Curtis PMC 1204X/1205X/1209/1221 Manual
14
WIRING
Fig. 9 Control wiring for
inhibiting plug braking,
in order to allow
freewheeling.
A2M-
B-
B+
FORWARD
REVERSE
MAIN
KEYSWITCH
INTERLOCKS
PEDAL
MICROSWITCH
FUSE
POLARITY
PROTECTION
DIODE
F/R SWITCH
(DPDT, center off)
+
–
BYPASS
Bypass cont. output
REV input
Emergency reverse
(see Fig. 10)
FWD input
F/R cont. output
KSI
Plug Braking
The standard forward/reverse control wiring (as shown in Figure 8 by the thin
lines) provides plug braking. The forward/reverse switch should be in the positive
feed to the contactor coils, so that they can be turned off by the keyswitch,
interlocks, and pedal microswitch. The coil of one contactor or the other is
energized to select the direction desired. The contactor coils should have suppres-
sion diodes connected across them to improve switch contact life.
Freewheeling: Wiring to Inhibit Plug Braking
If a non-SRO controller has the HPD option, this feature can be used to inhibit
plug braking by briefly turning off the controller’s KSI input when the forward/
reverse switch goes through neutral. As shown in Figure 9, another set of contacts
is added on the forward/reverse switch. Therefore, a double-pole, double-throw
(DPDT) center-off switch must be used for this setup. A “hesitation switch” is
recommended, to ensure the switch is in neutral long enough to actuate HPD and
inhibit plug braking.
Plug braking can be reactivated during freewheeling by releasing the throttle and
reapplying it.
NOTE: Contact factory for information on wiring SRO controllers for
freewheeling.
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