National Crane Published 10-30-2014 Control # 040-09 2-29
1400H OPERATOR AND SERVICE MANUAL OPERATING CONTROLS
JIB JACK
Operation
The jib pin alignment device consists of a hydraulic jack
mounted horizontally on the underside of the jib. A handle for
the jack is provided and is installed above the jack on the
side of the jib.
The purpose of the jib pin alignment device is to aid in
installing the fourth or “last” jib pin when setting up a jib. This
device has been designed to line up the bottom jib pin hole
on the left side of the crane.
To use the device, follow the proper procedure outlined
in the Owner's Manual to install both jib pins on the right side
of crane and the top pin on the left side. Next remove jack
handle and using the flattened end, close jack release valve
by turning handle clockwise until it is firmly closed. Insert the
round end of the handle into the handle sleeve and pump
jack until ram contacts boom sheave case. Continue to pump
slowly until jib pin hole is exactly aligned with hole in boom
ear. At this time the final jib pin can be easily tapped into
position.
If hole alignment is “over shot” due to jacking too far, the
jack can simply be relieved and the process repeated. To
relieve the jack, use the flattened end of jack handle to slowly
turn relief valve counter clockwise no more than one full turn.
After all jib pins are installed, relieve jack. The jib pin
alignment device is also useful when removing the “fourth”
pin. Use the jib jack to relieve jib weight induced pressure on
the “fourth” pin and it will be much easier to remove.
Once the jib has been erected or stowed, it is important
that the jack handle be properly placed back on its stowage
hooks and that the cotter key be properly placed in the
stowage hook to retain the handle on the hook.
Important: Avoid “shock loads” created by quickly
opening and closing the release while jack is under load.
This may result in overloading of the hydraulic circuit
and possible damage to the jack.
When jib is stowed on side of crane, always leave ram
and handle sleeve pushed all the way down to reduce
exposure to rusting.
To Next Page
Loading...
