A. The inlet valve for live steam is opened and closed by the movement
of a metallic diaphragm in the valve which is opened by spring pressure
on one side and closed by steam pressure on the other side. To regulate
this pressure, stiffen the spring to carry more, weaken it to carry less
by turning the handle connected to this spring either up or down.
116. Q. If steam heat gauge showed the required pressure and cars were
not being heated properly, how would you proceed to locate the trouble?
A. First note where the hand on the steam heat gauge stands when steam
is shut off; if it does not drop back to zero see how much it lacks of
this and note the rise of pressure shown by the gauge when steam is
turned on. This is to test the gauge. If gauge is not correct, pay no
attention to it, but send back steam enough to heat the train. Over
sixty pounds will usually make the hose couplings on the cars rise up
and leak at the joints.
117. Q. When engine is detached from the train, what precaution should
you take to prevent freezing of the steam heat train pipe? What to
prevent damage of steam heat hose?
A. Open steam throttle to allow a very little steam to pass into steam
heat train pipe to prevent its freezing. If end of hose is liable to
strike frogs or crossings, hang it up where it will be safe.