A pole shoe spreader,
screwdriver.
should also be used to prevent distortion
of the field frame. Careful installation of
the field coils is necessary to prevent
shorting or grounding of the field coils
as the pole shoes are tightened into
Where the pole has a long lip on
place.
one side and a short lip on the other,
the long lip should be assembled in the
direction of armature rotation so it be-
comes the trailing edge of the pole shoe.
S o l e n o i d Checks
A basic solenoid circuit is shown in
Solenoids may differ in
appearance but can be checked elec-
trically by connecting a battery of the
s p e c i f i e d v o l t a g e , a switch and an amme-
ter to the two solenoid windings.
F i g u r e 10D-6. Checking Solenoid
Hold-in Winding
U s e a carbon pile to decrease the battery
voltage to the value specified in
Table 10D-2 and compare the ammeter
A high
specifications.
r e a d i n g with
reading indicates a shorted hold-in wind-
reading
excessive
and
a
low
ing,
resistance. To check the pull-in winding
connect from the solenoid switch terminal
(S) to the solenoid motor (M or MTR)
(see Figure 10D-7 on page
terminal
10D-7).
T o c h e c k f o r g r o u n d s , m o v e b a t t e r lead
Figure 10D-5. Internal Solenoid
f r o m ( G , Fi g u r e 10D-6) and from ( M T R ,
Circuit
Figure 10D-7 o n p a g e 1 0 D - 7 ) t o s o l e n o i d
Ammeter should read zero. If
case.
With all leads disconnected from the sole-
not winding is grounded.
noid, make test connections as shown to
the solenoid switch terminal and to the
second switch terminal (G), to check the
hold-in winding (see Figure 10D-6).
HOLD-IN WINDING
PULL-IN WINDING
RATED
CURRENT
CURRENT
VOLTAGE
6 . 8 Amps Max.
20 V o l t s
5 Volts
9 t o 1 1 . 5 Amps
24
Table 10D-2. Solenoid Specifications