Operation Manual
64
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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 off 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 80. Boom Access Cover
Fig 81. Extend Cylinder Lower Down Valve
Warning
Keep fingers 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.
Fig 82. Extend/Retract Section of Proportional Valve
6. Locate needle valve on extend cylinder. Loosen nut on
valve, then loosen valve with hex wrench.
7. Thread a 125mm long M8-1.25 cap screw into the
manual operator of the extend/retract section on the
proportional control valve (the second (2) section from
boom side, on top of the valve) and use it to manually
operate the valve to retract the boom.
8. When boom is fully retracted, tighten valve with hex
wrench, then tighten nut to secure valve
9. Locate needle valve on lift cylinder. Loosen nut on valve,
then loosen valve with hex wrench.