US2933074A - Length compensating device - Google Patents

Description

April 9, 1960 R. c. MQSER 2,933,074

LENGTH COMPENSATING DEVICE Filed Sept. 21, 1953 2 Shets-Sheet 1 if i V i .9 /76 L I; M 1?;

April 19, 1960 R. c. MOSER LENGTH COMPENSATING DEVICE.

2 Sheets-Sheet 2 Filed Sept. 21. 1953 LENGTH COMPENSATIN G DEVICE Robert C. Moser, Clearwater, Fla., assignor to B. C. Skinner, Jacques B. Skinner, B. L. Skinner, Bruce W. Skinner, and Vivien S. Miles, copartners, doing business as S-M Tappet Sales, Dunedin, Fla.

Appiication September 21, 1953, Serial No. 381,213

1t Claims. (Cl. 123-90) The present invention is directed to mechanical length compensating means which are particularly useful as incorporated in the operating linkages for valves of an internal combustion engine, and may be referred to as mechanical valve tappets but which may be located at a point to contact directly the normal rotary cam or at some other point in the linkage of elements to the valve stem. The present application is a continuation-in-part of my prior'application Serial No. 189,695, filed October 12, 1950, now Patent No. 2,751,896, issued June 26, 1956.

The invention comprises a length compensating device of. improved form adapted to maintain proper contact relation of the adjacent elements of the operating linkage and eliminate the need for clearance spacing therein commonly known as lash and to reduce noises and maintain a proper timing of the engine valves and effect a proper seating thereof.

With my invention, a novel effective tappet structure is provided, automatically self-adjustable and which is usable both with. the cams of cam shafts designed for the usual mechanical tappet operation, or for the cams of cam shafts designed for hydraulic tappets which are automatically adjustable, between which and valve stems or push rods no clearance or lash is present.

It is the primary object and purpose of my invention to provide a novel, exceptionally practical and eifective valve tappet, usable under all conditions of internal combustion engine design, either with engines designed for mechanical tappets or hydraulic tappets, and which may be installed in new engines or used for replacement of tappets in engines in service. An understanding of the invention may be had from the following description, taken in connection with the accompanying drawings, in which:

Fig. l is a vertical section substantially on the plane of line Ii-1 of Fig. 3, through a tappet made in accordance with my invention, and shown in association with an operating cam therefor and an engine valve which is opened or closed by the movements of the tappet, the parts of the tappet being shown in one position;

Fig. 2 is a fragmentary vertical section of the lower part of the tappet, with the parts thereof in another position which they take during engine operation;

Fig. 3 is a horizontal section and plan view, the section being substantially on the plane of line 3-3 of Fig. 1;

Fig. 4 is a fragmentary section through the upper portion of the tappet on substantially the same plane as Fig. 1, the tappets in Figs. 1 and 4 respectively slightly differing in structure for use, one in conjunction with intake valves of internal combustion engines, and the other with the exhaust valves thereof;

Fig. is a vertical section of a portion of an engine a form 2,933,074 Patented Apr. 19, 1960 ice showing the length compensating means in'a different a function similar to the spring washers of Figs. 1 and 4; and

Fig. 8 is a fragmentary horizontal section taken on line 8-8 of Fig. 2.

Like reference characters refer to like parts in thedifferent figures of the drawing.

The tappet includes in its structure a tappet body which has a closed horizontal lower end 1 and cylindrical walls 2 integral therewith, the body being open at its upper end, and having an oil drainage opening through the wall 2 near the lower end 1. With my invention the lower side of the lower closed end 1 which bears against the actuating cam for the tappet is in a plane inclined slightly to the horizontal or axis of the tappet. As indicated in Fig. 1 the lower face 1a is at a small angle to the plane 1b which is perpendicular to the tappet axis. The incline; tion may have different values dependent upon circumstances but will normally lie within the range of .005 to .030 inch per lineal inch of the diameter of the tappet body. This is to prevent axial turning of the tappet body, and to give a positive uniform stress between the cam and such body. The function of thei'nclined bottomin combination with the inertia adjusting means will be described more fully hereinafter, but for the present it is noted that for the proper operation of the adjusting means it is desirable to prevent rotation of the tappet in cases where that can be reliably effected.

At the open upper end portion of the walls 2 of the body the interior opening is increased in diameter a small amount, providing an annular horizontal shoulder below the upper end of the walls 2 against which a ring 3 of metal is placed. An interiorly threaded sleeve 4 is formed at its upper end with an integral outwardly extending annular flange 5, the exterior diameter of which is slightly less than the interior diameter of the enlarged upper portion of the openings into the body. Flange 5 is located over the ring 3 and the sleeve extends downwardly through the central opening of the ring.

"A specially constructed screw is threaded through the sleeve 4. It includes a head 6 at its upper end, from which-an exteriorly threaded section 7 extends downwardly through the sleeve 4, and having its uppermost threads below the uppermost threads of the sleeve to avoid vanish binding or wedging. Around the screw shank an annular groove 8 is cut at the lower end of the threaded section 7, below which is a shorter threaded section 9, having a limited number of screw threads thereon. The shank of the screw is extended below the threaded section 9 in a plain cylindrical terminal section 10 from which a pin 11 extends radially to one side. The threads are at a sufficiently fiat pitch that the screw will not turn in the sleeve from downward pressure on head 6.

A weight 12 is mounted on the section 10 for free turning thereabout. The pin 11 extends through a slot 13 provided in the weight 12 which is open at its lower end at the lower end of the weight, and is of an arc spiralled upwardly and laterally as shown.

A nut 14 is screwed onto the lower short threaded section 9 of the screw, having an annular recess at its upper end which receives a split spring ring 15 in the 3 groove 8. Such ring serves as a stop against which the nut comes when it is applied to the threaded section 9 and screwed thereon. The distance between the upper side of the weight 12 and the lower side of the nut 9 is such that when the weight .is in its uppermost position (Fig. 2) the pin 11 is at the open lower end of the slot. The weight normally, by gravity, will drop to lower position as in Fig. 1 with the pin at the upper closed end of the slot 13. V

The nut at opposite sides is recessed by recesses having sides at right angles to each other, preferably, as shown at 16. Such nut around its upper end portion is formedwith an integral outwardly extending flange 17, beveled at its upper outer corners. The flange terminating atone of the recesses 16 which have been described, is cut away for a distance back from each of the sides of the other recess 16, as shown at 18 in Fig. 3.

A torsion spring 19 is located around the sleeve 4 which at its upper portion is of a greater diameter than at-its lower portion below a flange 20, similar to the flange 17, and having parts thereof removed similarly to the cut away portion 18 of flange 17. Flange Z is beveled at its lower outer corners. The diameter of the nut 14 between the flange 17 and a lower outwardly extending flange 14a thereon is likewise greater than the lower portion of the sleeve 4. Therefore, the intermediate coils of the spring 19 between the nut 14 and the flange 20 on the sleeve 4 is a short distance from the sleeve, while the lower end coils of the spring 19 bind upon or are cinched against such nut 14 and the upper coils cinched against the upper portion of sleeve 4. The end of the lower coil of the spring is bent inwardly in a hook 19a which engages against the shoulder made at a recess 16, as shown in Fig. 3. The opposite end of the spring at its upper coil has a terminal portion 1% extending through an opening in the flange of the interiorly threaded sleeve 4. A split spring ring retainer 21 of spring wire is received in an annular groove at the upper end portion of the walls 2 of the tappet body and at the inner side thereof, against which the flange 5 of the sleeve 4, at its upper side, engages. Flanges 17 and20 prevent the lower and upper end coils from movement in avertical direction.

By having the end coils of the spring 19 cinched upon the enlarged portion of sleeve 4 above the flange 20 and upon the nut 14 respectively, the corresponding end hook portions 1% and 19a are relieved of considerable stress as the spring is subjected to rapidly repeated variations in tensioning in the operation of the engine. The initial desired tensioning of spring 19 may be adjusted by progressively ratcheting the hook portion 19a from one slot 16 to the .next in the nut 14. It may be noted that the tension of spring 19 acts on nut 14 in a direction tending to screw it into engagement with stop ring 15. 'When the tappets of the present invention are to be used in engines originally equipped with the usual mechanical tappets and the linkage between the cam and engine valve has a certain amount of clearance or socalled lash, then the tappets hereof are equipped with an auxiliary spring means having a range of expansion and contraction corresponding to the amount of the original lash. In the form shown in Fig. 1 the auxiliary spring means comprises a dished washer 22 inserted between the flange 5 of the sleeve 4 and the supporting ring 3, and in Fig. 4 two such washers are employed in reversed relation to each other. Such washer or washers in strength are less than the valve spring with which associated, so that the dished washer or washers completely collapse at a load less than the pre-load of the valve spring. The washers in the trade are commonly known as Bellville washers. The washers .are selected to have a collapsible or contracting range in accordance with the cam shape and clearance of the particular engine in which the present tappet is to be employed. Normally the exhaust valves have a greater clearance than:

the inlet valves andconveniently the single washer of Fig. l may be used for the inlet valves and double washers as shown in Fig. 4 for the exhaust valves. As above" indicated, however, when the tappet of my invention replaces tappets of either hydraulic or other forms in engines in which no lash or clearance is originally pro-' vided and the cams are of appropriate design, the wasliers 22 are not needed.

In Fig. 6 another arrangement of spring washer means is shown. In this case the supporting ring 3 of Fig. 1 is omitted and the shell of the tappet 30 is provided with a thickened annular wall portion 31 provided with an inclined shoulder 32. The bottom face of the flange portion 33 of the nut 34 is similarly inclined and inserted between the opposed inclined faces is a. spr ng washer 35 which may be fiat. The amount of spring adjustment. and auxiliary shortening of the tappet at that point will depend of course upon the radial width of the washer and washers may be selected in accordance with the requirements. Conveniently a relatively narrow washer may be employed for the inlet valves which commonly are designed to have a clearance of about .006 inch for example, and a much wider washer for the exhaust valves in the same engine, such exhaust valves being designed to have for example a clearance of about .014 inch. The flat type of spring washer suchas employed at 35 in Fig. 6 has the advantage of being easier and more economical of manufacture than the dished type shown in Figs. 1 and 4.

Fig. 6a shows a similar arrangement but employi ig a washer 35a which is slightly dished, that is, the radial section .shown slopes upwardly to the right. A small change in the lash or collapsible clearance may be accomplished by reversing the washer. For example a washer which is .125 inch wide with an angle of about one half of one degree will have a rise of about .001 inch and reversing the washer will produce a variation of about .002 inch in the lash. An angle of one degree will produce a variation of about .004 inch upon reversal of the washer. Major variations in the clearance may be obtained by using a plurality of washers in different superposed relation. Fig. 7 shows two flat spring steel washers 36 and an intervening dished washer 37. The latter is not designed to flex and may be made of ordinary soft iron and substantial thickness and therefore cheaper. For example the thickness of the dished washer 37 may be in the order of 4 inch and that of the spring washers 36 about .020 inch. Itwill be understood that Fig. 7

.and likewise Figs. 6 and 6a are not in accurate propormeans may be obtained by variation in the radial width of the spring washers.

The valve body 2 and the parts associated therewith are raised and lowered by the rotation of a cam 23 in the usual manner. The stem 24 of an engine valve is engaged at its lower end by the upper side of the head '6 of the described screw, the usual heavy spring 26 being associated with the valve and which when free to do so will close the valve 25 against its seat to make a tight closing engagement therewith.

The flanges 17 and 20 cut away as indicated at 18 on the flange 17, and similarly on the flange 20, facilitate the assembly of the spring 19 with the sleeve 4 and nut 14, as the ends of the end coils of the springs may be readily introduced to pass under flange 17 and over flange 20 and be turned until a sufiicient number of the end coils are around such nut and the upper portion of.

the sleeve-4am connect therewith with a tight binding engagement. As heretofore described the tension of spring 19 is adjusted to the desired degree by ratcheting the hook end 19a backward over the shoulders provided by the recesses 16 in the nut 14. The spring is assembled under a pre-load of suflicient amount to cause an 'u'pw'ardpush of the screw with a force of from 3 to 12 pounds in practice.

In the operation, with the tappet in its lowermost position as in Fig. 1, and with the circular or base circle portion of cam 23 bearing against the side in of the body, the weight .12 is at its lower position hanging upon and being supported by the pin 11. On rotation of the cam to lift the tappet such weight remains in lower position until the uppermost position of the tappet is reached.

.At the peak of its rise against the cam the tappet body stops and the weight 12, due to the momentum of its upward movement, moves upwardly on the section of the screw and strikes against the lower side of the nut 14, at which time the weight is moving solely in a vertical direction, as the pin 11 (Fig. 2) is in the substantially vertical lower end portion of the slot 13. The weight remains in such position as the tappet body and other parts associated therewith move downwardly with accelerated speed, until the tappet has reached its lowermost position and is stopped against further downward movement, resting upon the circular or base circle portion of the cam. The weight thereupon moves downwardly and is spun about the vertical axis of the screw, striking the pin 11 at the upper closed end of the slot 1 3'with an impactforce in a horizontal direction, which turns the screw. Assuming that the tappet is the right length oris slightly too long, the flange 5 of the nut will be compressed into frictional engagement with the supporting shoulder. of the tappet body, or the spring washer 22 or equivalent form of washer if one is employed, and the screw 7 will turn in the sleeve or nut 4 in a downward direction to shorten the effective length of the tappet making a clearance between the valve stem 24 and the head 6 of the screw. This insures that the valve will reach and properly engage its seat so as to close the port of the engine at which the valve is located.

immediately following, while the lower end of the body 1 is upon the circular or base circle portion of the cam 23, such clearance is automatically taken up by the torsion spring 19 which will cause relative turning between the nut 4 and the screw 7 in the lengthening direction until the head 6 comes against the lower end of valve stem 24. Any difference between the amount that the screw is thus wound back by the spring 19, and that it was operated in the opposite direction by the impact of the weight 12 on the pin is the amount of valve growth on the preceding cycle of the engine.

A further operational characteristic of the tappet will now be described. As previously pointed out the annular flange 5 of the nut 4 has an outer diameter slightly less than the interior diameter of the upper portion of the body 2 in which it is located and accordingly is relatively free to rotate therein when not forced into frictional engagement with its seat. The importance of this may be demonstrated by a review of certain features of the operation. There is a time element involved in which the torsion spring 19 normally must stop the rotation of the screw caused by the inertia member 12 and effect a reverse rotation to restore the screw relative to the nut to at least the approximate original position. Although the time element is only a fraction of a second, it nevertheless is substantial and material and, particularly at high speed of the engine, there might not be sufricient time to effect the necessary amount ofreverse rotation to accomplish the required lengthening. This may result, therefore, in the tappet continuing to produce even aunet shortening of the tappet although it was already short enough. By having, however, thenut free toturn in the body of the tappet when there is no vertical force thereon, then when the weight 12 strikes the pin 11 and causes the screw to turn, the torque will likewise be transmitted to the nut through the spring and also the effect of the friction at the screw threads, causing the nut to turn with the screw. Therefore there would be little or no shortening of the tappet but there would be an appreciable time for some lengthening at each cycle. In other words, if the tappet were already short enough, and particularly it it were too short, there would be no overshortening and the length would be progressively increased in rapid order to a proper operating condition.

The above, of course, only occurs when there is practically no pressure on the screw from the valve stem since if there is continued pressure after the valve seats then the frictional engagement of the flange 5 on its support holds the nut against rotation and the screw will turn in the nut upon impact of the weight. In this respect it is noted that any frictional resistance at the flange 22 is effective at a longer torque arm than the frictional resistance at the threads tending to turn the nut. Therefore, when there is weight applied to the screw it will turn in the nut, because the relatively light tension of the torsion spring 19 is not sufficient to overcome the friction of the nut at its support in the body. In general the tappet functions automatically in accordance with the requirements. If the tappet is too short then the nut turns and over-shortening is avoided and the tappet is quickly lengthened to the proper condition, but if the tappet is too long the nut is restrained and a certain amount of shortening each cycle is assured to achieve the proper operating condition.

An important feature in connection with the combination and operation just described is the selection of a thread of proper pitch. The screw as commonly employed has a diameter of about of an inch, and it has been found that the pitch should be in the range of 10 to 32 3 threads to the inch. The slope on such a thread is a little less than 5 for a pitch of 10 threads and about 1 /2 for a pitch of 32 threads. It is quite preferable, however, to keep the pitch within the narrower range of 16 to 24 threads to the inch which corresponds to about 3 to 2. With a finer thread than 24 to the inch the reduction in length resulting from a given relative angular adjustment between the screw and nut effected by the impact of the weight is small and the shortening may be too slow. On the other hand, normally with a coarse pitch screw having a greater inclination the screw turns more easily in the nut under axial thrust and the inertia weight may cause the screw to turn too far into the nut such that at high engine speeds there is not sufficient time for complete restoration. With the construction described, however, having a nut freely mounted a relative steep pitch, such as 16 threads to the inch with a slope of about 3", may be employed.

A feature which cooperates with the above described elements and characteristics to insure unvarying dependable operation is the provision of the inclined bottom on the tappet body or shell which houses the screw sub-assembly, to maintain the tappet against notation which would normally occur from the actionof the cam. The rotation of the screw '7 under the effect of the weight and the torsionspring, and the rotation of the nut are matters of relative rotation and action, and any rotation of the tappet body would necessarily have its effect. If the action of the cam were such as to rotate the tappet at a constant uniform speed and in a single direction then it would be possible to compensate therefor in the proportions and characteristics of the inner working parts such that the inertia hammer and associated parts would function satisfactorily. But with a normal square bottom tappet body or shell, e.g. the friction and pressure forces acting thereon tending to cause rotation are variable and .irnpact end-in the range of 40 to 50".

"7 further are subject to change under conditions of wear and use over periods of time, and correspondingly the rotation of the tappet may be variable and erratic, with corresponding effect on the functioning of the length compensating means. Furthermore there is a substantial amount of friction between the upper surface of the tappet adjusting screw and the contacting element in the valve operating linkage and if the tappet were caused to rotate this would tend to cause the screw to be threaded into, or out of, its nut as the case might be and which would correspondingly oppose or amplify the effect of the inertia compensating means. The inclined bottom contact face of the tappet shell, designed to maintain the cam engaging lifter element against rotation, cooperates in a very desirable manner in rendering the operation uniform and dependable. This feature is of importance whether the compensating element is located to contact the cam, or at some other point in the operating linkage as will be described in connection with Fig. 5. In some installations the rotational forces may be so strong or other conditions exist such that it is impractical to attempt to prevent rotation by means of the inclined contact face. Increasing the amount of the angle increases the ability of the tappet to resist spinning but an angle larger than a particular value may result in disturbance of the originally designed valve timing. The limit in this respect will vary in different cases but an' angle greater than about is seldom practical and usually the angle should be in the range below about 2.

It is of course apparent that when the clearance between the valve stem 24 and the head 6 of the screw occurs through the impact of the weight 12 against the pin 11, 'the washer or washers 22 of Fig. 1, or corresponding washers of other figures, in those installations where they are used, will tend to resume their normal position, and the return of the screw'head 6 against the head of the valve stem 24 will be with the ring 3 and flange 5 separated as shown in Fig. 1, thereby providing the constant clearance required for running on the cams of a cam shaft designed to accommodate standard lash type lifters. Such washer or washers are completely collapsed when, upon the upward movement or lift of the tappet, the force of the valve spring 26 comes into action holding the valve closed until such collapse has occurred after which the valve is lifted. V

The weight 12 and the slot 13 therein embody features which contribute to the best operation of the device. The slot 13 has aconstant radius and such slot is located in such a manner as to allow the upper closed end of the slot to strike the pin a blow having a component in the horizontal direction to wind the torsion spring 19. The lower end of the slot is located so that in association with .the pin 11 the weight is impelled to move vertically until the upper surface of the weight 12 abuts the lower surface of the nut 14. Some variation is permissible in the angle of the different portions of the slot butin general the angle with respect to a radial plane through the axis of the screw should preferably be, at the bottom open end portion, in the range of O" to 20, and at the upper The slot 13 should be located and shaped to provide substantially a line contact with the pin along its extent to insure a freely sliding engagement, and particularly at the closed end of the slot to eliminate a cushion action at the critical moment of impact when the parts are covered with lubricating oil. Such a shape is shown in the cross secbe conveniently formed by a tapered milling cutter which provides line contacts for the pin 11, as indicated at 13a,

as it advances along the slot, and at the end of the slot as indicated at 13b (Fig. 2).

-The compensating device has been described and is adapted, however, to be inserted at other points in the i tional view of Fig. 8. Since the slot is open ended it may linkage and FigIS illustrates one such other installation. The general arrangement embodies an overhead valve 40, and an operating linkage which includes ,a rocker arm 41, and vertical rod members having a mushroom type tappet 42with a. base adapted to engage cam 43. Typical of various original designs and installations the tappet.42 has a small stem making it difiicult to install a replacement compensating tappet at that point. Such a compensating means, however, is shown inserted in the linkage at 44 with a connecting rod45 of appropriate length extending between it and the tappet 42. The compensating device 44 is constructed interiorly similarly to that shown in Figs. 1 to 3 but is modified otherwise to connect appropriately with the rocker arm 41 and rod 45. The upper end 46 of the adjusting screw has e.g. a socket in which fits the rounded lower end of a set screw secured in the rocker arm, and the bottom of the body of the compensator has a similar socket to receive the upper rounded end of rod 45. The lower end of rod 45 is similarly fitted in the upper end of tappet. Suitable passages may be provided to conduct lubricating oil from the rocker arm through the successiveelements to the tappet 42.

In the normal original engine designs such as that shown, the tappet usually has a bottom which is fiat and therefore permits rotation, or it may have a special shape to accentuate the rotation for known reasons. By reason of the unavoidable frictional effects between the contacting ends of the linkage elements including the engagement of the upper end of rod 45 with the bottom of the compensating element 44 such rotation would be transmitted in variable degree to the element 44. This is prevented in the apparatus of Fig. 5 by substituting for the original a tappet 42 having a bottom inclined similarly to the inclination on the bottom surface of the body or shell 2 in Fig. 1. In other words, the plane of the bottom indicated by the line 48 is inclined to a plane 49 perpendicular to the axis of the tappet by angle A which is of the order indicated in connection with the body or shell 2 of Fig. 1. The position of the tappet 42 and the showing of the angle of inclination A assumes that the cam 43 normally rotates in a clockwise direction.

With the length compensating means described, changes in longitudinal dimensions of the valve stem and all elements in the valve operating linkage are fully compensated for and the elements are maintained in contact and perfect valve timing is correspondingly maintained with consequent maximum engine efliciency. The only clearance which takes place between the screw head and the valve stem or push rod is for substantially an instant of time as the tappet reaches its lowermost position to insure positive and complete setting of the valve against its seat, with substantially instantaneous closing of such clearance through the action of the spring 19. Such clearance and its closure occurs at each cycle of engine operation and insures that under all temperature and other conditions of the engine the tappet, when lifting the valve and for a short period of time before the lifting occurs, will be in contact with the valve stem or push rod and there will be no noises of impingement of the head of the screw against valve stem or push rod during the time that the longitudinal expansion of valve stem or push rod occurs after starting a cold engine and until it is fully warmed up; or at other times when tappets are faultily adjusted. Of even more importance is the fact that the present tappetassures that the engine valves will be seated at the proper time and, in addition tothe resulting increased engine efiiciency, it avoids the major noise caused by a valve striking its seat at high velocity when it reaches itsv seat too early while the tappet is riding on a steeper Pfiflofthe cam. The tappet is noiseless, is far simpler in structure and operation than a hydraulic tappet, less liable to get out of order and 9 need repair or replacement, more economical to produce and serves fully every purpose, function and effect, insofar as elimination of noise and assuring proper valve operation are concerned, as do hydraulic tappets. Also hydraulic tappets are prone to leak down oil therein when stopped at any portion of the associated cam rise, which is eliminated with the present tappet, which does not have oil leakage.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim: a

1. In a length compensating device adapted to be embodied in an axially reciprocatory valve linkage, cooperating male and female screw members having a threaded connection with a thread pitch in the range of 10 to 32 threads per inch, said members being adapted to be threaded together in one direction to shorten the linkage and being provided with a torsion spring connecting said members normally tending to effect a relative rotation in the opposite direction to lengthen the linkage, a first one of said members being adapted to have thrust applied directly to the end thereof, an axial support for the other member said other member being freely rotatable in said support when relieved of axial thrust.

2. In a length compensating device adapted to be embodied in an axially reciprocatory valve linkage, cooperating male and female screw members having a threaded connection with a slope in the range of 1 /2 to 5 degrees, said members being adapted to be threaded together in one relative direction to shorten the linkage and being provided with a torsion spring connecting said members normally tending to effect a relative rotation in the opposite direction to lengthen the linkage, said male member being adapted to receive axial thrust in the linkage, and a support for said female member with a seat for engaging a portion of the female member and supporting the latter against axial thrust, said female member being rotatable on the seat when free of axial thrust.

3. In a linkage length compensating device adapted to be embodied in an axially reciprocatory valve linkage, the combination of a sub-assembly comprising cooperating male and female screw members having a threaded connection with a slope in the range of 2 to 3, a torsion spring connecting said members, a first one of said members being adapted to have thrust applied to the end thereof, an inertia hammer means adapted to act upon said first member and effect rotation thereof against the spring torsion in the direction of threading the members together, and an axial support for the second one of said members with the latter being freely rotatable therein when unloaded whereby said sub-assembly will rotate in said support under the influence of said inertia hammer means during periods of freedom from axial thrust in the linkage.

4. In a linkage length compensating device, an open ended hollow supporting body, cooperating male and female screw members therein having a threaded connection with a slope of about 3, said female member having an enlarged flange portion adapted to be sup ported on a shoulder in said body, a torsion spring connecting said members, said male member having means adapted to receive axial thrust in the linkage and transmit it to said flange portion to force it down upon said shoulder, said female member being freely rotatable with respect to said supporting shoulder when relieved of axial thust but restrained against rotation by frictional engagement at said flange when subjected to axial thrust, and an inertia hammer means adapted to act on said male member to rotate it against the spring torsion in the direction of threading said members together when said female member is restrained against rotation, said female directly 10 member being permitted to rotate with said male member when free of axial thrust.

5. In a linkage length compensating device embodying an inertialength adjusting means, cooperating male and female screw members, a'torsion springconnectedto said members to effect relative rotation in the lengthening direction, an inertia hammer mounted on one of said members slidable coaxially thereof, a pin extending radially from the latter said member, said hammer having a radial slot to receive the pin,'said slot extending axially thereof and having a portion spiralled with respect to the axis and terminating in a closed end adapted to strike the pin and cause rotation of the pin and thereby of the said latter member in a direction opposite to said spring, said slot along the sides and at the closed end being shaped to present substantially a line contact with said pin.

6. In a linkage length compensating device embodying an inertia length adjusting means,cooperating male and female screw members, a torsion spring connected to said members to effect relative rotation in the lengthening direction, an inertia hammer in the form of a sleeve mounted on one of said members slidable coaxially there of, a pin extending radially from the latter member, said hammer having a radial slot to receive the pin, said slot being open ended at one edge of said sleeve and extending axially of the sleeve with a spiralled closed end, the spiralled end being arranged to effect a rotation of the sleeve as it advances and imparts a rotative impact on the pin as it is engaged by the end of the slot and thereby to cause rotation of the said latter member in a direction opposite to said spring, said slot along the sides and at the closed end being shaped to present substantially a line contact with said pin.

7. In a linkage length compensating device embodying an inertia length adjusting means, cooperating male and female screw members, a torsion spring connected to said members to effect relative rotation in the lengthening direction, an inertia hammer comprising a sleeve mounted coaxially of one of said members slidable vertically thereof, a pin extending radially from the latter member, said sleeve having a radial slot to receive the pin, said slot being open ended at the bottom and extending along a spiral path upwardly axially of the sleeve to a closed upper impact end, the bottom portion of said slot being arranged at an angle in the range of 0 to 20 with respect to a plane through the axis of the sleeve and the upper portion thereof adjacent the closed end being ar ranged at an angle in the range of 40 to 50 with respect to such a plane, said slot along the sides and at the closed end being shaped to present substantially a line contact with said pin.

8. In a length compensating device the combination of, a pair of concentric members having complemental opposed conical surfaces and a collapsible intervening spring means comprising a pair of substantially flat flexible washers, and a spacer washer between the two flexible washers having a conical shape substantially corresponding to the inclined shape of the said opposed surfaces of said members.

9. In a length compensating device the combination of, a hollow cylindrical body member, an inner member axially movable within and concentrically of said body member, said members having opposed annular surfaces similarly inclined to form complemental conical seats; a

and an intervening spring means comprising a pair of substantially flat flexible washers, and a relatively inflexible spacer washer between the two flexible washers hav-' ing a conical shape substantially similar to that of said opposed surfaces.

10. In a length compensating device the combination comprising; a hollow cylindrical shell; an annular shoulder in said shell having an outward concave, substantially conical surface; an inner member telescopically received in said shell with clearance; an annular filange on said 7 References Cited in the file of this patent UNITED STATES PATENTS Ware Feb. 13,1923 Tucker Mar. 31, 1931 Holmes 'Jan. 5, 1937 Holmes et al 'Apr. 29, 1941 Engemann Mar. 10, 1953 Engemann Mar. 31, 1953 Pearson May 24, 1955

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