Elliott Digger Derrick, Operation & Maintenance Manual, Page: 214 / 376

Four Section Boom Operation-common EEC-0021 V1.3
Four Section Boom Operation
position of the section can be used. It is often difficult to pry the very most inner
sections over.
B. Extended boom straightness is critical in proper boom operation. The extended
boom straightness required is a deviation of .50 inch (13mm) or less from the
theoretical centerline of the boom. A stringline from the center of the winch to the
middle of the sheavecase on the last section will provide a theoretical centerline.
The top rear pads should be adjusted accordingly to provide proper clearances to
achieve a straight extended boom.
C. Assemble the top/rear wear pads and plates. The top/rear wear pads on this boom
are adjustable to account for lateral tolerances that occur during the manufacturing
process of the boom sections.
D. The wear pad on each side at the top/rear of the boom can be adjusted over a range
of 3/16 inch (4.8mm) by rotating, end for end, the wear pad and plate or the wear
pads and plate independently. This is possible because the holes in these parts are
offset from the center. The holes are .06 inch (1.6mm) off center in the plate and .03
inch (.8mm) off center in the wear pad. Various combinations of rotation of these
parts allow the adjustment.
Once the boom is located, the wear pad and plate combinations can be inserted into the
space between the boom sections and aligned over the holes in the sections. If the
holes in the plate are not centered over the holes in the sections, the wear pads and
plates have to be removed and adjusted either towards or away from the side plate of
the next larger section until the holes will align. When properly aligned the wear pad
should be tight against the side plate of the out boom section and the extended boom
should be straight to previously mentioned specifications.