(2) Install brake return spring.
(2) Visually inspect boom for cracks, breaks,
(3) Install two brake spring rods, springs, and
or excessive wear at boom foot, point, or saddle blocks.
secure with retainers.
Inspect bumper blocks for excessive wear.
(4) Install back plate in brake drum. Make
(3) Repair boom by replacing worn bumper
sure lever (fig. 4-6) is in proper position, then secure
blocks, or welding small cracks. Report large cracks,
back plate to mechanism with flatwasher (fig. 4-9)
bends, or excessive wear beyond scope of organization
lockwasher, and capscrew.
repair to direct support maintenance.
(5) Connect hydraulic hose at coupling nut,
Note.
position clevis on lever, then secure with pin.
When shovel boom has been
returned to direct support for repair
4-10. Shovel Boom
or replacement, be sure the returned
a. Removal.
or
replacement
boom
comes
(1) Remove shovel dipper (para 4-4).
equipped with boom point sheaves,
(2) Remove dipper handle (para 4-5).
bridle bar, shipper shaft. and crowd
(3) Lower shovel boom (para 2-12b) to
and reverse mechanism.
cribbing similar to that shown in figure 4-1 and
c. Installation.
disconnect boom from crane-shovel unit (para 4-2).
(1) Install shovel boom (para 4-2).
b. Cleaning, Inspection and Repair.
(2) Install dipper handle (para 4-5).
(1) Clean shovel boom with an approved cleaning
(3) Install shovel dipper (para 4-4).
solvent and dry thoroughly.
(4) Perform preventive maintenance checks
and services (para 3-6).
Section II. CLAMSHELL, CRANE, AND DRAGLINE FRONT AND ATTACHMENTS
(3) Refer to reeving diagram of front end
4-11. General
attachment in use, disconnect boom hoist, hoist,
The clamshell, crane, and dragline front end
digging, or drag cables at dead end socket, then wind
attachments use a similar boom arrangement, which
cables on drums slowly, while guiding cable end through
consists of the base section, an upper section, and
sheaves.
which may be lengthened by insertion of boom
(4) Use wedges between cribbing at boom
section(s) (para 4-13). For crane operation, there is the
foot and boom; drive them in from each side to take
jib boom attachment that may be installed as required
weight off boom foot pins; remove cotterpins, then
remove boom foot pins (fig. 4-10).
(5) Move crane-shovel basic unit away from
operation, a fairlead and sheaves (para 4-16) is installed
boom.
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 indicator (para 4-23).
according to operation being performed, or length of
(3) Remove two pendant cables (fig. 4-10)
boom in use.
from boom point, remove cotterpins and pins, then
This section will cover organizational maintenance as
remove cables from boom spreader.
outlined in Maintenance Allocation Chart.
(4) Remove 16 nuts, lockwashers, and bolts
securing base section to upper section, or boom
4-12. Drum Cable Lagging
(extension) section (fig. 4-11).
The drum lagging for crane, clamshell, and dragline are
Note.
removed, or installed, in manner similar to that
described in paragraph 3-131.
When boom (extension) selection is
installed in boom, proceed as in step
4-13. Boom
(5) below.
a.
Removal.
(5) Remove 16 nuts, lockwashers, and bolts
(1) Disconnect boom backstop from gantry
securing boom (extension) section to upper section,
then remove boom (extension) section from upper
4-10 (2) Lower boom (para 2-12b) to rest on
section.
cribbing (fig. 2-6).
(6) Separate the two 10 foot pendant cables
4-10
