TM 9-4520-251-14
4-23 COUPLING (CONT)
Location/Item
Action
Remarks
ALIGNMENT (CONT)
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
Engage safety chain to louver to avoid serious injury whenever front
half hood is raised.
Visually check end fittings on engine, fan and hub assembly shaft at each end of coupler. There
should be no noticeable difference in Iongitudal alignment when viewed from above or the sides.
Wear approved ear protection equipment within–25 feet (7.6 meters)
of operating heater. Failure to do so may result in impairment or loss
of hearing.
Start and run engine until engine runs smoothly with the choke fully opened. Continue to run engine
for approximately 10 minutes. Refer to para 2-7.
Heat exchanger casing and exhaust stack may become dangerously hot.
Do not touch these parts during or immediately after operation
Perform maintenance only after heater has cooled.
Stop engine and check coupling sleeve for heat by holding bar hand on sleeve. It should feel cool
to mildly warm.
If coupling sleeve is hot to the touch, the engine is misaligned with the fan and hub assembly shaft.
To align, restart engine and loosen engine support knobs sufficiently to allow movement of engine sup-
port. Engine vibration should correct alignment. Tighten engine support knobs with engine running.
Stop engine and wait until coupling cools down.
Repeat steps b and c above. Stop engine.
If coupling sleeve is still hot to the touch, loosen engine from engine support capscrew and nuts
sufficiently to allow movement of engine on engine support.
Restart engine, engine vibration should correct alignment.
While engine is running, tighten engine to engine support capscrews and nuts. Stop engine and
tighten remaining capscrews and nuts.
Repeat steps b and c. Stop engine and check coupling temperature.
If these procedures do not produce desired results as stated in para a. above, pin slots in engine
support will have to be enlarged for more side to side movement or engine will have to be shimmed
with appropriate material for vertical alignment.
Repeat steps b and c. Stop engine and check coupler temperature.
Repeat steps b. through I. until desired results are achieved as stated in paragraph a.
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