Operation Manual73
Preventive Maintenance
Boom Emergency Lower Down Valve
Both of the lift and extend cylinders are equipped with a
needle valve which allows the cylinder to retract without the
direct assist of the machine’s hydraulic power. This feature is
intended to be used only in the event of total loss of engine or
hydraulic pump failure with an elevated boom.
In any event, the vehicle should be secured until the situation
has been properly evaluated. Secure the vehicle and area by
following the procedures below:
1. Clear the area around the vehicle of all personnel.
2. Place the shift lever in NEUTRAL and engage the parking
brake switch to the ON position.
3. Section o a large area under the boom with tape to
restrict any personnel from entering this potentially
dangerous area.
4. If the load is in a position where it can be removed safely,
completely remove the load from the carriage and/or
attachment. Otherwise leave the load in place.
5. Remove boom access cover on back of boom.
Fig 91. Boom Access Cover
Fig 93. Lift Cylinder Lower Down Valve
Warning
Keep ngers and feet away from moving
parts or pinch points to prevent pinching or
crushing. Failure to do so can result in death
or serious injury.
6. Locate the needle valves on extend cylinders. Loosen nut
on valve, then loosen valve with hex wrench (repeat for
both sides).
7. Fully lower boom with control handle in cab.
8. When boom is fully retracted, tighten valve with hex
wrench, then tighten nut to secure valve. Repeat for both
cylinders.
Fig 92. Extend Cylinder Lower Down Valve (Boom Access Cover Removed)
9. Locate needle valves on lift cylinders. Loosen nut on
valve, then loosen valve with hex wrench (repeat for both
sides).
10. Fully lower boom with control handle in cab.
11. When boom is fully lowered, tighten valve with hex
wrench, then tighten nut to secure valve (repeat for both
sides).
12. Install boom access cover.
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