The Euroflex coupling is torsionally stiff with zero backlash and torque is transmitted through pure tension in the flexing elements. Figure 1 shows holes A, C & E in the flexing elements, bolted to the driving machine flange, whilst holes B, D & F are fastened to either the spacer or the driven machine flange.

Torque is transmitted from bolt C to B, A to F and E to D.

Flexibility is achieved when the flexing elements bend between the drive and driven bolts as shown in Figure 2.

The principal reasons why the Euroflex couplings, out perform others in its class is on account of the two fundamental design principles adopted by us.

1. Flexing Element Design:

   In the Euroflex design, the flexible elements have a polygonal outer profile with a circular central hole. The design ensures that, all the forces in the flexible elements are purely tensile and also provides for the maximum material at the points of bending, leading to very low bending stresses, while permitting high misalignment capacity.

   It is this design feature of the flexible element which enable the Euroflex couplings to offer smaller diameters, for a given torque, than, would otherwise have been possible.

    

2. Coupling Bolts:

   The coupling bolts in the Euroflex design are manufactured out of high tensile steel and are adequately sized to transmit torque through friction rather than shear. The bolts are preloaded to achieve adequate bolt extension thereby inducing a large tensile load in the bolts, which is adequate to prevent both bending of the bolts as well as slip between the flexing elements. The prevention of slip is very important to prevent the flexing elements from fretting.

• Misalignment Capability:

Misalignments arise in all rotating machinery due to various reasons, like temperature variations, bearing wear, foundation settling etc.

The type of misalignments faced by rotating equipment is depicted in Figure below:

Axial misalignment is the variation in axial distance between the shafts of the driving and driven machinery.

Angular misalignment is the effective angle between the two shaft centerlines and is usually quantified by measuring the angle between the shaft centerlines as if they were extended till they intersect. If the shafts are flanged, it is simply the enclosed angle between them if they were to be brought to a position of contact.

Radial or Parallel misalignment is the transverse distance between the two shaft centerlines and is quantified by measuring the radial distance between the centerline of one shaft if it were to be extended to overlap the other.

The Euroflex couplings are designed to accept axial, angular and radial misalignments and the degree of misalignment is limited by the imposed stresses in the flexing element.

The axial misalignments imposes a tensile bending stress in the flexing element, which is depicted by the bending of the beam between the anchor points (see figure), while angular or radial misalignment introduces a bending in the span of the flexing element.

Thus, the permitted amount of axial and radial misalignments is dependent on the number of bolts and geometry of the flexing element.

Axial and Parallel misalignments are inversely related, in other words, when one increases, the other decreases. Further this misalignment capability is determined by assessing the combined steady and fluctuating stresses experienced by the flexible elements.

• The hallmark of the Euroflex design is the expertise to accurately determine the cyclical stresses under all conditions of coupling operations. A proof of the same is the unmatched 1 degree angular misalignment capability that the Euroflex coupling offers on all 4 Bolt designs.

These stresses for the entire range of operating conditions are plotted on the Modified Goodman Diagram, for evaluating the fatigue life of the flexible element material

Curve 1 is a plot of the fatigue data generated by the life cycle testing of the flexing element material (AISI 301) which shows an infinite life at a bending stress of 410N/mm2 (10 11 Cycles).

• The Euroflex design criteria ensures that the imposed bending stresses do not exceed 290 N/mm2 and all continuous and short term conditions must necessarily have a plotted operating point falling within the area under Curve-2. Thus any point within this area has a minimum cyclic factor of safety of 2.0.

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