TM 55-4920-221-14
T3 variable control supports by removing two screws
(4) Install and secure bus bar (30) on GEN+
(8).
terminal as described above, to bus bar (36) with screw
(23) and nut (24).
(4) Remove T3 variable control (10) from
control panel by removing eight screws from T3 variable
(5) Connect electrical leads to terminals of
control support.
relay mounting pad assembly.
(5) Remove two brackets (20) and supports
(6) Position and secure external impedor box
from brackets by removing screw (14), spacer (13), four
(18) on frame in control panel, with four cap screws (19),
screws (22), and nuts (23).
flat washers (20), spacers (21), and nuts (22).
(6) Remove T1 variable control (44) in a
(7) Connect electrical leads.
similar manner.
(7) Remove T2 variable control knob (38) as
116. FIELD RHEOSTAT.
in (1) above.
a. Removal.
(8) Tag and disconnect electrical leads from
(1) Loosen setscrew on field rheostat knob (1,
terminals on T2 variable control (16).
(9) Remove T2 variable control (1'6) from
(9).
control panel by removing two screws (17), lockwashers
(2) Tag and disconnect electrical leads from
(18), and nuts (19).
terminals on field rheostat (9).
b. Cleaning and Inspection.
(3) Remove rheostat (9) and brackets (20)
from control panel by removing four screws (22) and
(1) Clean parts with a cloth dampened in dry
nuts (23) securing brackets to panel.
cleaning solvent, P-D-680.
(4) Remove two brackets (21) from rheostat
(2) Visually inspect controls for cracks,
by removing two screws (11).
breaks, or damaged windings.
b. Cleaning and Inspection.
(3) Inspect control arm and control shaft, for
sticking or binding.
(1) Clean parts with cloth dampened in dry
(4) Inspect threaded parts for worn or
cleaning solvent, P-D-680.
damaged condition.
(2) Visually inspect rheostat for cracks or
c. Installation.
breaks, damaged windings, contact arm, binding shaft,
also loose or corroded terminals.
(1) Attach T2 variable control (16) on control
(3) Inspect threaded parts for worn or
panel with two screws (17), lockwashers (18), and nuts
damaged condition.
(19).
c. Installation.
(2) Connect electrical leads to T2 variable
control terminals.
(1) Attach two brackets (21) on field rheostat
(3) Place T2 variable control in the 0 position.
(9) securing with two screws (11).
(4) Install T2 variable control knob (38) on
(2) Position field rheostat inside control
shaft of variable control, and secure with setscrew.
panel.
(5) Install two brackets (2'0) on T3 variable
(3) Align bracket and panel mounting holes
support, and position assembled brackets and supports
securing with four screws (22) and nuts (23).
in control panel. Align mounting holes and secure with
(4) Connect electrical leads to rheostat
four screws (22), nuts (23), spacer (13), and screw (14).
terminals.
(6) Attach T3 variable control (10) on support
(5) Secure rheostat knob (1) on rheostat shaft
with eight screws.
with knob setscrew.
(7) Place rheostat brace (7) between T1 and
T3 variable control supports and secure with two screws
117. T1, T2, AND T3 VARIABLE CONTROLS
(8).
(RHEOSTATS).
(8) Connect electrical leads to T3 variable
a. Removal.
control terminals.
(1) Rotate T3 variable control (10, figure 10)
(9) Place T3 variable control in 0 position.
in 0 position, loosen setscrew, and remove T3 variable
knob (37) from shaft of T3 variable control.
(10) Attach T3 variable control knob (37)
securing with setscrew.
(2) Tag and disconnect electrical leads from
terminals on T3 control.
(11) Install T1 variable control (44) in a similar
manner.
(3) Remove rheostat brace (7) from T1 and
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