A. About 160 miles per pint.

80.  Q. How many drops per minute should ordinarily be fed?

A. This will vary with the size of the locomotive and the work to be performed.  On small yard engines one drop per minute for each cylinder is usually sufficient and one drop for the air pump every two or three minutes.  This depends on the condition of the pump and the service being performed.  For large engines in slow freight service four to five drops per minute, and for large engines in heavy fast passenger service from five to seven drops per minute should be fed.  Air pumps in freight service where the brake pipe is in moderately good condition can usually be run with one or two drops per minute when handling long trains of cars equipped with air brakes.

81.  Q. Will any bad results ensue from filling the lubricator full of cold oil?

A. Yes; when the oil gets hot it will expand and may break the glass or bulge or burst the lubricator.

82.  Q. If a sight feed gets stopped up, how could you clean it out?

A. Close the water valve and the regulating valves to the other feeds.  Open drain cock and draw out a small quantity of water so as to bring the oil in top part of lubricator below the top end of oil pipe leading to feed arm, then open wide the regulating valve to feed that is stopped up and the pressure from the equalizing tube will force the obstruction out of the feed nozzle and up into the body of the lubricator.  Next, close this regulating valve until the feed glass fills with water, then open water valve and start feeds.

83.  Q. How would you clean out chokes?

A. First, shut off boiler pressure and condenser valve; next, remove feed valve bonnet, then open main throttle valve, when the steam from steam chest will blow back through the choke plug, clearing it of any obstruction.

84.  Q. What is superheated steam?

A. It is the saturated steam separated from the water from which it is generated with more heat added, increasing its temperature from 100 degrees to 250 degrees Fahrenheit above the saturated steam temperature.

85.  Q. What is the advantage of superheating or increasing the temperature of the steam?

A. By increasing the temperature of the steam the volume of a given weight of steam is increased and all losses due to cylinder condensation are eliminated, which result in a reduced steam consumption, a saving in coal and water and increased boiler capacity.

86.  Q. How is the increased temperature obtained by the use of the superheater?

A. By admitting the saturated steam into a partitioned receiver which has a number of 1-1/2-inch pipes attached to it.  These are located in and extend nearly the full length of the large flues, the steam having to pass through these 1-1/2-inch pipes on its way back to the receiver, absorbs the heat from the gases passing through the large tubes, causing its temperature to rise, or in other words, become superheated.