Operator`s manual

Ladder deceleration prior to maximum elevation and ladder stoppage at maximum elevation of 75 degrees

are controlled by two micro switches (7) and (8) in the Elevating Cylinder Limit Switch Assembly on the left

side of the ladder turntable (see Figure 8-10). As the ladder is elevated, a wire connected between the

assembly and Section One of the ladder causes a camshaft to turn. A few degrees before maximum

elevation, a cam lobe closes the deceleration micro switch (7). Current is reduced to the B side of the

Elevation Solenoid (20) by two resistors (11). The reduced current causes the Elevation Solenoid to

operate and the rate of ladder elevation is reduced. When the ladder reaches maximum elevation a

second cam lobe opens a micro switch (8). Current is cut to the B side of the Elevation Solenoid. The

Elevation Solenoid operates and the corresponding Proportional Valve closes, preventing further elevation

of the ladder using the Ladder Elevation Joystick. When the ladder is lowered, a spring in the Elevating

Cylinder Limit Switch Assembly turns the camshaft in the opposite direction and retracts the wire.

To protect the ladder and ladder bed from undue stress, a micro switch (12) at the ladder bed opens when

the ladder is brought to rest on the ladder bed, causing a solenoid-operated switch (35) to open. Current

is cut to the A side of the Elevation Solenoid (20), preventing any further attempt to depress the ladder.

6.4.8 Ladder Circuits Below the Turntable

For the wiring diagram of circuits below the Turntable, refer to Figure 6-7.