Operator`s manual

7.2 LADDER BED LOCK ASSEMBLY
The Ladder Bed Lock is designed to hold the ladder on the Ladder Bed while the truck is travelling. It is
controlled pneumatically and operates in conjunction with the PTO control switch in the cab. When the
PTO Shifting Valve is switched to "ENGAGE" air pressure is transferred to the Air Cylinder Assembly (see
Figure 7-2, number 12). This causes the piston in the Air Cylinder (see Figure 7-3, number 4) to move to
the opposite end of the cylinder.
The Air Cylinder piston is linked to the right locking arm and the cylinder housing is linked to the left arm
(see Figure 7-2). When the piston moves in the Air Cylinder it lengthens or shortens the linkage to the
arms. When the piston moves inward and shortens the linkage, the Locking Arms (see Figure 7-2,
number 1) slide inward, away from the ladder rails, and unlock the ladder from the ladder bed. When the
piston moves outward and lengthens the linkage, the locking arms slide outward, toward the ladder rails,
and lock the ladder to the ladder bed (see Figures 7-4 and 7-5).
7.3 PARKING BRAKE OVERRIDE VALVE
The Parking Brake Override Valve is located under the dash, to the right of the Warning Light Control
Panel (see Figure 7-6). By stopping the flow of compressed air from the truck air tank to the Parking
Brake Control Valve which is operated by the yellow Parking Brake Control on the dash, the Override.
Valve prevents the release of the Parking Brake by the truck operator when the ladder is not on the ladder
bed.
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