From an article of ours in an American journal in May, 1978

new plant equipment ime                                                                                                                                                    may 1978 35

Automatic misalignment
take-up on gear shafts

by Cesare Albusceri
Ing. V. Fachini S.p.A. - Milano

Axial misalignment of spur-gear drives may cause significant trouble; it is mostly due to poorly installed bearings, bearing support sag, temperature changes, elastic deformation of the shaft. Whaever the reason, any misalignment affects the conract area of thc gear-teeth and might cause irregular wear, vibration, chatter, abnormal noise, jamming, etc. To prevent these occurrences, Ing. V. Fachini S.p.A. of Rho, Milan, Italy, designed, developed and patented an automatic device for misalignment take-up. The device provides for constant, even distribution of the load across the full width of the meshing teeth and does away with the abovementioned trouhles. The device essentially consists of a coupling connecting the shaft to the driving gear. A support, integral with the shaft,carries the gear in such a way that it can oscillate freely. The device's components are shown in the exploded view of Fig. 1; Fig. 2 is the complete assembly. Motion is transmitted from shak 1 to gear 2 or viceversa, through sleeve 7. The sleeve has a crowned toothing at one end and a straight internal tonthing at the orher. Shaft 1 is integral with the crowned toothing 5 and carrics the spherical-profile wheel 3 whose centre of rotation is in 4. Gear 2 has the exrernal toothing 2', which meshes with gear l4, and the internal straight toothing 6. As apparent from Fig. 2, gear 2 can swing freely around centre 4 of the spherical joint 3. Sleeve 7 can rock around the centres 10, 11, set at the Fixed distance L, and follow the oscillation of gear 2 with respect to shaft 1. Thus, the device accurately transmits motion between shaft and gear wheel allowing the latter to swing around centre 4. Fig. 3 shoivs an application of this device to transmit motion from shaft 12 to shaft 15. The two shafts are out of true, the axis of rotation of shaft 15 being actually 15'. The device (item 13 in the figure) keeps gear 2 constantly meshed with gear 14 and prevents load concentration, vibration and consequent abnormal wear.


Typical concentrated-load wear pattern of the teeth of a gearwheelpair, as occurring after a few hours in operation because of gearwheel misalignment.
 Tooth profile of the 3200-kW self-aligning pinion. No significant wear is apparent after 100.000 running hours, as proved by the tool marks still present on the tooth sides.
The tooth wear pattern commonly found in poorly lubricated gears under concentrated-load conditions. Self-aligning pinion in which the angle between the axes is brought out.
Rear view of the integral support frame for a 3400_kW self-aligning pinion. Special reducer for a 3400-kW mill drive.
We are organized to design and build highly reliable speed-reducers and speed-multipliers, which are used in every industry. Specifically, we manufacture special units of any size or power, designed around the customer's specific requirements.

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