© Mitsubishi Forklift Trucks 2013. All
© Mitsubishi Forklift Trucks 2013. All
rights reserved.
rights reserved.
Revision: B
Revision: B
Document ID: 615023
Document ID: 615023
76 (244)
76 (244)
PBV20N2
PBV20N2
Service
Service Manual
Manual
6.5
6.5
Traction
Traction
The movement of the truck is
The movement of the truck is controlled by the traction controller. Before the truck can
controlled by the traction controller. Before the truck can
be driven, the battery must be
be driven, the battery must be connected, the main key switch must be closed and the
connected, the main key switch must be closed and the
system must have
system must have passed the self-test procedure.
passed the self-test procedure.
When the truck is
When the truck is powered on and in the standby mode, it can
powered on and in the standby mode, it can be driven by turning the
be driven by turning the
accelerator at the end of the
accelerator at the end of the tiller arm forward or
tiller arm forward or backward. In the electrical schematic
backward. In the electrical schematic
diagram, the accelerator is presented in zones 12 to 15
diagram, the accelerator is presented in zones 12 to 15 on page 3 of the
on page 3 of the electrical
electrical
schematic diagram. The accelerato
schematic diagram. The accelerator unit receives its
r unit receives its positive 24 volt electrical supply
positive 24 volt electrical supply
from the pin 2 of the connector XA1C. The negative connection is supplied directly from
from the pin 2 of the connector XA1C. The negative connection is supplied directly from
- B.
- B. When the accelerator is turned forward or backward, it
When the accelerator is turned forward or backward, it indicates the direction to the
indicates the direction to the
traction controller via the pins 4
traction controller via the pins 4 and 8 of the
and 8 of the connector XA1B. It also provides a varying
connector XA1B. It also provides a varying
voltage to the pin 4
voltage to the pin 4 of the connector XA1C. The voltage varies between 0, 3
of the connector XA1C. The voltage varies between 0, 3 and 4.7
and 4.7
volts, depending on the position of the accelerator control. The voltage increases as the
volts, depending on the position of the accelerator control. The voltage increases as the
accelerator is moved to either extreme.
accelerator is moved to either extreme.
6.6
6.6
AC motor operation
AC motor operation
In the induction motor (=
In the induction motor (= asynchrono
asynchronous motor), the stator
us motor), the stator is powered with alternating
is powered with alternating
current and designed to create a rotating magnetic field, which rotates in
current and designed to create a rotating magnetic field, which rotates in time with the
time with the
AC oscillations. In
AC oscillations. In the induction
the induction motor, the roto
motor, the rotor rotates at a slowe
r rotates at a slower speed than t
r speed than the
he
stator field and therefore the magnetic field through the rotor is
stator field and therefore the magnetic field through the rotor is changing (rotating). The
changing (rotating). The
rotor has windings in the form
rotor has windings in the form of closed wire loops. The rotating magnetic flux induces
of closed wire loops. The rotating magnetic flux induces
currents in the rotor windings as
currents in the rotor windings as in a transformer. These currents in turn
in a transformer. These currents in turn create
create
magnetic fields in the rotor that
magnetic fields in the rotor that interact with the stator field. Due
interact with the stator field. Due to Lenz's law, the
to Lenz's law, the
direction of the created magnetic field is such
direction of the created magnetic field is such as to oppose the change in current
as to oppose the change in current
through the windings. The cause of induced current in the rotor
through the windings. The cause of induced current in the rotor is the rotating stator
is the rotating stator
magnetic field, so to oppose it, this rotor starts to rotate in the direction of the rotating
magnetic field, so to oppose it, this rotor starts to rotate in the direction of the rotating
stator magnetic field to make the relative speed between the rotor
stator magnetic field to make the relative speed between the rotor and the rotating
and the rotating
stator magnetic field zero.
stator magnetic field zero.
For these currents to be
For these currents to be induced, the speed of the physical rotor must
induced, the speed of the physical rotor must be lower than
be lower than
that of the stator's
that of the stator's rotating magnetic field or the magnetic field would not be moving
rotating magnetic field or the magnetic field would not be moving
relative to the rotor
relative to the rotor conductors and no currents would be induced. As the speed of the
conductors and no currents would be induced. As the speed of the
rotor drops below synchronous speed, the rotation rate of the magnetic field in
rotor drops below synchronous speed, the rotation rate of the magnetic field in the rotor
the rotor
increases, inducing more current in the windings and creating more torque. The ratio
increases, inducing more current in the windings and creating more torque. The ratio
between the rotation rate of the magnetic field as
between the rotation rate of the magnetic field as seen by the rotor (s
seen by the rotor (slip speed) and the
lip speed) and the
rotation rate of the stator's r
rotation rate of the stator's rotating field is called "slip". Under load, the
otating field is called "slip". Under load, the speed drops and
speed drops and
the slip increases enough to create sufficient torque to turn
the slip increases enough to create sufficient torque to turn the load. For this reason,
the load. For this reason,
induction motors are sometimes referred to
induction motors are sometimes referred to as asynchronous motors. An
as asynchronous motors. An induction
induction
motor can be used as
motor can be used as an induction generato
an induction generator, or
r, or it can be unrolled to form
it can be unrolled to form the linear
the linear
induction motor, which can directly
induction motor, which can directly generate linear motion.
generate linear motion.
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