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HD-96044N page 2 of 4
Crank Disconnect Relay
An understanding of the crank disconnect function for your par-
ticular system is critical to speed switch installation. It is also
important to consider the 5 A current limitation of K1 relay con-
tacts. Figure 1 illustrates the use of a low-current pilot relay to
operate the high-current starter solenoid. In operation, battery
voltage is supplied through the normally closed contacts of the
speed switch crank disconnect relay K1. When the engine starts,
K1 energizes and its normally closed contacts open. This action
de-energizes the pilot relay and inhibits the starter from operating
until the engine nearly stops. The normally open contacts may be
used if a contact closure is required to disable the cranking func-
tion for your system.
Overspeed and Underspeed Relay
NOTE: Underspeed relay available on HD9063-USOS only.
The overspeed and underspeed functions of the speed switch may
be used in various systems to effect engine shutdown or actuate an
alarm in the event of engine overspeed or underspeed. Figure 2
illustrates the overspeed/underspeed function being used to control
a fuel rack solenoid. In this application, battery voltage is available
to the solenoid through normally open contacts of the relay (K2
overspeed) (K1 underspeed). If the engine speed exceeds the nor-
mal overspeed or underspeed set point, relay K1 or K2 energizes
and this voltage energizes the solenoid, shutting down the engine.
Similarly, the normally closed contacts may be used if engine shut-
down is to be initiated by removal of battery voltage.
I
N
C
R
E
A
S
E
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N
C
R
E
A
S
E
CRANK
DISCONNECT
OVERSPEED
EXT.
MAG.
PICKUP
123456789101112
(+) (+)( ) ( )
EXT.
TEST
EXT.
POWER
NC
NO
C
NC
NO
C
INTERNAL
CRANK
DISCONNECT
RELAY
CONTACTS
INTERNAL
OVERSPEED
RELAY
CONTACTS
2-3/4 in.
(70 mm)
4-1/2 in.
(114 mm)
2-1/4 in.
(57 mm)
Mounting
Holes
4 in. (102 mm)
Mounting Holes
Mounting
Standoffs
4 Places
3/4 in.
(19 mm)
HD9063 and HD9063-USOS
1
Overspeed Relay K2
Contact opens on overspeed or
underspeed and drops out solenoid.
OPTIONAL
Energize
NO
Off
Start
NO NC
2 31
Underspeed Relay K1
NO NC
2 3
Battery
Starter
Switch
Starter Contactor
Relay
Starter
Energize
Hold
321
Battery
Crank
Enable
Crank
Disconnect Relay
K1
Battery
Starter
Pilot Relay
To
Starter Solenoid
MOUNTING DIMENSIONS
Figure 1
Figure 2
Mounting
1. Drill four 3/16 in. (5 mm) diameter mounting holes (refer to
mounting hole dimensions above).
2. Align the plastic standoffs on the HD9063 with the 4 mounting
holes and push gently until standoffs snap into place.
CAUTION: Pushing too hard could damage board.
Mounting
1. Drill four 1/4 in. (6 mm) diameter mounting holes (refer to mount-
ing hole dimensions above).
2. Secure with four 10-32 screws.
RELAY FUNCTIONS