Curtis PMC 1209B/1221B/1221C/1231C Manual
18
WIRING
Fig. 13
Bi-directional
twist-grip throttle with a
standard 20 k
Ω
pot and a
controller with the
optional 5k
Ω
–0 throttle
input.
Pots for Twist-Grip Throttles
Twist-grip throttles either twist in only one direction (and are used only for
acceleration), or they twist both ways (and are also used for reversing, by means
of microswitches that select a direction contactor). For twist grips that twist in
only one direction, the controller throttle input can be from a 5 k
Ω
pot as shown
above in Figure 12.
For twist grips that twist both ways, a pot capable of going from zero in
neutral to 5 k
Ω
in each direction can be used. A mechanism can be designed to
make a standard pot turn in the same direction regardless of which direction the
twist grip is turned.
A third method of accommodating bi-directional twist-grip throttles uses a
standard potentiometer and a controller with a nonstandard throttle input. As
shown in Figure 13, a standard 20 k
Ω
pot is used, with its end terminals wired
together. The resistance goes
from 5 k
Ω
at neutral to zero at
the extremes: the opposite of the
standard throttle input con
fi
gu-
ration. Contact the factory if you
need this type of controller.
WARNING: with the in-
put circuit shown in Figure 13,
potentiometer or wiring open
circuits turn off the controller’s
output. However, pot wiring shorts appear the same as a normal zero ohm
signal to the controller, and will produce full speed operation if the short occurs
while the power is on.
TO
THROTTLE
INPUT
2
0
k
Ω
PO
T
SPEED
INCREASES
BOTH WAYS
