 reestablishes the clearance at 48,- and the inertia of weight 6| becomes efl'ective to momentarily increase the eil'ective operating clearance in the linkage. Spring 63 is weak enough so that as the rocker arm loses speed in coming to rest in valve-closed position, the weight 5| continues to move counterclockwise (by virtue of its inertia), and projection 5| strikes pin 50'. The impact causes a. small counterclockwise movement of eccentric 6B and momentarily elevates the rocker a slight amount to increase the effective operating clearance. Then, while the 'valve and tappet are at rest in valveclosed position, the spring 52 moves the eccentric 60 clockwise to take up the lost motion, leaving in the linkage only the clearance established at 48.

Again, the principle oi operation is similar to that of Figs. I to VII. Once each valve cycle the eil'ective operating clearance is momentarily increased, and is then immediately diminished to the desired value.

The "initial position 01' the valve or driven link referred to in the claims is the position occupied by the valve when it is seated, or the position occupied by the driven link before it is moved by the action of the driving link.

In compliance with the patent statutes I have disclosed the best forms in which I have contemplated my invention, but it will be understood that the scope of the invention as defined in the claims is not limited by the forms of the inating clearance in the linkage, which clearance is 1 closed each cycle by movement of the driving link relative to the driven link and is restored upon the return of the driven link to initial position, and adjustment means are provided to regulate such clearance, the improvement which comprises: an inertia member movably mounted on one of .said moving links and operative to automatically move said adjustment means when the driven link is in initial position to increase said'clearance, and restoring means automatically operative to restore the adjustment means to the position of desired clearance.

2. In a vibratory mechanical linkage oi the type in which there are intermittently actuated driving and driven links with an effective operating clearance in the linkage, which clearance is closed each cycle by movement of the driving link relative to the driven link and is restored upon the return of the driven link to initial position, and adjustment means are provided to regulate such clearance, the improvement which comprises: a weight movably mounted on one of said moving links and automatically operative each cycle by virtue of its inertia when the driven link is in initial position to move the adjustment means in the direction of increased clearance, and restoring means operative to then move the adjustment means in the reverse direction to diminish the clearance to the desired value.

3. In a vibratory mechanical linkage of the type in which there are intermittently actuated driving and driven links with an eifective operating clearance in the linkage, which clearance is closed each cycle by movement of the driving link relative to the driven link and is restored upon the return of the driven link to initial position, and adjustment means are provided to regulate such clearance, the improvement which comprises: means to bias the adjustment means in the direction tending to diminish the clearance. means to arrest the adjustment means in the position of desired clearance, and inertia means movably mounted on one of said moving links and automatically operative when the driven link is in initial position to momentarily increase said clearance by momentarily overpowering the bias oi said adjustment means.

4. In a vibratory mechanical linkage of the type in which there are intermittently actuated driving and driven links with an efl'ective operating clearance inthe linkage, which clearance is closed each cycle bymovement oi the driving link relative to the driven link and is restored upon the return oi the driven link to initial position, and adjustment means provided to regulate such clearance, the improvement which comprises: means to bias the adjustment means in the direction tending to diminish the clearance, means to arrest the adjustment means in the position or desired clearance, and a weight movably mounted on one of said moving links and automatically operative each cycle when the driven link is in initial position to momentarily increase said clearance by the inertia of the weight overpowering the bias of said adjustment means.

5. In an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization. which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open and which is restored on return of the valve to initial position, the improvement which comprises said organization including: adjustment means to regulate said clearance, means to bias said adjustment means in the direction to reduce said clearance, spacing means to arrest .the adjustment means in the position of desired clearance, and an oscillating weight movably mounted on one of the moving parts of the linkage and operative each cycle by inertia when the valve is in initial position to momentarily overpower the bias of said adjustment means and thereby increase said clearance momentarily.

6. In an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open, the improvement which comprises said organization including: an adjustment screw which is, threaded into the tappet, means to rotatlvely bias the screw in the direction to decrease the clearance, means to arrest the screw in the position of desired clearance, and means automatically operative on each closing of the valve to momentarily overpower the bias of said adjustment screw.

'7. In an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open, the immovement which comprises said organization including: an adjustment screw which is threaded into the tappet, means to rotatively bias the screw in the direction to decrease the clearance, means to arrest the screw in the position of desired clearance, a weight carried by the adjustment screw and freely movable thereon in a longitudinal direction throughout a limited zone, and means to rotate the weight as it moves longitudinally so that the inertia oi the weight becomes effective at the end of the welghts movement to momentarily overpower said bias of the screw upon closing of the valve.

8. In an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open, the improvement which comprises said organization including: an adjustment wedge movable to vary the clearance, means to bias the wedge in the direction to decrease the clearance, means to arrest the wedge in the position of desired clearance, and inertia means automatically operative to momentarily overpower the bias of said wedge.

9. In an engine having a valve biased to closed position, a cylically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open, the improver'nent which comprises said organization including: an adjustment wedge movable to vary the clearance, means to bias thewedge in the direction to decrease the clearance, means to arrest the wedge in the position of desired clearance, a pivot movable with the valve, and a weight mounted on said pivot and operative by inertia to strike the wedge upon closing of the valve to momentarily increase said clearance.

10. In an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open, the improvement which comprises said organization including: an adjustment wedge movable to vary the clearance, means to bias the wedge in the direction to decrease the clearance, means to arrest the wedge in the position of desired clearance, a pivot movable with the valve, a swinging weight mounted on said pivot and operative by inertia to strike the wedge upon closing of the valve to momentarily increase said clearance, and a spring attached to said weight.

11. In an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet relative to the valve before the valve begins to open and which is restored upon the return of the valve to initial position, the improvement which comprises said organization including: an adjustable eccentric movable to vary the clearance, means to bias the eccentric in the direction to decrease the clearance, means to arrest the eccentric in the position of desired clearance, and an oscillatory weight automatically operative when the valve is in initial position to momentarily overpower the bias of the eccentric.

12. In-an engine having a valve biased to closed position, a cyclically actuated tappet for opening the valve, and an organization of moving parts interposed between the tappet and the valve, there being an effective operating clearance in said organization, which clearance is closed each cycle by movement of the tappet rel ative to the valve before the valve begins to open, the improvement which comprises said organization including: an adjustable eccentric movable to vary the clearance, means to bias the eccentric in the direction to decrease the clearance, means to arrest the eccentric in the position of desired clearance, an annular weight making a bearing fit with the eccentric, and means effective on closing of the valve to apply kinetic energy of the weight to the eccentric as a force momentarily overpowering the bias of the eccentric.

13. In combination, a tappet, an adjustment screw coaxial with the tappet and making threaded engagement therewith, and an oscillatory weight carried by said screw, the weight oscillating longitudinally with respect to the screw.

14. In combination, a tappet, an adjustment screw coaxial with the tappet and making threaded engagement therewith, means to rotatively bias the screw in the direction to unscrew it from the tappet, an annular weight carried by the adjustment screw and having a zone of free move ment longitudinally of the screw. and means to impart rotary movement to the weight as it moves longitudinally of the screw.

15. In combination, a hollow tappet, an ad justment screw threaded into the tappet, a contact button at the outer end of the screw and movable axially with respect thereto, means to limit the movement of the button axially of the screw, means to bias the button outwardly of the screw and bias the screw outwardly of the tappet, an annular weight carried by the adjustment screw and having a zone of free movement longitudinally of the screw, and means to impart rotary movement to the weight as it moves longitudinally of the screw.

HERBERT H. ENGEMANN.

CERTIFICATE OF C ORRECTI ON.

Patent No. 2,176,895.

HERBERT H October 21 1959. ENGEMANN.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 1h, for "Fig. 11" read Fig. 11; line 25, for "resorting" read restoring; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 5th day of December, A. D. 1959.

Henry Van Arsdale,

Acting Commissioner of Patents.

weight to the eccentric as a force momentarily overpowering the bias of the eccentric.

13. In combination, a tappet, an adjustment screw coaxial with the tappet and making threaded engagement therewith, and an oscillatory weight carried by said screw, the weight oscillating longitudinally with respect to the screw.

14. In combination, a tappet, an adjustment screw coaxial with the tappet and making threaded engagement therewith, means to rotatively bias the screw in the direction to unscrew it from the tappet, an annular weight carried by the adjustment screw and having a zone of free move ment longitudinally of the screw. and means to impart rotary movement to the weight as it moves longitudinally of the screw.

15. In combination, a hollow tappet, an ad justment screw threaded into the tappet, a contact button at the outer end of the screw and movable axially with respect thereto, means to limit the movement of the button axially of the screw, means to bias the button outwardly of the screw and bias the screw outwardly of the tappet, an annular weight carried by the adjustment screw and having a zone of free movement longitudinally of the screw, and means to impart rotary movement to the weight as it moves longitudinally of the screw.

HERBERT H. ENGEMANN.

CERTIFICATE OF C ORRECTI ON.

Patent No. 2,176,895.

HERBERT H October 21 1959. ENGEMANN.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 1h, for "Fig. 11" read Fig. 11; line 25, for "resorting" read restoring; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 5th day of December, A. D. 1959.

Henry Van Arsdale,

Acting Commissioner of Patents.

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