TM-5-3805-254-14-P-2
TRUCK, DUMP, 20 TON, 6X4, ON-OFF HIGHWAY 71,000 GVW, IHC MODEL F-5070 (CCE)
TECHNICAL MANUAL; OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT AND DEPT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS INFORMATION AND SUPPLEMENTAL MAINTENANCE INSTRUCTIONS)
JUNE 1980
TM-5-3805-254-14-P-2 - Page 848 of 894
TROUBSHOOTING
Improved highways permit sustained high speeds.
The fact that engines and entire power trains can now
cruise at higher R.P.M. can introduce vibration
frequencies, that were not critical in the past. At slower
speeds these items would get by or only pass through
critical periods while accelerating or decelerating through
the gears.
In the past, drive line vibrations such as bent tubes,
joints out of phase or alignment, bad angles due to short
couples, clutches out of balance, gears and shafts in
auxiliaries out of balance, were fairly obvious. These
items will become more critical in vehicles running at
sustained high speeds.
Critical vibrations associated with higher speeds are
not the old thumping or bumping type, but are high
frequency vibrations which sting or tingle the soles of
your feet, tickle the end of your fingers, etc. This type of
vibration will cause gear seizures, bearing failure due to
retainer rivet failures, promote brinelling, fretting,
corrosion, etc.
(h) Gear whine is usually caused by lack of backlash
between mating gears-improper shimming of P.T.O. units
is the big offender here.
Noise in Neutral
Possible Causes:
(a) Misalignment.
(b) Worn, or scored countershaft bearings.
(c) Worn drive gear bearings.
(d) Sprung, or worn countershaft.
(e) Excessive backlash in gears.
(f) Worn mainshaft pocket bearing.
(g) Scuffed gear tooth contact surface.
(h) Insufficient lubrication.
(i) Use of incorrect grade of lubricant.
Noise in Gear
Possible Causes:
(a) Worn, or rough mainshaft rear bearing.
(b) Rough, chipped, or tapered sliding gear teeth.
(c) Noisy speedometer gears.
(d) Excessive end play of mainshaft gears.
(e) Refer to conditions listed under Noise in Neutral.
Oil Leaks
Possible Causes:
(a) Oil level too high.
(b) Wrong lubricant in unit.
(c) Non-shielded bearing used at front or rear
bearing cap. (Where applicable.)
(d) Seals (if used) defective or omitted from bearing
cap, wrong type seal used, etc.
(f) Transmission
breather
omitted,
plugged
internally, etc.
(g) Capscrews loose, omitted or missing from
remote control, shifter housing, bearing caps,
P.T.O. or covers, etc.
(h) Welch "seal" plugs loose or missing entirely from
machined openings in shifter housing or case.
(i) Oil drain-back openings in bearing caps or case
plugged with varnish, dirt, covered with gasket
material, etc.
(j) Broken gaskets, gaskets shifted or squeezed out
of position, pieces still under bearing caps, clutch
housing, P.T.O. and covers, etc.
(k) Cracks or holes in castings.
(L) Drain plug loose.
(m) Also possibility that oil leakage could be from
engine.
Walking or Jumping Out of Gear:
For clarification we would like to separate walking out
of gear and jumping out of gear into two distinct groups.
Walking out of gear is usually associated with power
applications or coasting on long smooth grades, i.e.,
when power is applied the shift lever moves into the
neutral position. Occasionally it may be impossible to
hold the shift lever in gear by hand.
Sometimes this condition may also be noted when
coasting down a long relatively smooth grade or power is
being applied on the coast side of the gear.
Dana/Spicer transmissions and auxiliaries are
provided with "hopping guards" for most gear positions.
Therefore, if the units are walking out of gear it could be
caused by:
(a) Interference or resistance in the shift mechanism
preventing full engagement of the sliding clutch gear or
(b) If the gear has been shifted completely into position
some other malfunction which could move the gear or
the shaft itself out of its proper location.
(c) On new or rebuilt units the wrong parts or old
defective parts may have been used; thereby rendering
the hopping-guard feature useless.
High mileage units
may start walking out of gear due to the general
deterioration or rounding of clutch teeth due to numerous
slip-outs or partial engagements due to conditions listed
below.
(d) Walkout on coast side could be caused by lack
of hopping guard feature for this particular gear position.
If remote controls are used, the mechanic must satisfy
himself that the remote units are satisfactory and that
auxiliary is actually at fault. A number of items that would
prevent full engagement of gears are:
839
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