Wixroyd Universal Joints SIMPLE UNIVERSAL JOINTS DOUBLE UNIVERSAL JOINTS QUICK COUPLING UNIVERSAL JOINTS

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1 Wix_set_4.qxp 11/10/ :33 Page 1 Wixroyd are used in a wide variety of applications. 6514/28 There are a variety of universal joints available. SIMPLE UNIVERSAL JOINTS 1) - find their field of application where shafts offset towards each other at an angle are to be interlinked and where the unequal angle speeds of the joints are tolerated. DOUBLE UNIVERSAL JOINTS 2) find their field of application where large bending angles are required and where two shafts offset in relation to each other are to be linked with a double joint. They may also be used to achieve a uniform drive-off motion. See technical appendix for details. QUICK COUPLING UNIVERSAL JOINTS 3) are ideally suited where quick change of shafts is required. Axial arrest of the shaft is achieved through two ball bearings engaging with a round key or indent machined into the shaft. LENGTH COMPENSATING UNIVERSAL SHAFTS 4) suited to applications where there is some distance between the two points of drive, the shaft may be extended or compressed to suit the application. Three standard compressed lengths are offered, other sizes are available on request. 617

2 Wix_set_4.qxp 11/10/ :34 Page 2 Wixroyd AVAILABLE SURFACE FINISHES JOURNAL OR NEEDLE PRECISION BEARINGS 1) Journal Bearings universal joints with journal bearings are limited to slow drive applications, the maximum speeds being dependent upon their angle and the load they are exposed to the maximum speed must not exceed 1000 rpm. Journal bearings are supplied as standard. Zinc Plating: ensures excellent corrosion protection. Zinc plating the standard finish supplied. Formula for sizing of the joints (approx): At Mdmax Speed x bending angle <= 500 At 0,5 x Mdmax Speed x bending angle <= 5000 Chrome Plating: excellent corrosion resistance, aesthetic shiny surface. Only on request and for Chromating (olive): corrosion resistance. Only on request and for PLEASE NOTE: THE MdMAX VALUES LISTED FOR EACH PRODUCT REPRESENT THE LIMIT VALUES WHICH MUST NOT BE EXCEEDED, THEY MAY BE FULLY EXPLOITED ONLY AT SMALL BENDING ANGLES FOR INTERMITTENT OPERATION. 2) Needle Bearings universal joints with needle bearings find their field of application where a precise transmission of forces is required at high speeds (upto 5000 rpm). They offer extremely high efficiency at the bending angle. The ground trunnion of the joint rests in needle bearing bushes sealed with rubber or-rings, they are maintenance free with a special anti-friction grease pre-applied. Needle bearings can be supplied on request. Chromating (yellow): corrosion resistance. Only on request and for RECOMMENDED BEARING MAINTENANCE Adequate lubrication of journal bearings must be ensured for universal joints in permanent operation, lubrication with oil or suitable grease should be made daily to maintain life of joint. Bellows can be used to encase joints, to prevent ingress of dirt or grit, and thus extend life of the joint see our part no Phosphating: does not provide corrosion resistance, is for aesthetics only, further treatment is required to provide corrosion resistance. Only on request and for PLEASE REFER TO TECHNICAL INFORMATION FOR FURTHER INFORMATION Installation criteria & layout variations. Transmission ratios and torques. Additional moments acting on the cardan shafts, bearing forces for input and output shafts. Principles for the dimensioning of cardan shafts. 618

3 Wix_set_4.qxp 11/10/ :45 Page 15 1) INSTALLATION RESPECTIVELY LAYOUT FOR CARDAN SHAFTS 1.1 Installation criteria The uniform motions produced by an angled single universal or ball-and-socket joint generate at the driven end an irregular motion pattern (refer to (2) motion patterns and torques). This irregularity in motions is balanced if two single joints are interlinked to form a shaft. For a complete balancing of this phenomenon the following conditions have to be met: a) Same bending angle on both joints (B 1 = B 2 ) b) The two inner joint forks shall be located on one level c) Input and output shafts shall also be on one level Exception: At a spatially angled cardon shaft input and output shafts are not on one level. In this case uniform drive motions are achieved by offsetting the joint forks in relation to each other so that they are located within the bending levels formed by their joints. It is also essential, that the spatial bending angles are of the same magnitude. Note: Wrongly assembled cardan shafts, will not compensate for the irregularity of the drive end but rather aggrevate the conditions with the result of damaging or even destroying bearings and splines. On assembling the shaft section ensure that the arrows on the splineshaft and the spline hub are perfectly aligned. 1.3) Layout variations Z-layout Input and output shafts being located parallell on one level. ß 1 = ß 2 W-layout Both shafts intersecting on one level ß 1 = ß 2 Spacial layout (combination of Z and W) Input and output shafts are intersected at a spacial offset. No common level necessitating a displacement of the inner joint forks (see also 1.1 exceptions ) ß R = ß R2 The resultant spacial bending angle ßR, produced by the vertical and horizontal deviations is calculated: tan ß R = tan 2 ß v + tan 2 ß h 2) TRANSMISSION RATIO AND TORQUES 2.1 Turning angle for single joint in dependence on the bending angle ß ø 1 = Input turning angle ø 2 = Output turning angle If a single joint is angled by the bending angle ß and turned in this condition, the turning angle ø 2 of the output shaft will deviate from the turning angle ø 1 of the input shaft. The following relation being created between the turning angles: tan ø2 = tan ø 1 cos ß As demonstrated on the adjoining diagram, the maximum advance occurs at about 45 and the max. after running at approx 135. Fork position ø 1 = O is achieved if the input fork is located on the bending level of the joint. 619

4 Wix_set_4.qxp 11/10/ :46 Page Motion respectively moment pattern for single joints in dependence on the bending angle ß. M d1 = Input torque M dii = Output torque W 1 = Input angle speed W II = Output angle speed On observing the motional respectively moment phenomena on single joints it is noted that a constant input angle speed and a constant input moment produce irregular motion respectively moment pattern on the output. Generation of these irregularities become obvious on observing the moment pattern at the fork position ø 1 = 0 and ø 1 = 90 as depicted on the adjoining diagram. Torques are exclusively transmitted on the universal joint level and the joint being either located vertically in relation to the input or output shaft - depending on the fork position. A drive moment is thus produced which fluctuates between M d1 cos ß and M d1 /cosß twice per revolution. The transmitted force is however constant apart from the inevitable friction moments within the bearings. M ai = w II w II = M dii M dii = w I w I M di Whereas: N I = N II = constant M di w I = M dii w II = constant For fork position ø 1 = 0 applies: M di = 1 = w II max M diimin cos ß w I and for fork position ø 1 = 90 applies: M di = cos ß = w II min M diimax w I 2.3 Motion respectively moment patterns on the cardan shaft in dependence on the bending angles ß1 and ß2 The information disclosed in 2.2 show the angle speeds on the output of a single joint follow a sinoidal pattern within a period of 180. The magnitude of the angle speed wiimax is thereby opposed to the minimum value of the torque MdIImin and viceversa. From this it can be derived that a uniform output is achieved if the first joint is followed by a second one, the latter being displaced by 90 as the irregularity of the first joint is then compensated by the second one. The displacement of 90 applies always if the two inner forks are located on the bending angle formed by the joint. It is also essential that the two bending angles ß1 and ß2 are equal on the two joints (see also Sections 1.1 and 1.2) If the two bending angles are unequal a complete compensation is not possible. For ß 2 > ß 1 applies then: w II = cos ß 1 M dii = cos ß 1 (w I )max cos ß 2 (M di )max cos ß 2 w II = cos ß 2 M dii = cos ß 2 (w I )min cos ß 1 (M di )min cos ß 1 620

5 Wix_set_4.qxp 11/10/ :47 Page 17 3) ADDITIONAL MOMENTS ACTING ON THE CARDAN SHAFT Bearing forces for input and output shafts Section 2.2 discloses that the torque is only transmitted on the joint intersecting levels and that the universal joint may, according to the fork position, be located vertically to either the input and output shaft. A brief explanation of the additional forces respectively moments acting on the cardan shaft and the bearing of input and output shafts. 3.1 For Z-layout Shown below is the pattern followed by additional forces for cardan shaft with a Z-layout i.e. for the for k positions ø1 = O and ø1 = 9O. It demonstrates how the centre part of the cardan shaft is exposed to the extra stresses produced between M di cos ß by the fluctuating torque (torsional stresses) and the additional moment M ZII (periodical stresses). The input and output shafts are also exposed to periodical bending stresses by M ZI respectively M ZIII. The bearing forces thus generated (A and B) fluctuate twice for every revolution between 0 and maximum. 3.2 For W-layout W-layout is in addition exposed to the force S, generated by the aligned pattern of the additional moment M ZII : this force attains its maximum at the fork position ø1 = O acting on the input respectively output shaft via the front surface of the universal joint trunnion. The resultant periodically fluctuating bearing forces A and B can be considerably elevated at a small joint spacing L and a large bending angle ß. 3.3 By axial displacement forces In telescopic cardan shafts, which are altered in length during the moment transmission, additional bearing forces have to be considered in regard to Z and W layout. These forces being produced by friction occuring within the spline profile. The axial displacement force Pa caused by these bearing forces being calculated as follows: Pa = 2 MdI µ( 1 + sinß )[N] dm Ü The dm of the mean profile diameter and Ü being the overlapping of the spline profile. The friction value µ shall be assumed about 0.11 to 0.15 depending on arrangement and lubricating coditions for steel mating steel. Bearing forces acting on input and output shafts for Z-layout Bearing forces acting on input and output shafts for W-layout 4 PRINCIPLES FOR THE DIMENSIONING OF CARDAN SHAFTS Dimensioning of cardan shafts depend on various criteria and facotrs which cannot be listed in detail within the scope of this paper. Generally applicable rules cannot be laid down. The information following shall be regarded as initial and approximate data as to the dimensioning of such shafts. 4.1 Torques The maximum permissible torque Mdmax as determined for the individual joint sizes are generally applicable only for brief peak loads. The permissible permanent torque shall be calculated under consideration of the essential factors such as impact, bending angle, speed as per each application. 4.2 Impact factors Cardan shafts may, depending on their application and position, being exposed to impacts exceeding by far the rated torque. These extra loads have to be taken into account (input factors). In the following some of the factors as applicable to the most widely used drives: Drive with flexible coupling without flexible coupling Turbine or electric motor 1 1 to 1,5 IC engine, 4 or more cylinders 1,25 1,75 IC engine, 1 to 3 cylinders 1,5 2 Diesel engine 4 or more cylinders 1,5 2 Diesel engine 1 to 3 cylinders 2 2,5 It may be taken as a matter of course that not only the input but, in many cases, also the output may generate such impact loads. General valid guidelines cannot be furnished as too many factors are applicable. 621