Versalift VST-9000I-E100, Service And Installation Manual

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102-5 VERSALIFT VST-9000-I-E
THEOR
Y
OF OPERA
TION
Ignition Relay - The 12 volt, double-pole, double-
throw, latching ignition relay is mounted in the
electrical box. One set of points is in the start circuit
and the other set of points is in the ignition circuit.
Pressure Switch and Air Cylinder - The pressure
switch is mounted on the turret wing and connected,
by an air line, to an air cylinder mounted on the
platform control panel. When the air cylinder is
operated, air pressure is produced and the electrical
contacts in the pressure switch close. The truck
engine is started or stopped depending on the
position of the ignition relay contacts.
Toggle Switch (Lower Controls) - A single-pole,
three position, momentary toggle switch is mounted
on the lower control cover. The truck engine is
started or stopped depending on the position of the
toggle switch.
OPERATION THEORY OF START/STOP
CIRCUITS
Start/Stop Circuit - When the master control toggle
switch is activated and the ignition switch is in the
“on” position, current fl ows to terminal 7 on the
terminal block. Current from terminal 7 fl ows to the
ignition relay. The ignition relay supplies current to
the start or stop relay depending upon the latching
position. The latching position is toggled between
the start and stop position each time one of the
start/stop switches is operated.
In order for the start system to operate, the ignition
relay must be latched in the start position and one
of the start/stop switches must be held in the start
position. With the start relay energized, current
from the battery fl ows to the starter solenoid.
To activate the stop system, the ignition relay must
be latched in its stop position and one of the start/
stop switches must be held in the stop position.
With the stop relay energized, the ignition circuit
and the start relay control circuit are broken and the
engine stops.
MANUAL ENGINE THROTTLE CONTROL
The throttle control electrical schematics will aid in
understanding the electrical system. The manual
throttle control components and their function are
described in detail below.
Truck Ignition Switch - All current used for
operating the throttle control system comes from
the truck ignition switch.
Throttle-control Relay - This relay is a 12-volt,
double pole, double-throw, latching relay mounted
in the electrical box.
Pressure Switch And Air Cylinder - The pressure
switch is mounted on the turret wing and the air
cylinder is mounted on the platform control panel.
A small air line connects the two components
together. When the air cylinder is operated, air
in the line is compressed. When adequate air
pressure is produced, the electrical contacts in the
pressure switch close and the electrical solenoid on
the engine is activated or deactivated, depending
on the position of the latching relay.
Throttle Actuator - The throttle actuator is mounted
in the engine compartment. It is activated by an
electrical signal from the throttle control latching
relay. Gas and diesel engine models use an
electrical solenoid actuator.
Toggle Switch (Lower Controls) - The toggle
switch is a two-position, maintained switch mounted
on the lower control cover. The throttle control relay
is energized when the toggle switch is operated.
OPTIONS
EMERGENCY POWER
The emergency power option wiring schematic
will aid in understanding the emergency power
system. Refer to the specifi c option schematics.
The electrical components and their functions are
described in detail below.
Motor - The motor is a 12 volt DC motor that can
operate an auxiliary hydraulic pump in the event
that the main pump cannot be used. Power to
operate the motor is obtained from the truck battery.
Solenoid - The power solenoid is mounted on the
motor and is used to complete the circuit between
the truck battery and the motor. The control coil of
the solenoid does not have an internal ground for
completion of the control circuit. Ground connection
is controlled by a control in the platform.
Pressure Switch And Air Cylinder - The air
cylinder and pressure switch are identical to the
ones used for the start/stop system. Refer to the
start/stop system theory for a description of how
they work. Operation of these two components
completes the solenoid control circuit.
Toggle Switch (Lower Controls) - The single-pole,