Background Art Universal joints of the mechanical type are widely used for transmitting torque between a pair of rotating members. But, these universal joints require periodic servicing and maintenance, such as frequent lubrication of the bearings and connections thereof. This is especially vexatious to the truck or automobile owner, since the servicing job takes time and effort. Moreover, in many vehicular applications these joints are almost inaccessible, so that the required periodic main¬ tenance is omitted and the life of the universal joint" is grea,tly reduced.

For the most part, mechanical universal joints permit the transmission of power at larger angles of misalignment than is the case with flexible couplings which utilize a yieldable material in compression. On the other hand, such flexible couplings usually require no lubrication and therefore are particularly useful in locations where access is difficult. Exemplifying the art in this area are U.S. Patent No. 3,724,239 issued April 3, 1973 to M. M. Calistrat, and an article by Mr. R- R. Grundtner in the December 18, 1969 issue of

Machine Design entitled "Couplings." However, although these compression-type flexible couplings advantageously absorb drive line shocks, they suffer several disadvan¬ tages. Firstly, they are often relatively complex and costly in construction. Secondly, they are typically limited to only a few degrees of angular misalignment. Thirdly, they sometimes impose undesirable reaction loads on the connecting shaft members and their support bearings, substantially reducing the service life thereof.

And fourthly, under heavy loads the elastic cushions ten to fail prematurely from fatigue or by permanent deforma tion.

Another type of flexible couplind is disclosed in British Patent Specification No. 1,503,110 to Regie Nationale Des Usines Renault, published March 8, 1978. In that reference a grooved intermediate torque trans¬ mitting ball member of elastic or plastic material is connected by two wire ring elements individually having head forming a practically closed circular annulus. The axes of the ring elements are at right angles to each other and are also nonintersecting or offset. However, that construction is undesirable because of the complexi ties evolving from .such offset axes and the reduced contact area between the interlaced ring element heads and the grooves in the ball member. Not only are un¬ desirably low load-carrying and speed capacities antici¬ pated with that coupling, but also the ring elements mus be undesirably deformed during introduction of the ball member making that construction more difficult to assemb

The flexible coupling of the present invention is directed to overcoming one or more of the problems as set forth above.

^' Disclosure of Invention In accordance with one aspect of the present invention, a flexible coupling is provided which has resilient body means for transferring torque between first and second shaft members. A first arm means connects the first shaft member to the resilient body means at one end, and a second arm means connects the second shaft member to the resilient body means at the other end. Advantageously, first and second retaining means releasably and positively couple the resilient bod means respectively"to the first and second arm means at the opposite ends of the resilient body means.

The flexible shock-absorbing coupling of the present invention desirably has a body of flexible material disposed in compression generally between the

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first and second arm means, a low number of parts, a 15° angular misalignment capability, and requires no lubrication. •

Brief Description of the Drawings ^• Fig. 1 is an exploded, diagrammatic perspective View of the flexible coupling of one embodiment of the present invention.

Fig. 2 -is an enlarged, diagrammatic, side eleva- tional view of the embodiment of Fig. 1, with portions broken open to better show details of construction thereof.

Fig. 3 is a diagrammatic and slightly enlarged cross sectional view of the flexible coupling of Figs. 1 and 2 as taken along line III-III of Fig. 2.

Fig. 4 is a side elevational view similar to Fig. 2, only showing a second embodiment of the present invention.

Fig. 5 is a side elevational view solely of the resilient body means of Fig. 4 to better show details of construction thereof. Fig. 6 is' an end elevational view of the resilient body means of Fig. 5.

Best Mode for Carrying out the Invention

Referring initially to Figs. 1 and 2, the flex¬ ible coupling 10 of one embodiment of the present inven- tion has a centrally located resilient body means 12 for transmitting torque and compensating for misalignment between a first shaft member 14 and an opposite second shaft member 16. The resilient body means 12 has a longitudinal central axis 18, opposite first and second ends 20,22, and first and second channel means 24,26 oriented substantially parallel to ^' .the central axis at right angles to each other and extending',fully between the opposite ends.

In order to releasably and positively connect the shaft members 14,16 to the resilient body means 12, first and second arm means 28,30 and first and second retaining means 32,34 are provided. The first arm means 28 preferably includes a pair of generally longitudinally

oriented arms 36 connected to or integral with the first shaft member 14 and defining a profiled notch 38 and a pair of shoulders 40 between the arms at the base thereof In the instant example, each of the arms 36 has a gener- ally rectangular cross section and is provided with a threaded bore 42 centrally thereof. Likewise, the second arm means 30 preferably includes a similar pair of arms 44 connected to or-integral with the second shaft member 16, a profiled notch 46, a pair of shoulders 48, and a pair of threaded bores 50.

The first retaining means 32 preferably include a generally U-shaped retaining cap 52 defining a bight portion 53 and a pair of arms 54 longitudinally alignable with the arms 36 and having the same general cross sectio A longitudinally oriented bore 56 extends through each of the arms 54 to permit a fastener or bolt 58 to extend therethrough for screw threaded engagement with one of the threaded bores 42. In a similar manner, the second retaining means 34 includes a retaining cap 60 having a ^' bight portion 61, a pair of arms 62, a pair of bores 64, and a pair of fasteners or bolts 66 extendable through the bores 64 for engagement in the threaded bores 50 of the opposite shaft member.

More specifically, the resilient body means 12 includes an elastomeric body 68 having an interrupted external cylindrical surface 70. Moreover, the first channel means 24 includes an opposite pair of radially outwardly facing longitudinal channels 72 which are generally U-shaped in cross section to receive the first arms 36,54, and the second channel means 26 includes an opposite pair of similar channels 74 to receive the second arms 44,62. Preferably, for axial compactness, a first end channel 76 is defined in the first end 20 of the elastomeric body for substantially fully receiving the bight portion 61 of the retaining cap 60, and a similar second end channel 78 is defined in the opposite end 22 for substantially fully receiving the bight portion 53 of the other retaining cap 52. In this way th

caps do not extend longitudinally outwardly from a geometric center 80 of the flexible coupling 10 beyond the first and second ends 20,22 of the elastomeric body.

In addition, the elastomeric body 68 also pre- ferably defines a pair of spaced recesses 82 at each end 20,22 intercommunicating the first and second end channels 76,78 and the respective pair of longitudinal channels 72,74 and having a width similar to that of the longitu¬ dinal channels. As representatively shown in the broken open portion of Fig. 2, each recess 82 is bounded in part by a root or end bearing surface 84 which is adapted to be contacted by the shoulders 40 and 48 of the first and second arm means 28,30.

Referring now to the cross sectional view of the resilient body means 12 illustrated in Fig. 3, it may be noted to include a plurality of metallic reinforcement members 86 arranged in spaced apart relation through the elastomeric body 68 in a direction substantially parallel to the central axis 18. In the instant example, the reinforcement members 86 are preferably arranged in a plurality of formed metallic reinforcement sheet sets 88, with each set encompassing or surrounding a single one of the longitudinal channels ^' 72,74. Each of the sheet sets 88 includes a plurality of spaced apart, but nested channular sheets of progressingly larger size radially inwardly toward the axis 18 and away from the arms 44, 54, etc. These sheets are preferably equally spaced apart between the channels at the outer cylindrical surface 70, and are preferably each bent to a substanti- ally radial orientation with respect to the central axis at a preselected distance from the axis corresponding generally to the base of the channels 72,74. Each of the metallic reinforcement members 86 is bonded or otherwise firmly secured to a plurality of elastomeric layers or resilient members 90 which are appropriately constructed to fill the varying spaces between the reinforcement members of the sheet sets.

A second embodiment of the present invention shown in Figs. 4 through 6 and is similar to the first embodiment of Figs. 1 through 3, ^' except that a resilien body means 12' is provided that is substantially spheri cal in overall construction. Particularly, the resilie body means 12' includes a spherical body 102 having an external spherical surface 104 interrupted by first and second pairs of radially outwardly facing and longitudi nally oriented channels 106,108 at right angles to one another as is apparent when viewing Figs. 5 and 6. Eac of the channels 106,108 is defined in part by a bottom root surface 110 which is preferably defined as a porti of a cylindrical surface. Like the first embodiment, t irst pair of arms 36' and the .associated retaining cap arms 54' are seated within the first pair of channels 106, and the second pair of arms 44' and the retaining cap arms 62" are seated within the second pair of chann 108. Thus, the retaining caps 52' and 60' have semi- cylindrical internal surfaces 112 seated against the corresponding root surface 110, and the retaining caps have freedom of movement within the profiled notches 38' and 46' provided in the first arm means 28' and second arm means 30'. With this construction the arms 36' and 44' have only cylindrical surface portions or pairs 114 as representatively shown in Fig. 4 for mating engageme with the root surfaces 110.

Industrial Applicability The flexible coupling 10 is particularly usef as a replacement for a conventional U-joint in a vehicl such as in the drive line of a track-type tractor. It useful, for example, in those areas of a vehicle that a inaccessible for^periodic .maintenance and. where a con¬ siderable amount of axial misalignment must be accommod ted. in operation, and as is best appreciated by reference to Figs. 1 and 2, the first and second retain means 32,34 are axially inserted in the first and secon channel means 24,26 from the opposite ends 20,22 of the

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resilient body means 12 and at a 90° angle from each other until the bight portions 53,61 are fully received in the end channels 78,76 and contact the end bearing surfaces 84. This subassembly can then be inserted into the first shaft member 14 until the shoulders 40 contact the end bearing surface 84, whereupon the bolts 58 can be screwthreadably installed through the aligned arms 54,36 so that the first, retaining cap 52 is firmly secured to the first shaft member. The second shaft member 16 is then inserted axially into the remaining channel means and contact made between the shoulders 48 and the end surface 84, whereupon the other bolts 66 are screwthreadably used to secure the second retaining cap 60 to the second shaft member. Torque is introduced into the flexible coupling

10 as by rotation of the first shaft member 14 so that, for example, the arms 36,54 can move in a clockwise direction when viewing Fig. 3. The elastomeric material 68 of the resilient body means 12 is thereby compressed between the first set of arms 36,54 and the juxtaposed second set of arms 44,62, with the reinforcement members 86 serving to better distribute loads therebetween and to better retain the elastomeric material against the action of high centrifugal forces. The material in compression thereby transmits torque in the same clockwise direction to the second shaft member 16, while simultaneously automatically absorbing dynamic shocks and minimizing the transmission of noise since there is no direct metal-to- • metal connection between the connected shaft members. As best shown in Fig. 2, the flexible coupling 10 is effective to permit a considerable amount of axial misalignment between the shaft members 14 and 16. Parti¬ cularly, the flexible coupling can accommodate up to about a 15° driving angle or degree of axial misalignment between the shaft members as is indicated by broken lines in the drawing. ^' During accommodating such movement it is of substantial significance to note that the retaining cap 60, for example, is advantageously free to rock or pivot

about the geometric center 80 of the resilient body mea

' 12 within the clearance provided by the profiled notch 38.

The second embodiment resilient body means 12 5 shown in Figs. 4 through 6 operates substantially as previously described, and is of more economical constru tion. The second embodiment can be axially shorter tha the first embodiment and can be useful, for example, in those less severe working applications wherein the axi 0 mum operating speed and torque transmission capacity ar considerably lower than that of the first embodiment. Preferably, the second embodiment would also be streng¬ thened internally by the introduction of suitable rein¬ forcement members like the first embodiment, but not 5 shown, to increase its capacity.

It is thus apparent that the flexible couplin 10 are simple and economical in construction, are sub¬ stantially maintenance free, and can accommodate both shock loading and a considerable degree of misalignment 0 Furthermore, they are easy to assemble and disassemble place on a vehicle.

Other aspects, objects, and advantages of thi invention can be. obtained from a study of the drawings, the disclosure, and the appended claims. 5

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