Double-Reach Scissor Arms
4500 SRM 971
9.
Install a safety chain between the inner frame
and scissor arm weldment B so the weldment
cannot move.
Move the crane and chains or
slings so they are a support for scissor arm weld-
ment A.
10. Remove the two capscrews, lockwasher, end cap,
and two thrust washers from the top pivot point
of scissor arms 1B and 2B.
WARNING
The scissor arms are heavy and can cause an
injury if allowed to fall. Have another person
help you support the scissor arm during re-
moval and installation.
11. Install labels for correct installation of the right-
hand or left-hand scissor arms. Carefully remove
the three capscrews, the lockwashers, the end
cap, and the two thrust washers at the center
pivot for scissor arm 1B and scissor arm weld-
ment B. Make sure the crane is the support for
scissor arm weldment A so it cannot fall. Hold
scissor arm 1B and slide it off the bushing and
stub shaft of scissor arm weldment B. Remove
the bushing and the other two thrust washers at
the center pivot. Remove the bushing and the
other two thrust washers from the stub shaft at
the end of the scissor arm. Remove scissor arm
2B following this same procedure. Move scissor
arm weldment A and put it on the floor without
damaging the hose sheave mount.
12. Use the crane and chains or slings as a support
for scissor arm weldment B so it cannot fall. Do
not damage the hose sheave mount. Carefully
remove the safety chain.
WARNING
The points between the scissor arms and the in-
ner frame are pinch points and can cause an in-
jury. Do NOT put your finger in the hole when
you remove the pins. Use the brass drift to re-
move the pins.
13. Remove the shoulder bolts and pivot pins that
fasten scissor arm weldment B to the inner
frame. Move scissor arm weldment B and put it
on the floor without damaging the hose sheave
mount. Remove the bushings.
CLEAN AND INSPECT
WARNING
Cleaning solvents can be flammable and toxic
and can cause skin irritation.
Always wear
the proper protective equipment including
eye protection and petroleum resistant gloves
when handling. Always follow the recommen-
dations of the manufacturer.
CAUTION
DO NOT use steam to clean sealed bearings.
DO NOT use compressed air or immerse in sol-
vent to clean sealed bearings. Sealed bearings
self contained and permanently lubricated.
Wipe bearings off with a clean cloth and turn
to check for proper operation.
Replace if
movement is restricted or if bearing does not
turn smoothly.
Clean all of the parts of the scissor arm assembly
with solvent. Dry the parts with compressed air. In-
spect the parts of the scissor arm assembly for dam-
age and wear. Replace all bushings and load bear-
ings.
ASSEMBLE AND INSTALL
For the following procedures, refer to Figure 11.
NOTE:
Use safety chains on the inner frame and
mast weldments to keep the inner frame and mast
weldments from moving. Install the safety chains as
described in Safety Procedures When Working Near
Mast in this section.
NOTE:
Always use new bushings and load bearings.
Install a thin coat of multipurpose grease on all
new bushings, all thrust washers, all shims, all stub
shafts, and all pins of the scissor arm assembly.
WARNING
The points between the scissor arms and the in-
ner frame are pinch points and can cause an in-
jury. Do NOT put your finger in the hole when
you remove the pins. Use the brass drift to re-
move the pins.
1.
Use a crane and chains or slings as a support
for scissor arm weldment B. Do not damage the
hose sheave mount. Move the weldment into a
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