Jill?‘ 7, 1947- ‘2,414,003 T. H. THOMPSON MECHAN ICAL MOVEMENTS 'Filed July 9, 1945 ‘ 4 Sheeté-Sheet, 1 .[?venivr TOM H. THOMPSON 2;; 7:219 ai‘i‘af'neys Jan. 7, 1947. ' t 'T, Ht THOMPSQN . MECHAN I CAL MOVEMENTS‘ 2,414,003 Jan- 7, 1947- T. H. THOMPSON. MECHANICAL MOVEMENiS Filed July 9, 1943 ' 2,414,003 ' 4 Sheets-Shéet 3 Jan. 7, 1947. T. H. THOMPSON 2,414,003 ‘ MECHANICAL MOVEMENTS Filed July 9, 1945 4 Sheets-Sheet 4 TOM H. THOMPSON 6y kzls‘ azivrneys M’ 2,414,003 Patented Jan. 7, 1947 UNITED STATES PATENT OFFICE 2,414,003 MECHANICAL MOVEMENTS Tom H. Thompson, Larchmont, N. Y., assignor to Builder-Thompson Engineering and Research Corporation, New York, N. Y., a corporation of Michigan Application July 9, 1943, SerialvNo. 494,071 8 Claims. (Cl. 74-—571) 2 This invention relates to mechanismand meth od adapted to convert rotary motion to or from reciprocatory motion by means of a straight-line motion, i. e., the motion of a connecting rod of theoretically unlimited length. The mechanism movement contributed by that assembly. It is this latter type of movement which is the primary is of a type in which two circular eccentrics, one inside the other, are employed to cause the con mechanisms where a mechanical movement such version. The object of the invention is to obtain adjustment of the length of the reciprocatory movement‘in a simple manner. It is character 10 istic of the invention that each of the two circu lar eccentrics above mentioned is itself divided into two eccentrics of equal lift and that the opposite rotation ‘of the eccentrics in a pair gives the change in length of the reciprocatory motion 15 while simultaneously the relatively opposed rota ’tion of the inner and outer pairs of eccentrics causes-translation of the reciprocatory motion into rotary motion. ' It is also characteristic of object of the present invention. . In modern engines, pumps, compressors, brakes, torque converters, metering devices or other as above describedv is used, it is frequently desir able that the length of the ireciprocatory move; ment be variable. In some mechanisms itis even desirablethat the direction of ‘an oscillationvbe reversed, as far as concerns its'timed relation to the rotary movement. _If, for example, a mech anism of this type were employed in a pump, the time of projection of the pistons could sometimes be changed to advantage so as to cause the pump to push the water or other liquids in the reverse direction without stopping the drive of the-pump‘. Again, if the mechanical movement were em-j ployed in a device such as an airplane engine, it the preferred form of the invention that when 20 would be possible to change the direction of rd tation of the propeller without stopping the en gine. In the mechanism which I employ, the lift of the ‘other eccentric automatically adjusts same elements which give the reciprocation are itself to equality. progressively used to reduce the lift or reciproca In my Patent No. 2,316,114, dated April 6, 1943, for a Machine element, there is shown a mecha 25 tion to zero and then to increase the lift in the opposite direction. As shown, for example, in my nism for translating rotary motion to or from re the lift of one of the eccentrics is changed, the ciprocatory motion by means of a straight-line movement which theretofore had been obtained by the well-known “Scotch yoke.” The two cir cular eccentrics, one inside the other, of that prior patent are embodied in the present invention, which may be considered an improvement upon that earlier invention. The subjects-matter of my pending-applications Ser. No. 481,336, ?led. March 31., 1943, and. Ser. No. 403,896, ?led July 24, 1941, are also embodied in the mechanism shown in the present application. ' 'In straight-line motion mechanisms in which two circular eccentrics, one inside the other, are employed in connection with the conversion of rotary motion to or from reciprocatory motion, .the two eccentrics revolve in opposite directions to give the reciprocatory motion. In the present speci?cation the elements ‘which go to make up the inner eccentric will be termed the “primary eccentric assembly,” and the elements which go to make up the outer eccentric ‘will be termed the “secondary eccentric assembly.” The two ‘eccentrics cooperate together to accumulate the total‘lift. The movement of each assembly as a ' unit with relation to the other assembly should be distinguished carefully in function from the movement of the elements within one assembly with relation to each other. in obtaining the vari ations in length of the part of the reciprocatory said‘prior application Ser. No. 481,336, the cylin- ‘ ders are arranged in a radial manner in a rotor. The rotation of the rotor need be merely relative to the shaft associated with the primary eccen tric-that is to say, it may be the primary which will do the rotating, and the rotor containing the cylinders may be stationary. The present in vention can be employed in either type of device. Speaking generally, the present invention con templates splitting the primary and secondary eccentric assemblies each into a pair of eccentrics. Each of these four elements is in itself an ec centric embracing 0r embraced by the companion element with which it goes to make up one eccen ' tric pair. In the drawings: Fig. 1 is a view in elevation, partly broken away, of a rotary pump made in accordance with my invention, viewed from the control end; Fig. 2 is a view in elevation of the control end plate of the pump of Fig. 1;‘ ‘ Fig. 3 is a view similar to Fig. 2 showing the parts adjusted for full stroke; ‘ Fig.4 is a vertical view partly in section on th axis of the rotor through the pump of Fig. 1, taken on the line 4-4 of Fig. 1; Fig. 5 is a view in vertical section in a plane normal to the axis of the rotor taken on the line 5——5: of Fig. 4; ' 2,414,003 3 4 Fig. 6 is a view in horizontal section of the pump of Fig. 1, seen along the axis of the rotor taken on_.the line 0—6 of Fig. l, with the pump at zero stroke; Fig. 7 is a view in vertical section similar to As already mentioned, in the form of pump shown in the drawings the obtaining of the Fig. 5, showing the parts in full stroke; Fig. 8 is a detail view of one piston and cylinder of Fig. '7, at another rotational position; necessary reciprocatory motion involves the ro tation of the rotor 40 and pistons 00 and the holding stationary of the elements which are functionally at the other end of the machine element. These elements are the inner torsion equalizer shaft 10 and the primary inner eccen trics 80, which will be described next. The eccentrics are divided into two pairs, the Figs. 9 to 11 inclusive show the means articu lating the secondary assembly; Fig, 9 being an end view of the three eccentrics at zero stroke inner pair being known as the primary assembly. position; Fig. 10 being a view of the parts in side In this primary assembly the inner part is turned elevation at zero stroke; and Fig. 11 an end "inside out” in a manner similar to that in elevation of the parts at full'stroke; which the primary is turned inside out in my Figs. 12 and 13 are diagrammatic views of the 15 application Ser. No. 403,896, above referred to. movements of the eccentrics and yoke about This is a source of simplicity of construction pump center, Fig. 12 showing the parts at .zero and——what is probably even more important stroke, and Fig. 13 the same parts at the end of compactness. The primary inner eccentric con a stroke; the small dotted circle indicating‘pump sists of the round, so-called torsion equalizer center. shaft 10 held in an eccentric position with re The invention will be shown and described lation to pump center by two inner eccentrics embodied in a pump, i. e., a device in which 80 which support it at its ends. These two ec rotary motion is being converted into recipro centrics 80 are keyed on ‘the shaft 10 and are catory motion. In order to simplify the descrip held in position by roller bearings 80! (Fig. 6) tion of the machine, I will ?rst describe .the movement of the parts when in ‘motion during constant operation and while no adjustment of the stroke or lift is being made. Then I will draw attention to the mechanisms and connec which in turn are supported by the end plate 305 and ?ange 402. The end plate 305 at the control end of the housing is bolted to the hous ing end plate 303 and can be seen in Figs. 2, 3, 4 and 6. Except when the stroke of the pump tions which make it possible'to adjust the stroke. . is being adjusted, there is no movement of the It should be noted that the movements of roller bearings BM in the stationary end plate the parts are relative and that while in the ex 305. The ?ange 402 supporting the eccentric 80 ample shown in the ‘drawings the primary eccen at the drive end of the housing is bolted to the tric assembly does not rotate when the machine rotor 40 and the drive shaft 50 and rotates with is merely pumping, the cylinders and pistons 35 them. There are roller bearings 403 between rotate. In other words, the device, in analogy .the outer shoulder of the ?ange 402 and the to the terminology for engines, is a “rotary” stationary drive end plate 3!" of the casing. The pump, i. e., the cylinders and pistons rotate about means for adjusting the stroke and which keeps the pump center and the casing stands still. the inner primary eccentric from turning at The invention, of course, is equally useful in a other times will be described later. “radial” pump or engine, 1. ‘e., one in which In the so-called “reversal” of the primary inner the cylinders do not rotate and the relative mo eccentric, the small torsion shaft 10 occupies only tion is obtained by rotation applied at the pri a. minimum diameter which makes it possible to mary assembly. The principal parts of the eas have the primary outer eccentric 9E3 lie within the ing are the drive end plate 301, the rotor .hous radial dimensions of theeccentrics 60. This outer ing 302 and the control end plate 303 (see Fig. v6) . eccentric 90 extends the complete distance be Mounted for rotation about pump center is a tween the two eccentrics ~80 and, like the eccen rotor 40 in which are six radial openings con trics ‘BU-except when the stroke or lift of the stituting the cylinders in which pistons 60 re pump is being changed (as will be explained ciprocate radially. These Openings are distrib later)--turns with the torsion shaft ‘i0 and the uted equi-angularly about pump center. The eccentrics 80. These elements, by turning ,in the rotoris turned by a drive shaft 50 which passes one direction, combine with the secondary eccen freely‘through an opening in the drive end plate tric assembly turning in the opposite direction, to 30! and is connected directly to the rotor by a give the “lift” or stroke of the pump. flange 402. It will be noted that with the primary inner ec The piston 50 in each cylinder is connected centric reversed and the primary outer eccentric to a piston in the cylinder diametrically opposite member 90 of straight uniform diameter, the ec vto it. forming one unitary element, as can be centricity 0r lift transmitted to the secondary seen in Fig. 5. As can be seen in this side eleva assembly does not occur around the center of the tion, the pistons and piston rods 602 are con 60 internal diameter of the secondary eccentric as nected by a yoke 60! and the circular eccentrics sembly, where the lobes of the latter element are which cause them to reciprocate are located in spaced. When the stroke of the primary is be— this yoke. This unitary structure can be termed ing adjusted the torsion shaft 10 .moves up and the yoke element. The ‘length of the element is down a predetermined center line of the pump. such that when one'piston is fully retracted its As in the case of the primary eccentric, the mate is fully advanced. There are six istons secondary eccentric also is composed functional in the preferred embodiment-shown in the draw -ly of two main elements-an inner and an outer ings. The pistons arearranged in equiiangular eccentric. The inner part or element of the sec relation so that the cylinders .in the ‘rotor are 60° apart. If a different number of pistons are ondary eccentric may also ‘be termed a main cam shaft. In the structure shown in Figs. 5 and 6 of the drawings, it is composed of two parts, a single ribbed unitary sleeve I00 and three eccen used, the angle between two pistons will be dif ferent. The number of pistons should be even. ‘It will be seen thatthe yokes Bill and pistons 60 have equi-angularly spaced ‘reciprocatory paths of movement. tric lobes i0l for the pairs of pistons spaced around the element in equi-angular relation. These angularly spaced pistons are about 60° 2,414,003 5 apart, as can also bev seen, for example, in my application Ser. No. 403,896, above referred to. There is a space between each lobe and its ‘neigh bor in which to place articulating ‘disks, to be described later. In distinction to the inner secondary cam or eccentric cluster I00, the outer eccentrics'for the three pistons are separate from each other and each surrounds merely its own lobe of the inner part of the secondary eccentric. These outer ec centrics are designated in the drawings by the reference characters III], III, H2. If desired, roller bearings H3 can be placed between the outer secondary eccentrics H0, HI, H2 and the yoke 6M, and smaller roller bearings I M can be placed between the inner and outer secondary ec centrics. It will be well at this point to review the gen eral manner of operation of the four eccentrics which constitute the primary and secondary ec centrics. While each pair of eccentrics can be ‘It may be noted at this point by looking at Fig. 7 that with the pistons in one extreme position, the inner and outer eccentrics of the primary as sembly are not giving their maximum lift. I have found it desirable not to use the remainder of possible lift in the primary, and it will be noted that the part of the movement which is used is the one which has the larger component of move ment in the straight-line motion direction. In ‘order that the reader may not be confused, it is pointed outthat the outer primary eccentric 9!} and the elements 10 and 80 composing the pri mary inner eccentric are not rotated relatively to each other to give a higher lift than is shown in Figs. '7 and 13, and therefore the maximum theo retical lift of the primary will not occur. The effective lifts of the inner and outer eccentrics are‘ equal. Figs. l2and 13 are merely diagrammatic illus trations of the positions of the eccentrics and yokes at zero and full stroke of the embodiment of the invention shown in the drawings. These functionally considered as one eccentric in cer correspond to Figs. 9 and 11. The small dotted tain'respects, I shall call each pair of eccentrics circle in each case is pump center and the small and associated parts an eccentric assembly. est solid circle is the position of the inner torsion When the stroke is not being changed, 1. e., ad equalizer shaft 10 and of the inner primary ec justed or varied, the two eccentrics of the primary centrics 80. assembly turn relatively in one direction with a As already referred to, in the example shown in ?xed lift, and the two eccentrics of the secondary the drawings, the manual adjustment of the assembly turn in the opposite direction with. a .?xed but equal lift providing the cumulated or 30 stroke of the pump is obtained by movement of the primary eccentric assembly only. The parts total lift. This causes reciprocation of the pis about to he described can be seen best in Figs. tons. As long as one pair of the four eccentrics 1 to 4, and in Fig. 6. The manual adjustment is so mounted that the eccentrics in that pair are is rotational in a plane normal to the drive shaft not at liberty to turn with relation to each other, 50 and it is controllably obtained by rotation of it has been found that the eccentrics forming the 1 the hand-wheel ‘fill located on the upper end of other assembly will not change their relation to a worm screw shaft 102 carried by a bracket 1&3 . each other. I have discovered that with the struc mounted on the outer end of the ?ange 364 on the ture shown, despite the lack of direct connection control end plate 393 (Fig. 4). The rotation of between the parts, the lift of the primary and secondary eccentrics will automatically maintain 4-0 the worm screw shaft 102 is translated into verti» equality if the two elements of one eccentric are cal movement by means of a primary control block 164 threaded on theworm screw shaft and rotated in opposite directions with relation to each other. Thus, for example, in the pump shown‘ in the drawings if the parts 80 and 90 of the primary eccentric are turned slightly in o‘p posite directions from the positions shown in Figs. v6 and '7, thereby changing the lift of the primary eccentric, the combined effect of the change in the primary and of the yoke opening 69! is si multaneously to cause the two parts of the sec ondary eccentric to rotate in opposite directions, thereby equalizing their lift to that of thepl‘i mary eccentric. I believe it to be novel to have two cams or eccentrics, one inside the other, ro tating in opposite directions to cause reciproca tion of a third element, and at the same time to guided vertically by the bracket ‘563. ‘This block is connected to the inner and outer eccentrics of the primary eccentric assembly by two arms 1'65, 106 which extend laterally on opposite sides of the screw shaft ‘M2 at a level approximately op posite the center of the drive shaft 5%. Each of these arms provides the necessary turning ad 50 justment for one of the eccentrics of the primary assembly. The angular movement of the eccen trics caused by these arms is equal. Thus the arm 135 at the left of the screw shaft m2, as viewed in Fig. 1, connects with the outer primary 55 eccentric 9i] and the right arm 16% serves to turn the inner eccentric cams 3&1 and torsion shaft ‘H1. As can be seen in the vertical sectional view, Fig. so construct each of those two eccentrics that the 6, the left arm ‘Hi5 has a horizontal slot 10‘? in lift of the two eccentrics can be changed while which slides the outer end of a pin ‘Hill mounted in the mechanism is continuing to cause reciproca tion of the third element, and to do this in such a 60 a collar 139 which‘ fits around the outer eccen tric 99 and is keyed thereto by key l iii. There is manner that the machine automatically keeps the an open slot ‘H5 in the end plate 335 to permit lift of the two eccentrics equal. the movement of the pin ‘F98 without conflict I will now describe the mechanism which is the with the end plate. It will be seen that unless direct or primary means of adjusting or varying the screw shaft 702 is turned, the primary control the stroke or lift of the pump. The fundamental block ‘Hi4, arm ‘Hi5, collar led and key ‘Hi3 will requirement is that the two eccentrics which with serve to hold the outer primary eccentric 99 their associated parts constitute the primary ec against rotation, but that if the screw is turned, centric, may be rotated slightly in opposite direc the resultant raising or lowering of the arm ‘Hi5 tions. Since the two eccentrics are circular ec— will rotate‘the eccentric. Lowering of the control centrics, it will be seen that the cumulated lift block ‘H14 will turn the eccentric counterclock of ‘the primary will be changed.‘ > It will be wise, as viewed in Fig. 1. Correspondingly, lower changed, for one thing, in the maximum lift to ing of the control block ‘164 will serve to turn the be obtained from the primary assembly because , cams 80 ‘and torsion shaft l3 clockwise. The the high points of the inner and outer eccentrics imechanism to do this can be seen in Figs. 2 ‘and - 8'0 and 9B are further separated than heretofore. v2,444,003 8 '3 and in the .upper right-hand corner of Fig. 6. There is a slot 10? in the arm 106 corresponding to the slot in the arm 195 and moving horizontally in that slot ‘H3’! is a pin l'l I fastened in the end of an arm ‘H2 (see Figs. 2 and 3). This arm is automatically whether the pump is standing still or operating. If we were dealing with a construction in which there was only one yoke Gill and one outer second Cr ary eccentric, the secondary assembly would have mounted on the end of the torsion shaft '10 by a to be adjusted simultaneously with the primary screw l 53 and is locked to the cam 80 at the right assembly by means connected to the secondary. end of the machine by a pin 1 it (see Fig. 6). The It will be obvious from the description hereto screw 7 I3 and the pin ‘H4 are on opposite sides of pump-center and swingingthe arm 1 I 2 causes ro 10 fore given that the rotor turns in a clockwise direction as viewed in Fig. 5 and that as a result tation of the cam 89 and the torsion shaft 10 an of that turning the pistons move radially back and forth in their cylinders between the bottom and top positions shown in Fig. 7. At the bottom shaft and therefore turns with the shaft and the and top positions the periphery of the rotor is ?rst-mentioned cam 80. In Figs. 1, 2, 4 and 5 in contact with ?ller pieces 1504, 405 which present the parts are shown set at zero, the position in curved contact faces to the periphery of the rotor. which no lift is caused by turning of the rotor 40. As can be seen by comparing the positions of the In Fig. 3 the block ‘194 is shown lowered to the parts in Fig. 7 and in Fig. 8, this separating of maximum degree used in the machine, which cor the plates around the periphery of the rotor responds with the position of the parts in Figs. 20 inside the casing in the two parts makes it pos 6 and '7. sible to give apumping action. As seen in Fig. 7, As set forth in my previous applications, the equi-angular amount. The cam 80 at the other end of the torsion shaft is rigidly fastened on the mechanism herein used is a straight-line motion mechanism in which circular eccentrics are used that are mounted one inside the other and which occupy the entire space inside the element next outside of it. The outside eccentric of the sec ondary assembly fills the entire space inside its for example, there is a space outside between the rotor and the inside of the casing which is ta pered from the inlet port 406 toward the filler pieces 494, 495, and the tapered structure exists between the ?ller pieces and the discharge outlet 467. It is believed that the operation of the device will be obvious from the description ‘here tofore given, but it is desired to point out that I have found that adjustment of vthe two eccen the direction in which the liquid is pumped can trics forming the primary assembly by means of be changed if the adjustment of stroke above turning the screw shaft 102 will cause the sec described is carried to the opposite side of the ondary assembly to adjust its eccentricity auto zero position (pump center) shown in Figs. 1, 2, matically to equal that of the primary. This, of 4 and 5. Thus if the block 104 were screwed course, simpli?es the mechanism needed and only upwardly instead of downwardly, the torsion shaft manual adjustment of the primary assembly is it’! would be moved in a straight line to the other necessary to cause the entire apparatus to be side of pump center, causing the top piston in adjusted to the new setting. (It is fundamental Fig. '7 to go to the top point of its stroke. It in straight-line motion mechanism that circular will be seen that there would be liquid in the eccentrics be used inside one another with the lift of the primary and secondary means at all 40 cylinder as it is cut off from the discharge outlet dill’ by the ?ller piece 405 and that the subse times equal.) I have found that this adjustment quent movement of the cylinder would carry it takes place in spite of the fact that one part of into contact with the port 1306 which theretofore the secondary assembly rotates in one direction was the intake port, and the piston would push and the other part in the opposite direction. The the liquid out into that port. The effect of chang mechanism shown in the drawings, however, does have dead center at the top and bottom positions ing the timing of the pistons in this manner in of the rotor and for those positions it is advisable a pump is to make it possible to change the di rection in which the liquid is being pumped, with to provide means insuring that the direction of rotation of the eccentrics does not change. Thus out stopping the rotation of the drive shaft at it is possible at those dead center positions for 50 all. The advantages and uses of such a con the secondary assembly to go into greater or lesser struction will be obvious. This is especially true lift positions. I have devised the following novel when it is taken in connection with the fact that means of preventing this and overcoming other the output of the pump can be varied. Similarly objections which will be mentioned as the descrip through a hydraulic torque converter the speed tion proceeds. In the ?rst place, the outer ec 55 or direction of rotation of the drive shaft of the centrics of the secondary assembly are kept in fluid motor can be varied. In other words, by equi-angular relation to each other by the ar simply changing the setting of the two eccentric ticulating means which will be described herein elements of one of the‘ eccentric assemblies in after, so that a common point on one, in the case the mechanical movement, it is possible to go to of the mechanism shown in the drawings, is 120° any other portion of a complete cycle of move away from the corresponding point at the neigh ment. boring outer eccentric, regardless of the position Stated another way, my invention provides that any such outer eccentric is in with relation means whereby a full stroke in one direction to the lobe of its inner eccentric. I also ?nd that can be changed to zero stroke, passing through it is useful for the proper functioning of the the zero point into a full stroke in the opposite mechanism to have the equal radial disposition direction while the machine is operating, with of the cylinders about the periphery of the rotor. out changing or altering the position of the The ?xed relation of the three lobes of the inner driving means itself. In. this statement I am as eccentric of the secondary assembly also per suming that we are dealing with a pump of the forms a function in proper operation of the de type mentioned in the opening of the speci?ca vice, and with these features each secondary unit tion; and by “driving means” I refer to the drive is helped past its dead center position by the shaft. The same principle will apply in the case other two units, and the adjustment of the ec ' of an engine. ' centricity of any secondary unit to equal the ad There is another novel feature shown in the justment of the primary assembly takes place 75 drawings. This is the articulation. As above yoke 60!. With circular eccentrics so embraced, 2,414,003 mentioned, it will be noted that the outer ele ments of the secondary eccentric assembly for each piston element are free and independent of each other. (I have already pointed out that they have no ?xed connection to the other ele ments of the secondary eccentric to which each one belongs.) , In placing three outer secondary cams upon a shaft consisting of three inner secondary cams at 120° relation to each other, these outer sec ondary cams must bear a constant rotational relation to each other at all times to insure the operation of the variable assembly. Thus where there are three outer secondary cams they should always be at 120° relation to each other, regard is operating circular eccentrics and means for ad justing said eccentrics to vary the lift caused thereby and for locking‘ these two eccentrics in adjusted positions a secondary eccentric assem bly acted upon by said primary eccentric assem bly and comprising a unitary inner member hav ing a plurality of eccentric lobes side by side spaced around the member equi-angularly and an outer eccentric on each lobe and means associated with the secondary assembly keeping said outer eccentrics spaced apart equi-angularly; recipro cating elements embracing said outer eccentrics and means guiding said reciprocating elements wherebyrelative rotation of the primary and-sec ondary assemblies in opposite directions causes secondary assembly is varied. Owing to the fact conversion of motion, and adjustment of the lock ing means varies the lift of both primary and sec that the lobes of the three outer elements of the ondary assemblies equally. less of how the stroke resulting from the entire 2. In a straight-line harmonic motion mecha the outer eccentrics are turning about different 20 nism for converting rotary motion to or from re ciprocatory motion, driving and driven connec centers, there are no points on the complemental tions, cooperating primary and secondary eccen faces of any two of the outer eccentrics opposite tric assemblies and reciprocatory elements em each other which remain in ?xed relation to each bracing the secondary eccentric assembly, said other when the lift of the secondary eccentric is primary assembly comprising a pair of co-operat changed. ing circular eccentrics and means adjustably con I have shown in Figs. 9, 10 and 11 a form of trolling the relation of the two eccentrics rela means for articulating the outer secondary cams tively to each other, thereby controlling the lift so that they are always 120° apart, regardless of the assembly; said secondary assembly engag of their relation to the inner secondary cams, secondary eccentric are set 120° apart, so that this mechanically preferable construction involv 30 ing said primary eccentric assembly and compris ing the use of diiferential disks and cranks. Thus in the side view of Fig. 10 the three secondary cams Hil, HI, H2 have differential disks H5 located between them which are free to rotate on the inner secondary member about the com mon center of that inner secondary member. These articulating differential disks rotate in re lation to the inner secondary cam assembly one full revolution for every full revolution of the inner secondary eccentric member. While its ro- < tation is not at a uniform rate, its variable speed is governed by the relation of the cams with ing a plurality of circular inner eccentrics in ?xed equi-anguiar relation to each other about a com-J mon axis but lacking rigid connection to any other part of the machine, an outer circular ec centric surrounding each such inner eccentric and surrounded in turn by one of the driven or driving connections and means for guiding said connections in equi-angularly spaced paths of re ciprocatory movement, whereby when the lift of the primary assembly is adjusted the secondary assembly automatically assumes equal lift. 3. In a straight-line harmonic motion mech anism for converting rotary motion to or from re which it is joined by the cranks H6. This can ciprocatory motion the combination of primary be seen from Figs. 9 and 11. These cranks H6 and secondary circular eccentric assemblies of are able to swing radially outward at one end equal lift adapted to act one on the other, the as the diameter of the path of the outer sec primary of said eccentric assemblies comprising ondary cams increases. It will be observed that two co-operating circular eccentrics and means there is a crank H6 from each cam to the adja associated with said primary eccentric assembly cent diiferential disk I I5, and another crank from the differential disk to the cam ring eccen 50 adjustably controlling the lift, the secondary of said eccentric assemblies lacking rigid connection tric 0n the other side or the disk. This construc to any other part of the mechanism and com tion takes care of itself automatically and keeps prising a unitary element engaging said primary the lifts equal. The connections between disks eccentric assembly‘ and having a plurality of ec and the eccentrics are necessary because the centrics rigidly ?xed side by side with their lobes points of connection are not at the points of in equi-angular relation to each other about a intersection of the lift lines of the two eccentrics, nor are they in common relation to the center lift line. common axis, a circular eccentric on each such lobe and a reciprocatory element surrounding each such eccentric, means guiding said recipro It will be seen that the pump which I have de scribed is one which has no operating crank, and 60 catory element and means maintaining each ec centric on said lobes in ?xed angular relation to that I have produced a variable pump in which the other eccentrics on said lobes, whereby when two sets of two eccentrics each, with equal effec tive lift, by working simultaneously in oposite the lift of the primary eccentric assembly is changed by its adjustable control, the secondary directions provide reciprocation of a third mem ber, but at the same time the individual assem 65 assembly automatically equalizes its lift to that of the primary assembly. blies of the sets of eccentrics are variable at will 4. In a straight-line harmonic motion mecha with relation to each other in a very simple man nism for converting rotary motion to or from re ner while the pump is working. It is always ciprocatory motion, primary and secondary pairs possible to vary the stroke and keep the effective eccentricity of one assembly to the other equal, 70 of co-operating circular eccentrics, means adapted ‘to lock the primary pair of eccentrics together, as is necessary in a device of this type. said means also being adapted to adjust the lift What I claim is: of the said pair of eccentrics by rotating them in 1. In a straight-line mechanism for converting opposite directions, the secondary pair of eccen rotary motion to or from reciprocatory motion, a primary eccentric assembly comprising two co 75 trics comprising an inner group of eccentrics with anagooa 11 121 lobes arranged in ?xed equi-angular relation to at‘ all times, whereby the secondary assembly is each other about a common axis and engaging one of said primary pair of‘eccentrics and an outer eccentric group'consisting a circular eccen tric surrounding each lobe of the inner eccen tric group, in combination with a driving or driven maintained in‘ proper timed relation. 7'. In a‘ straight-linereciprocating mechanism connection embracing each outer eccentric, and means guiding said connections in equi-angularly spaced‘paths of reciprocatory movement whereby when the lift of the primary assembly is adjusted the secondary assembly automatically equalizes its lift. 5. In a straight-line reciprocating mechanism adapted to'change rotary motion to or from re ciprocatory motion, the provision of four cir cular eccentrics forming‘ cooperating eccentric assemblies consisting of pairs of adjacent eccen tries, the reciprocatory motion being functionally applied'or received at the periphery of one of said eccentrics, said pairs of adjacent eccentrics be ing constructed and arranged‘ to have relatively opposite rotation as'units to give the conversion for converting, rota-ry'motion to or from recipro catory motion, a- primary eccentric assembly ad justable as to its lift, a secondary or outer eccen tric assembly comprising an inner member hav ing‘ a plurality of eccentric lobes side by side spaced arounda center in ?xed equi-angular rela—> 10 tion, and‘ an outer eccentric on each‘lobe, in com bination' with means adapted to cause movement of theinner and outer eccentrics of the secondary assembly with relation toeach other for the‘pur pose'of changing the lift of thesecondary assem bly, and articulating‘means holding said outer eccentrics together in'equi-angular relation when the-eccentrics are~rotating oppositely to the inner secondary member to change the lift. 8; In a straight-line‘ mechanism’ for convert ing rotary motion to or from reciprocatory mo tion, the provision of four co-operating circular eccentrics forming primary and secondary ec of motion to' or from reciprocatory motion, and means‘ adapted to cause movement of the two‘ secondary eccentric assembly surrounding said eccentrics of said pairs equally in' opposite direc primary eccentric assembly, a yoke surrounding tions with relation to each other for the purpose justabl'e as‘ to its’ lift, a secondary or outer ec centric assembly comprising an inner member an eccentricv of said secondary assembly to and from which eccentric the reciprocatory motion is given or received, means guiding the- recipro catory movements of said yoke in combination with adjustable control means adapted to-adjust the-relative-positions of the- primary pair of ec centrics to each other and of the secondary pair of eccentrics to-each other and thereby adjust the having a plurality of eccentric lobes side by side lift, whereby the‘ application of motion to the of changing the length of the reciprocatory move ment. _ 6'. In‘ a straight-line reciprocating mechanism for‘ converting rotary motion to or from recipro catory‘motion, a primary eccentric assembly ad' centric assemblies of 'pairs of'eccentrics withl'said spaced around a center‘ in ?xed equi-angular 35 yoke will cause- rotation of one pair with a lift relation, and an outer eccentric on each lobe, in equal tothe lift of‘the-other pair of eccentrics. combination with articulating means linking said outer eccentrics‘ together in‘ equi-angular relation TOM H. THOMPSON.