Toro ProCore 648 Service Manual page 96

Lockout Circuit (Fig. 2)
The lockout circuit is used on the ProCore to provide cur-
rent for the raise and lower hydraulic solenoid valves
(SVL, SVR and SVQ). This circuit is composed of the
transport limit #2 proximity switch, the lockout relay, the
lockout latch relay, the lift/reset switch and diode D2.
When this circuit is closed, current is provided to the aer-
ator control module to allow energizing of the solenoid
valves. Lockout circuit protection is provided by fuse F3.
Coring Head Raised
With the coring head in the raised position, the transport
limit #2 proximity switch is closed which completes the
lockout circuit. Hydraulic solenoid valve operation is
possible at this time which allows the coring head to be
lowered and aeration to occur.
Aerating
Once the lockout circuit has initially been closed by
transport limit #2 proximity switch, the lockout latch relay
and diode D2 allow a latch circuit to keep the lockout
relay energized and hydraulic solenoid valve operation
to continue while aerating.
Electrical System
Coring Head Stranded
If the coring head is stranded in the lowered position
(e.g. the engine runs out of gas while aerating), the
transport limit #2 proximity switch will be open and will
prevent the relays in the lockout circuit from energizing.
In this situation, no current will be available to the sole-
noid valves so the coring head cannot be raised. Press-
ing the lift/reset switch provides the necessary ground
path for completing the lockout circuit. Once the lockout
circuit is closed, solenoid valve operation is resumed to
allow the coring head to raise.
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ProCore 648