Figure 6 illustrates the boom truss assembly.
Refer to the boom truss assembly parts list
for the hardware required. The XM520 uses
Phillystran® cable to guy the boom. The cable
is one continuous piece from one boom end
to the other. Note the Phillystran cable safety
loop that goes around the mast truss bracket.
Attach the truss bracket (91) to the mast 3 feet (1m) above the boom to
mast clamp using the 3/8" hardware provided. Position the truss bracket
on the same side of the mast as the boom to mast clamp. Unscrew the
turnbuckle ends until there is 1/2" (1.2 cm) of thread remaining. Place
the jaw of each turnbuckle (23) into the holes of the truss bracket. Place
a thimble (59) on the eye of each turnbuckle. Place three loose cable
clamps (24) onto the cable end. Reference Figure 6 and place the cable
clamp saddle over the load bearing cable. The load bearing cable is the
cable that attaches to the boom end. Feed the cable through a turnbuckle
eye. Run the cable back through the cable clamps. Place three additional
cable clamps on the end of the cable. Feed the cable through the other
turnbuckle eye. Run the cable back through the cable clamps. Feed
enough cable through these parts until the center of the Phillystran cable
coil is located at the truss bracket. Insure there is enough slack in the
cable to form a loose safety loop between the turnbuckles. Tighten the
cable clamps beginning with the clamp closest to the thimble.
Refer to Figure 1E for attachment of the cable to the boom ends. Place a thimble (59) on the 1/4-20 x 1" bolt. Place three loose cable clamps
(24) onto the cable end. Feed the cable end through the element bracket and around the thimble. Run the cable back through the cable
clamps. Tighten the cable to remove the majority of the sag from the boom. Space the cable clamps 2 inches (5.1 cm) apart. Insure the load
bearing cable is seated in the cable clamp saddle as shown above. Tighten the cable clamps beginning with the clamp closest to the thimble.
Cut off excess cable 2” (5.1 cm) after the third cable clamp.
Adjust each turnbuckle to bring each boom end level with the center. Phillystran cable has a minimal amount of stretch over time. A safety
wire can be placed through the turnbuckle openings to keep the turnbuckles from unscrewing.
40
24
59
91
207
208
209
24
24
24
24
23
207
208
209
3209
23
2”
(5.1 CM)
SAFETY
LOOP
59
35
Figure 6
ID
Part #
Description
Dimensions
Qty
40
PS40
Phillystran
1/8” x 40’
1
Cable
(.3 x 10.7m)
24 024624
Cable
1/8”
12
Clamp
(.3 cm)
23 024623
Turnbuckle
5/16”-4”
2
(.79-10.2 cm)
91 194791
Truss
2” x 42” x 1/8”
1
Bracket
(5.1 x 10.2 x .3 cm)
35 170035
Aluminum
3-1/2”
1
V-Block
(8.9 cm)
59 024259
Thimble
1/8”
4
(.3 cm)
207 010207
SS Flat
3/8”
2
Washer
(.95 cm)
208 010208
SS Lock
3/8”
2
Washer
(.95 cm)
209 010209
SS Nut
3/8”
2
(.95 cm)
3209 013209
U-Bolt
2-7/8”
1
(7.3 cm)
6 - Boom Truss Assembly
XM520
10
Bottom of saddle
Load bearing
strand lays in
bottom of saddle.
