T O 35C2-3-442-2~
P-8-627-34
TM 5-6115-457-34
TM-07464A-35
Section VIII. TACHOMETER DRIVE GROUP
a. Clean parts with an approved clean-
GENERAL.
8-53.
ing solvent. Scrub parts thoroughly using
a stiff bristle brush.
The tachometer drive group is
b. Dry parts with filtered low pressure
mounted and driven off the fuel pump. The
compressed air or a clean lint-free cloth.
tachometer drive senses engine speed and
actuates the overspeed switch when engine
8-57. INSPECTION.
speed is between 2400 to 2450 RPM. When
a. Inspect bearings (8, 15 and 21) for
the overspeed switch is actuated, the switch
scoring, pitting, scratches and cracks.
contacts close and signals the STOP-RUN-
Replace defective bearings.
RELAY to shut down the engine, this opera-
tion protects the engine from being damaged
b, Inspect housing for cracks. Replace
due to overspeeding.
cracked housing.
REMOVAL.
8-54.
c . Inspect gear teeth for nicks, burrs,
cracks and broken teeth. Nicks and burrs
a. Refer to Operator and Organizational
that extend below the hardened surface of
Maintenance Manual and remove overspeed
the gear teeth are cause for rejection of
switch.
the gear.
b. Refer to figure 8-14 and remove
d. Inspect gear teeth for wear that may
tachometer drive group by removing bolts
have destroyed the original tooth shape.
(1), lockwashers (2) and clamps (3 and 4).
If this condition is found, replace gear.
8-55. DISASSEMBLY.
e. Inspect gear shafts for nicks, burrs
and scratches.
Refer to figure 8-14 and disassemble
tachometer drive group in the order of in-
f . Discard seal.
dex numbers assigned. Pay particular
attention to the following.
8-58. R E P A I R .
Bearings (8, 15 and 21) are press
a. Remove minor nicks and burrs from
fitted. If necessary, remove bearings
gear teeth and gear shafts using a smooth
using suitable removal tools.
file or hone.
8-56. CLEANING..
b. If gears must be replaced, press
WARNING
gears from shaft using a suitable arbor
Cleaning Solvents are flammable and
p r e s s . Apply an approved adhesive to gear
moderately toxic to skin, eyes and
diameter of shaft and press gear onto shaft.
respiratory tract. Eye and skin
Press fit must withstand 10 ft-lbs torque.
protection required. Good general
ventilation is normally adequate.
REASSEMBLY.
8-59,
Compressed air used for cleaning and
Refer to figure 8-14, and reassemble
drying purposes can create airborne
tachometer drive group in the reverse order
particles that may enter the eyes.
of index numbers assigned. Pay particular
Pressure shall not exceed 30 psig.
Eye protection is required.
attention to the following:
8-31
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