plotting scale into alinement with the vertical centerline
six disk adjusting screws (fig 2-1) around the edge of the
of the plotting disk With the plotting scale alined with the
plotting disk with a screwdriver, rotate the disk (without
disk centerline at one end of the scale, the opposite end
rotating the frame assembly) until the scale and
of the scale must be in alinement with the centerline. If
centerline are in alignment, then tighten the screws
it is not, loosen the
Section III. OPERATION UNDER UNUSUAL CONDITIONS
c. If the board plotting has been exposed to
excessively wet and damp conditions, lubricate the
In addition to the normal operating procedures for
moving parts of the vernier bracket assembly with
usual conditions, special instructions for operation under
Wipe off all excess grease
unusual conditions are contained herein. In addition to
the normal preventive maintenance service, special
d. Lightly lubricate the adjusting thumbscrew and
care In cleaning and lubricating must be observed where
locknut at the upper end of the scale assembly (fig. 2-1)
extremes of temperature, humidity and atmospheric
and all clamp wingscrews on the support and brace
conditions are present or anticipated. Proper cleaning,
lubrication, storage and handling of lubricants not only
insure operation and functioning but also guard against
2-10. Operation in Humid or Salty Atmosphere.
a. Inspect mechanisms frequently when operating
in hot moist areas.
b. Moist and salty atmospheres have a tendency to
2-8. Operation in Extreme Cold.
emulsify oils and grease and destroy their rust
a. In climates where the temperature is
preventive qualities Inspect all parts frequently for
consistently below zero degrees F, It is necessary to
prepare material for cold weather operation.
c. When not in use stow the instrument in chest
description of operations in extreme cold, refer to TM 9-
making certain that the chest Is free of foreign matter
2-11. Operation in Dusty or Sandy Conditions.
a. Protect instrument from direct exposure to dust
It is imperative that the approved
or sand by erecting a vertical barrier to prevent sand or
extreme cold weather practices and
dust to blow on instrument.
precautions be followed: TM 9-207
b. Under extremely dusty or sandy conditions extra
must be considered an essential
care must be exercised when cleaning the instrument
supplement to this manual.
with a clean cloth. Examine and remove all dust and
sand from the plotting board and carrying chest before
b. Exercise the various controls through their
stowing the board plotting
entire range; at intervals as required to aid in keeping
2-12. Preparation for Travel.
them from freezing in place and to reduce the effort
a. Replacing board plotting, M18 In the chest is
required to operate them.
essentially the reverse of the procedure for preparing
c. Never apply heat from strongly concentrated
the board plotting for use (para. 2-5) However, note the
sources directly to an external surface Sudden
temperature change may cause breakage or
b. Locate each component in its proper place. Be
malfunction of the instrument
certain to clean each item as it is stowed in the carrying
d. When plotting board Is not in use, pay particular
chest, if time and field conditions permit. Remove all
attention to protecting It by stowing the instrument in its
grease from wingscrew threads of the one-man, two-
chest to prevent accumulation of snow and Ice from
man and rest brackets to preclude eventual saturation of
entering the working parts. Make certain that the chest
the foam inserts
Is dry and free from foreign matter.
c. Strap each leg in the cradle assembly with stow
2-9. Operation in Extreme Heat.
d. Orient vernier bracket assembly on the platform
a. Avoid prolonged exposure to the direct rays of
the sun; provide shade as much as possible.
e. Orient the platform assembly In conjunction with
b. Perspiration from the hands is a contributing
the vernier bracket assembly as noted on the corner
factor to rusting because they contains acid and salt.
foam insert in the bottom of the chest Also, be certain
After handling the Instrument, clean and wipe dry
the three leg sockets of the support assem-