The Elements of Machine Design Volume 2; Chiefly on engine details

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...142, and the unit for the other proportional numbers is S. The value of m is about 3-12. 146. Marine engine connecting-rod end.--Fig. 117 shows another form of connecting-rod end. This is of simple and massive form, and is often used in marine engines. The brasses are lined with white metal or Babbitt's metal cast shallow recesses. If lx is the diameter of the bolt at the bottom of the screw thread and / the working stress,--Si2/= m p. 4 The diameter I at top of threads will be nearly enough for the present purpose r12 tiv Hence Putting/= 5,000 for wrought iron and 6,600 for steel & = o-200o to o-o218 Vp for wrought iron = 0-0174 to o-oicjo n/p for steel. It is a good thing to turn part of the shank of the bolt to a diameter equal to that of the bottom of the screw thread. This gives the bolt a little elasticity without weakening it. The proportional numbers in the figure are reckoned to the unit 7/8 8 or 2,. Fig. 118 shows a somewhat similar big end for a connecting rod. Here the brasses are designed so that they can be machined all over and are cored internally to diminish weight. The bolts are turned down so as to bear only at those points where they most effectively support the brasses and caps and prevent lateral movement. Figs. 119, 120, show connecting rods designed by Mr. W. F. Mattes.1 In fig. 119 the end has jaws long enough to hold both brasses. The cap hooks over projections on the jaws, turned concentrically with the rod, and the cap is bored to fit the projections. Thus the bolts are relieved of any straining action except the longitudinal tension, which they are best capable of resisting. The cap is lighter than in the ordinary marine-engine type. As compared with a cap secured by a transverse bolt as in fig. 116, the forging of the 1 'Tr...