A. Working hard or slipping when the dampers are open and the door closed, or too thin a fire.
40. Q. Name the various adjustable appliances in the front end by which the draft may be regulated.
A. The exhaust nozzle, the diaphragm and the draft pipes or petticoat pipe.
41. Q. What object is there in having the exhaust steam go through the stack?
A. To create a draft through the tubes and fire-box.
42. Q. How does this affect the fire?
A. The exhaust steam escaping through the stack tends to empty the smoke-box of gases and produces a partial vacuum there, atmospheric pressure then forces air through the grates and tubes to refill the smoke-box, and in this way the draft through the fire is established and maintained.
43. Q. Explain what adjustments can be made and the effect of each adjustment on the fire.
A. Larger or smaller nozzle tips cause less or greater draft on the fire; raising or lowering the draft pipes and diaphragm causes the engine to burn the fire more at the rear or front end of the fire-box; the size and position of the draft pipes increase the draft through the top or bottom flues; the latter adjustments should always be attempted before reducing the nozzle.
44. Q. What does it indicate when the exhaust issues strongest from one side of the stack?