commercial practice in their repair. Refer to the
level of electrolyte is 1/4 inch from bottom of
wiring diagram (fig. 1-3) and conduct a syste-
matic inspection using an ohmmeter to isolate
Caution: Do not use water which has passed
the trouble. Remedy the trouble by splicing
through a water softener. This water is chemic-
leads where required and applying electrical tape
ally destructive to a lead-acid battery. It is not
to prevent short circuits from occurring. Refer to
equivalent to distilled water.
direct support maintenance for replacement of a
complete wiring harness or repair to wiring en-
(1) Add water slowly. Water should be
cased in flexible metal conduit.
added before charging to insure prompt mixing
with the electrolyte.
(2) In sub-freezing temperatues battery
3-48. Motor Brush Replacement
must be put on finish charge for one hour after
Motor brush replacement (fig. 3-16) for the
water has been added.
travel motor or hydraulic pump motor is the
d. Cleaning the Battery. The entire battery
and battery compartment should be kept clean
and dry. If the electrolyte has been spilled or
(1) Remove screw, nut and lockwasher
corrosion has formed on the battery proceed as
securing brush covers to motor housing and re-
move brush covers.
(1) Add one pound of bicarbonate of soda
(2) Remove screw and lockwasher securing
to one gallon of warm water. Pour solution over
corrosion or spilled electrolyte.
(3) Pull back on brush spring sufficiently
(2) When foaming action stops rinse off
to release brush and pull brush out of brush
the entire battery with clear water.
Caution: Vent plugs must be installed in
(4) Repeat steps (1) through (3) for re-
moval of remaining brushes.
cells to prevent soda solution from getting into
b. Inspection. Compare length of used brush
the cells. Do not use steam or very hot water to
with length of a new brush from stock. Replace
any brush worn to half (or less) the length of
e. Charging the Battery. Batteries normally
new brush, as given below.
discharged more than one third of their capacity
daily should be recharged daily. Other batteries
(1) Install new brushes in brush holders
in use should be charged at least once a week.
with short side of brush toward spring side of
Do not charge batteries more often than neces-
holder, so brush friction surface contour mates
sary to reduce gassing and water loss. Plan on re-
with surface of armature commutator. If brush
charge time, for a completely discharged battery,
edge meets commutator, reverse brush in hold-
of about eight hours, proportionally less for
er. Fasten brush leads to holder with removed
partially discharged batteries. Charge as follows:
screws and lockwashers.
(1) Disconnect battery leads at battery con-
(2) Hook brush springs over brushes and
nector receptacle and connect charger to battery
check pressure exerted on brush with brush
half of connector.
spring pull scale. Pressure should be 26 ounces
(2) Using procedure appropriate to the
to 32 ounces at time scale lifts spring from brush
charger being used, adjusted initial charging
on either motor.
rate for a fully discharged battery of 130 to 160
(3) Install brush covers and secure in posi-
tion on motor housing with removed screw, nut
(3) At end of charging time disconnect
charger and observe cell vent; caps for signs of
excessive gassing. This is usually indicated by
3-49. Relay Contact Replacement
electrolyte around the fill hole of the cell.
Relay contact maintenance is restricted to those
f. Removal. Reverse the procedures outlined
relays having contacts visible for inspection, and
replaceable without removing the relays. Main-
g. Installation. Refer to paragraph 2-4e.
tenance requiring more than contact or interlock
switch replacement, shall be performed by direct
3-47. Wiring Harness
support maintenance personnel. Contacts require
Repair of the wiring harness is limited to iso-
replacement when the silver has worn down to
lating shorted and open circuits and using good
the steel support.