2. Q. Why is one cylinder on a compound locomotive called the
high-pressure cylinder and the other one a low-pressure cylinder?

A. The high-pressure cylinder takes that name because it works live
steam direct from the boiler at high pressure. The low-pressure cylinder
receives the steam after the first expansion and works with a low
pressure. It is always larger than its companion high-pressure cylinder
in order to get the same power from the low-pressure steam.

3. Q. In the Schenectady two-cylinder compound, what is the duty of the
oil dash-pot?

A. It is intended to prevent the too rapid movement of the intercepting
valve which might damage the valve or seat, and it is necessary that the
dash-pot should be full of oil to make it work properly.

4. Q. Explain how a Schenectady two-cylinder compound may be operated as
a simple engine.

A. To operate the compound as a simple engine, the separate exhaust
valve is opened which will cause the intercepting valve to move and stay
in position to allow the high-pressure cylinder to exhaust direct to the
atmosphere and admits live steam at a reduced pressure to the
low-pressure cylinder. This should be done when starting a train or when
moving very slowly and about to stall on a grade. The engine should not
be operated simple while running except when at low speed.

5. Q. Explain how a two-cylinder compound is changed from simple to
compound.