(6) Cut-out relay unit.
" O N " position, then slide the safety
0.048 inch
Air gap
clip (21-B) off the stop button (21-C)
0.035 inch
Point opening
a n d depress the start button (21-A)
(do not hold the "START" button de-
Satisfactory clos-
i n g range
pressed more than 10 seconds) to start
25 to 27 volts
26 volts
Adjust to
the varidrive assembly. Check for
correct rotation of the generator
Note. The Auto-Lite 25-ampere 3-unit
vibrating contact type generator regulator
pulley (par. 93c).
VBC 4002UT ordnance number 7524309,
(8) If it is necessary to change the rota-
tion of the generator (correct rotation
f o l l o w i n g procedures in this section. Refer
is important, otherwise, the generator
to referenced table and TM 9-1825-B for
tabulated data when performing tests on this
w i l l have no output), stop the vari-
regulator.
d r i v e assembly by pushing the stop
c. Preparation.
b u t t o n (21-C), let the varidrive as-
sembly come to a complete stop, and
(1) T u r n all range selector switches be-
place the drive reversing switch (fig.
neath the meters on the test stand to
12) in the opposite position (par. 93c).
t h e maximum reading position, all
r h e o s t a t s fully counterclockwise, and
Warning: Before reaching into the
all on-off toggle switches to off posi-
high voltage compartment to change
tion (some toggle switches have center
the position of the drive reversing
p o s i t i o n as "OFF") (fig. 32).
switch, place the toggle switch on the
circuit breaker (fig. 11) in the "OFF"
(2) M o u n t a 2 5 - a m p e r e g e n e r a t o r o f
position, as high voltage exists in the
known serviceable condition (pars.
surrounding area of this compart-
111 and 112) on the low speed driving
ment.
head (5, fig. 7) (par. 95).
d. Test Procedures for Control Units as an
(3) C a l i b r a t e the tachometer indicator
c i r c u i t r y as prescribed in paragraph
Assembly.
97c if this procedure has not been per-
(1) T h i s test is performed as prescribed
f o r m e d previously (par. 111c(3)).
f o r generator performance test para-
(4) C o n n e c t the generator terminals and
regulator is connected in the circuit of
housing (ground) to the generator
t h e test stand as specified in para-
i n p u t binding post panel of the test
stand using applicable leads as shown
o f the 40-ohm 30-ampere maximum
in figure 31. These leads are listed in
rheo-reg switch is changed, (2) below.
The 40-ohm field current rheostat
(5) C o n n e c t a connecting link (fig. 65)
( 1 6 ) is not used for this test as the
between "B-" and "G-" as shown
g e n e r a t o r regulator compensates for
in figure 31.
this item.
(6) Mount the 25-ampere generator regu-
(2) The position of switches and controls
lator undergoing test on the regulator
p e r t i n e n t to the tests in paragraphs
m o u n t i n g bracket and connect it to
( 3 ) through (6) below are listed in
the regulator binding post panel using
applicable harness and leads as shown
position indicated in column 3a of the
in figure 31. These leads and harness
t a b l e before tests are started except
are listed in appendix II (figs. 73 and
f o r one change which is the 40-ohm
74).
3 0 - a m p e r e maximum rheo-reg switch
Note. Do not connect the two leads shown
k e y no. 17 in the table). Place this
as dotted lines on illustration 31 for this test.
switch in the "REG" position instead
(7) Check to see if the toggle switch on
the circuit breaker (fig. 11) is in the
of the "RHEO" position.
65
