A. Air pressure.
44. Q. Can and should steam pressure be used?
A. Yes. However, steam should never be used except in an emergency when 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.