Toyota Orderpicker Model
7BPUE
15
Service Manual Section
9.
Theory of Operation
Lower
(54)
The
lower
button commands the carriage to
lower. When the lower button is pressed, the
lift/lower proportional solenoid valve closes and
the load holding solenoid valve opens. The
proportional valve opens and allows hydraulic
fluid to return from the lift cylinders to the
reservoir.
When lower is no longer requested, the
proportional valve opens and the load holding
valve closes.
See Figure
9
-
13
on page
9
-
44.
(The electrical
schematic legend is on page
9
-
2.)
1.
As the control handle lower switch is
closed, a digital ground is applied to
JPC 13
-
7
on the carriage manager.
2.
The carriage manager sends a lower
command message to the
steer/tractor
manager over the transmit/receive lines.
Figure
9
-
1
1. LEDs 11 1-116
on Steer/Tractor Controller
3.
The steer/tractor manager provides the
negative potential for the
lift/lower
proportional valve coil at
JPT12-8,
indicated by the load holding solenoid
LED
(IL6-7)
on the steer/tractor manager. See
Figure
9
-
1 1
on page
9
-
4 1.
The lift/lower
proportional valve ramps closed (this valve
is normally open).
4.
The steer/tractor manager provides the
negative potential for the load holding
valve coil at
JPT12-9,
indicated by the load
holding solenoid
LED (IL6-9).
See
Figure
9
-
1 1
on page
9
-
4 1.
The coil
energizes and the load holding valve
opens.
5.
The steer/tractor manager varies the
negative potential for the
lift/lower
proportional valve coil at
JPT12-8,
indicated by the load holding solenoid
LED.
The lift/lower proportional valve
gradually opens allowing hydraulic fluid to
return to the reservoir. See Figure
9
-
12.
00700
-
CL222
-
05,
1
5
March
2005
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