Lincoln Electric Exploring the Idle Solenoid System in Lincoln Ranger 8 Welders

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E-3	THEORY OF OPERATION	E-3
	FIGURE E.3 –ENGINE IDLE SYSTEM, IDLE SWITCH & IDLE SOLENOID

			SHUNT	+
POWER	IGBTs	CHOKE		-
MODULE

ENGINE			CHARGING
PROTECTION
LIGHT			SYSTEM LIGHT
			(CODE 10926 ONLY)
ENGINE	ENGINE	GLOW	ENGINE
PROTECTION				WELD
CIRCUIT	SENSORS	PLUGS	ALTERNATOR
				WINDING

FUEL

ENGINE

PUMP

ROTOR

FUEL

SOLENIOD

HOLD COIL

PULL COIL

STATOR

AMP

STARTER

START

EXCITER

120/240 VAC

42 VAC

WELD CONTROL

DISPLAY

BUTTON

IDLE

WINDING

AUX.WINDING

WINDING

P.C. BOARD

VOLT

SOLENOID

CURRENT

DISPLAY

PULL

HOLD

240

SENSOR 14

COIL

COIL

VAC

120

PIN

6

GLOW

FLASHING

RECEPTACLES

vac

AMPHENALS PIN

PLUG

12V.

BUTTON

PULL COIL

BATTERY

PC BOARD

IDLE

RUN

OUTPUT

MODE

WELDING

SWITCH

STOP

SWITCH

CONTROL

SWITCH

TERMINAL

Engine Idle System

ARC

SWITCH

CONTROL

Idle Solenoid Operation:

Idle Switch Operation:

The engine speed is controlled by a two stage solenoid

connected to the engine speed control lever. When the

When the engine is started it operates at high RPM. If

solenoid is inactive, the engine operates at high RPM,

the idle switch is in the high position

the automat-

and is controlled by the governor.

When the solenoid

ic idle system is inactive and the engine will continue to

is activated, the speed control lever is pulled to a pre-

operate at high RPM.

set low RPM setting.

If the engine is started with the idle switch in the auto

The solenoid is powered by battery voltage directly

position,

or if the idle switch is moved to the

from the run/stop switch.

The control PC board and

auto position while the engine is running, a 12 second

pull coil PC board activate the pull and hold coils by

on the control PC board is started. If there is no signif-

providing a path to ground.

icant current flow detected from the weld or auxiliary

When the machine goes to low idle speed, the control

outputs during that 12 second time, the idle solenoid

PC board grounds the hold coil of the idle solenoid and

will be activated, dropping the engine RPM to preset

at the same time it sends a signal of about +14VDC to

low idle speed. If a load is applied during the 12 sec-

the pull

coil

PC

board.

This

DC

signal remains at

ond delay, the engine speed will remain high.

+14VDC for the entire time that the hold coil is active.

While operating at low RPM; if the idle switch is moved

When the signal is applied to the Pull coil PC board, the

to high, or there is a load detected from either the weld

board will energize the pull coil of the idle solenoid for

of auxiliary outputs, the idle solenoid will be deactivat-

a brief moment, normally less than one second.

This

ed, allowing the engine governor to increase the RPM

momentary activation of the pull coil supplies the need-

to high speed.

ed power to reliably move the speed control lever to the

When the idle switch is in the “auto” position and the

low idle position.

machine is under load and running at high RPM. If the

load is removed, the machine will continue to run at

high RPM for 12 seconds, then drop to low RPM,

unless a load is re-applied during that 12 second delay

NOTE:

Unshaded areas of Block Logic Diagram are the subject of discussion.

RANGER 305D