Systems Overview
Toyota Pallet Truck Service Manual
Theory of Operation
3-8
00700-CL390-04, Issued: 2 February 2004
flow through the drive motor armature at
M-. It also provides current flow through
the field windings in the correct polarity at
F1 and F2.
•
the drive wheel begins to rotate in a
forward direction at a speed proportionate
to throttle input.
Reverse
When the directional/speed control is rotated in
the reverse direction from neutral:
•
the reverse directional switch (SW4) is
closed and B+ voltage is applied to
PMC-11 of the motor controller
•
resistance across the throttle
potentiometer (VR-4 to VR-2) increases
from zero ohms to a maximum of 6,500
ohms. Throttle input voltage is then
generated at PMC-16 wrt PMC-14. As
throttle input voltage rises above the
neutral band threshold, the motor
controller begins to provide current flow
through the drive motor armature at M-. It
also provides current flow through the
field windings in the correct polarity (F1
and F2).
•
The drive wheel begins to rotate in a
reverse direction at a speed proportionate
to the throttle input.
Emergency Reverse
(Models 6HBW30, 6HBE30 and 6HBE40)
When the emergency reverse switch (belly
button switch SW7) is closed with the control
handle lowered in travel mode (SW2 closed), the
control system responds in various ways,
depending upon how the truck was operating
when SW7 closed.
•
Truck traveling in tractor-first direction:
full
braking torque is applied to the drive
motor and then accelerates in the
forks-first direction.
•
Truck stopped or traveling in forks-first
direction:
full accelerating torque for
forks-first direction is applied to the drive
motor.
Travel in forks-first direction will continue until
the emergency reverse switch (SW7) is released.
When the emergency reverse mode is activated,
the motor controller ceases to respond to the
normal travel command from the directional/
speed control. To reset the truck for normal
travel, return the directional/speed control to
the neutral position.
Strip Curtain Bypass
(Models 6HBE30/40 only)
When the truck is traveling tractor first and the
horn button on the grab rail is pressed, the
emergency reverse switch is disabled until the
horn button is released.
Manual Coast Mode
(Standard on 6HBE30/40, Optional on 6HBW30)
Manual Coast is an operating mode where the
brake remains released at all times and speed is
restricted to 3.5 mph (5.6 km/h). Manual coast
is intended for order picking while walking
beside the pallet truck.
The manual coast system uses a manually
actuated spring loaded plunger to keep the
control handle in the travel (brake released)
position.
To engage manual coast, the control handle is
lowered into the operating range and the “flip
over” coast selector is engaged. Manual coast is
disengaged by reversing the above process.
When manual coast is engaged, coast interlock
switch (SW27) activates RLY2, supplying a
Mode Select 1 input at PMC-3. This input, in
conjunction with the status of the mode select
input at PMC-4, creates a fixed PWM (40%) to
the traction motor armature circuit. This limits
the fixed speed to 3.5 mph (5.6 km/h).
Even with the manual coast lever in the no
coast position, maximum speed is limited to
3.5 mph (5.6 km/h) as the motor controller is
restricted to speed mode M1. Top (rabbit) speed
in both directions is selected by pressing and
releasing the rabbit button while forward or
reverse travel is requested through the twist
