Fig. 12.
| Fig. 13. | Fig. 14. |
Forms of Bolts.—At (a), fig. 12, is shown a bolt with a square head and a square neck. If this form of bolt is passed through a square hole the square neck prevents the bolt from turning when the nut is being screwed up. Instead of a square neck a snug may be used for the same purpose, as shown on the cup-headed bolt at (b). The snug fits into a short groove cut in the side of the hole through which the bolt passes. At (a) the diagonal lines are used to distinguish the flat side of the neck from the round part of the bolt above it. At (c) is shown a tee-headed bolt, and at (d) an eye-bolt. Fig. 13 represents a hook bolt. A bolt with a countersunk head is shown in fig. 11. If the countersunk head be lengthened so as to take up the whole of the unscrewed part of the bolt, we get the taper bolt shown in fig. 14, which is often used in the couplings of the screw shafts of steamships. The taper bolt has the advantage of having no projecting head, and it may also be made a tight fit in the hole with less trouble than a parallel bolt. Bolts may also have hexagonal heads.
Fig. 15.
Fig. 16.
Studs, or stud bolts, are shown in figs. 15 and 16; that in fig. 15 is a plain stud, while that in fig. 16 has an intermediate collar forged upon it, and is therefore called a collared stud.