A. The stack, exhaust pipe or petticoat pipe are out of plumb.
45. Q. What is the effect of leaky steam pipe joints inside the smoke-box?
A. The engine will not steam freely.
46. Q. What causes "pull" on the fire-box door?
A. The partial vacuum in the front end; when excessive it indicates dampers closed, fire clinkered or insufficient opening for the admission of air under the fire.
47. Q. If upon opening the fire-box door you discover there what is commonly called a red fire, what might be the cause?
A. The grates may have become clogged with ashes or clinkers so that sufficient air could not pass through them to the fire.
48. Q. Is it not a waste of fuel to open the fire-box door to prevent pops from opening? How can this be prevented more economically?
A. Yes. This can usually be prevented by putting the heater into the tank, or putting on the injector, or by more careful firing.
49. Q. Describe the principle upon which the injector works.