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November, 1909 res a ddaaddddda g ZZ RSS SEEDED 2 K<Se : TAE Marine REVIEW Lobe ia SSeS ws Le ea OO Y ' Up od 7a CLL WH, JY tH i eh Pom Fics. 2, 3 aNp 4--ELEVATION, PLAN AND "FLOATING center bearing dividing the tooth feces Py and P., of which Pr 18 right-handed and P2 left-handed. The large gear, being much stiffer, re- quires only two bearings. The float- ing frame is made very deep vertical- ly, so as to be excedingly stiff to withstand deflection by the nearly vertical forces at the bearings. It is also amply stiffened in the horizontal plane to obviate deflection from the weaker horizontal forces. The float- ing frame is shown in plan in Fig. 3, whilst Fig. 5, on the following page, shows the pinion shaft and the flex- ible shaft S by which it is driven. At the end of this shaft is a coupling C driven by the turbine shaft T. The axes of the gear and pinion are Cross SECTION OF GEAR CASE, SHOWING FRAME." horizontal and parallel to one another. when everything is in correct adjust- ment. But: it will be evident that the I-beams B are virtually a hinge, and if the large gear G was not in place, or the coupling C connected, the axis of the floating frame and pinion could easily be deflected in the ~ vertical plane through a small angle by a slight flexure of the webs. The coupling consists of two flanges Ci and C,, mounted on the shafts T and S$, and connected by two transverse links Is and Ls, and by a center pintle, care being taken not to make this restrainst redundant. The shaft T can, therefore, only ro- tate the shaft -S through the links L; Ie, but 'as. these are transverse, 445 no longitudinal forces can be trans- mitted. Even when seriously out of adjustment, the longitudinal are so small as to be negligible. The pinion, therefore, has perfect free- dom of longitudinal movement in its bearings. Further, the pinion is driv- en iby the shaft S, which passes completely through it to the end dis- tant' from the coupling, where it is keyed and bolted. This shaft is so flexible that it imposes practically no constraint on the pinion and float- ing frame such as would prevent slight angular yield of the I-beams B. It is evident, therefore, that, both as to its longitudinal position in the floating frame and in the angular position of its axis, the pinion is sole- ly under the control of the forces transmitted by the teeth of the large gear. : forces Neglecting the very slight friction of the well lubricated teeth, the total forces at the tooth contacts, indicated by B, E and BY, EY. Fig. 5, will be nearly at right angles to the teeth at Band By that is, they will beat 30 degrees to the vertical. Hence the two parallelograms of forces shown will be similar. Now the horizontal forces at BD, Bt D® are the only axial forces acting on the pinion. If these are not equal, the pinion will at once shift longitudinally, which it is free to do, till they are equal. The two parallelograms of forces then be- come equal *to one another in every respect, and the vertical force B F is equal to the vertical force B' F*. But besides this longitudinal movement of - the pinion, the frame in which it is mounted is free to rotate about the cen- ter point O by flexing the I-beams. Hence it follows that the moment of the vertical force B F about O must. be: equal to that: af .B* F*-about: tie same. point; and .as-B His> Bi Fine arms of. thése jevers:O. B and O 2B' must be equal. Thus it is claimed that not only wiil the total forces on the teeth P* and P? be equal, but the distribution will 'be so similar that the centers of pressure B and B'* will ibe similarly placed. This, it is contended, practically as- sures a good distribution of pressure under all conditions of load. For, by sufficient running of the gear, it may readily be assured for one particular load: and 1° the pinion and floating frame are made sufficiently stiff, this condition will not ibe -- seriously changed by increase or decrease of load. The strength of both pinion and floating frame are far in excess of that requisite to sustain the maxi- mum forces to which they. will be