US1937135A

US1937135A - Support

Info

Publication number: US1937135A
Application number: US654638A
Authority: US
Inventors: Wood Joseph Kaye
Original assignee: General Spring Corp
Current assignee: General Spring Corp
Priority date: 1933-02-01
Filing date: 1933-02-01
Publication date: 1933-11-28
Anticipated expiration: 1950-11-28

Description

Nov. 28, 1933.

J. K. WOOD SUPPORT Filed Feb. l, 193s e sheets-sheet 1 J. K. WOOD Nov. 28, 1933. i

SUPPORT 6 'sheets-sheet 2 Filed Feb. 1,. 1935 Sam W INVENTOR JasfPH YE D AT1-o EY Nov. 2s, 19.33.l Y J. K. woon SUPPORT Filed Feb. 1. 1933 e sneetsheef 5 INVNTOR U NN m fast-PH /IAy B ff AT1-o NEY J. vK. Woon SUPPORT Filedk Feb, 1, 1933 R Y o E .v0.m.\, en@ klem. Aww M \/r 5a u E y r//a m m A JsfP/f /ey /1/000 Nov. 28, 1933.

:tha: r l EL Nay. 28, 1933.

J. K. woon 1,937,135

SUPPORT `Filed Feb. 1. 1933 6 sheets-sheet 5.

Nov. 28, 1933.

J. K. WOOD SUPPORT Filed`Feb-. l. 1933 6 Sheets-Sheet 6 Patented i Nov. 28, 1933 UNITED STATES f SUPPQRT Joseph Kaye Wood,

signor to General Mount Vernon, N. Y., as-

Spring Gorporaton, New

York, N. Y., a corporation ofNew York Application February 1, 1933. Serial No. 654,63

` 22 claims. (61.'248531) This invention relates to a support which permits movement of its load for a substantial distance along its line of pull, while affording to said load an approximately constant supporting force.

More particularly, the invention relates to a spring support such, for example, as is described and claimed inmy Patent No. 1,816,164, dated A. July 28, 1931, in which the moments of the weight of the load and the pull of the spring upon a pivoted member are adjusted relative to one another, so thatthe force applied to the load is more nearly constant than in the device illustrated and described in my said prior patent.

In my prior patent above referred to, I have '15 described and claimed a support or hanger in which a movement of the load is accommodated by means of a spring, and the variation in tension of the spring when extended or contracted is compensated for by means of a pivoted lever.

.20 To this end, the lever is so mounted that the change in the moment arm (i. e., the perpendicular distance from the line of` action of the force to the pivot of said lever) at which the spring acts on the lever varies, e. g., due to the rotation of z5 the lever about its pivot, so as to compensate at leastl partially for the increase or decrease in tension of the spring when distorted or relaxed. As set forth in my said patent, complete compensation is not secured by the preferred embodimentdescribed therein, and there remains a small variation in the force with which the load is supported, e. g., between five and ten per cent 0f the Weight of the load.

It is an object of the present invention to re- .25 duce or eliminate entirely the variation in' the force applied to the load. It is a .further object of the invention to provide means for adjusting the force applied to the load in "any position without interfering with the constancy of the applied force in the various `positions for which the device is designed. A further object of the invention is so to design the hanger that the range of operation will always fall within the rangeof maximum compensation, due to rotation of the fispivoted member upon which the spring acts. A further object. of the invention is to provide a bearing surface for the load upon said pivoted member which will substantially avoid any horizontal component,v i. e., any component divergent from the line of pull of the load, i. e., which in every normal position will be tangent to a line perpendicular to the line of pull of the load at the point of contact.

In the drawings I ferred embodiment of have illustrated two prethe invention and various modifications thereof, al1 designed to accomplish these various objects, and which will serve to i1- lustrateithe practical application of the invention for the purpose of explaining its principle and operation.

Fig. 1 is a side elevation of a preferred form of the invention;

Fig. 2 is a cross-section taken on line 2--2 of Fig. 1;

Fig. 3 is a cross-sectiontaken on line 3--3 of Fig. 1;

Fig. 4 is a longitudinal sectional view of the spring barrel shown in dotted lines of Fig. 1;

Fig. 5 is a graph showing the moment of the spring` on the pivoted member plotted against the angle at the pivot of said member dened by the two points of pivotal connection of the spring;

Fig. 6 is a diagrammatic view similar to Fig. 1

showing an alternative type of compensating device;

Fig. 7 is a diagrammatic view similar to Fig. 1, showing still another alternative compensating device; i

Fig. 8 is a view in side elevation of another embodiment of the invention;

Fig. 9 is a vertical section taken on line 9 9 ofFig. 8;

Fig. 10 is a vertical section taken on line 10-,10 of Fig. 7;

Fig.'11 is a side elevation of a pipe clamp suitable for use in connection with the present invention;

Fig. 12 is` an end elevation of a. pipe clamp suitable for use in connection with the present invention;

Fig. 13- is a side levation similar to Fig. a of Aanother preferred form of the invention; and Fig. 14 is a vertical section taken on line 14-14 of Fig. 13.

Fig. 15 is a modied form of the device shown in Fig. 13.

Referring rst to Figs. 1 to 4, the device there illustrated comprises a frame 10 which may be vsupported by means of bolts 11, a horizontal shelf 12, and rollers not shown mounted on the frame by means of -bolts 13. 'I'hese rollers are spaced from one or both of the bolts 11 soy as to permit substantial horizontal movement upon the shelf 12, and thereby to allow the support to adjust itself laterally to the line of pull of theload.

A spring 15, which in thiscase is secured within a barrel 16 so as to'be compressed between the head 17 thereof and a movable head 18 secured to the rod 19 by means of the nut 20, is' .anchored by means of trunnions 21 in the nection of the end of the spring extends beyond the pivots 21, and whereas the opposite end of the springs fall short of the pivot 26, obviously this is immaterial, since for all practical purposes the

pivots

26 and 21 are to be considered as the points of connection of the spring to the force-transmitting means 27 and the anchoring means 10, respectively, although the end of the spring which is connected to the pivot 26 through the bar 1Q is actually beyond the pivot 21, while the end which is connected to the p ivot 21 through the barrel 16 is midway between the

pivots

21 and 26.

The rod 19 is pivotally connected at 26 to the force-transmitting member 27 which, in this case, is shown as a crank lever, and this lever, in turn, is pivoted on the frame 10, as shown at 28.

The load in illustrated in these figures is supported by a yoke 30 which, as shown, may be connected through a turnbuckle 31 for adjustment, and through the ends of this yoke, is mounted a pin 32 which preferably carries a roller 33, and extends for a substantial distance on ether side of the yoke so as to enter the slots 34 in the frame 10. The

sides of the cam slot 34 acting upon the pin 32l serve as a supplemental compensation means by varying the moment arm of the load on the member 27 to correct such variation in support as would otherwise remain.

A specially shaped cam 36 is provided as the bearing surface for the roller 33 on the forcetransmitting member 27, and in the present case this is shown as removably positioned on the force-transmitting member 27. This construc chosen merely for convenience.l

tion, however, is as I have preferred accurately to grind the cam block 36 apart from the lever 27. Obviously, this could be integral instead of separable, as shown.

The surface of this block 36 is a slightly modied involute curve, but I have found it simplest and most satisfactory to use an empirical method in its design. Paper models may be made to scale corresponding to the lever 27, to the frame with its slot 34 and to the roller 33, the block portions 36 on the lever 27'being larger than required. These parts may be mounted upon a drawing board and moved through the intended range of operation. Beginning with the pin 32 at one end of the slot 34, mark on the model which represents the cam block 36 the point at which the line of pull of the load intersects the circumference of the roller 33. The model representing the roller 33 and pin 32 is then moved a short distance at a time along the slot 3 4, and at each position of the roller the model representing the lever 27 is moved about the pivot 28 until the last point thus marked is on the perpendicular to the line of pull from its intersection'with the circumference of the roll 33. The nev.7 point of intersection is then marked. When the opposite end of the slot has been reached. the points thus marked are joined in a smooth curve which will be substantially the desired curve for the cam 36.

The curvature of the slot 34 may be determined in the following manner. With the particular spring and design, the required supplemental compensation may be determined either mathematically or experimentally', and the the embodiment of my inventionl with the extension thus change in leverage, i. e., the perpendicular distance from the center of the pivot 28 to the line of pull of the load, from the point of tangency between the roller 32 and the block 36, may be calculated for the upper and lower limits of movement. This will give a centerV point as shown at 32 and the points at the top and at the bottom of the slot 34, and with these three points determined, an arc' is describedthrough them which will closely approximate the center line of the desired slot. The vertical position of this slot is such that the pin 32 falls in the center of the slot when the force-transmitting member 27 is at the center of its normal movement.

Other types of supplemental compensation may be used; With the slot as just described, the moment of the load upon the force-transmitting member 27 is varied .byvshifting the load-carrying member 30 toward and away from the pivot 28. A similar effect, however, can be obtained by varying the moment of the spring upon the member 27 by shifting the rod 19, `or the spring 15a if a long extension spring is used instead of the compression spring 15 shown in Fig. 4, toward or away from the pivot 28. This I have illustrated diagrammatically in Fig. 7.

In Fig. 6, I have shown another alternative method of supplemental compensation in which the pin 32 rides in a vertical slot 34a in the frame 10 to hold the load-carrying member 30 substantially along its line of pull, .whereas a cam ,member 40 having a slot 41 for the pin 32 is formed as part of an extension 22a of the adjusting slide 22 on each side of the frame l0. A slot 43 for the pin 28 is preferably provided as an additional guide. Thus the movement of the' load serves to adjust the trunnion 21, and theretension of the spring at dilerthe load so as substantially to complete the compensation for variation in the moment which would be exerted by the spring` if not so adjusted.

In both the embodiments of Figs. 6 and 7, the slot 34a serves to control the leverage of the load upon the pivoted member 27 so as to maintain 120 a constant moment arm, while the supplemental compensation affects the moment of the spring upon the member 27. The actual curvature will, of course, depend upon the characteristics of the spring, and the position of the

pivots

21, 26 and 125 28. With these factors determined, the curvature of the cam slot can be readily determined mathematically or, empirically. For example, with these factors xed, the extension of the spring required at each position 27 may be calculated for Fig. 7

=extension required where i M=Moment of the load on the member 27; P:=Perpendicular distance from pivot 28 to the line of pull of the spring for which extension is to be determined; 14C

F-:Force exerted by the spring in the position from which extension is to be measured;

K=Load/deflection ratio of the spring determined for each angular position of the member 27, the shape of 14: the cam can be readily plotted. f Figs. 6 and 7 are intended only as examples to emphasize the fact that the supplemental compensation is not limited to the particular means of the member 130 shown in Fig. 1, but that. any means responsive tto the movement of the load which varies either `tl1e tension of the spring or its mechanical advantage upon the load may serve to complete the compensation. g Nor are these modified forms recommended, as compared with the preferred forms of Figs. 1, 8 and 13, since they require more accurately machined cams and are subject to greater friction because of the pull of the spring on the cam follower against the cam face.

In all of these supports, it is to be understood,

of course, that friction will. introduce a variable error that is not subject to correction. In speak- `ing of constant tension, compensation, balance, and correction, I preferto static conditions and recognizethe existence of some variations due to friction. It is also recognized that in practical construction,-the tolerances necessary in practical manufacture will cause errors, and for this reason, I prefer designs such as shown in Figs. 1 to 4, 8, and 13, in which the effect of such inaccuracies is In order that a given support of standard specifcations mayy be used for a substantial range of loads, it is desirablto provide for adjustment to vary the location of the load upon the spring, and vice-versa. Such adjustment has already been described for the purpose of compensation t 1) by varying the moment arm of the l'oad on the lever 27, (2) by Vvarying the moment arm of the spring upon the lever 27, and (3) by changing the initial tension of the spring, or, in other words, the point along its line of extension at which the spring begins to exert a tension. The last of theseI methods is preferred for adjustment to the load when a design such as that shown in Figs. 1, 8, or 13 is adopted. since this adjustment will not interfere with the automatic compensating adjustment. In Figs. 1 to 4, I have shown two methods of accomplishing such adjustment. In the first place, the initial tension of the spring can be adjusted directly by means of the nut 20, and in the second place, a similar adjustment may be made somewhat more easily in cramped locations by means of a slideand bolt 22 to 24. vThe latter does vary slightly the triangle between the

pivots

26, 28 and 21, and consequentlythe moment arm at which the spring acts upon the lever 27 at any given position thereof, but is positioned and designed so that this variation is relatively unimportant.

I'he rails 23, in Figs. 1, 6 and 7 are so disposed that when the slide 22 is moved, the axis of trunnions 21 follows a fixed straight line which passes through the axis of pivot 28. The reasons for this will be better understood by reference to Fig. 5.

lIn this figure, I have plotted the moment exerted by the spring 15 upon 'the force-transmitting member'. 2,7 at the various angles measured between the lines of centers 26-28 and 28-21. The curve which results is somewhat similar to a sinusoidal curve, resulting from the superimposing of the sine curve representingthe moment arm of the Aspring plotted against the angle 26-28-21 and the sine curve resulting from plotting the tension or extension of the spring against the same angle. The horizontal axis on which the former curve is plotted is the center of the sine curve, whereas the latter curvev is tangent to the horizontal axis, if the spring begins to act at the zero angle and is entirely above or extends below the axis, depending upon the point at which the action of the spring begins. Since all negative values are imaginary and have no .real existence in this latter curve, it will be disy continuous if the spring does not come' into action at the zero angle. The latter curve, moreover, will have its maximum at 180, and its minimum at 0, whereas the former curve will have its maximum at 90 and its' minima at 0 and 180, so that the resultant curve is a modified sine curve in which the right hand side of each node j is steeper than the left, and which, for a substantial distance near its maximum, is approximately flat. The positions of the

pivots

26, 28, and 2l are chosen according to my invention so that' the cente'r of the normal movement falls approximately at the maximum of this curve, and the range of normal operation is substantially entirely along the flat portion of the curve. Thus, within this range, the variation from perfect balancing of the load by the spring and pivoted arm may be kept comparativelyslight.

These curves may be determined for any particular combinations of spring. force-transmitting member, and other related parts, by measuring or calculating the moment arm and the force exerted by the spring at the successive positions, calculating the moment and plotting against angle. I have found that with a support designed as illustrated herein, the spring is preferably chosen to bring the maximum of the curve in the neighborhood of 112, as illustrated by the curves b and c shown in Fig. 5. The position of this maximum will depend upon the ratio of the distances 21-28/26-28 between pivots and the initial length of the spring.

AAnother way of determining the design so as to assure operation along the flat maximum portion of the curve is as follows;v

Choose a convenient distance between the pivots 21-28 and a convenient length between the pivots 26-28. I have found that a ratio of two to one, or three to one, between these distances is generally most desirable.

Choose an initial length for the spring. which should be such that the spring will be well within its limit of elasticity throughout its operating range, but will begin to be distorted before the operating range is reached. I have found that a very satisfactory initial length is two-thirds of the distance between the` pivots 26 and 21 when the angle 21-23-26 is at 90, i. e., an initial length such that the spring will be distorted onethird of its length when the arm 27 has been moved to the 90 position.

With these factors fixed, the moment arm and 'the extension of the spring in various angular positions of the arm 27 ar'e easily calculated by 130 -ating range at this maximum angle.

The initial length of the spring,` has already been assumed, but the characteristic of the spring, i. e., thefload/deilection ratio, remains to be determined. This will depend upon the load which is to be supported, andupon the moment arm at which 'the load acts'upon the member 27. When these are known, they are multiplied together to give the moment'of the load on the 150 it arm 27, and since the moment of the spring must be the same in order to balance the load, the figure thus obtained is divided by the maximum value on the curve, already plotted (i. e., the moment which a spring with the load/deflection ratio of one would exert), to give the required load/deflection ratio for the spring. Of course, if two springs are used, the characteristic thus calculated will be the combined characteristic of the two springs, and in fact, any number of springs or other resilient devices equivalent to springs can be used in the same way. The above applies particularly to the case of the spring l5a, as shown in Figs. 8 and 13, or as it would be applied to Fig. 1 in the manner illustrated in Fig. 7. Where the spring extends beyond the pivot 2l, as is situation may appear somewhat complicated, but if it is remembered that the spring 15, together with the parts 16 'to 20, inclusive, is the equivalent of the spring 15a, and that the points of connection of this spring means are 26 and 21, this apparent complication will cause vno difflculty to those skilled in the art.

Grdinarily, for practical designs, I have found it best to choose the initial length of the spring and the ratio of the distances 21--28 to 26--28 so that the angle of maximum moment will fall in the neighborhood of about to about 115, though these limits may be exceeded.

When the initial tension or precompression (or, stated in another way, the position of the member 27 at which the action of the spring begins) of the spring l5 is adjusted by moving the pivot 21 along the line between the

pivots

21 and 28, the angle at which maximum moment is attained is changed only very slightly, and the range of operation continues to fall uponthe flat portion of the curve. Thus I have shown in Fig. 5 curves b and c resulting from adjustment in this way. rlhe curve a illustrates the case in which the spring is distorted from the instant it leaves the dead center, or the zero angle position, and the curves b and c illustrate cases in which the spring is relaxed suciently so that it does not begin to be distorted until a substantial angle is reached, about 45 in the case of curve c. The curve c may result from the curve b by the adjustment of the trunnion 21 alongthe line of centers between it and the pivot 28, or by other adjustment which changes the precompression or extension of the spring in the operating range without shifting the maximum of the curve to any great extent.

If adjustment should be effected by a shifting of the trunnion away from the line of centers, or otherwise adjusting the parts so that the angle between the linesof centers 26-28 and 28--21 at any given position of the load is altered by the adjustment, the maximum of the curve would be shifted laterally so that it occurs at a seriously dierent angle; and this would throw the operating range of the parts over onto a steeper part of the curve, where the compensation would be less complete. Particularly where a supplemental compensating means, such as the curved slot 34 or the variations illustrated by Figs. 6 and 7, is used, it would be objectionable thus to shift the operating range to a different portion of the curve, because thereby the variations which call for the supplemental compensation would be changed, and the supplemental means would no longer satisfactorily correct for the variations in moment exerted by the spring.

Although I have found the trunnion slide adthe case in Fig. 1 the ,of the duplication of slots resales justment 22, 23 24, particularly satisfactory, I have in the construction illustrated in the drawings shown an alternative adjustment which may be used instead of, or in addition to, the ton adjustment. Thus the nut 20 may be adjusted along the :rod 19 so as to compress or relax the spring 15 within the barrel 16, without moving the trunnions 21. The same eiect, of course, could be obtained by a shortening oi the rod 19 at any other point, e. g., by a turnbuclne beyond the barrel 16, or by ,an adjustment of the pivot 2e, or by the adjustment of the neas ri in the barrel I6. Numerous other methods of adjustrnenty may be chosen, including methods o2 altering mechanical advantage of the spring upon the load, as well as methods of changing the precompression of the spring, if it is remembered that the angle between the center lines 26.--28 and 28-21 is to be maintained, regardless ci the adjustment.

In Fig. 8 is shown another type of hanger which is particularly desirable where a substantial space may bev provided between the load and its support. In this case, a yoke bar 50 is secured to the I-beam 51, or any other member upon which the load is to be carried, as for example, by means of the hook clamp 52, in which the pivoted hooks are secured over the flanges of the -beams by means of the bolt 53. The frame 10a, in this case, is welded to the yoke bar 50 and secured to the clamp 52 by a bolt 54, which may be threaded at either or both ends to provide adjustment. The force-transmitting members27a are, in this case, preferably duplicated so as to effect better balancing of forces on vthe frame 10a, and the springs 15a are, of course, also duplicated, and in fact Ivhave found it preferable, for reasons of economy, to use two springs side by side for each lever 27a, so that four springs in all would beused for the support as shown in Fig. 8. Compression springs in barrels may be used here, as in Fig. 1, but I prefer to use the springs 15a as shown. At their upper ends, the springs are held by the bolts 24a, which are adjustable along the line between the center vof the bearing portion of the spring eye 21a and a pivot 28a. In this case, as in the embodiment illustrated in Fig. 1,- the tension of the springs may be adjusted by means of the bolts 24a, without substantially aecting the angle between the center lines 26a-28a and 28a-21a.

In this case, as in the embodiment illustrated in Fig. 1, I prefer to provide upon the forcetransmitting members 27a bearing blocks 36, which are shaped as already described in connectionwith Fig. 1. Slots34are provided in the frame 10a for the same purpose as the corresponding slots already described in connection with Fig. l. In this case, however, the load-carrying yoke 30a is provided with horizontal slots 56 which accommodate sidewise movement of the pins 32 carrying the rollers 33, so that they may follow the contour of the cam` slots/34. These horizontal slots 56 could, of course, be used in the construction shown in Figs. 1 to 4, but in that case are not necessary because the slight horizontal movement of the load-carrying member 30 itself is not objectionable. In this case, however, because 34 and pins 32, it is essential that relative movement in a horizontal direction be allowed between at least one of the pins 32 and the load-carrying member 30a. It is furthermore of substantial advantage thus to relieve the load-carrying member from the necessity for bodily movement, and to allow it to act ros 'bolts 11, as shown in Fig. 1. Such lateral consistently exactly along its une of pun. In this case, the adjustment of the load-carrying mem-l ber to the position of the load is obtained by .means of the adjusting nuts 31a, instead of by the turnbuckle as shown in Fig. 1. In this case,

yalso, we may provide, as shown inv Figs. l1 and 12, for any lateral motion of the load by rollers 13a operating upon the shelf 12a associated with the load-carrying member a, instead of the corresponding rollers associated with the support adjustment, however, is not essential.

It will be observed in Fig. 8 that the rollers 33 and the bearing blocks 36 on .the pivoted arms 27a are positioned, when at the centers of their normal range of movement, so that the bearing points of the rollers 33 upon the blocks 36 are substant tially on a horizontal line through the center of the pivot 28a, and the slots 34 are substantially along arcs centered on a horizontal line through the centers of the rolls 33 when in said position. With this relation of the parts the moment of the friction upon the arms 27a is kept at a minimum, and thereby the-error which results therefrom is also minimized.

In Figs. 13 and 14, another simpler embodiment t of the invention is illustrated. In this case, the

frame 10b is required only to provide a rigid connection between the upper point ofsupport 21a for the spring, and the pivot point 28h, and of course to provide a connection to the point of support, e. g., through a clamp 52 similar to that illustrated in Fig. 8. The load-carrying member 30h is in this case essentially the same as that illustrated in Fig.A 8, and the pivoted levers 27b are substantially thesame as the levers 27 and 27a already shown and described, except that in this case the bearing blocks 36 are omitted, and instead the pins 32h are secured directly to the levers 27b. The portion of the lever 27b which causes the pin 32D to follow an arc centered at the axis 28h is therefore, in this case, the means for controlling the 4moment arm of the load on the lever 27b, and assumes, therefore, the function of the corresponding controlling means in the other embodiment of the invention,-namely the slots 34 and 34a. In order to minimize any error due to friction, I prefer to mount the pins 32h in the levers 27b by means of anti-friction bearings, but except for the disadvantages resulting from increased friction, these pins could be secured therein merely by means of set screws or pins, and allowed tol slide in the slots 56 of the load-carrying member 30a. The remainder of the device may be substantially identical with that illustrated in Fig. 8.

In Fig. 13, the slots 56 are made to accommodate normal movement of the levers 27b, but to limit the movement beyond the normal range. Thus, even if the Asprings 15a should break (which is extremely unlikely to happen, if a suflicient factor of safety is allowed in the choice of a spring) the load would not be completely dropped but the pins B2b would strike the ends of the slots 56 at the bottom of the normal range, and the member 30h would thereafter be rigidly supported upon the pins B2b. This means of limiting the movement of the load-carrying member is most simple and satisfactory where special provision is made for lateral adjustment, as shown, for example, at 12 and 13, or 12a and 13a, or Where an angular adjustment of the entire device would not be objectionable.

In Fig. 15, I have shown another way in which this may be simply accomplished, and at the same ing range of the lever 27b its principle and operation,

time provision may be made forlateral adjustment without thel use of any separate or supplemental device. In this case, the member A30e. is not cut out as shown in Fig. 13, but extends across the member 10b. A slot 60 is provided` adjacent the vpivot 28e and the pivot 28e is extended into the slot 60.v The slot` 60.is of a width suicient to accommodate the permissible lateral movement, and of a height suflicient to accommodate the normal operating movements; and the slots 56a are, in this case, 'madeen'ough longer than in the embodiment illustrated in Fig. 13 so' as to accomvmodate the desired lateral movement. Upon horizontalexpansion of a supported pipe, or lateral shifting, for any other reason, of the load, the member 30o is moved laterally over the`pins 32h, but otherwise the device will operate exactly as already described in connection with Fig. 13. If, however, any extraordinary conditionshould arise which would tend to move the member 30e beyond its permitted operating range, the pin 28e would contact with the member 30e at the upper end of the slot 60, and the load would thereby be supported directly upon the pin 28e, and through it upon the member 10b.

VIn the 'embodiment of Figs. 13, 14 and 15, the triangle dened by the two points of connection of the spring 26h and 21a and the pivot 28h is designed as already described, so that the operatwill fall on the flat portion of the moment-angle curve, vand will be approximately centered at the maximum of said curve. The pins B2b are mounted on the levers 27b so that in their operation they describe an arc about the center 28b and this arc is also chosen so that the maximum moment of the load 'is approximately at the same position of the lever 27b as the maximum moment of the spring thereon,-that is, in the case shown, the line between the pivots 28b and 32B, when the lever 27b is at the maximum of the moment-angle curve, is perpendicular to the line of pull of the load. I have found that with the parts thus designed, the variation in the moment of the load upon the armv 27b, due to the arcuate movement of the pin 32h, will effect substantially complete 'compensation for the variation in moment of the spring upon the arm 27b, lso that thel force exerted upon the load will remain substantially constant. thermore, I have found that the effect of friction is comparatively slightv when the parts are designed and constructed in the relation shown in Figs. 13 and 14.

In all of these examples, the support is designed for a hanging load, but it will be apparent to those skilled in the art that the load may be supported Fur-V invention and certain modifications thereof, it is to vbe understood that these are given only as examples to aid in explaining the invention and and that the invention is not in any way limited to these particular forms. I

What I claim is:

1. An adjustable support comprising spring means, anchoring means to which the spring means is pivotally connected, a pivoted forcetransmitting means pivotally connected to the opposite end'of the spring means, a load-carryting means, and a distortion of the of said parts so as 2. Anadjustable support as defined in claim- 1, in which the adjusting means is adapted to vary the initial tension of said springl means while the line between the/pivot of the spring on the anchoring means and the pivot of the force-transmitting means on its support remains substantially fixed.

3. An adjustable support as deiined in claim l, in which the means for adjusting the initial tension of the spring is adapted to shift the pivotal connection 'between the spring means and the anchoring means along the line between said pivotal connection and the pivot of the forcetransmitting means upon its support.

4. An adjustable support as defined in claim l, which includes supplemental compensating means adapted to correct for objectionable variations in the force which would be exerted upon the load by said spring without saidsupplemental means. l

5. A spring device comprising anchoring means, spring means secured to said anchoring means so as to permit angular movement of the springv about the point of attachment, force-transmitting means connected to the opposite end of said spring so as to permit angular movement therebetween and supported so as tol permit angular movement about its point of support, a load-carrying means bearing upon said force-transmitguide means adapted to control the 'moment arm of said load-carrying means upon the force-transmitting means when the angular position of the latter about its point of support is varied, and means for adjusting the spring while at any given position within its normal range of movement, and While the line between the center of angular movement of the spring relative to the anchoring means and the center of movement of the forcetransmitting means relative to its support remains substantially xed.

6. A support comprising' spring means, anchoring means to which the spring means is pivotally connected, a pivoted force-transmitting means pivotally connected to the spring means, loadcarrying means connected to the force-transmitting means, and means for varying the moment arm at which the load-carrying means acts upon the force-transmitting means so as to regulate the turning moment exerted upon said forcetransmitting means to correct any variation in the force which would be lexerted upon the load if such correction were not made.

7. A support comprising spring means, anchoring means to which the spring means is pivotally connected, a pivoted force-transmitting means pivotally connected to the spring means, loadcarrying means connected to the force-transmitting means, and` means for shifting at least one of these points of connection upon the movement to regulate a turning moment exerted upon said force-transmitting .means to correct any variation in the force which would be exerted upon the load if such correction were not made.

8. A support as defined in claim 7, in which the correcting means is a cam adapted to vary the leverage of the force-transmitting means on one of the parts connected thereto.

necmss 9. An adjustable support as defined in claim '1, in which the means for regulating a turning moment exerted upon the force-transmitting means comprisesa cam surface adapted to shift the bearing point of the load on said force-transmitting means at the latter is moved, and thereby to vary the mechanical advantage of the spring upon the load soy as to correct for objectionable variations in the force which would be exerted upon the load by said spring without the effect of said cam. t

10. A support as defined in claim '7, in which the correcting means is adapted to vary the moment arm of the load upon the force-transmitting means and the latter has a bearing surface for the load-carrying member shaped so that-in every normal position it is tangent to a line substantially perpendicular to the line of pull of the load at the point of contact of the load-carrying v member thereon.

11. A support comprising spring means, anchor- -least one of said members being adapted to vary the moment arm at which a force acts upon said pivoted member to compensate at least in part for the change in tension of the spring means upon deformation of said spring when the pivoted member is moved, and the bearing surface of said pivoted member upon which the load-carrying member is supported being shaped so that it is always tangent to the load-carrying member and at the same point to a line substantially perpendicular to the line of pull of the load.

l2. A spring device comprising anchoring means, spring means secured to said anchoring means so as to permit angular movement of the spring about the point of attachment, a forcetran'smitting member connected to the opposite end of said spring so as to permit angular movement therebetween and supported so as to permit angular movement about its point of support, a load-carrying member slidably connected to said force-transmitting"member, and a guide means adapted to control the radial position of said load-carrying member upon the force-transmitting member when the angular position of the latter is varied, and in which the bearing surface n of the force-transmitting member upon which the load-carrying member is supported comprises a cam shaped to present at every position within the normal range of movement of said parts a surface tangent to the portion of the load-carrying member which bears thereon, and tangent at the same point to a line substantially perpendicular to the direction of pull of the load.

13. A spring ldevice as defined in claim 12, in which the guide means is adapted to vary the perpendicular distance of the direction of pull of the load from the center of angular movement of the yforce-transmitting member relative to its support, and thereby to change the turning moment of the load upon said force-transmitting i the parts relative to each other ing means to which the spring means is pivotally connected, pivoted force-transmitting means pivotally connected to the opposite end of the spring means, a load-carrying means supported from force-transmitting means, the pivots between the spring and anchoring means, between spring means and force-transmitting means, and between force-transmitting means and its support,

-being positioned so that in approximately the center of its normal operating range the spring means will exert a maximum turning moment upon the force-transmitting means.

16. A spring y device comprising anchoring means, spring means secured to said anchoring means so as to permit angular movement of the spring about the point of attachment, a forcetransmitting means connected to the opposite end of said spring so as to permit angular movement therebetween and supported so as to permit angular movement about its point of support, a load-carrying means slidably connected to said force-transmitting means, and a means adapted to control the moment arm o f said load-carrying means upon the force-transmitting means when the angular position of the latter about its point of support is varied, in which device the spring and its anchoring means are so related to the force-transmitting means that when near the centers of their normal ranges of movement, the spring produces a maximum turning moment on the Aforce-transmitting member.

17. A spring device as defined in claim 16, in which the bearing surface for the load-carrying means on the force-transmitting means is near a line perpendicular to the line of pull of the load at the center of angular movement of the force-transmitting means relative to its support.

18.` A support comprising spring means, an,

choring means to which the springmeans is connected, pivotally supported force-transmitting means connected to the spring means,'load-carrying means supported upon said force-transmitting means, and means for controlling the moment arm at which the load acts upon the force-transmitting means, the bearing surface for said load-carrying means upon the forcetransmitting means being, when at the center of its operating range, near a line perpendicular from the axis of the pivot of the force-transmitting means to the line of pull of the load.

19. A support comprising spring means, anchoring means to which the spring means is pivotally connected, pivoted force-transmitting the spring means so that the moment of the spring on said force-transmitting means is at a maximum near the center of its operating range, load-carrying means supported from the forcetransmitting means, and means for varying the moment arm of the load upon the force-transmitting means so that said load a'cts thereon at approximately its maximum moment arm, near the center of its normal operating range.

20. A support as defined in claim 19, in which the means for varying the moment arm of the load-carrying means upon the force-transmitting means is an arm connected to the forcetransmitting means so as to rotate therewith, and to which arm the load-carrying means is pivotally connected, and which is positioned so that at the center of its operating range the line through its two pivots is approximately perpendicular to the line of pull of the load.

21. A support comprising spring means, anchoring means to which the spring means is pivotally connected, pivoted force-transmitting means pivotally connected to the opposite end .of the spring means, load-carrying means, and an arm connected to the-force-transmitting means to rotate therewith, and adapted to forni a pivotal support for the load-carrying means, said load-carrying means and said arm being positioned relative to thepulls of the spring and of the load respectively, so that the moments of lthe spring and of the load thereon reach their maximums at approximately the same position of said load-carrying means.

22. A spring device comprising a pair of pivotally supported force-transmitting members pivoted about the same axis, springs pivotally supported at one end, and pivotally connected to said force-transmitting means at their other ends, a pin rotatably mounted in each of the force-transmitting members at substantially the samedistance from the common pivot and circumferentially positioned about said pivot so that at approximately the center of their normal range of movement both will fall upon the diameter through the common pivot perpendicular to the line of pull of the load, and a load-carrying member having bearing surfaces for said pins substantially perpendicular to the line of p ullof the load, and of suicient length to accommodiate lao