The strength of materials and structures

📖 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. 1872 edition. Excerpt: ...while the latter will yield chiefly at the point of junction of the screw thread with the shank. Hence, when subjected to stress, the stretching will be distributed in the former, but in the latter the screw threads will be drawn out of pitch, and will no longer match the nut. If these two bolts are treated alike, say by using a screw key with a long handle, so as to twist off the nut by tension, or by combined tension and torsion, then the former bolt, although lighter in weight, will yet require more turns of the screw key before it will give way than the latter. Practically it is the stronger, and it is important that this should be understood, because the same principle is applicable in many other cases. It is not essential that the screw thread should be in relief, with a small shank, the uniformity of sectional area may be maintained in other ways. For many purposes it is convenient that the shank of the bolt should fit the bolt hole, and the bolt hole must be large enough to admit the screwed part, Hence, in these cases, the shank of the bolt requires to be maintained equal in diameter to the outside diameter of the screw thread. To secure uniform section in the bolt, various plans have been adopted. In some bolts, the shank is made hollow from the head up to the neighbourhood of the screw thread. These bolts have been used in fixing armour plates. In other bolts, the shank has been made of cruciform section, or of a square or triangular section with rounded corners. All these plans give satisfactory results, so far as depends on the uniformity of the section. The condition of uniformity of section, in practical operations, is liable to be modified, either for the better or the worse, in many ways. For example, the effect produced in the...