An Introduction to Machine Drawing and Design Part 13

(_c._) Give sketches showing how you would grip and drive a round iron bar for the purpose of turning it between the centres of a lathe. (10.)

(_d._) Explain the action of the governor shown in Example 1 (fig. 86). (10.)

(_e._) Describe in detail how the mud-hole door in Example 2 (fig. 88) is removed for the purpose of cleaning the boiler and how it is replaced and the joint made steam-tight. (10.)

(_f._) Describe how the parts of the spur wheel in Example 3 (fig. 87) are put together, and explain why the wheel is made in segments. (10.)

_Examples to be drawn._

1. Loaded governor for small gas engine. Draw and complete the two views, partly in section as shown (fig. 86). Scale full size. (35.)

2. Mud-hole mouth-piece for Lancashire boiler. Draw and complete the two views shown (fig. 88). Scale 3/8ths. (35.)

3. Point for segments of large spur wheel. Draw and complete the views shown (fig. 87). Scale 3/16ths.

_Note._--As the radius of the wheel is too large for your instruments, the circ.u.mference at the joint may be set out straight, as in a rack. (35.)

[Ill.u.s.tration: FIGS. 86 AND 87.]

[Ill.u.s.tration: FIG. 88.]