At six mouth Intervals, lubricate the fan motor top and botttom
bearings. Each bearing is covered by a brass cap containing a felt disk
which holds the oil. The brass cap has a hole through which the oil
is applied to the felt (fig. 10) . Use a small oil can and apply 3 or
4 drops of LO, Oil, lubricating, light, to each bearing. Once a month
apply a few drops of Oil (LO) to the lens mount pinion shaft and
pinion gear (figs. 13 and 14) . The rack and pinion should be free
from dirt or `foreign matter when the oil is applied.
Section II WEATHERPROOFING
Signal Corps equipment, when operated under severe climatic condi-
tions such as prevail in tropical, arctic, and desert regions, requires
special treatment and maintenance. Fungus growth, insects, dust, cor-
rosion, salt spray, excessive moisture, and extreme temperatures are
harmful to most materials.
26. Tropical Maintenance
A special rnoistureproofing and fungiproofing treatment has been
devised which, if properly applied, provides a reasonable degree of
protection. This treatment is fully explained in TB SIG 13, Moisture-
proofing and Fungiproofing Signal Corps Equipment, and in TB SIG
72, Tropical Maintenance of Ground Signal Equipment.
27. Winter Maintenance
Special precautions are necessary to prevent poor performance or
total operational failure of equipment in extremely low temperatures.
These precautions are fully explained in TB SIG 66, Winter Main-
tenance of Signal Equipment, and in TB SIG 219, Operation of Signal
Equipment at Low Temperatures.
28. Desert Maintenance
Special precautions are necessary to prevent equipment failure in
areas subject to extremely high temperatures, low humidity, and exces-
sive sand and dust. These precautions are fully explained in TB SIG
75, Desert Maintenance of Ground Signal Equipment.
29. Lubrication at Extreme Temperatures
The effects of extreme heat or cold on materials and lubricants are
explained in TB SIG 69, Lubrication of Ground Signal Equipment.
Observe all "precautions outlined in TB SIG 69 when operating
equipment under conditions of extreme heat or cold.