US3737156A - V-type torsion bar tillage tines - Google Patents

Abstract

The invention provides a spring assembly and an energy absorbing linkage wherein end constraints on an elongated resilient member are effective to place the elongated member in torsion, such torsion permitting large deflections of the spring or linkage while maintaining a relatively low stress level in the resilient member. The spring assembly can be conveniently made in the form of an energy linkage unit, such a unit being suitable for building planar or lattice spring structure, or for use in an installation as a means of alternatively storing and releasing energy.

Description

United States Patent 1 Ward [ 1 June 5, 1973 [54] V-TYPE TORSION BAR TILLAGE TINES [75] Inventor: Walter H. Ward, Vereenigning, Transvaal, Republic of South Africa [73] Assignee: South African Farm Implement Manufacturers Limited, Vereeniging, Transvaal, Republic of South Africa [22] Filed: Oct. 8, 1971 [21] App]. No.: 187,664

[52] US. Cl ..267/l54, 267/57 [51] Int. Cl. ..Fl6l' 1/16 {58] Field of Search ...267/l54, 57

[56] References Cited UNITED STATES PATENTS 3,337,236 Peterson ..267/57 2,797,434 7/1957 Vigmostad ..267/l54 2,591,281 4/l952 Musschoot..... ....267/l54 3,276,762 10/1966 Thomas ..267/l54 Primary Examiner.lames B. Marbert Attorney-RobertL. Farris [57] ABSTRACT The invention provides a spring assembly and an energy absorbing linkage wherein end constraints on an elongated resilient member are effective to place the elongated member in torsion, such torsion permitting large deflections of the spring or linkage while maintaining a relatively low stress level in the resilient member. The spring assembly can be conveniently made in the form of an energy linkage unit, such a unit being suitable for building planar or lattice spring structure, or for use in an installation as a means of alternatively storing and releasing energy.

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sum 090F10 lnvenlor WALTER H. WARD M WM A ltorneys V-TYPE TORSION BAR TILLAGE TINES The present invention relates to energy storing linkages and especially to spring assemblies therefor.

According to the present invention a spring assembly consists of an elongated resilient member, first and second load attachments positioned on the member at spaced locations, the line extending between them defining a longitudinal axis, said first load attachment being adapted to apply torque to said resilient member, said second load attachment comprising first, second and third journal elements wherein said first journal element and said second journal element are connected by primary pivot means for pivotal movement relative to each other about a primary axis, and the second journal element and third journal element are connected by secondary pivot means for pivotal movement relative to each other about a secondary axis, said third journal element being fixed to or integral with said resilient member.

Preferably the primary pivot axis is inclined to said longitudinal axis and the secondary axis is arranged perpendicular to said primary axis.

According also to the present invention an energy absorbing linkage unit comprises two spring assemblies as defined above wherein the first load attachment is common to both resilient members and transmits equilibrating torque from one resilient member to the other and wherein said first journal element is common to both assemblies.

According also to the present invention an energy absorbing linkage comprises a plurality of energy absorbing units connected together.

Further the invention includes an installation incorporating a linkage unit as referred to wherein angular displacement of the spring through 90 causes an energy input and a further deflection through 90 causes a release of energy. Alternatively the resilient member is pretwisted on assembly so that the first 180 of deflection causes an energy input and a further deflection through 180 causes a release of energy.

The embodiments of the invention will now be described with reference to the accompanying drawings of which:

FIG. 1 is a diagram of a representative spring assembly in accordance with the invention;

FIG. 2 is a detail of a part of the spring assembly in FIG. 1;

FIG. 3 is a vector diagram of moments as applied to the embodiment in FIG. 1;

FIG. 4 illustrates a bending moment, torque and stress diagram representative of FIG. 1;

FIG. 5 is a polar diagram representative of the function of the embodiment in FIG. 1;

FIG. 6 is a further embodiment of spring assembly according to the present invention;

FIG. 7 is a vector diagram of moments as applied to the embodiment in FIG. 6;

FIGS. 8 14 show various views of an agricultural chisel plow tine embodying the present invention;

FIGS. 15 and 16 show a side elevation and plan view of further chisel plow tine embodiments of the present invention;

FIGS. 17 to 27 illustrate various views of energy storing linkages employed in a variety of possible applications in accordance with the present invention;

FIG. 28 is a view of a spring assembly in which the spring rate can be adjusted in accordance with the present invention; and

FIGS. 29 to 31 are plan, side and end views of a representative embodiment of a resilient linkage member in accordance with the present invention.

FIGS. 1 and 2 show the moments acting on the end ofblade 10 atspring attachment 12 which constitutes the second load attachment. The upward or bending moment M is generated by the external forces E applied to the far end of theblade 10 which constitutes the first load attachment. For convenience these are represented by equal and opposite loads. The moment M and the reactive moments R and T are all represented as vectors in the right hand or clockwise direction (which could be counterclockwise, of course, depending on direction of bending moment M) as shown in FIG 3. The clevis 14, which constitutes the second journal element can be connected to theboss 16, which constitutes the third journal element, bypivot pin 18 and is itself rotatable on a stub axle 19 in abore 20 inajournal member 22, which constitutes the first journal element. The longitudinal axis of the resilient member is designated I... The axis ofbore 20, being the primary axis, is designated P. The vertical axis corresponding to the primary axis, is designated S. The axis about which the bending moment M acts is designated N. The clevis 14 cannot generate any moment about axis P because it is free to rotate on stub axle 19. It can only generate a moment R in the plane of the clevis a component of which will balance M, i.e. R cos 0 M where 6 is the angle between axes P and L. The other component,R sin 0, is balanced by moment T which is supplied by a torque arising from twist of the blade. In FIG. 1 thefirst load attachment 11 is represented byparallel bars 24 between which theblade 10 can slide vertically and which react the torque T. Thetorque reaction point 26 onblade 10 lies betweenbars 24. Thus, the prime purpose of the first load attachment is to react the torque T. By neglecting possible side effects from other forces T M tan 6, and whatever the variation in the forces E, there will be a variation in T governed largely by the above relationship.

The deflection of the whole spring assembly is found, at least to a first approximation, by considering the twist in that portion of theblade 10 under torque i.e. betweenboss 16 andbars 24. Theblade 10 will have inherent characteristics of length, sectional dimension and elastic modulus of material and in general the twist is given by the equation:

Where 4) angle of twist T torque c torsional rigidity l= effective length of the blade In general 0 is a function of the shear modulus of elasticity, the area of cross section and the moment of area inertia of the cross section. This and the length become an invariable factor for a givenblade 10. The angle of theblade 10 moves up is denoted t1: and in general terms can be regarded as the angular deflection of thetorque reaction point 26. The relationship between theangle 0, Q5 and \l; is:

= 1 cos U-lcos 9 for a single blade such as 10. being fixed for a particular structure,cos 0 will be less than unity and the angular deflection '11 will usually be somewhat larger than the blade twist angle 4). The deflection of theblade 10 in bending under moment M will be easily calculated but if the blade has the proportions shown in FIG. 1 it will be much smaller than the deflection due to twist- Referring now to FIG. 4, this represents the bending moment and torsion diagram along the length l of theblade 10 and are not to any particular scale. The bending moment M at theboss 16 generates the stress distribution shown on the right. It will be seen that the extreme fibers of theblade 10 under bending are heavily stressed but that the imposition of a torsion does not add to this stress at all. Similarly, the central region is stressed by the torsion and the imposition of the bending does not contribute any large additional stresses in this region. Thus it affords the possibility of being able to use some material of lower cost than spring steel.

Theblades 10 can be designated to resist the bending loads which are to be experienced and can then be converted into springs of suitable characteristics by selection of 0 (the angle of inclination) between the primary axis P and the longitudinal axis L. When 0 0 there will be no reaction at all from the second attachment and when 0 90 there will be no torque applied to the blade and no corresponding torsional deflection.

The broader aspects of the invention as regards deflection and movement will now be described with reference to FIG. 5. The spring may be mounted so that it can rotate in a vertical plane as seen in FIG. 1 through one or more complete revolutions. The first load attachment would be such as to preserve its torque reaction properties throughout the movement which would be generally about axis N. For this purpose thebars 24 have been shown as parts of spaced circular rails in FIG. 1. Assume that theblade 10 is shown in its free state in FIG. 1 and that movement occurs in an upward and generally anti-clockwise direction from this position. Assume also that the angle t]; increases from zero during the movement. During the first 90 of movement thespring blade 10 will be deflected and will be absorbing energy until 90 position is reached. Further movement from this point will reduce the deflection progressively and there will be an energy release until when ill 180 and the spring will be back in its free state. During the third andfourth quadrants of movement there will occur an energy storage followed by an energy release respectively.

FIG. 5 shows a polar diagram from which the geometry of the spring deflection in terms of the three angles can be studied. This diagram is based on the formula previously given. The radial lines define angular displacement tli, the contours define the value of 6 (the angle between the primary and longitudinal axes) and the angle of twist d) is given by a vertical scale alongside of the polar diagram. It has just been described how energy input occurs in the first and third quadrants and energy release occurs in the other two quadrants as the angle l1: increases. However at 90 or T.D.C. (top dead center) the spring goes on center with maximum energy locked in and this energy may be released by either continuing the rotation or by reversing it. Reference is made to the areas shaded at (b 5 to 10 and d) 25 to 30 for the 6 30 contour. The energy, which is proportional to these shaded areas put into the spring for 5 of deflection is much less nearer the T.D.C. position than earlier during the total deflection. This means that the energy storage rate at high deflection is lower than at lower deflection. In the past considerable thought has been devoted to achieving effective spring characteristics of this kind by the use of elaborate linkages. The release of energy is at an increasing rate as the blade approaches zero-torsional deflection.

It is possible to make a storage cycle extend over 180 by employing pretwist of theresilient blade 10. Such an arrangement is shown in FIG. 6. Theblade 10 is twisted and constrained at the first load attachment by means of ablock 25 but is permitted to move in an are between thebars 24 as before.Stops 28 are introduced to constrain the blade at the second load attachment end. With reference back to FIG. 5, assuming in a spring where 0 45 of pretwist, i.e. 45, has been introduced, then the scale of twist angles is changed from therange 45 to 0 to 45 to the range of 0 to 45 to and hence the zero for this scale is move to 0' at B.D.C. (bottom dead center). Consequently, the 180 angular from B.D.C. to T.D.C. will cause 90 of twist in one direction, i.e. acontinuous energy input over two quadrants. Movement through the remaining two quadrants (or reverse movement) will release the energy. The amount of pretwist does not have to be as much as 45 degrees and in the case where \l/ 17 and 6 30 the base line from which to measure angle ill would be the 150 330 radial line and the T.D.C. or maximum twist point would occur after of angular deflection.

If astop 28 is arranged, say 5 degrees after T.D.C. point, the spring, having passed over T.D.C., will not return and will stay against the stop thus constituting an over-center device.

FIG. 6 also shows an arrangement in which a spring assembly is provided with a second load attachment having a provision for selectively varying theangle 0. Thefirst journal element 22 is mounted on arail 32 and can be clamped in position by a screw 34. It will be seen that when the angle between N and P becomes zero the axis P is coincident with axis N and when 0 becomes negative theblade 10 twists in the opposite direction on receiving the same external loads. The corresponding vector diagram when 0 becomes negative value is shown in FIG. 7.

Reverting to a 360 movement with two storage and two release cycles it should be noted that one storage/- release cycle takes placeby torsional deflection of theblade 10 in one angular directioni.e. plus qb, and during the other cycle in the other direction i.e. (1:. It is possible to restrain theblade 10 against angular deflection only in one of these directions and to let it go free in the other.

In the foregoing description it has been assumed that one end of the assembly is fixed and the other parts of the spring assembly move relative to it. Clearly the other end could be fixed if desired without affecting the fundamental operation. I

If the characteristics of the blade and the choice of angle 6 is such that a large twist in the order of 90 occurs for a given load then the total bending characteristics will change because of progressive change in the bending section along the blade. Thus the total deflection may have a large proportion of it attributable to bending deflection. From a stress point of view this is not desirable because the stresses become additive but it may be acceptable in certain applications.

One of the difficulties of the spring assembly described in FIGS. 1 and 6 is the nature of the first load attachment which has to provide a torque reaction irrespective of the angular deflections and the provision of a static torque reaction member over a large arc is often inconvenient.

This difficulty is overcome by arranging the spring assemblies in pairs so that the torque from one spring equilibrates that from the other. This can be done in at least two ways exemplified in FIGS. 8 to 14 and FIGS. 15 and 16.

FIGS. 8 to show in side elevation, lower plan view and partial end elevation, a chiselplow tine assembly 40 mounted on atoolbar 41 which carries amovable bracket 42 clamped to it by abridge piece 43 andbolts 44. Aspring attachment assembly 45 is bolted to the underside of thebracket 42 bybolts 46. Thesupport assembly 45 consists of two main parts. These are shown, for the sake of clarity, separated from each other in FIGS. 13 and 14 respectively and in assembled position in FIG. 12. One part is constituted by ablock 47 which has a centralcircular aperture 48. Thebolts 46 pass partially through this aperture as seen in FIG. 11. Twokeyways 49 and 50 are provided in theaperture 48 of the block at diametrically opposed positions. A projectingboss 51 is bored to accept along pin 52 shown in FIG. 9. The other part is a clevis support 53 shown in FIG. 12 and has a cylindricalcentral portion 54 having anannular groove 55 cut in its periphery. Thecentral portion 54 is adapted to fit snugly into theaperture 48 inblock 47 and thebolts 46, when inserted, partially pass through thegroove 55 and hold thecentral portion 54 in position while enabling it to be rotated. Twobosses 56 each project at equal angles to the central portion and each of these is bored to receive stub shafts 57 which each carry at their outer ends aclevis 58. FIG. 12 is a plan view of the clevis support assembly.

FIG. 14 shows a detail of oneclevis 58 pinned to ablade adaptor plate 59 with apin 60 which is fast with the latter by having abolt 61 pass through both. Thebolt 61 and asecond bolt 62 also pass through the end of aspring blade 63 to hold the blade end fast with theplate 59.

Thus the construction is such that once the clevis support 53 is fixed in theblock 47 by a key in anappropriate keyway 49 or 50, theclevises 58 are permitted to rotate freely in thebosses 56 subject to the constraints applied by theblade 63. Theblade support plate 59 is also permitted to swivel freely on thepin 60 but is also subject to spring force constraint.

Thespring blades 63 on each side side extend to the right, as seen in FIGS. 8 and 9, to form a mounting for thetine 70. A torsionlockout yoke member 71 is applied at the end of the straight portions of theblades 63. This is a bracket having twoslots 72 through which theblades 63 pass with small clearance.

The construction of chisel plow tine assembly described in FIGS. 8 to 14 is designed to transmit certain loads to the frame by means of tool bar mounting assembly 40. These loads are all generated at the tine and in general their resultant is in a rearward direction and displaced below the apex of the two blades which constitute a Vee. These originating forces are carried into the structure and appear as a force and a bending moment at theyoke 71. The force places bothblades 63 in pur tension and this is carried through theclevises 58 and thesupport assembly 45 to thebracket 42 andtool bar 41. Negligible deflection occurs during the transmission of this force through the spring assembly. The bending moment present at the apex is divided into equal parts and each passes along ablade 63 to arespective plate 59 as a constant bending moment. This is applied to therespective clevis 58 with the results described previously with reference to FIG. 1 except that the torques carried by the twoblades 63 are equal and opposite and are mutually equilibrated by theyoke 71.

FIGS. 15 and 16 show in side elevation and plan view a chisel plow tine mounted on a parallel arm linkage unit wherein the spring assemblies are mounted one above the other. The tine point is simply mounted on acurved bar 74 which is bolted to the foot of a standard 75. The standard 75 is carried by two vertically spaced blade spring assemblies constituted by twoblades 76 and 77 pivoted onrespective clevises 78 and 79 themselves rotatable in clevis supports 80 and 81 which are integral with or fixed to one of a pair ofclamp brackets 83 and 84.Bolts 85 hold the clamp brackets on to asquare toolbar 41. It will be seen that theclevises 78 and 79 are equally and oppositely orientated on each side of a common vertical plane of theblades 76 and 77 and transmit equal and opposite torques arising from vertical loads applied to the standard 75. It should be recognized that horizontal forces and bending moments arising from ground contacts are likely to be taken as tension and compression loads in the blades and only vertical shear forces causing bending moment at the front ends of theblades 76 and 77 are likely to cause torsional deflection. With particular reference to FIG. 16 it will be seen that in the unloaded state the two clevises form a hinge axis about which the tine can pivot quite freely but as soon as it is loaded in bending and by draft loads it will tend to centralize partially due to the uneven torsion reactions generated. It can be arranged that a tine of this kind be tuned to vibrate from side to side to provide a soil shattering action if such is desired.

Turning now to arrangements involving multiples of paired spring assemblies which can be conveniently termed spring units, FIGS. 17 and 18 show a tine wherein several Vee springs 81, 82, 83 are nested together and each Vee blade provides its own torque equilibration across the apex of its Vee. The opposite front ends of the Vees are mounted inopposite members 84 which constitutes the first journal element referred to. Theinner Vee blade 81 only is clamped between the lockingplate 87, the others being free to accommodate differential movement without inhibiting the spring action.

FIGS. 19 and 20 show an arrangement employing several single but pairedblades 90, 91-91, etc. In this case each blade has its own individual pivot pin 9292 etc. which again constitutes the second journal element. The arrangement as a whole consists of similar upper andlower assemblies 94 and 95 suitable for mounting awheel 96 of a vehicle.

While the arrangements shown in FIGS. 17 to 20 show arrangements of spring units in parallel, the following figures show various forms of end connected spring units.

FIGS. 21 and 22 show in plan and side elevation respectively an equalizer bar wherein twounits 101 and 102 are mounted on asingle support assembly 103 the latter constituting the first journal element for all four of thesecond journal members 104 and is itself journalled to rock in a pair ofhangers 105. Loads would be applied or reacted at the apices of the two units which are bolted together and be carried through to thehangers 105.

FIGS. 23 and 24 show an arrangement of multiple spring units wherein one end of each unit is suspended by aclevis 111 journalledin a commonfirst journal element 112 and the apices are pin connected together. The units, in groups of four are connected in a plane to make a large spring complex capable of large deflec tions to the extent that the twoload pads 113 meet in the middle.

FIGS. 25 and 26 show an arrangement wherein both ends of theblades 121 are mounted onclevises 122, 123 which are journalled in respectivefirst journal elements 124, 125 the multiplicity of springs defining a complex similar to FIGS. 25 and 26. It should be noted in this case however that load is applied byarrows 126 as a linear force throughclevis 124 to the blade. This results in a moment at the other end which generates torque at 124 in one direction. Similarly a torque arises from the reaction forces 127. It is arranged that the torques cause the same twist in the blade i.e. one in one direction at one end and the other in the other direction at the other end.

FIGS. 27 shows an arrangement wherein blade units having pin connected apices are arranged symmetrically in a three dimensional lattice. Three double units would seem to be the minimum necessary to sustain a complex of this kind. More double springs would be incorporated with an orange-segment effect and would be limited at one level by the width of the spring units. Several levels, columns, and ranks of spring groups could be arranged if desirable.

FIG. 28 shows a practical arrangement of the adjustment of angle discussed with reference to FIG. 6. In this embodiment, which is a wishbone type suitable for a vehicle suspension, thechassis member 130 carriesbosses 131 which each rotatably support ashaft 132 having ayoke 133 at one end and alever arm 134 at the other. Theyoke 133 defines the first journal element and an openrectangular bracket 140, runnioned in theyoke 133, defines the second journal element. Aboss 135 welded on to the inboard end of eachspring blade 136 constitutes the third journal element and is secured in thebracket 140 by apin 137. The apex ends of theresilient members 136 are fixed in a pierced end fitting 138 capable of taking load. Thelever arms 134 are both connected by aY link 139 to a hydraulic ram which is remotely operated.

Operation of theram 140 causes rotation oflevers 134,shafts 132 andyoke 133 to change the angle 6. This means that a driver of a truck could adjust the ridge height to a required level as the truck is loaded and also be given an indication, by reading the oil pressure required to achieve ride height, of the load carried.

The resilient members used in the FIG. 28 embodiment could be of the type shown in FIGS. 29, 30, 31 which are a side elevation, plan and end elevation, re-

spectively. The resilient member is a thin walled tube tapering in side elevation and in plan and changing in section from an elipse at the pivot pin end to a circle at the apex end. This enables greater resistance to bending while permitting a fairly uniform torsional stress level to be maintained along the length of the tube.

When the spring unit is in the form of a Vee it will be appreciated that the torque about the longitudinal axis of one arm of the Vee is not in the same plane as the torque in the other arm. Hence a component of the two torques will equilibrate each other but the other components will be additive and will be balanced by part of the applied load. Thus the equation:

sin U cos 0 will not give the true deflection and it will be modified by the incorporation of a further term which is a function of B which is the half angle of the Vee. Moreover, the pattern of energy storagein the storage cycle will differ from the pattern of energy release during the release cycle though the total energy stored and given up will be the same.

It should be understood that the primary and secondary axes can be defined by rubber bushes in torsion or like devices wherein sliding of surfaces over one anothermay not take place. v

The main advantages of the present invention are that it affords spring means which can be constructed inexpensively from inexpensive materials and with good scope for unconstrained design.

I claim:

1. A spring assembly consisting of an elongated res'ilient member, first and second load attachments positioned on the member at spaced locations, the line extending between them defining a longitudinal axis, said first load attachment being adapted to apply a torque load to said resilient membensaid second load attachment comprising first, second and third journal elements wherein said first journal element and said second journal element are connected by primary pivot means for pivotal movement relative to each other about a primary axis that is inclined to said longitudinal axis and the second and third journal elements are connected by secondary pivot means forv pivotal movement relative to each other about a secondary axis said third journal element being integral with said resilient memher.

2. A spring assembly according to claim 1 wherein said secondary axis is arranged perpendicular to said primary axis.

3. A spring assembly according to claim 2 wherein said secondary axis intersects the primary and longitudinal axes at their junction.

4. A spring assembly according to claim 1 wherein said first load attachment is adapted to apply linear loads to said resilient member.

5. A spring assembly according to claim 1 wherein said first load attachment is adapted to apply bending loads to said resilient member.

6. A spring assembly according to claim 1 wherein said first load attachment is similar to said second load attachment.

7. A spring assembly according to claim 1 having means for varying the spring rate thereof comprising a carrier for said first journal element movable to vary the angle between said longitudinal axis and said primary axis.

8. An energy absorbing spring assembly according to claim 1 and comprising two resilient members wherein the first load attachment is common to both resilient members and transmits equilibrating torque from one resilient member to the other and said first journal element is common to both assemblies.

9. A spring assembly according to claim 8 wherein said resilient members are spaced from each other in the direction of the secondary axis and said first load attachment is attached to each said resilient members and transmits equilibrating torque in bending.

10. A spring assembly according to claim 8 having means for varying the spring rate of the unit comprising carrier means for both said first journal elements movable to vary the angles between said longitudinal axes and said primary axes.

11. A spring assembly according to claim 10 wherein said carrier means is constituted by fourth journal elements which are connected to said first journal elements by tertiary pivot means defining respective carrier axes.

12. A spring assembly according to claim 11 wherein said fourth journal elements are movable by remote power means.

13. A spring assembly according to claim 8 having means for holding said resilient members in a preloaded state.

14. A spring assembly according to claim 13 wherein said preloaded state is a torsional deflection of the resilient members and said means for holding said resilient members is a stop which prevents their rotation.

15. A spring assembly according to claim 14 wherein said resilient member is given a pretwist of up to 90 about its longitudinal axis and between the secondary axis and the first load attachment.

16. A spring assembly according to claim 14 wherein said first journal elements are mounted in a rotary block capable of rotation in a housing to impart said torsional deflection.

17. A spring assembly according to claim 15 which includes a plurality of units wherein all of said units have a common first load attachment.

18. A spring assembly according to claim 17 wherein all of said units have a common primary axis.

19. A spring assembly according to claim 17 wherein at least two of said units have separate primary pivot means defining separate primary axes.

20. A spring assembly incorporating a plurality of units according to claim 11 wherein each unit is endconnected to another unit.

21. A spring assembly according to claim 20 which includes at least four units wherein each unit is connected at one end to another through a common first load attachment and at the other through a common first journal element.

22. A spring assembly according to claim 21 wherein said units all lie in a common plane.

23. A spring assembly according to claim 21 wherein at least six units are arranged in three dimensional form.

24. A spring assembly according to claim 20 which includes at least four units wherein each unit is connected at each of its ends to one other through a load attachment constituted by first, second and third journal elements.

25. A spring assembly according to claim 24 wherein at least four units are arranged to lie substantially in a plane.

26. A spring assembly according to claim 24 wherein at least six units are arranged in three dimensional form.

27. A spring assembly incorporating a unit according to claim 11 wherein the angular displacement of the spring through causes an energy input and a further deflection through 90 causes a release of energy.

28. A spring assembly according to claim 27 wherein a preload equivalent to a predetermined angular displacement of the spring is imposed there being pro-, vided a limit stop permitting deflection just in excess of 90 to permit the spring to deflect to this limit and stay against it.

29. A spring assembly incorporating a unit according to claim 8 wherein the resilient member is pretwisted on assembly so that the first of deflection causes an energy input and a further deflection through 180 causes a release of energy.

Claims (29)

1. A spring assembly consisting of an elongated resilient member, first and second load attachments positioned on the member at spaced locations, the line extending between them defining a longitudinal axis, said first load attachment being adapted to apply a torque load to said resilient member, said second load attachment comprising first, second and third journal elements wherein said first journal element and said second journal element are connected by primary pivot means for pivotal movement relative to each other about a primary axis that is inclined to said longitudinal axis and the second and third journal elements are connected by secondary pivot means for pivotal movement relative to each other about a secondary axis said third journal element being integral with said resilient member.

2. A spring assembly according to claim 1 wherein said secondary axis is arranged perpendicular to said primary axis.

3. A spring assembly according to claim 2 wherein said secondary axis intersects the primary and longitudinal axes at their junction.

4. A spring assembLy according to claim 1 wherein said first load attachment is adapted to apply linear loads to said resilient member.

5. A spring assembly according to claim 1 wherein said first load attachment is adapted to apply bending loads to said resilient member.

6. A spring assembly according to claim 1 wherein said first load attachment is similar to said second load attachment.

7. A spring assembly according to claim 1 having means for varying the spring rate thereof comprising a carrier for said first journal element movable to vary the angle between said longitudinal axis and said primary axis.

8. An energy absorbing spring assembly according to claim 1 and comprising two resilient members wherein the first load attachment is common to both resilient members and transmits equilibrating torque from one resilient member to the other and said first journal element is common to both assemblies.

9. A spring assembly according to claim 8 wherein said resilient members are spaced from each other in the direction of the secondary axis and said first load attachment is attached to each said resilient members and transmits equilibrating torque in bending.

10. A spring assembly according to claim 8 having means for varying the spring rate of the unit comprising carrier means for both said first journal elements movable to vary the angles between said longitudinal axes and said primary axes.

11. A spring assembly according to claim 10 wherein said carrier means is constituted by fourth journal elements which are connected to said first journal elements by tertiary pivot means defining respective carrier axes.

12. A spring assembly according to claim 11 wherein said fourth journal elements are movable by remote power means.

13. A spring assembly according to claim 8 having means for holding said resilient members in a preloaded state.

14. A spring assembly according to claim 13 wherein said preloaded state is a torsional deflection of the resilient members and said means for holding said resilient members is a stop which prevents their rotation.

15. A spring assembly according to claim 14 wherein said resilient member is given a pretwist of up to 90* about its longitudinal axis and between the secondary axis and the first load attachment.

16. A spring assembly according to claim 14 wherein said first journal elements are mounted in a rotary block capable of rotation in a housing to impart said torsional deflection.

17. A spring assembly according to claim 15 which includes a plurality of units wherein all of said units have a common first load attachment.

18. A spring assembly according to claim 17 wherein all of said units have a common primary axis.

19. A spring assembly according to claim 17 wherein at least two of said units have separate primary pivot means defining separate primary axes.

20. A spring assembly incorporating a plurality of units according to claim 11 wherein each unit is end-connected to another unit.

21. A spring assembly according to claim 20 which includes at least four units wherein each unit is connected at one end to another through a common first load attachment and at the other through a common first journal element.

22. A spring assembly according to claim 21 wherein said units all lie in a common plane.

23. A spring assembly according to claim 21 wherein at least six units are arranged in three dimensional form.

24. A spring assembly according to claim 20 which includes at least four units wherein each unit is connected at each of its ends to one other through a load attachment constituted by first, second and third journal elements.

25. A spring assembly according to claim 24 wherein at least four units are arranged to lie substantially in a plane.

26. A spring assembly according to claim 24 wherein at least six units are arranged in three dimensional form.

27. A spring assembly incorporating a unit according to claim 11 wherein the angular displacement of the spring through 90* causes an energy input and a further deflection through 90* causes a release of energy.

28. A spring assembly according to claim 27 wherein a preload equivalent to a predetermined angular displacement of the spring is imposed there being provided a limit stop permitting deflection just in excess of 90* to permit the spring to deflect to this limit and stay against it.

29. A spring assembly incorporating a unit according to claim 8 wherein the resilient member is pretwisted on assembly so that the first 180* of deflection causes an energy input and a further deflection through 180* causes a release of energy.

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