Operator`s manual

The rate of the ladder elevation, depression, rotation, extension and retraction is controlled by the amount
of current received by the Elevation, Rotation and Extension Solenoids (18), (19) and (20). The farther the
Joysticks are moved away from their neutral positions, the greater the current to the solenoids, which
control how much the Proportional Valves (see Figure 5-2, number 16) will open. Solenoids (18), (19) and
(20) must overcome a slight hydraulic pressure before the Proportional Valves will open. At 12 VDC a
solenoid will cause the corresponding Proportional Valve to be fully open in one direction or the other,
depending on which way the Joystick has been moved. As the Joystick is returned to its neutral position,
current to the solenoid is reduced and the corresponding Proportional Valve will close as the current is
reduced. There is a deadman switch on top of each Joystick. When a Joystick is moved from its neutral
position, the switch must be pressed down in order for current to flow from the Joystick to the
corresponding solenoid via a Current Regulator. When the switch is released, current from the Joystick to
the solenoid is cut.
The Throttle Control Button (21) increases engine rpm from 550 to 1200 when the button is pulled up.
When the Energy On Control Light (24) is lit, it indicates there is current to the Joysticks. When pressed
down, the Cut-Off Switch (23) cuts current to the Joysticks. Switch (31) controls the Ladder Console Lights
(32). The Engine Start Button (27) can be used to restart a stalled engine and the Contact Rings (10)
direct current from below the Ladder Turntable to above the Turntable. The Diodes (15) and (17) protect
the Solenoids (18), (19) and (20) against a high voltage surge.
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