lift. Where the piston short strokes, it is generally
caused by over-lubrication of the steam end.

64. Q. What are some of the common causes for the compressor running
hot?

A. The overheating of the compressor may be due to any one of the
following causes: Running at high speed; working against high pressure;
packing rings in air piston badly worn; air cylinder worn; defective air
valves; air passages or air discharge pipe partially stopped up; leaky
piston rod packing; lack of lubrication.

65. Q. What will cause the compressor to run slow?

A. This may be caused by leaky air piston packing rings; final discharge
valves leaking, or air passages partially stopped up. A defective
governor may also cause the compressor to run slow.

66. Q. What will cause the compressor to run very fast and heat, and not
compress any air?

A. This may be caused by the strainer becoming clogged with ice or dirt,
preventing air entering the cylinder.

67. Q. If, when steam is first turned on, the piston makes a stroke up
and stops, where would you look for the trouble?

A. The shoulder on the reversing rod may be worn; the opening in the
reversing plate too large to engage the shoulder on the reversing rod;
loose reversing plate studs preventing the piston traveling far enough
to reverse the compressor, or the main valve stuck in its position at
the right.

68. Q. If the piston makes a stroke up and a stroke down and stops,
where is the trouble?

A. This may be caused by a loose reversing plate, or the button on the
lower end of the reversing rod worn or broken off, or the nuts off the
piston rod in the air end, or the main valve stuck in its position at
the left.

69. Q. What will cause the piston to make a quick up stroke?

A. This may be caused by a broken or stuck open upper receiving or lower
discharge valve.

70. Q. What will cause the piston to make a quick down stroke?

A. Lower receiving or upper discharge valve broken or stuck open.

71. Q. If a receiving valve breaks or sticks open, how may it be
located?

A. The air will flow back to the atmosphere as the piston moves toward
the defective valve and may be detected by holding the hand over the
strainer.

72. Q. If a receiving valve in a cross-compound compressor breaks, what
may be done?

A. Remove the broken valve, blocking the opening made by its removal,
and as there are two upper and two lower receiving valves the compressor
will now take air throu