SQUARE NON-STANDARD THREAD

BUTTRESS THREAD

A buttress thread is used as leading. It is used to transmit great power in one direction for example in jacks, presses, etc. Profile of a buttress thread is shown in fig. 4.10 according to State Standard 10177-82. The sizes of nominal diameters and pitches coincide with the proper parameters of a trapezoidal thread.

Thread denotations consists of the Latin letter S, external (nominal) diameter and other parameters according to the general rules of marking the threads.

Example of conventional denotation of a buttress screw-thread with the nominal diameter 80mm, the pitch 10mm, an external thread with the tolerance band 7h: S80x10-7h.

Figure 4.10 - A buttress thread profile

а) b)

Figure 4.11 - Conventional drawing of a buttress thread:

a) on the outside; b) in an opening.

The profile of a square non-standard thread (fig.4.12) is rectangular or square. The thread doesn’t have a conventional denotation, that is why all sizes of the thread (fig. 4.13) are marked on the drawing. It is used as a leading thread (for example, in jacks etc.)

Figure 4.12 - Profile of a square non-standard thread

Figure 4.13 - The conventional drawing of a square non-standard thread

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