Q. Why do high speed engines have a short stroke in comparison with the diameter of their cylinders?
A. So that they can run at a high rate of speed without exceeding the limit of piston’s travel.
A. It maintains a uniformity of motion of the crank, notwithstanding the unequal moving force upon the crank-pin.
Q. Is the force upon the crank-pin unequal, even when the pressure from the cylinder is uniform throughout the stroke?
A. Yes. No matter what the pressure on the piston is, it has no effect in turning the engine when the crank is in line with the guides, which is termed “on the center.” As the crank gets away from the centers, the effect of a given pressure becomes greater, and reaches its maximum when the crank is nearly at right angles with the guides.
Q. How does the fly-wheel counteract the jerky motion of the crank which would result from this?
A. By its tendency to resist an excessive moving force, and by its momentum keeps the engine in motion when the moving force is deficient.
Q. What would you do if the cylinder gets worn or cut from too tight rings or lack of oil?
Q. What would you do if the crank-pin heats, gets worn or cut?
A. If bent it should be turned true again; if not bent it can be filed and polished perfectly true by hand.
Q. What would you do if the main bearings heat?
A. Loosen the caps and apply plenty of good oil. If this does not stop it take off the caps, examine the oil holes to ascertain why the oil does not reach the bearing. If the bearings have become rough and cut, the shaft will have to be smoothed again.
Q. Would any harm result from starting an engine with the drip cocks closed?
A. Yes, the condensed steam filling the space would smash the cylinder or piston head.
Q. What do you mean by atmospheric pressure?
A. The weight of the atmosphere, which is 14.7 lbs. per square inch at sea level.
Q. How hot can you get water with exhaust steam under atmospheric pressure?
Q. Does atmospheric pressure have any influence on the boiling point?
Q. Would you run an engine with throttle wide open, or partly open?
A. Wide open on governor engines, as it is more economical.
Q. How many pounds of water required per horse-power for the best engines?
Q. At what temperature has iron the greatest tensile strength?