(2) Visually inspect boom for cracks, breaks,
(2) Install brake return spring.
or excessive wear at boom foot, point, or saddle blocks.
(3) Install two brake spring rods, springs, and
Inspect bumper blocks for excessive wear.
secure with retainers.
(3) Repair boom by replacing worn bumper
(4) Install back plate in brake drum. Make
blocks, or welding small cracks. Report large cracks,
sure lever (fig. 4-6) is in proper position, then secure
bends, or excessive wear beyond scope of organization
back plate to mechanism with flatwasher (fig. 4-9)
repair to direct support maintenance.
lockwasher, and capscrew.
Note.
(5) Connect hydraulic hose at coupling nut,
When shovel boom has been
position clevis on lever, then secure pin.
returned to direct support for repair
or replacement, be sure the returned
4-10. Shovel Boom
or
replacement
boom
comes
equipped with boom point sheaves,
a. Removal.
bridle bar, shipper shaft, and crowd
(1) Remove shovel dipper (para 4-1).
and reverse mechanism.
(2) Remove dipper handle (para 4-5).
c. Installation.
(3) Lower shovel boom (para 2-12b) to
(1) Install shovel boom (para 42).
cribbing similar to that shown in figure 4-1 and
(2) Install dipper handle (para 4-5).
disconnect boom from crane-shovel unit (para 4-2).
(3) Install shovel dipper (para 4-4).
b. Cleaning, Inspection and Repair.
(4) Perform preventive maintenance checks
(1) Clean shovel boom with an approved
and services (para 3-6).
cleaning solvent and dry thoroughly.
Section II. CLAMSHELL, CRANE, AND DRAGLINE FRONT END ATTACHMENTS
digging, or drag cables at dead end socket, then wind
4-11. General
cables on drums slowly, while guiding cable end through
The clamshell, crane, and dragline front end
sheaves.
attachments use a similar boom arrangement, which
consists of the base section, an upper section, and
(4) Use wedges between cribbing at boom
which may be lengthened by insertion of boom
foot and boom; drive them in from each side to take
section(s) (para 4-13). For crane operation, there is the
weight off boom foot pins; remove cotterpins, then
jib boom attachment that may be installed as required
remove boom foot pins (fig. 4-10).
(5) Move crane-shovel basic unit away from
boom.
operation, a fairlead and sheaves (para 4-16) is installed
at revolving frame. All of these attachments use the
b. Disassembly and Reassembly.
boom backstop (para 4-22), radius (boom angle)
(1) Remove two cotter pins (fig. 4-10) and
indicator (para 4-23) and boom harness spreader (para
pin, then remove boom backstop. Disassemble boom
backstop (para 4-20).
cables (table 1-2), although size and lengths differ
(2) Remove radius (boom angle) indicator
according to operation being performed, or length of
boom in use. This section will cover organizational
(3) Remove two pendant cables (fig. 4-10)
maintenance as outlined in Maintenance Allocation
from boom point, remove cotterpins and pins, then
Chart.
remove cables from boom spreader.
412. Drum Cable Lagging
(4) Remove 16 nuts, lockwashers, and bolts
securing base section to upper section, or boom
The drum lagging for crane, clamshell, and dragline are
(extension) section (fig. 4-11).
removed or installed, in manner similar to that described
in paragraph 3124.
Note.
When boom (extension) section is
4-13. Boom
installed in boom, proceed as in step
(5) below.
a. Removal.
(1) Disconnect boom backstop from gantry
(5) Remove 16 nuts, lockwashers, and bolts
securing boom (extension) section to upper section,
then remove boom (extension) section from upper
(2) Lower boom (para 2-12b) to rest on
section.
cribbing (fig. 2-6).
(3) Refer to reeving diagram of front end
attachment in use, disconnect boom hoist, hoist,
4-10
