the equalizing tubes balances the pressure which comes from the steam
chest when the engine is working steam.

20. Q. How should the lubricator be filled?

A. First close all valves connected with the lubricator, open drain plug
and remove filling plug, allowing water to escape until oil appears
with it. Drain plug should then be closed. Fill the oil tank in the
usual way, being careful not to overflow it; then replace filling plug.
If the supply of oil is insufficient to fill the lubricator, water can
be used to finish it, as the lubricator will begin feeding sooner when
filled full.

21. Q. After filling lubricator, what should be done?

A. Open the steam throttle to the lubricator wide, then carefully open
the water valve, but do not open the feeds until sure the chamber in the
glass is filled with water.

22. Q. How long before leaving terminal should the feed valves be
opened? Why?

A. About fifteen minutes; this time is necessary to allow oil to feed
through the oil pipe and reach the steam chests.

23. Q. How many drops should be fed per minute?

A. From one to seven, timed by the watch, depending on conditions.
Cylinders of large size require more oil than smaller ones.