TM 11-5840-360-14-1-1
3. While turning the drive sheave (see Figure 5-4),
4. Extend loose end of hose and add lubricant
MIL-L-6086B Grade M through hose end until oil level is
check that the grooves in the drive sheave are aligned
with the grooves on the driven sheave. If they are not,
correct. Total capacity is 2.32 quarts (2.2 liters) .
adjust as follows.
NOTE:
For operation below -15F (-24C) use
4. Remove three hex screws from bottom of drive
sheave hub; place these screws in the three threaded
MIL-L-6086B, Grade L.
holes in the hub and tighten in a uniform pattern (this
loosens the hub and sheave from the motor shaft).
5.7.2.2 Drive System Inspection (V4). - Inspect the
antenna system as follows.
5. Adjust the vertical position of the drive sheave
1. Loosen the captive screws and open the access
on the motor shaft to correct alignment.
door on front of pedestal. Remove top and bottom
6. Remove the three hex screws from the bottom
access covers at rear of pedestal.
of the drive sheave hub and place them in the three
CAUTION
unthreaded holes in the hub; tighten into the sheave in a
BE AWARE OF THE ANTENNA
uniform pattern.
ARRAY POSITION AT ALL TIMES
7. Repeat step 2; if alignment is incorrect, repeat
WHILE
PERFORMING
THE
steps 4 through 7 until alignment is achieved .
FOLLOWING STEPS.
2. While manually rotating the antenna, check the
5.7.1.5 Cover Gasket Inspection.
- Perform the
belts for any signs of stretching, deterioration, fraying,
following steps:
breaks, cracks, or loss of flexibility.
1. Remove the waveguide clamp located
underneath the pedestal.
3. Verify that the belts and the sheave surfaces
that come in contact with the belt are clean and free
2. Remove the screws that secure the hinged
from oil.
pedestal top to the fixed bottom plate.
4. Check for smoothness of rotation (no binding or
3. Swing the hinged pedestal top into its service
roughness); inspect gear box for signs of oil leaks, and
position.
drive motor for evidence of excessive heating.
4. Inspect the sponge rubber gasket around the
5. Verify that V-clamp at top of rotary joint and fan
bottom of the hinged pedestal housing for deterioration
assembly at top of drive motor shaft are secure.
or breaks.
5.7.2.3 Belt Tension Check and Alignment (V4).
5. Check for evidence of water seepage on surface
Perform the following steps.
of fixed base plate where gasket mates.
1. Remove bottom access cover at rear of
6. Swing pedestal down, tighten securing screws
pedestal.
and attach waveguide clamp.
2. Using a tension gauge, check for belt deflection
7. Remove access hatch cover from front of
of 1/8" when 4 to 5 pounds of tension are applied to
pedestal and drive motor cover from top of pedestal.
each belt at a point adjacent to the belt feedthrough port
8. Inspect cover gaskets for deterioration or
in the housing. If tension is incorrect, adjust as follows.
breaks; check gasket mating surfaces for signs of
3. Open access door on front and remove top
seepage.
access cover at rear of pedestal.
4. Loosen lock nuts on turnbuckle and slightly
5.7.2 Antenna Pedestal AB-1248 (V4)
loosen turnbuckle anchor bolts.
5. Adjust turnbuckle to increase or decrease belt
WARNING
tension as necessary; temporarily snug turnbuckle lock
WHEN PERFORMING MAINTENANCE
nuts.
AT THE ANTENNA, SET ANTENNA
6. Repeat step 2. If tension is correct, tighten
SAFETY SWITCH TO OFF.
turnbuckle lock nut and anchor bolts; if incorrect, loosen
lock nuts and repeat steps 5 and 6 until correct tension
5.7.2.1 Lubrication (V4). - Check gear box lubricant
is achieved.
level as follows.
NOTE:
1. Loosen captive screws and open access door on
If tension between the belts is non-
front of pedestal.
uniform or if sufficient tension
2. Observe oil level in filler hose; level should be
cannot be achieved by adjustment,
9/16 inch above upper edge of gear box lip. If low,
replace one or both belts as
perform steps 3 and 4.
necessary per paragraph 5.18.2.1.
3. Hold upper end of filler hose and loosen clamp
screw at upper end of hose; keep end of hose above oil
level as hose is disconnected from fitting.
5-5
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