Theory of operation, Automatic idle system, E-4 outback® 185 – Lincoln Electric OUTBACK SVM204-A User Manual

Page 38

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THEORY OF OPERATION

E-4

OUTBACK® 185

AUTOMATIC IDLE SYSTEM

The Outback® 185 is equipped with an automatic
engine idle system. A solenoid is used to pull the
engine throttle to a preset low speed position when 12
volts DC is applied. When no voltage is applied, the
solenoid is released allowing the engine governor to
control the RPM.

The “high” and “auto” positions on the rotary
run/stop/idle switch control the supply of positive (+)
battery voltage to the idle solenoid. When the switch is
in the “high” position, the solenoid is shut off and the
engine will remain in high idle. When the switch is in
the “auto” position, positive (+) battery voltage is
applied to the solenoid and the negative (-) connection
is controlled by the PC board as described below.

The following explanation assumes that the rotary
switch is in the “auto” position and the engine is oper-
ating at low RPM.

FIGURE E.4 - AUTOMATIC IDLE SYSTEM

Weld and auxiliary current are detected by a toroidal
current sensor that is connected to the PC board.
When sufficient current flows through the sensor; the
PC board detects this and immediately interrupts the
negative (-) connection to the solenoid. The solenoid
is released and the engine RPM increases to the high
setting. When the current flow stops, the PC board will
begin a time delay of about 12 seconds. If the current
flow begins again during this time delay, the solenoid
remains inactive and the engine continues to operate
at high RPM. If no current flow is detected at the end
of the 12 second delay, the negative (-) connection to
the solenoid is restored and the engine will drop to low
idle RPM.

NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion