air is not available.

45. Q. What precaution should be taken regarding steam check and
throttle?

A. That they are tight and check working properly, to insure that steam
is kept from entering main reservoir, for if it should do so it would
burn out the gaskets in the air brake equipment, allow moisture to
accumulate, which would result in freezing and bursting of equipment as
well as being dangerous.

46. Q. What would cause the gear to fail to hold links in intended
cut-off, and allow them to raise and lower without operating valve in
the cab being changed?

A. Leaks in main valve and piston packing.




=WALSCHAERT AND BAKER-PILLIOD VALVE GEARS=


1. Q. Give a brief explanation of the Walschaert valve gear.

A. The Walschaert gear has an eccentric crank attached to the end of the
main pin on each side of the locomotive, with an eccentric rod from this
pin to the connection at the bottom end of the link. This eccentric is
located so it serves for both forward and back motion. The link swings
on a center trunnion and cannot be moved up and down as the Stephenson